Bioactive flavonoids from Pachyrrhizus erosus seeds and Millettia leucantha var. leucantha stem bark

Abstract

Phytochemical study on the seeds of Pachyrrhizus erosus revealed the presence of eight known compounds including dehydroneotenone, (+)-dolineone, (+)-12a-hydroxydolineone, (+)-12a-hydroxypachyrrhizone, (-)-12a-hydroxyrotenone, neotenone, pachyrrhizin and (+)-pachyrrhizone. All isolates were identified and completed 1H-and 13C-NMR data. Additionally, eleven compounds were obtained from the phytochemical investigation of the stem bark of Millettia leucantha var. leucantha. These included two new compounds, 2,4,6,β-tetramethoxy-3',4'-methylenedioxychalcone และ 2',4',6'-trimethoxy-3,4-methylenedioxychalcone, two new natural products, 2',4'dimethoxy-3,4-methylenedioxychalcone and 2',4',6'-trimethoxy-3,4-methylenedioxychalcone, and other seven known compounds, namely desmethoxykanugin, dihydromilletenone methyl ether, 2'-hydroxy-3,4,4',6'-tetramethoxychalcone, karanjin, lanceolatin B, 3',4'-methylenedioxy,5,7-dimethoxyflavone and 3',4'-methylendioxy-7-methoxyflavone. The structure determination of all isolates were accomplished by spectroscopic analyses (UV, IR, MS and NMR) and compared with the literary data of known compounds. The isolated compounds were also subjected for biological activities evaluation, involving antimicrobial, anti-Herpes Simplex Virus (HSV), cyclooxygenase-2 (COX-2) inhibitory and cytotoxic activies. (+)-12a-Hydroxydolineone and (+)-12a-hydroxypachyrrhizone from P.erosus, and dihydromilletenone methyl ether and 2',4',6'-trimethoxy-3,4-methylenedioxychalcone from M. leucantha showed moderate anti-HSV activity, whereas desmethoxykanugin demonstrated moderate COX-2 inhibitory activity. Furthermore, 2',4'-dimethoxy-3,4-methylenedioxychalcone and 2',4',6'-trimethoxy-3,4-methylenedioxychalcone showed significant cytotoxic activity against NCI-H460 cell line. This work verified that no isolated compound showed antimicrobial activity.