Department of Chemistry and Physics

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A HPLC-MS/MS method for screening of selected antibiotic adulterants in herbal drugs
(The Royal Society of Chemistry, 2022) Mwankuna Christopher Johnson; Uwamaliya Grâce Ange; Mariki Eliapenda Elisante; Mabiki Faith; Malebo Hamisi M.; Mdegela Robinson; Styrishaveb Bjarne
The use of herbal products adulterated with conventional drugs increases the risk of developing microbial resistance and causes herb-to-drug interaction, leading to severe clinical consequences. The complex nature of herbal products has been a challenge for the unambiguous identification of adulterants. The improved analytical selectivity and sensitivity of hyphenated techniques such as high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) enable the confirmatory screening of adulterants in herbal products. Simultaneous screening of adulterants is necessary and efficient because it has been established that more than one chemical adulterant may be present in one herbal product. An HPLC-MS/MS method for the simultaneous detection and quantification of amoxicillin, ampicillin, metronidazole, ciprofloxacin, sulfamethoxazole, and trimethoprim in powdered herbal drugs was developed. Deuterated metronidazole-d3, trimethoprim-d3, ciprofloxacin-d8, and sulfamethoxazole-d4 were used as internal standards (ISs). For each analyte, two transitions were monitored using protonated molecules as precursor ions. The extraction of analytes from herbal products was performed using a simple methanol : water : formic acid (90 : 10 : 0.05, v/v) extraction solvent. Chromatographic separation was done in a gradient of 0.01% formic acid in methanol and 0.01% formic acid in MilliQ water. The calibration curves were linear (r2 $ 0.996) over the range of 0.005–2.5 mg mL 1 for all compounds except metronidazole, whose range was 0.005–1 mg mL 1. The limit of detection (LOD) ranged from 0.012 to 0.046 mg mL 1, while the limit of quantification (LOQ) ranged from 0.066 to 0.153 mg mL 1. The accuracy, expressed as the recovery of spiked herbal products, ranged from 45% to 114%. The precision, expressed as relative standard deviation (RSD) at two concentration levels, ranged from 1.6% to 15.9%. The matrix effect expressed as the matrix factor (MF) ranged from 0.79 to 0.92. The developed method was applied to powder herbal products purchased in Tanzania. Amoxicillin, ampicillin, trimethoprim, sulfamethoxazole, and ciprofloxacin were not detected in all samples. Metronidazole was detected in eight samples with the highest concentration of 1.38 mg g 1. The developed method is suitable for the detection of all the studied antibiotic adulterants in herbal products. Quantification can be performed for all the compounds except ciprofloxacin due to its lower recovery.
A new ellagic acid rhamnoside and other biologically active compounds from roots and stems of Synadenium Glaucescens pax
(Sokoine University of Agriculture, 2023-05) Rwegoshora Frank
Medicinal plants have been used as a source of drugs and drug templates. The extracts of Synadenium glaucescens Pax (SG) from roots and stems contain bioactive secondary metabolites against bacterial and viral infections. However, majority of its pure compounds were uncharacterized and their phytochemical profiles in different phytogeographical regions were unknown. Therefore, this study aimed at characterization of more compounds which are promising drug leads. Furthermore, the study investigated the phytochemical profiles of SG from three regions of Tanzania. Samples of SG were collected from Njombe, Morogoro and Tanga regions as representatives of three phytogeographical zones of Tanzania. All sample were dried in a cold and dark room between 15 to 18 oC at the Tanzania Tree Seed Agency-Morogoro. Samples were pulverized using a laboratory milling machine (Christy Hunt Engineering Ltd, England) to afford approximately 1 mm particles’ size. The isolation of pure compounds involved root barks and stem barks of SG from Njombe. Phytochemical profiling involved five parts (root barks, root wood, stem barks, stem wood and leaves). Sample extraction was done by total maceration using either methanol or ethanol. Fractionation of the crude extracts was done through vacuum Liquid chromatography