Abstract:
Chromatographic separation of ethyl acetate extract from Embelia schimperi berries led to
isolation of embelin 2,5-dihydroxy-3-undecyl- 1,4-benzoquinone(1). Embelin was identified on
the basis of physical and spectroscopic data. Three quantities of compound 1 weighing 0.02g
each were used to synthesize three derivatives by addition of sulphonyl, acetyl and alkyl imino
groups to the parent compound’s structure. The synthesized compounds were identified as 2,5-
dihydroxy-5-sulpho-3-undecyl-1,4-benzoquinone (2), 1,2,4,5 tetra acetoxy-3-undecyl benzene
(3) and 2,5-dihydroxy-1-di-ethyl imino-3-undecyl-4- benzoquinone (4) on the basis of MS and
FTIR spectroscopic data. Embelin and its synthetic derivatives were tested against clinical strains
of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Candida albicans.
Plate titration technique was used; and presence or absence of microbial growth after respective
incubation periods used to determine antimicrobial activity. The incubation period for
antibacterial test was 24 hours and 48 hours for antifungal test respectively. Compound 1 and 4
were found to be active against S. aureus (gram positive bacteria) at dilutions of 100 ppm and
200 ppm respectively while compounds 2 and 3 were inactive. Compounds 1, 2, 3 and 4 were inactive against P. aeruginosa, E. coli (gram negative bacteria) and C. albicans (fungi) at all
dilutions. The inactivity of embelin and its synthetic derivatives could possibly be attributed to
inability of compounds to penetrate through the cell walls of P.aeruginosa, E.coli (gram negative
bacteria) and C. albicans (a fungus). Retention of activity against S. aureus in compound 4 is an
indication that effect of functional groups on properties of parent compound should be
considered prior to derivatization. Addition of certain functional groups may affect compounds
properties such as solubility, polarity and stability which determine the uptake and metabolism of
a drug in the target organism.
