Articles, Conference and Workshop Papers Collection

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Antimicrobial silver nanoparticles derived from Synadenium glaucescens exhibit significant ecotoxicological impact in waste stabilization ponds
(Springer, 2024-08) Alinanuswe J. Mwakalesi; Douglas Mushi
In recent years, there has been an exponential increase in the production of silver bionanoparticles due to their widespread commercialization and technological applications. However, there is limited understanding of the impact of silver bionano- particles on biological agents commonly used in wastewater treatment, particularly in waste stabilization ponds (WSPs). This study aimed to synthesize new silver nanoparticles (sg-AgNPs) from Synadenium glaucescens root using an environmen- tally friendly method and optimized biosynthesis parameters, and evaluate their antimicrobial activity and ecotoxicological impact on WSPs using standardized approaches. The average primary sizes of the sg-AgNPs in the five samples were not significantly different (P > 0.05), indicating the effectiveness of the eco-friendly method and the importance of optimal biosynthesis conditions. Analysis from UV–Vis spectroscopy, energy-dispersive spectroscopy (EDX), transmission electron microscope (TEM), and X-ray diffraction (XRD) confirmed that sg-AgNPs exhibited typical characteristics of green silver nanoparticles. Furthermore, sg-AgNPs showed strong antimicrobial activity (MIC, 0.012–0.094 mg/ml) against gram-positive bacteria (Escherichia coli), gram-negative bacteria (Staphylococcus aureus), non-filamentous fungi (Candida albicans) and filamentous fungi (Aspergillus niger). While the Synadenium glaucescens root proved to be a valuable precursor for produc- ing effective antimicrobial sg-AgNPs, the introduction of sg-AgNPs into WSPs significantly impacted algal chlorophyll-a production and survival of ostracod population. These results shed light on the ecotoxicological risks of sg-AgNPs for WSPs organisms and highlight the suitability of algae and ostracods as model organisms for ecotoxicological studies in WSPs.
Adsorption kinetics of picloram on chitosan‑modified Strychnos pungens fruit shell activated carbon
(Springer, 2025-09) Liberatus J. Mpaka; Alinanuswe J. Mwakalesi
Activated carbon (AC) fabricated using Strychnos pungens fruit shells (biowaste) and encapsulated in a chitosan biopolymer (CHO) was applied for the removal of picloram from aqueous solutions. The synthesized activated carbon-chitosan beads (ACCHO) were characterized using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Infrared spectroscopy (IR) and Emmett Teller (BET) surface area analysis. The findings demonstrated the successful encapsulation of AC to produce ACCHO with both crystalline and amorphous properties. The application of ACCHO for picloram removal was affected by solution pH, adsorbent dosage, and initial picloram concentration. The efficiency increased with adsorbent dosage, reaching an optimum at 40 g/L. Similarly, efficiency increased as pH increased from 2 to 6, but declined at pH 8. Optimal conditions of pH 6, 40 g/L ACCHO dosage and 50 mg/L picloram produced 88% removal efficiency. The picloram adsorption kinet- ics best fitted the pseudo-first order (PFO) model. Langmuir and Freundlich adsorp- tion isotherms provide a good description of the picloram adsorption process. The adsorption mechanism on ACCHO was postulated to involve multiple interactions caused by electrostatic and weak forces of attraction. The results of the current study suggest that ACCHO can be used as a potential adsorbent for removing picloram and similar chemicals from contaminated water.
