Physical characteristics, lupinifolin content, and biological activity of the wood of Myriopteron extensum (Wight & Arn.) K. Schum.

Abstract

Myriopteron extensum (Wight & Arn.) K. Schum. of the family Apocynaceae is the medicinal plant used in folk medicine for its antitussive, tonic and antidote properties. This medicinal plant has often been substituted for other plants that have the same synonyms as Cha-em. This study revealed that the macroscopic characters of the dried stem of the wood of M. extensum were spherical liana, externally smooth dark brown, yellow wood inside, sweet, nonunique smell. Powdered drug of the wood of M. extensum possessed the microscopical characters including parenchyma cell with starch grains, bordered pit vessels, stone cells, fibers, and starch grains. Chemical identification using High Performance Liquid Chromatography revealed lupinofolin in hexane extract from the wood of M. extensum at 0.063 mg/g. The in vitro evaluation of antioxidant activity of the wood of M. extensum demonstrated that various solvent extracts including those of ethanol, hexane, dichloromethane, and n-butanol exhibited IC₅₀ in the range of 80.50 – 474.86 µg/mL by DPPH assay and showed reducing power in the range of 70.97 – 434.18 mM FeSO₄/g by FRAP assay. Among all of the extracts, the highest DPPH scavenging activity and the highest reducing power were found in the dichloromethane extract (DPPH; IC₅₀ 80.50 µg/mL and FRAP; 434.18 mM FeSO₄/g). However, all these extracts of M. extensum did not give antibacterial activity against Streptococcus mutans, the major cause of tooth decay, and did not show α-glucosidase inhibitory activity at the highest tested concentrations of 1000 and 25 µg/mL, respectively.