Biological activities of Asparagus racemosus.

Cytotoxic, antioxidant, tyrosinase inhibitory, antimicrobial activities of the crude ethanol extract of dry powdered roots of Asparagus racemosus (Liliaceae) were investigated. The LC(50) to brine shrimp was 2189.49 microg/ml; the EC(50) for DPPH radical scavenging was 381.91 microg/ml; the IC(50) for tyrosinase inhibition was 7.98 mg/ml. The extract was active at 5-20 mg/ml against various pathogenic microbial (16 species, 18 strains) using the agar dilution assay, with the minimum inhibitory concentration (MIC) between 10-20 mg/ml for enteropathogens, the MIC between 5-20 mg/ml for dermatopathogens, and MIC = 10 mg/ml for a pneumonia causing bacteria Klebsiella pneumoniae. TLC and HPLC finger printing showed the presence of steroids-terpenes, alkaloids and flavonoids.

Biological activities of Schefflera leucantha.

This study investigated various biological activities of the ethanolic extract of dried ground leaves of Schefflera leucantha Viguier (Araliaceae). The extract possessed very low cytotoxicity to brine-shrimp with the LC(50) of 4,111.15 microg/ml; the significant antioxidant activity on DPPH with the EC(50) of 71.90 microg/ml; the inhibitory activity on mushroom tyrosinase with the IC(50) of 10.53 mg/ml using the dopachrome microplate-assay. The extract of 5-20 mg/ml range in the agar dilution assay were active against various pathogenic microbial (11 species, 11 strains), with the minimum inhibitory concentration (MIC) of 5 mg/ml against Clostridium spp.; MIC=10 mg/ml against enteropathogens as Bacteroides spp., Enterococcus faecalis ATCC 29212, Lactobacillus spp., Peptococcus spp. and Streptococcus mutans; MIC=10 mg/ml against a pneumonia causing bacteria Klebsiella pneumoniae and a dermatopathogen as Propionibacterium acnes; MIC=20 mg/ml against dermatopathogens as Staphylococcus aureus ATCC 6538, Streptococcus spp. and Candida albicans ATCC 90028. TLC fingerprints of the specific extracts from the leaf powder exhibited zones of steroids-terpenes and flavonoids. HPLC fingerprint of the flavonoid extract was performed.

Biosynthesis of beta-sitosterol and stigmasterol in Croton sublyratus proceeds via a mixed origin of isoprene units.

A green callus culture of Croton sublyratus Kurz established from the leaf explants appeared to actively synthesize two well-known phytosterols, beta-sitosterol and stigmasterol. The phytosterol biosynthesis was highly active during the linear phase of the culture. Feeding of [1-13C]glucose into the callus culture at this growth phase showed that the label from glucose was highly incorporated into both phytosterols. Isolation of the labeled products followed by 13C NMR analysis revealed that the phytosterols had their 13C-labeling patterns consistent with the acquisition of isoprene units via both the mevalonate pathway and the deoxyxylulose pathway with relatively equal contribution. Since the biosynthesis of phytosterol has so far been reported to be mainly from the classical mevalonate pathway, this study provides a new evidence on the biosynthesis of phytosterols via the novel deoxyxylulose pathway.