In vitro and in silico studies of antibacterial activities of secofriedelane derivatives from Senna alata (L) Roxb.

In this study, six compounds were obtained from a methanolic extract of air-dried leaves of and one of them, a triterpenoid (secofriedelane) named as 7-(2-carboxyethyl)-3, 4b, 6a, 8, 10a, 12a-hexamethyl-8-vinyloctadecahydrochrysene-3-carboxylic acid () was isolated for the first time from this plant. Then, its chemical structure was detailed and characterised by FT-IR, H and C- NMR and ESI-MS. Besides, two chemical-modified derivatives of secofriedelane (, ) were synthesised by methylation and allylation reactions, respectively, and their antibacterial activities were also evaluated. The results revealed that all the triterpenes showed, against gram-positive and -negative bacterial strains, good and moderate antibacterial activities with bactericidal effects that were enhanced by the methyl groups and altered with the allyl ones. Moreover, the molecular docking results of , and in the DNA gyrase (2XCT) active site showed that triterpene has a good score very close to reference (ciprofloxacin).