Undescribed (2–7′)-Neolignans and Polyoxygenated Cyclohexene Glycosides from the Aerial Parts of Piper Mutabile C. DC. and Their Inhibitory Effects on Nitric Oxide Production

A phytochemical study of the aerial parts of Piper mutabile C. DC. revealed seven undescribed compounds [two (2 -7 ' )-neolignans and five polyoxygenated cyclohexene glycosides] and six known propenylcatechol derivatives. The chemical structures of the isolated compounds were elucidated by extensive HR-ESI-MS and NMR analyses, as well as comparison with the literature. The absolute configurations of the (2 -7 ' )-neolignans were confirmed by GIAO 13 C NMR calculations with a sorted training set strategy and TD-DFT calculation ECD spectra. The (2 -7 ' )- neolignans and polyoxygenated cyclohexene glycosides are unusual in natural sources. Undescribed neolignans 1 and 2 inhibited NO production in RAW 264.7 cells, with respective IC 50 values of 14.4 and 9.5 mu M.