Commiphora swynnertonii-derived silver nanoparticles significantly enhance the selectivity of the medium for isolating fungal species
(Springer, 2026-02) Celina Ntibigwahake; Alinanuswe Mwakalesi; Eliapenda Elisante Mariki; Douglas Mushi
Silver nanoparticles (Ag-NPs) were synthesized using an eco-friendly and economically feasible procedure from the root bark of the medicinal plant Commiphora swynnertonii, with optimized physicochemical variables in the reaction medium. The formation of Ag-NPs was visually monitored by a color change in the reaction mixture and confirmed by various analyses, including UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The synthesized Ag-NPs were tested for their antimicrobial properties and applied to enhance the detection and selective isolation of fungal species on potato dextrose agar (PDA). The optimal synthesis conditions for Ag-NPs were found to be at 60 °C, pH 9, 0.004 M AgNO₃, 40 mL of C. swynnertonii root bark extract, and a reaction time of 10 min. Under these conditions, the Ag-NPs exhibited a maximum absorption peak at 413 nm, spherical shapes, and an average size of 40 ± 15 nm. EDX analysis confirmed the presence of a substantial amount of silver in the synthesized nanoparticles, while FT-IR analysis identified functional groups on their surfaces derived from the root bark of C. swynnertonii. The Ag-NPs demonstrated enhanced antimicrobial activity against Gram-positive and Gram-negative bacteria (MIC, 0.058 mg/mL) compared to filamentous and non-filamentous fungi (MIC, 0.116 mg/mL). PDA without Ag-NPs supported bacterial and fungal growth, whereas PDA with Ag-NPs completely inhibited bacterial outgrowth while permitting fungal outgrowth. This study underscores the potential of C. swynnertonii root bark extract for synthesizing antimicrobial Ag-NPs with applications in controlling pathogenic bacteria and improving the detection sensitivity and selectivity of fungal growth media, particularly PDA.
In vitro evaluation of antiproliferative and cytotoxic effects of Annona stenophylla (Engl. & Diels), Strophanthus petersianus (Klotzsch), and Synadenium glaucescens (Pax) extracts against MCF-7 breast cancer and Vero cell lines
(Elsevier, 2026-06) Roberto Nhamussua; Mohammed Ibrahim; Alinanuswe Mwakalesi; Faith Mabiki; Lyndy McGaw
Breast cancer remains a major global health burden, underscoring the development of safer and more effective anticancer agents. Medicinal plants represent an important source of bioactive metabolites with potential se- lective cytotoxicity. This study evaluated the antiproliferative activity and selectivity of extracts from Annona stenophylla, Strophanthus petersianus, and Synadenium glaucescens against the MCF-7 breast cancer and the Vero cell lines, with doxorubicin used as a positive control. Root, stem and leaf extracts were obtained through sequential solvent extraction, and cytotoxic activity was assessed using the MTT assay. IC50 values were deter- mined to quantify cytotoxicity. Statistical differences among treatments were determined using Tukey’s HSD post hoc test, and the selectivity index was determined to compare the relative cytotoxicity between cancerous and non-cancerous cell lines. The RSPE (root ethyl acetate extract of S. petersianus) exhibited the highest anti- proliferative activity against MCF-7 cells (IC50 = 0.12 μg/mL; p < 0.05), while other extracts from the same plant produced IC50 values of up to 12.61 μg/mL. In contrast, substantially higher IC50 values were observed in Vero cells (1.73 to 265.81 μg/mL; p < 0.05), resulting in a high selectivity index of 31.33, 28.40 and 21.08 for SSPM, SSPE and LSPE (stem methanol, stem ethyl acetate and leaf ethyl acetate extracts S. petersianus), respectively. A. stenophylla extracts exhibited variable cytotoxicity against MCF-7 (IC50: 3.14 to 37.96 μg/mL; p < 0.05) and Vero (5.36 to 42.33 μg/mL), yielding moderate selectivity (1 70 μg/mL), with only SWSGE (stem wood ethyl acetate of S. glaucescens) exhibiting a statistically signicant effect at tested concentrations of 3.90, 31.30, 15.60 and 125 μg/mL (p < 0.05), but not at 1.90, 31.30 and 62.50 μg/mL. In contrast, the other extracts showed no signicant difference relative to the control group (p > 0.05) and poor selectivity. Doxorubicin (positive control) exhibited an IC50 value of 0.30 μg/mL in MCF-7 and 53.69 μg/mL in Vero cells, corresponding to an SI of 178.97. S. petersianus demonstrated potent and selective antiproliferative activity against MCF-7 cells, highlighting it as a source for anticancer agents. Further mechanistic and phytochemical investigations are warranted.