in solvent gradient systems from Hexane, ethyl acetate/ dichloromethane and finally methanol/ ethanol. Concentration of extracts was done using rotary evaporator at <60 oC. Isolation of pure compounds was done by column chromatography in a solvent gradient system. A single spot on the thin layer chromatography plate in both treatments was an indicator for a pure compound. Structures of compounds were elucidated through (1D and 2D) of a 600 MHz Bruker Avance III HD nuclear magnetic resonance (NMR) machine. Confirmation of structures involved LC/GCMS, FTMS-ESI, NIST library and in comparison, to the literature. The SciFinder database was used for reference of a new compound. The processing NMR spectral data was performed using Bruker TopSpin 3.6.2 while compound structures were drawn in ChemDraw Professional 16.0. Biological activities involved cytotoxicity and antibacterial tests of pure compounds. Cytotoxicity studies were done using Brine shrimp assay involving Artemia salina cysts which were hatched and used within 24 hours of incubation. The varying concentrations (2400- ȝJ PO LQ P/ RI % v/v DMSO were employed in duplicate. 7KH FRPSRXQGV¶ concentration killing 50 % of the nauplii larvae was determined. An In vitro antibacterial efficacy of pure compounds was done by using microtitre plate assay. Four standard strains of bacteria were used (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC51559, Escherichia coli ATCC25922 and Pseudomonas aeruginosa ATCC 27853. The activities of the compounds were evaluated using the observed MIC values. Determination of the phytochemical profiles on the thin layer FKURPDWRJUDSK\ SODWHV XVHG DQ RSWLPDO ȝ/ YROXPH RI mg/mL. The number of compounds were recorded at 254nm, 365nm of an ultraviolet lamp and after colour reaction. Data from the thin layer chromatography were analysed in JMP statistical software. A total of fifteen (15) compounds were isolated and elucidated. A new ellagic acid rhamnoside 3',4'-di-O- methylellagic acid-4-Į-L-rhamnopyranoside, 28 mg (32) was isolated as greyish powder. it showed high res. FTMS-ESI- of 476.0921 and melting point of 251.0~ 252.7 oC. Other known phenolics 3,4,3'-tri-O-methylellagic acid, 14 mg (33), hemicosanylferulate,65 mg (34) and octacosylferulate, 19 mg (35) were also isolated. The study also led to isolation of two hydrocarbons from the root barks: 1-nonacosene, 11 mg (38), and hexacosane,173 mg (39) and one fatty acid from the stem barks; hexacosanoic acid, 26 mg (40). The isolated triterpenoids include Lupeol, 65 mg (18) from the stem barks, euphol, 1855.5 mg (28) from both roots and stem barks, epifriedelanol, 167 mg (36) from both roots and stem barks and a steroid ȕ-sitosterol 64 mg (30) from the root barks. Cytotoxicity tests indicated that all the tested compounds were non-toxic (LC50 ! ȝJ P/) up to a maximum tested FRQFHQWUDWLRQ RI ȝJ P/ Octacosylferulate demonstrated strong activity against S. aureus (MIC= 0.125 mg/mL) Phytochemical screening by TLC indicated a significant variation in concentration and distribution of compounds in SG among the three regions (p< 0.0001). Njombe registered the highest number of compounds (mean= 12.4000) while Morogoro had the least of all (mean= 9.7000). Euphol, a triterpenoid in root barks was detected to be at the highest concentration in Tanga and the lowest in Morogoro. Derivatives of ellagic acid were detected in root barks at all ages and locations. The results also indicated continuous disappearance of red fluorescing compounds in stems barks and leaves as the plant age increased. The number of compounds increased with age while the optimal age for a maximum number of phytochemicals was 3 to 4.5 years. Furthermore, the stem barks registered the highest number of phytochemicals (>15). A new compound: 3',4'-di-O-methylellagic acid-4-Į-L- rhamnopyranoside along with 14 other known compounds were isolated from root and stem barks of SG. The isolated compounds during this study represent six major groups of secondary metabolites of pharmacological importance which are Phenolics, triterpenoids, steroids, long chain hydrocarbons, long chain amine and Fatty acids. This new compound is suggested to serve as a marker for standardization and quality control of any formulation from the root barks of S. glaucescens Pax.
