Sanan Subhadhirasakul and Pharkphoom Pechpongs

pp. 555 - 561

Abstract

Two steroids, β-sitosterol and stigmasterol (of their mixture in an approximate ratio 1:1) and a
terpenoid, friedelin, were isolated from a chloroform extract of Mammea siamensis flowers by means of chromatographic techniques. Chemical structures of the isolated compounds were identified by direct comparison
of their spectroscopic data with those reported in the literature and by comparing their TLC patterns with
those of authentic samples. The preliminary biological acitvities, such as antimicrobial activity (disc diffusion
method), DPPH-radical scavenging and brine shrimp lethality effects of various solvent extracts from M.
siamensis flowers were examined. The chloroform extract of M. siamensis flowers showed antibacterial
effects on Staphylococcus aureus and Bacillus subtilis with inhibition zone of 7.8 and 9.0 mm, respectively.
A methanol extract exhibited inhibition zone (6.0 mm) for B. subtilis. However, neither extract affected the
growth of either Escherichia coli or Candida albicans. Both the chloroform and the methanol extract did not
show antioxidative effect in DPPH radical-scavenging assay, whereas they exhibited lethality effects on
brine shrimps with LC₅₀ value of 5.2 and 43.2 µg/ml, respectively. Neither the mixture of β-sitosterol and
stigmasterol, or friedelin showed any effect on brine shrimps.