KOH-activated carbon from Aframomum angustifolium fruit shells for caﬀeine removal from aqueous solution
(Springer, 2025-12) Baraka Alfaksad Kasazi; Alinanuswe Joel Mwakalesi; Emmy Solomon Lema
This study reports on the preparation of activated carbon using Aframomum angustifolium fruit shells (FPAA) and its application for the removal of caffeine from aqueous solution. The activated carbon was prepared using KOH activation in a 1:2 ratio, followed by pyrolysis at 500 °C for 1 h. The activated carbon (AC-K) was characterized using the point of zero charge of potential of hydrogen (pHpzc), N2 adsorption–desorption analysis, scanning electron microscopy–energy-dis- persive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The surface of AC-K exhibited a mesoporous structure with an increased BET surface area from 335 to 407.6 m2/g. The classical method and response surface methodology (RSM) using Box–Bohnken design (BBD) were used to optimize the performance of AC-K to remove caeine from aqueous solutions. The results indicated that the adsorption aligned best with the Langmuir model (R2 = 0.996 and RMSE = 0.3531), indicating the formation of a monolayer film. In addition, the adsorption was described by the pseudo-second-order model (R2 = 0.995 and RMSE = 0.017). The highest caffeine removal eciencies were 78.67 and 90.40% as determined using classical and BBD methods, respectively. Therefore, the prepara- tion and use of an eco-friendly and previously unexplored precursor for activated carbon preparation is demonstrated in the current study. This study contributes to sustainable waste valorization while oering a promising alternative material for the removal of emerging contaminants such as caffeine from water systems.
Green synthesis and characterization of silver nanoparticles from aqueous extract of harrisonia abyssinica fruits
(MDPI - Engineering Proceedings, 2025-03) Alinanuswe J. Mwakalesi; Emmy S. Lema
The synthesis of silver nanoparticles using phytochemical reducing agents is the most preferred technique because of its low cost and environmental friendliness. Conse- quently, there are several reports published on the synthesis of silver nanoparticles using extracts from leaves, barks, roots, and fruit peels. However, information on the use of fruit extracts for the synthesis of silver nanoparticles is limited. Thus, the green synthesis of sil- ver nanoparticles (HAF-AgNPs) using phytochemicals extracted from Harrisonia abyssinica fruit (HAF) is reported in the current study. The silver nanoparticles were synthesized through chemical precipitation and characterized using UV-Vis spectrophotometry, trans- mission electron microscopy (TEM), energy-dispersive X-ray (EDX), and X-ray diffraction analysis (XRD). The ﬁndings showed that fabricated HAF-AgNPs were crystalline and spherical, and exhibited a strong UV-absorption band at 420 nm. The appearance of a peak at 3 keV in the EDX spectrum indicated metallic silver atoms in the fabricated nanoparticles. The fabricated nanoparticles exhibited antibacterial activity against Gram-positive (Staphy- lococcus aureus) and Gram-negative (Escherichia coli) bacterial strains. The antibacterial activity was stronger for Staphylococcus aureus (MIC = 5 µg/mL) compared to Escherichia coli (MIC = 10 µg/mL). The preliminary ﬁndings from the current study suggest that the nanoparticles prepared from the extract could serve as a potential antibacterial agent against Gram-positive and Gram-negative bacteria.
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.
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).
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.