Activity of sterols isolated from the leaves of commiphora swynnertonii (Burtt) against some nosocomial infectious bacteria
(The Journal of Phytopharmacology, 2022-09-04) Credo, David; Mabiki, Faith P.; Machumi, Francis; Chacha, Musa; Cornett, Claus
Commiphora swynnertonii (Burtt) is traditionally used for medicinal purposes both in humans and animals in Tanzania. Previously, its leaves extract has been demonstrated antibacterial activity. However, there is limited information on identification of pure compounds responsible for its observed antibacterial activity. Therefore, this study was conducted to isolate and evaluate antibacterial activity of pure compounds isolated from its leaves extract. Colum chromatographic separation of its dichloromethane leaves extract afforded the isolation of two sterols namely, Cholest-7-en-3β-ol (1) and β-sitosterol (2). Their structures were deduced by using NMR data experimentally obtained and comparison with spectral data available in literatures. The sterols were evaluated for activity against four nosocomial infectious bacteria namely; Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa to determine Minimum Inhibitory Concentrations (MIC) by broth microdilution method. Cholest-7-en-3β-ol (1) demonstrated strong activity against S. aureus (MIC= 0.5 mg/ml) and weak activities (MIC >2mg/ml) against other bacteria. β-sitosterol (2) exhibited weak activities (MIC >2mg/ml) against all tested bacteria. Therefore, presence of antibacterial active compound(s) such as Cholest-7-en-3β-ol (1) among others in the leaves of C. swynnertonii can justify its earlier reported antibacterial activity and further confirms the claimed traditional uses of this plant in the treatment of bacterial infections.
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture, 2023) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, v and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 µg mL–1 for all compounds except metronidazole, whose range was 0.005–1 µg mL–1 . The limit of detection ranged from 0.012 to 0.046 µg mL–1 while the limit of quantification ranged from 0.066 to 0.153 µg mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 µg g–1 . Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 µg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, v and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 µg mL–1 for all compounds except metronidazole, whose range was 0.005–1 µg mL–1 . The limit of detection ranged from 0.012 to 0.046 µg mL–1 while the limit of quantification ranged from 0.066 to 0.153 µg mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 µg g–1 . Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 µg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1 . Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine.
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture (SUA), 2023-05) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products
Analytical methods for screening and determination of conventional drugs adulterated in herbal products
(Sokoine University of Agriculture, 2023-05) Mwankuna Christopher Johnson
Herbal products are popular worldwide. Their popularity is threatened by untrustworthy manufacturers who add conventional drugs. The addition of conventional drugs increases the risk of developing antimicrobial resistance and herb-drug interactions. To safeguard the users and enhance the safety of herbal products, analytical methods for screening and determining conventional drugs adulterated in herbal products are required. Therefore, this study was carried out to develop analytical methods and apply them in screening and determination of antibiotic, antimalarial, pain killer and erectile dysfunction adulterants in herbal products. Thin layer chromatography methods for screening twelve conventional drugs in herbal products were developed and applied. The analytes were extracted from herbal products using a solvent mixture of acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). The mobile phase consisting of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol and sulfamethoxazole. Pyrimethamine, metronidazole and sulfadoxine were well separated by dichloromethane:ethyl acetate:methanol (77.5:12.5:10, v/v). In addition, acetyl salicylic acid, ibuprofen, diclofenac, quinine and lumefantrine were well separated by ethyl acetate:methanol:30% ammonia (75:22.5:2.5, v/v). Chromatographic separations were highly reproducible and more than 10 samples were analysed in one run. The developed methods were used to screen 229 herbal products. Consequently, 24.0% of the samples contained one adulterant while 21.4% contained at least two adulterants. A high performance liquid chromatography–tandem mass spectrometry method was developed and used for screening and determining six conventional antibiotics (amoxicillin, ampicillin, metronidazole, trimethoprim, sulfamethoxazole, and ciprofloxacin) in herbal products. The developed method had linear (r2 ≥ 0.996) calibration curves over the range of 0.005–2.5 μg mL–1 for all compounds except metronidazole, whose range was 0.005–1 μg mL–1. The limit of detection ranged from 0.012 to 0.046 μg mL–1 while the limit of quantification ranged from 0.066 to 0.153 μg mL–1. Accuracy, expressed as recovery of spiked herbal products ranged from 45% to 114%. The precision expressed as relative standard deviation at two concentration levels ranged from 1.6% to 15.9%. The matrix effect, expressed as matrix factor ranged from 0.79 to 0.92. The developed method was used to analyse 78 herbal products purchased from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Metronidazole was detected in eight samples with the highest concentration of 1.38 μg g–1. Another high performance liquid chromatography–tandem mass spectrometry method was developed and used to screen and determine eleven conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products. The developed method had linear (r2 ≥ 0.991) calibration curves over the range of 0.001–0.3 μg mL–1 for all compounds. The limit of detection ranged from 0.002 to 0.02 g mL–1 while the limit of quantification ranged from 0.006 to 0.08 g mL–1. Accuracy, expressed as recovery of spiked herbal products ranged from 52% to 128%. The precision, expressed as percent relative standard deviation at two concentration levels, ranged from 1.0% to 13.8%. The matrix effect, expressed as the matrix factor ranged from 0.77 to 0.97. The developed method was used to analyse 50 herbal product samples from Njombe, Morogoro, Manyara, Arusha, Mwanza and Dar es Salaam in Tanzania. Ten of the herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. The developed thin layer chromatography and high performance liquid chromatography–tandem mass spectrometry methods are considered valuable tools for a better understanding of the adulteration of herbal products by addition of conventional drugs. The thin layer chromatography methods can be used for preliminary screening of herbal products prior to confirmation by other techniques such as high performance liquid chromatography–tandem mass spectrometry. On the other hand, confirmation and quantification of the selected antibiotic and antimalarial adulterants in herbal products can be achieved using the developed high performance liquid chromatography–tandem mass spectrometry methods.
