Anti-inflammatory, antimicrobial and acetylcholinesterase inhibitory activities of friedelanes from Maytenus robusta branches and isolation of further triterpenoids

Abstract The new pentacyclic triterpenoids friedel-1-en-3,16-dione ( 1 ), 1α,29-dihydroxyfriedelan-3-one ( 2 ) and 16β,28,29-trihydroxyfriedelan-3-one ( 3 ) were isolated from Maytenus robusta branches in addition to the known, but new for this species, triterpenoid 12α,29-dihydroxyfriedelan-3-one ( 4 ). The structures and stereochemistry of the novel triterpenoids were established by IR, 1D/2D NMR and HR-APCIMS spectral data. In addition, the biological activity of compound 2 and the previously isolated friedelanes 5 – 8 (friedelan-3,16-dione, 29-hydroxyfriedelan-3-one, 29-hydroxyfriedelan-3,16-dione and 16β,29-dihydroxyfriedelan-3-one) was investigated. Compounds 2 and 8 were tested for their acetylcholinesterase properties and antimicrobial activity against the bacteria Staphylococcus aureus , Pseudomonas aeruginosa , Listeria monocytogenes , Citrobacter freundii , and the fungus Candida albicans . Compound 2 was the most active compound for both assays, with values of 32.3% acetylcholinesterase inhibition, 42% activity against the fungus Candida albicans and 34% against the bacterium Pseudomonas aeruginosa . Compounds 5–8 were assayed for their antiedematogenic activity using the carrageenan-induced paw edema assay. At maximum inflammation after three hours, compounds 6 and 8 showed 42% and 57% activity, respectively. After four hours, compounds 5 and 7 showed activity of 71% and 75% compared to 79% of the control indomethacin.