Unexpected heroes: invasive macrophytes boost performance of faltering waste stabilization ponds
(Water Practice & Technology, 2026) Liberatus J. Mpaka; Alinanuswe J. Mwakalesi; Douglas Mushi
Waste stabilization ponds (WSPs) are a widely used technology for removing organic matter and pathogens from wastewater. However, their effectiveness is often hindered by hydraulic overload, sludge accumulation, and the proliferation of invasive macrophytes–the impacts of these challenges are not fully understood. In this study, standard methods were used to assess WSPs under these operational challenges for the removal efﬁciency of physical, nutrient, and organic pollutants, as well as faecal indicator bacteria (FIB); the extent of macrophyte occupancy; and the level of FIB colonizing invasive macrophyte − 3− roots. Results indicated high removal efﬁciencies (73.38–99.67%) for turbidity, total nitrogen, NO− 3 , NO2 , NH3, PO4 , BOD5, total coliforms, Escherichia coli, enterococci, and Clostridium perfringens, whereas total dissolved solids, electrical conductivity, and total phosphorus showed considerably lower removal (33.5–45.2%). Signiﬁcant correlations (r = 0.47–0.96, P < 0.05) were found between the removal efﬁciencies of physical, nutrient, and organic pollutants, as well as FIB, and macrophyte occupancy. Furthermore, high densities of FIB colonizing the macrophyte roots suggest that these roots may have positively contributed to the performance of the WSPs. The ﬁnal efﬂuent complied with East African standards for all pollutants except turbidity, BOD5, and FIB. This study reveals that ignoring WSP maintenance signiﬁcantly compromises treatment performance, with potential implications for public health, and underscores the role of macrophytes in enhancing the performance of faltering WSPs.
Efficient and reusable activated carbon from aframomum angustifolium fruits’ shells for removal of ceftriaxone from aqueous solution: adsorption isotherms, kinetics, and thermodynamics studies
(Indonesian Journal of Chemistry, 2025-11) Baraka Alfaksad Kasazi; Alinanuswe Joel Mwakalesi; Emmy Solomon Lema
The accumulation of ceftriaxone antibiotics in aquatic systems is a growing global concern due to their potential risks to human and ecological health. The current study investigates the synthesis, characterization, and application of activated carbon (AC-FPAA-H3PO4) made from the shells of Aframomum angustifolium fruits. AC- FPAA-H3PO4 was synthesized using chemical activation (H3PO4, 4 M) followed by pyrolysis at 600 °C for 1 h and characterized using BET, FTIR, and SEM-EDX. AC-FPAA-H3PO4 exhibited a surface area of 1895.6 m2/g, which allowed for its reuse in 5 consecutive cycles without requiring active site regeneration. The optimal removal efficiency (97.8%) was achieved at pH 2, 298.15 K, 100 rpm, 20 g/L adsorbent dosage, and 200 mg/L ceftriaxone concentration. The adsorption process was described by Langmuir (R2 = 0.9862) and Freundlich (R2 = 0.9833) isotherms, and the kinetics were fitted to the pseudo-second- order model. The adsorption was spontaneous (ΔG = −6.80 kJ/mol) and exothermic (ΔH = −4.43 kJ/mol), with increased randomness at the solid-solution interface (ΔS = 7.69 J/mol K). The adsorbent demonstrated high efficiency in removing ceftriaxone from real water samples, including river water (99.36%) and well water (96.92%). The findings suggest AC-FPAA-H3PO4 is a promising adsorbent for removing ceftriaxone from an aqueous environment.
Effects of phosphoric acid concentration on properties of activated carbon from Strychnos spinose fruit shells
(Nature, 2026) John Chagu; Alinanuswe Joel Mwakalesi
The accumulation of agricultural wastes in the environment is an emerging challenge. Their thermochemical conversion to activated carbon represents an efficient form of utilization that minimizes the secondary pollution caused by conventional treatment methods, such as incineration and landfilling. This study reports the synthesis and characterization of activated carbon from an affordable, abundant, and underutilized source of Strychnos spinosa fruit shells. The activated carbon was prepared through chemical activation using phosphoric acid of different concentrations (30%, 60%, 100%, and 150%), followed by physical activation at 500 °C for 4 h. The influence of the activating agent concentrations on the properties of activated carbon, such as yield, moisture content, ash content and iodine number, was studied. Additionally, X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller and Infrared spectroscopy techniques were used to study characteristics of activated carbon. The results showed that the yield of activated carbon increased from 25.33% to 29.2% as the concentration of phosphoric acid increased from 30% to 150%. The increased acid concentration also increased the moisture content, ash content and iodine number of the activated carbon. The highest iodine number of 999 mg/g was obtained for the activated carbon with the surface area of 507.373 m²/g impregnated with 150% phosphoric acid. Similarly, the SEM images revealed larger pore sizes for activated carbon produced using 150% phosphoric acid compared to those produced using 30%, 60% and 100% phosphoric acid. The findings demonstrate that phosphoric acid concentration influences the properties and performance of the Strychnos spinosa fruit shell activated carbon.