Antibacterial and antifungal properties of silver nanoparticles synthesised using phytochemicals from zanthoxylum piperitum Leaves
(Tanzania Journal of Agricultural Sciences, 2023) Mwakalesi, A.J; M.J. Nyangi
Silver nanoparticles (AgNPs) have recently emerged as a potential treatment for diseases caused by multidrug-resistant microorganisms. The high surface area-to-volume ratio of AgNPs could deliver high performance as an antimicrobial agent. The current study investigated the synthesis and antimicrobial properties of AgNPs fabricated using phytochemicals extracted from Zanthoxylum piperitum leaves (Japanese pepper).
Antibacterial effects of single and combined crude extracts of synadenium glaucescens and commiphora swynnertonii
(2022) Ochollah, G, Mary; Olsen, E, John; Mdegela, H, Robinson; Kusiluka, J.M, Lughano; Mabiki, P, Faith; Msengwa, S, Zaituni
Background: Synadenium glaucescens and Commiphora swynnertonii are among the reported plants used traditionally for treatment of bacterial infections. This study reports antibacterial effects of single and combined extracts from leaves, stem and root barks of Commiphora swynnertonii and Synadenium glaucescens. Materials and Methods: Plants were collected from Manyara and Njombe regions in Tanzania. Extraction was done using dichloromethane and methanol. The extracts were assessed for antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa). Minimum Inhibitory Concentrations (MIC) was determined by broth microdilution, while Fractional Inhibitory Concentration (FIC) indices were calculated from MIC values of combined extracts to determine combination effects. Results: Strong antibacterial activities were demonstrated by all extracts of S. glaucescens (MIC 0.011-0.375mg/mL) against Gram-positive bacteria and methanol extracts of C. swynnertonii (MIC 0.047-0.375mg/mL). Synergistic effect was observed when combining methanol extracts of C. swynnertonii stem bark with S. glaucescens leaves against S. aureus (∑FIC 0.5), Other synergistic effects were observed against E. faecalis with dichloromethane extracts of C. swynnertonii stem bark and S. glaucescens stem bark (∑FIC 0.5), and C. swynnertonii root bark and S. glaucescens root bark (FIC index 0.3). For the remaining combinations, mainly additive effects were observed. Conclusion: Synergistic effects on bacteria were observed by combining different plant parts of S. glaucescens and C. swynnertonii suggesting that it could be beneficial to combine such extracts when used for antibacterial purposes.
Assessing significance of community documented climate impacts and adaptation preferences and options in the lake victoria region, Tanzania
(Ethiopian Journal of Environmental Studies & Management, 2017-02-13) Elisante, E.; Tungaraza, C.
