Flabelliferins, steroidal saponins from palmyrah (Borassus Flabellifer L.) fruit pulp 11. Preliminary investigations of effect on yeast and selected bacteria

Abstract

The isolation and partial characterization of four naturally occurring steroiclal saponins (flabelliferins) differing in their carbohydrate moiety and isolated from palmyrah fruit pulp was reported previously. These were called flabelliferin F-II (a tetraglycoside), flabelliferin F B and F C (triglycosides) and flabelliferin F D (a diglycoside). On testing for bioactivity, F-II, the bitter saponin (250 ug ml -1) inhibited yeast (Saccharomycca cerevisiae S11-F 3) growth to the extent of 50 - 75% while F B (60μg ml -1) inhibited growth completely. F C and F D were inactive. F B and F-II slowed the rate of alcoholic fermentation (F B being most potent). But F C and F D did not have any effect on alcoholic fermentation. However none of the 4 saponins affected the efficiency of alcoholic fermentation (86 - 90% ). Antimicrobial studies of flabelliferins using the Bauer - Kirby method showed that only F B was active inhibiting all bacteria tested, namely; Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Proteus rettigeri and Acinetobacter calcoceticus. The study is of interest in the area of structure activity relationships, as F B (active) and F C (inactive) are isomers (M.W. 868).