Screening anticancer activity by Brine shrimp lethality test of extracts of Annona stenophylla (Engl. & Diels), Strophanthus petersianus (Klotzsch) and Synadenium glaucescens (Pax)
(PLOS One, 2026-01) Roberto Luis Nhamussua; Faith Philemone Mabiki; Alinanuswe Joel Mwakalesi; Lyndy Joy McGaw
Cancer continues to be one of the main public health challenges, driving the search for new compounds with therapeutic potential. Medicinal plants represent a valuable promising source of bioactive metabolites, and the Brine Shrimp Lethality Test has been widely used as a preliminary tool to assess the toxicity of natural extracts, pro- viding clues to their possible anticancer activity. In this study, the cytotoxicity of the extracts of Annona stenophylla (Engl. & Diels), Strophanthus petersianus (Klotzsch), and Synadenium glaucescens (Pax) was investigated using the BSLT as a first step in screening for potential anticancer compounds. The plant materials were harvested in Tanzania and air-dried in the shade, and ground. The extracts were prepared by total sequential solvent extraction using cold maceration, starting with ethyl ace- tate, followed by methanol.
Synergistic effect of macadamia nut oil and Chitosan coatings on physicochemical characteristics of tomatoes during storage
(John Wiley & Sons Ltd, 2025-10) Tlehema Gwandu Umbayda; Anthony Daniel Funga; Alinanuswe Joel Mwakalesi
A signicant portion o globally produced ruits are lost between the armer and consumer, necessitating solutions like natural edible coatings or preservation due to their low cost and less toxicity. Tis study aimed to assess whether the combination o macadamia nut oil and chitosan posed synergistic eects on physicochemical properties o tomato ruits or the macadamia nut oil alone. A completely randomized design (CRD) with eight treatments was employed: S1 (control), S2–S4 (combined macadamia nut oil and chitosan coating), S5–S7 (macadamia nut oil coating), and S8 (chitosan). Te experimental setup was conducted over 20 days at rerigeration (4°C) and postharvest shed conditions (23.8°C–30°C, 65.8%–97.5% RH). Te coating solution made up o a combination o 2.5% v/v macadamia nut oil and 1% w/v chitosan showed signicant dierences (p ≤ 0.05) in slowing down the changes in pH rom 3.95 to 4.3, total chlorophyll content rom 0.19 mg/100 to 0.12 mg/100 mL, and lipid peroxidation rom 13.5 to 19.71 meq/kg. Moreover, coating solutions made by macadamia nut oil alone, especially with 1% v/v, showed the smallest increases in total soluble solids (SS) and total sugar content, and also they exhibited the smallest decreases in titratable acidity (0.64 to 0.08 g/L), ripening index (5.78 to 84.74), total carotenoids (17.02 to 24.585 μg/g), and rmness (355 N to 130 N). Comparative analysis indicated that 1% v/v macadamia nut oil had higher mean dierences (p < 0.05) or most physicochemical parameters than coating solutions comprising 2.5% v/v macadamia nut oil and 1% w/v chitosan. However, this nding highlighted that the combination o macadamia nut oil with chitosan oers a synergistic eect on specic crucial parameters (pH, total chlorophyll content, and lipid peroxidation) compared to macadamia nut oil alone. Further studies could investigate the an- timicrobial eect o tomatoes treated with a combination o macadamia nut oil and chitosan.