The study was conducted in Ukerewe Island in the Lake Victoria, Tanzania in order to ascertain the communities’ awareness on climate change impacts and adaptation/coping strategies. The methodology involved randomly selected 420 people mostly farmers and fishermen who were interviewed and involved in focus groups. It was observed that communities were aware of the changes in climatic parameters consequently impacting their livelihood. The most significant impacts were scarcity of water and poor crop production which received 100% support of the respondents. Other impacts included the change of water quality of the Lake Victoria (94.5%) and loss of biodiversity (35.7%). On the non-climatic factors, the major concern was on population growth (98.3%), loss of soil fertility (96%) and deforestation (84.8%). Of the suggested adaption options, provision of alternative food crops and fertility improvement to increase production were highly supported with highest total score of 48 on an arbitrary total assessment scale of maximum of 50. This was also observed on fish farming activities. The observations highlighted gender-based labour division imbalance where women and children were shown to shoulder the burden. It can be concluded that communities in the Lake Victoria region are affected by multiple impacts related to climate and also those not related to climate. Under various impacts communities set their own coping and adaptation strategies based on importance to livelihood. However, there is a need for proper guidance on how adaptation strategies are being executed.
Assessment of sources and transformation of nitrate in groundwater on the slopes of Mount Meru, Tanzania
(Springer, 2015-09-21) Elisante, Eliapenda; Muzuka, Alfred N. N.
The stable isotope compositions of nitrogen-nitrate ( 15 N-NO 3 ) and oxygen-nitrate ( 18 O-NO 3 ), and concentration of nutrients (NO 3 - , NH 4 ? , NO 2 - , PO 43- ) for water samples collected from springs, shallow wells and boreholes during dry and wet seasons were used to inves- tigate sources and biogeochemical transformation of NO 3 - in groundwater along the slopes of Mount Meru. About 80 % of all water sources had nitrate concentration higher than background concentration of 10 mg/l during both seasons, while NH 4 ? and NO 2 - concentrations were very low probably due to nitrification. Concentrations of NO 3 - above 50 mg/l were observed in some water sources. Concentrations of PO 43- in all groundwater sources were very low during the two seasons owing to dilution and adsorption. The d 15 N-NO 3 - for boreholes waters averaged ?11.6 ± 2.1 and ?10.7 ± 2.1 % during dry and wet seasons, respectively. Similarly, the d 18 O-NO 3 - of bore- hole waters for the wet and dry seasons averaged ?5.2 ± 1.3 and ?4.6 ± 1.9 %, respectively. With regard to dug wells, the d 15 N-NO 3 - of well water averaged ?13.3 ± 2.5 and ?12.5 ± 2.3 % during dry and wet seasons, respectively, while the d 18 O-NO 3 - for the wet and dry seasons averaged ?7 ± 2.3 and ?6.4 ± 2.1 %, respectively. The d 15 N-NO 3 - , for springs averaged ?11.2 ± 2.2 % during dry season and ?11.7 ± 3.5 % during wet season whereas the d 18 O-NO 3 - for the wet and dry seasons averaged ?7.3 ± 3.6 and ?5.9 ± 2.6 %, respectively. The isotopic data suggested that the source of NO 3 - in the water sources are dominated by sewage and/or animal manure and to less extent, soil organic N. Few samples collected in close proximity of manure heaps and sanitary facilities had d 15 N values between 16 and 20 %suggesting occurrence of denitrification.
Bacteriostatic and haemolytic activities of extracts and compounds of commiphora swynnertonii
(Research Journal of Pharmacognosy, 2023) Msengwa, Zaituni; Credo, David; Mafuru, Magesa; Mwesongo, James; Mabiki, Faith Philemon; Mwang’onde, Beda John; Mtambo, Madundo Mkumbukwa; Kusiluka, Lughano Jeremy; Mdegela, Robinson Hammerthon; Olsen, John Elmerdahl
Background and objective: Commiphora swynnertonii (Pax) is used in traditional medicine to treat infectious diseases. Previous studies have reported antimicrobial activity of this plant; however, the activity of compounds that are present in extracts of this plant has not been thoroughly documented. Likewise, the primary mode of action (bactericidal or bacteriostatic) and the possible toxicity on red blood cells have not been reported. Methods: Extracts of leaves, whole root, root bark, root wood, whole stem, stem bark and stem wood, were produced using hexane, dichloromethane, methanol and water. Cold and hot extraction methods were employed. Antibacterial activity of extracts was tested against selected medically important Gram-positive and Gram-negative bacteria by growth inhibition, minimum inhibitory concentrations and time kill assays. Moreover, haemolytic activity against sheep red blood cells was determined in vitro. Results: The hexane extracts of whole root and root bark, methanol extracts of root wood, and dichloromethane extracts from the leaves of C. swynnertonii inhibited the growth of S. aureus. MIC values for the extracts and compounds, indicated moderate activity against Gram-positive bacteria (Staphylococcus aureus, Streptococci species and Enterococci species) while the activity against Gram-negative bacteria (Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Salmonella species, Shigella sonnei and Yersinia enterocolitica) was weak. Time kill profiles showed the extracts have bacteriostatic activity against S. aureus, and low haemolytic effect, except for extracts of whole root and leaves at the concentration of 1000 μg/mL. Conclusion: Extracts of C. swynnertonii showed bacteriostatic activity against Gram-positive bacteria with low toxicity on red blood cells.
