Antimicrobial and α -glucosidase inhibitory activities of chemical constituents from Gardenia aqualla (Rubiaceae).

An aliphatic alkene namely pentapentacontene ( 4 ) was isolated for the first time from a natural source, Gardenia aqualla , along with fourteen other compounds including nonacosanol ( 1 ), tetratriacontanol ( 2 ), octatriacontanol ( 3 ), β -sitosterol ( 5 ) and stigmasterol ( 6 ), daucosanol ( 7 ), ursolic acid ( 8 ), uvaol ( 9 ), 3 β ,19 α ,23 β ,24 α -tetrahydroxyurs-12-en-28-oic acid ( 10 ), lupenone ( 11 ), oleanolic acid ( 12 ), vanillin ( 13 ), vanillic acid ( 14 ) and D-mannitol ( 15 ). α -glucosidase inhibitory assay revealed that MeOH and EtOAc extracts of leaves had the best activity with IC 50 of 9.65 and 20.03 µg/ml respectively. All the tested compounds showed dose dependent inhibition of α -glucosidase and some of them were found to be comparable to acarbose. Compound 10 was the most potent with IC 50 = 1.72 μM. It also showed the most interesting antibacterial activity, against the isolate strain of S. typhi and P. aeruginosa and also exhibited the most significant antifungal activities against all the tested yeasts.