Unveiling the hidden risks: heavy metal concentrations in soil and vegetables irrigated with Kalobe wastewater stabilization ponds, Mbeya, Tanzania
(Journal of Food Protection, 2025-10) Azaria Stephano Lameck; Dickson Mlelwa; John Chagu; Victor Sanga; Melkizedeck Hiiti Tsere; Gisandu K. Malunguja; Alinanuswe Joel Mwakalesi
This study evaluated the concentrations of heavy metals in wastewater, soil, and tomatoes and Napa cabbage irrigated with efuent from the Kalobe Wastewater Stabilization Pond (KWWSP) in Mbeya, Tanzania. Human health risks were assessed using Chronic Daily Intake (CDI), Target Hazard Quotient (THQ), Hazard Index (HI), and Target Cancer Risk (TCR) indices. The results showed that cadmium (Cd) in all ponds was below the FAO/ WHO permissible limits, while lead (Pb) and chromium (Cr) were below detection levels. Heavy metals in soil were found in the order of Pb (5.95 mg/kg) > Cr (0.63 mg/kg) > Cd (0.25 mg/kg), all within FAO/WHO acceptable limits, indicating suitability for agricultural use. Cd levels in Tomatoes (0.14 mg/kg) and Napa cab- bage (0.40 mg/kg) exceeded permissible limits. Cr levels in the Tomato and Napa Cabbage were 1.87 and 2.10 mg/kg, respectively, and were close to the safety threshold, suggesting health concerns with long-term consumption. Cd exposure through vegetable intake was within but near acceptable limits, while Cr exposure, particularly for Napa cabbage, exceeded recommended safety thresholds. This resulted in elevated noncarcino- genic risks (THQ and HI > 1) and carcinogenic risks (TCR above the USEPA’s acceptable range). These ndings suggest that consuming wastewater-irrigated Tomatoes and Napa cabbage may pose human health risks. Continuous monitoring of heavy metals, safe irrigation alternatives, and cropping restrictions using inade- quately treated wastewater is essential to safeguard public health and long-term environmental sustainability.
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.
Novel edible coating based on Macadamia Nut oil and chitosan to maintain the antioxidant and physical properties of tomato fruits
(Applied Food Research, 2024-06) Tlehema Gwandu Umbayda; Anthony Daniel Funga; Alinanuswe Joel Mwakalesi
Innovative approaches for extending the shelf life of tomatoes are required due to increased postharvest losses of climacteric-fruits. The use of edible coatings is recently considered as a promising approach due to their non- toxicity and affordability properties. The coatings form physical barriers that alter the internal atmosphere of the fruit and slow down a ripening process. The inuence of an edible coating comprising of chitosan and macadamia nut oil on the antioxidant and physical properties of tomato fruits is reported. The antioxidant and physical qualities of tomato fruits were investigated using different coating solutions. Various concentrations of macadamia nut oil, ranging from 1 % to 2.5 %, were used as independent coating solutions. Additionally, another set of coating solutions was prepared by mixing macadamia nut oil in the same concentration range (1 % to 2.5 %) with 1 % w/v chitosan. The tomatoes were dipped into the coating solutions and stored under a post- harvest shed (23.8–30 ◦ C, 65.8–97.5 % RH) for 20 days to monitor total phenolic content, total avonoid con- tent, ascorbic acid content, color, percentage weight loss, decay percentage, and shelf life after every 5-days interval. The results showed a signicant difference (P < 0.05) between coated and uncoated tomato samples. The coated tomatoes showed the signicant retention of total avonoid content, total phenolic content, hue angle and red-green (a*) compared to uncoated tomatoes. On contrast, the decrease of decay, weight loss, the lightness (L), blue-yellow (b*), chroma, and ascorbic acid content was lower for coated compared to control tomatoes. The ndings indicated that 1 % macadamia nut oil exhibited the highest retention of antioxidant and physical properties, and lowest decrease in ascorbic acid content from 0.014 mg/100 g on the 5th day to 0.0096 mg/100 g on the 20th day was observed. Thus, the ndings from this study suggest that the macadamia nuts can serve as a cheap and low-cost source of edible oil suitable for prolonging the shelf life of tomatoes and related fruits.