Base catalytic properties of organoamino-silica hybrids prepared using cashew nut shell liquid components as templates
(University of Dar es Salaam, 2011) Msigala, Sijaona Cassian
This work was aimed at finding the catalytic efficiency of organoamino-silica hybrids prepared over some components of cashew nut shell liquid (CNSL) as templates. Cardanol and anacardic acid as major components of CNSL, were screened for their efficiency as templates in synthesizing the hybrids. The hybrids were prepared by one-pot co-condensation of three classes of organoaminesilanes and tetraethoxysilane at two different loading ratios, namely 1:4 and 1:9. The results showed that anacardic acid and cardanol formed about 9.2% and 66.3% yields, respectively. Consequently most hybrids were therefore prepared using cardanol. A few hybrids were also prepared using a mixture of cardanol and dodecylamine, the later being a previously established template. The prepared hybrids were characterized by using HC1 acid titration technique, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Atomic Force Microscopy (AFM). Results indicated that the organic group loading ranged between 0.5 to 2.3 mmol per gram of silica, depending on the loading ratio, type of template and nature of the organoaminesilane. On the other hand, DRIFTS results revealed that the organoaminesilyl groups were successfully incorporated in the silica matrix for each category of the template used. Furthermore, by using AFM the grain size average for cardanol templated hybrids were found to be about 0.25 pm wide and those of the co-templated hybrids were about 0.4 pm wide with irregular shapes. The hybrids were tested for catalytic activity in a model Henry reaction, in particular a reaction between benzaldehyde and excess nitroethane. Results showed that 81% to 98% of benzaldahyde could be converted into product within 3 h showing that the prepared hybrids are suitable catalysts for the model reaction.
Chitosan enriched with ZnO–nanoparticles fabricated using Synadenium glaucescens (Pax) aqueous leaf extract maintains postharvest quality of banana
(Applied Food Research, 2024-09) Alinanuswe Joel Mwakalesi; Tlehema Gwandu Umbayda
Applications of edible coatings containing metallic nanoparticles for the preservation of post-harvest fruit quality have emerged as one of the most preferable strategies because of their enhanced antimicrobial properties. In the current study, zinc oxide nanoparticles were synthesized using Synadenium glaucescens leaf extract and added to chitosan for the post-harvest quality preservation of banana. The synthesized zinc oxide nanoparticles (ZnO- SydlNPs) were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental dispersive x-ray (EDX) and X-ray diffraction (XRD) techniques. The nanoparticles were found to form large particles due to aggregations of small particles of an average size of 11 ± 4 nm. The coating so- lution containing a mixture of chitosan and zinc oxide nanoparticles exhibited higher antimicrobial effects against Escherichia coli, Staphylococcus aureus, Puccinia asparagi and Candida albicans compared to chitosan. The inhibition diameters of chitosan and chitosan-ZnOSydlNPs against E. coli were 6 and 15 mm, respectively. Similarly, the average inhibition diameters of chitosan, chitosan-ZnOSydlNPs (0.1%) and chitosan-ZnOSydlNPs (0.3%) against Staphylococcus aureus, Puccinia asparagi and Candida albicans were 10 ± 2, 15 ± 0.5 and 16 ± 3 mm, respectively. The banana coated with chitosan-ZnOSydlNPs solutions exhibited higher titratable acid (maleic) than control and chitosan-coated samples. Additionally, banana coated with chitosan-ZnOSydlNPs lms showed lower total soluble solids, weight loss and ripening index compared to chitosan-coated and control samples. The ndings from the current study indicated that ZnOSydlNPs incorporated in polymeric materials (chitosan) could serve as a potential preservative of post-harvest qualities for banana and related fruits.
