Bioactive Lignans from <i>Hypoestes aristata</i>
Tshifhiwa Ramabulana, Luki-Marié Scheepers, Thirshen Moodley, Vinesh Maharaj, André Stander, N.M.S.Q. Gama, Daneel Ferreira, Molahlehi S. Sonopo, Mamoalosi A. Selepe
Abstract
Phytochemical investigation of extracts of the stems of Hypoestes aristata led to the isolation of nine lignans that included four known compounds, namely, hinokinin (1), savinin (2), medioresinol (3), and two cubebins (8a,b), three new butyrolactone lignans (4–6), and butyrolactol lignans 7a–c. The structures of the new compounds were established using 1D and 2D NMR and HRESIMS data. The absolute configurations of the new lignans were determined from their ECD data and the Mosher’s ester method. This is the first unequivocal assignment of the absolute configuration at C-7 and C-7′ of 7- and 7′-hydroxybutyrolactone lignans. The compounds were screened for inhibition of an HIV-1 protease enzyme, and compounds 1 and 6 exhibited moderate activity in this regard.