Thin layer chromatographic method for detection of conventional drug adulterants in herbal products
(MDPI, 2022-12-31) Mwankuna Christopher Johnson; Mariki Eliapenda Elisante; Malebo Hamisi Masanja; Styrishave Bjarne; Mdegela Robinson Hammerton
Commercially available conventional drugs have been used to adulterate herbal products. Considering the rapid growth of herbal products’ market, it is essential to screen herbal products for the presence of conventional drugs. Simple analytical methods are needed for the rapid screening of conventional drugs that are likely to be adulterated in herbal products. Thin layer chromatography (TLC) methods for screening twelve conventional drugs in herbal products have been developed and applied. The analytes were extracted from herbal products using acetonitrile:methanol:acetic acid:water (4:4:1:1, v/v). Solvent mixture of dichloromethane:ethyl acetate:methanol (75:15:10, v/v) separated well trimethoprim, sildenafil, paracetamol, and sulfamethoxazole while 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 found to be highly reproducible, and more than 10 samples can be analysed in one run. The method was applied in the screening of 229 herbal products. Consequently, 24.0% of the samples contained one adulterant, while 21.4% contained at least two adulterants. All conventional drugs detected in herbal products were not mentioned on the labels and therefore the consumers are kept unaware of their side effects and health problems. Further studies for confirming and quantitatively determining the adulterants in a wide range of products as well as a systematic toxicological analysis of the adulterants in herbal products are recommended.
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.
Optimization of HPLC–MS/MS method for determination of antimalarial adulterants in herbal products
(SPRINGER, 2023-01-12) Mwankuna Christopher J.; Kiros Feven; Mariki Eliapenda E.; Mabiki Faith P.; Malebo Hamisi M.; Mdegela Robinson H.; Styrishave Bjarne
The use of herbal products is booming all over the world because of being believed as safer than conventional drugs and free of side effects. However, there are untrustworthy manufacturers who adulterate herbal products by adding conventional drugs which might eventually lead to microbial resistance and herb-to-drug interactions. There is a need to develop methods for detecting adulterants in herbal products. A high performance liquid chromatography-tandem mass spectrometry (HPLC– MS/MS) method for simultaneous identification and determination of conventional antimalarials (chloroquine, quinine, sulfadoxine, pyrimethamine, mefloquine, lumefantrine, amodiaquine, artemisinin, dihydroartemisinin, artesunate and artemether) in herbal products was developed. Stable isotopically labelled compounds (artemether-d3, quindine-d3, and sulfadoxine-d3) were used as internal standards (ISs) for quantitative analysis. Extraction of analytes was performed using methanol: water: formic acid (90:10:0.1, v/v) and chromatographic separation was done in a gradient mode using mobile phase A: Ultrapure water containing 0.1% formic acid and 1 mM ammonium formate and mobile phase B: Acetonitrile/ methanol (50:50) containing 0.1% formic acid and 1 mM ammonium formate. The calibration curves were linear (r2 ≥ 0.991) over the range of 0.001–0.3 μg mL−1 for all compounds. The limit of detection (LOD) ranged from 0.002 to 0.02 μg mL−1 while the limit of quantification (LOQ) ranged from 0.006 to 0.08 μg mL−1. Accuracy, expressed as recovery of spiked herbal products ranged from 52 to 128%. The precision, expressed as percent relative standard deviation (%RSD) at two concentration levels, ranged from 1.0 to 13.8%. The matrix effect expressed as the matrix factor (MF) ranged from 0.77 to 0.97. The developed method was used to identify and quantify conventional antimalarials in herbal product samples from Tanzania. Ten out of 50 herbal products were found to contain amodiaquine, sulfadoxine, pyrimethamine, mefloquine, dihydroartemisinin, artemether and lumefantrine. The developed method is considered a valuable tool for getting a better understanding of the adulteration of conventional antimalarials in herbal products.

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