Secondary metabolites from newtonia paucijuga and erythrina sacleuxii and bioactivities of their extracts
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Date
2018-09
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Publisher
University of Dar es salaam
Abstract
The phytochemical investigations reported in this dissertation aimed at establishing
the chemical constituents, antiplasmodial and antimicrobial activities of the two
plants from the family Fabaceae, viz. Newtonia paucijuga and Erythrina sacleuxii.
The crude extracts were subjected to chromatographic separation to afford the pure
compounds. The antiplasmodial activities were evaluated using malaria imaging
assay method, while the antimicrobial activities were carried out by disc diffusion
and broth microdilution methods. Mearnsetin-3-O-a-L-rhamnopyranoside (2.26),
benzyl-3,4,5-trihydroxylbenzoate (2.28) and, the mixture of stigmasterol (2.37a) and
P-sitosterol (2.37b) were isolated from the ethanolic extracts of leaves, root and stem
barks of N. paucijuga, respectively. Chromatographic isolation of ethanolic extracts
of the E. sacleuxii leaves yielded a new wor-sesquiterpenoid namely, sacleuxenone
(2.38). The structure elucidation of the compounds was based on the ID and 2D
NMR, IR and Mass spectral data. The extracts from the leaves, stem and root barks
of N. paucijuga and leaves of E. sacleuxii exhibited moderate antibacterial activities
with activity index value ranging from 0.3 - 0.5 against Staphylococcus aureus,
Pseudomonas aeruginosa and Klebsiella pneumonia. The most potent were the
leaves and stem bark extracts of N. paucijuga (Al = 0.5). The minimum inhibitory
concentrations (MIC) for the active extracts ranged from 0.3 - 5.0 mg/mL against S.
aureus, P. aeruginosa, K. pneumonia and B. subtilis. All the extracts were active
against B. subtilis with MIC value of 0.3 mg/mL. No any activities were observed
against all the fungal species tested. On the other hand, all extracts exhibited
antiplasmodial activity against Plasmodium falciparum (3D7 strain) with an IC5o
value ranging from 2.6 - 24.6 jig/mL with selectivity index (SI) against human
embryonic kidney 293 cell lines ranging from 6.5 - 21.0. The most potent
antiplasmodial was Newtonia paucijuga root barks extract (NPRE) (IC50 = 2.6; SI =
6.5). Most extracts were safe against HEK 293 cell lines at the concentration of 40
pg/mL. Pure compound were not assayed for their antiplasmodial and antimicrobial
activities due to insufficient amount. The study indicated that ethanolic crude
extracts from N. paucijuga and E. sacleuxii have antibacterial and antiplasmodial
activities and are recommended for further investigations.
Description
A Dissertation Submitted in Partial Fulfilment of the Requirements for the
Degree of Master of Science with Education
Keywords
Secondary metabolites, newtonia paucijuga, Erythrina sacleuxii, Bioactivities