Colorimetric sensing of mercury in aqueous solutions using silver nanoparticles prepared from synadenium glaucescens root aqueous extract
(MDPI, 2023-03) Alinanuswe J. Mwakalesi; Magori J. Nyangi
Mercury contamination from various anthropogenic activities has been a recent global problem. Thus, developing cheap and efﬁcient techniques for sensing mercury is signiﬁcant for protecting humans and other organisms. The sensing of mercury using silver nanoparticles fabricated using phytochemicals extracted from Synadenium glaucescens roots (SYR) is reported. The successful synthesis of silver nanoparticles (SYR-AgNPs) was conﬁrmed by a strong plasmon resonance in the UV-Vis spectrum at 420 nm due to oscillations of electrons in the silver nanoparticles. The potential use of fabricated silver nanoparticles for the sensing of mercury ions from aqueous solutions was investigated. The prepared silver nanoparticles displayed a high selectivity for detecting mercury against other divalent metal ions (Hg2+ , Ba2+ , Ca2+ , Co2+ , Cu2+ , Fe2+ , Mg2+ , Ni2+ , and Pb2+ ). The addition of mercury changed the SYR-AgNPs’ color to colorless, and the observed change in color was proportional to mercury concentration. The application of silver nanoparticles for the sensing of mercury displayed a detection limit of 11.3 µM. Therefore, the ﬁndings in the current study indicate that the prepared SYR-AgNPs can serve as a potentially sensitive and selective readily available method for sensing mercury ions in environmental samples. The method can be useful in advancing the application of green technology for sensing heavy metals from environmental samples.
Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments
(nstitute of Oceanology PAS, 2005-08-16) Tungaraza, Clavery; Brion, Natacha; Baeyens, Willy
This paper compares two uptake rate models, Dugdale & Goering’s (D&G) model and Elskens’ model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea) from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens’ model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f -ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.
Contamination and health risk assessment of heavy metals in selected highly edible fish species from lake Nyasa, Tanzania
(Springer, 2023-04) Mwambene, Bupoki; Mwakalesi, Alinanuswe J.; Nehemia, Alex Nahnson
Heavy metal contamination emanating from increased industrial and anthropogenic activities poses considerable environmen- tal risks to water resources, aquatic biodiversity, and human health. These metals are major sources of various unfavorable environmental changes and human health hazards. This research investigated the potential contamination level and health risk assessment of heavy metals (Fe, Zn, Ni, Cu and Cr) in five highly edible fishes (O. microlepis, C. gariepinus, O.niloticus, R. moorii,B. meridionalis) from Lake Nyasa. The results indicated that gills contained higher amounts of heavy metals compared to muscles. The levels of Fe and Zn were higher in the gills of C. gariepinus and O.niloticus than O. microlepis, R. moorii, and B. meridionalis. Similarly, amounts of Cu and Cr were higher in the gills of C. gariepinus and O. microlepis. The general trend of heavy metal concentrations accumulated in selected fish species was Fe > Zn > Ni > Cu > Cr. The amounts of heavy metals found in the fish samples were within acceptable limits set by FAO and WHO. Furthermore, the risk assessments indicated that the current exposure levels are unlikely to cause serious health risks. However, the progressive monitoring of levels of heavy metals in various aquatic organisms from Lake Nyasa is important for the continued protection of human health against hazardous health effects.
Corrosion inhibition of Amino Pentadecylphenols (APPs) derived from Cashew Nut shell liquid on mild steel in Acidic medium
(Scientific Research Publishing Inc., 2016-08) Philip, Joseph Yoeza Naimani; Buchweshaija, Joseph; Mwakalesi, Alinanuswe J.
In this study, corrosion inhibiting properties of amino pentadecylphenols (APPs) derived from Cashew Nut Shell Liquid (CNSL) on mild steel in aerated 0.10 M HCl at 303 K were studied using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements. Both methods indicated the potential of a mixture of amino pentadecyphenols to serve as a corro- sion inhibitor in mild steel in 0.10 M HCl. Corrosion inhibition efficiencies were observed to in- crease with increase in the inhibitor concentration, with maximum corrosion inhibition of about 98% at inhibitor concentration of 600 ppm. The adsorption of the inhibitor on mild steel surface was found to obey Temkin adsorption isotherm, signifying physical adsorption of the inhibitor molecules on mild steel surface.
Corrosion inhibition of mild steel in sulphuric acid solution with tetradenia riparia leaves aqueous extract: kinetics and thermodynamics
(ResearchGate, 2022-01-23) Mwakalesi, Alinanuswe J.
