Thesis (M.Sc. in Pharm.)--Chulalongkorn University, 2015

Phytochemical investigation of the crude methanol extract of Dendrobium tortile (Orchidaceae) led to the isolation of a new compound, namely 4-(2-hydroxypropyl)-2(5H)-furanone, together with six known compounds,which included trans-tetracosylferulate, cis-hexacosanoyl ferulate, p-hydroxybenzaldehyde, 3,4-dihydroxy-5,4'-dimethoxybibenzyl, eriodictyol and dendrofalconerol A. The structures of these compounds were determined through analysis of 1-D and 2-D NMR and HR-ESI-MS data. All of the isolates were evaluated for their α-glucosidase inhibitory activity. Dendrofalconerol A showed strong activity when compared with the positive control acarbose, whereas 3,4-dihydroxy-5,4'-dimethoxybibenzyl and eriodictyol showed appreciable effects. An enzyme kinetics study revealed that dendrofalconerol A is a reversible non-competitive inhibitor of α-glucosidase. This is the first report on the chemical composition and the biological activity of D. tortile.