Abstract
Ph.D. (Chemistry)
Alchornea species (Euphorbiaceae) have been used in traditional medicine across Africa and are
well known to display broad spectrum biological activities including anti‐microbial, antiinflammatory
and anti‐cancer activities.
This project is aimed at discovering bioactive compounds for anti‐microbial and anti‐cancer
therapy from plants of the Alchornea species and developing suitable nanocarrier drug delivery
systems (DDS) as drug or compound transporters using gold nanoparticles and natural
polymers.
The plant material (roots, stems and leaves) was collected in bulk from an uncultivated
farmland of the Elounden Mount, in the Yaoundé central region of Cameroon. The extracts
were prepared using solvents of varying polarity in order to extract a wide range of
phytochemicals. The extracts of A. cordifolia, A. floribunda and A. laxiflora as well as those
isolated compounds that were sufficiently pure, were screened for antibacterial activity against
four Gram‐positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus and
S. saprophyticus) and four Gram‐negative bacteria (Escherichia coli, Klebsiella pneumonia,
Moraxella catarrhalis and Proteus mirabilis), as well as antimycobacterial activity
(Mycobacterium aurum and M. smegmatis). The anti‐cancer properties were similarly tested
against SNO oesophageal cancer, breast cancer (MDA‐MB‐231 and MCF‐7), and leukemia HL‐60
cell lines. The antimicrobial activities were evaluated using the micro‐dilution assay while the
anticancer activity was evaluated by means of cell viability (MTT assay, Alamar blue, trypan blue
and an ATP assays). The isolation of compounds and synthesis of derivatives were performed by
exhaustive chromatographic techniques and suitable organic reactions. The structures of the
compounds were determined by means of spectroscopic methods (FT‐IR, MS, 1D and 2D NMR).
Three compounds (AC3.1, AC2.4 and 3HB) were used to synthesize DDS and were characterized
using UV‐Vis, FT‐IR, TEM, SEM, XRD, EDS, DLS and zeta potential.