One of the most successful ways for maximizing profit and lowering costs is to use mild steel over other corrosion-resistant alloys. As a result, mild steel is the most commonly used metallic material in many industries, and its corrosion resistance has received a lot of attention. The mild steel corrosion inhibition using compounds derived from plants is the most practicable and preferable technique because of their linked low cost and green chemistry credentials. This study reports on the kinetics and thermodynamics of mild steel corrosion inhibition in sulphuric acid media utilizing Tetradenia riparia leaves aqueous extract as a potential green inhibitor. The investigations were carried out using the gasometric technique. The findings indicated that the corrosion inhibition efficiency (IE) increased with increasing inhibitor concentration with an optimal value of 90.6% at 500-ppm. The increase in temperature 298 to 338 K lowered the corrosion inhibition efficiency by only 4%. The adsorption kinetics of the extract on the mild steel fit into Langmuir, Temkin, EL-awady, and Freundlich models, but the Langmuir was the best. The results of this investigation show that adsorption of the extracted chemicals on mild steel in a sulphuric acid solution is feasible and most likely involves a combination of physical and chemical adsorption.
Cytotoxic activity of shorea macrophylla root fractions against HeLa and MCF-7 cells: LC–MS profiling and CDK2-targeted molecular docking
(Chemical Methodologies, 2026-04) Theint Su Wai; Nanik Siti Aminah; Muhammad Ikhlas Abdjan; Salar Hafez- Ghoran; Abdullahi Musa; Rico Ramadhan
Natural products remain an important source of anticancer drug leads. Shorea macrophylla (Dipterocarpaceae), a tropical tree with limited reported bioactivity, has not been systematically evaluated for the cytotoxic potential of its roots. In this study, the root was extracted with methanol and partitioned into n-hexane, ethyl acetate, and methanol residue fractions. The chemical composition of these fractions was characterized by LC-MS, and their cytotoxic activities were assessed against HeLa (cervical) and MCF-7 (breast) cancer cell lines using a resazurin assay. The major constituents of the most active fraction were further investigated by molecular docking against cyclin-dependent kinase (CDK) to explore potential mechanisms of action. LC-MS analysis revealed polarity-dependent differences in composition: the n-hexane fraction was enriched in lipophilic terpenoids and flavonoid aglycones (predominantly quercetin and kaempferol), the ethyl acetate fraction contained moderately polar phenolics, flavonoids, and oligostilbenes, and the methanol fraction was dominated by polar flavonoid glycosides. Consistent with these findings, the n-hexane fraction exhibited the strongest cytotoxicity against HeLa cells (IC50 = 3.95 µg/mL), followed by ethyl acetate (IC50 = 80.94 µg/mL); while the methanol fraction was inactive (IC50 > 500 µg/mL). All fractions exhibited weak activity against MCF-7 cells (IC50 = 183.20–447.80 µg/mL). Molecular docking indicated favourable binding of quercetin and kaempferol within the ATP-binding pocket of CDK, with binding energies of –56.18 and –52.56 kcal/mol, respectively. These results demonstrate a polarity-dependent cytotoxic profile and suggest that lipophilic flavonoids contribute to the observed activity, highlighting Shorea macrophylla root as a promising source of bioactive compounds.
Dependence of air quality on meteorological parameters in Dar es Salaam, Tanzania
(Tanzania Journal of Natural and Applied Sciences, 2010) Mkoma, Stelyus L.; Kimambo, Offoro N.; Mabiki, Faith P.; Tungaraza, Clavery T.
The influence of meteorology on air quality in Dar es Salaam was investigated. Precipitation, temperature, relative humidity and wind speed were measured during wet and dry seasons of 2005 and 2006 period and their relationship with reported mass of particles of aerodynamic diameter smaller than 10 μm (PM10) for the site was assessed. Results indicate that the highest median concentrations for the PM10 mass (58 μg/m 3 ) was observed during the 2005 dry season and the lowest median (40 μg/m 3 ) during the 2006 wet season. It is interpreted that reasons for the higher levels of the PM10 mass in the dry season are due to temperature inversions, soil dust dispersal and absence of rain wash-down. The observed PM10 levels are also affected by the variations in sources strengths and in meteorological conditions such as mixing height, precipitation, relative humidity, wind speed and direction as supported by air mass trajectories.

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