Saponins and Volatile Constituents from Lonicera japonica Growing in the Western Himalayan Region of India †

Abstract

Chemical investigation of the leaves and fresh flowers of Lonicera japonica lead to the isolation of a new pentacyclic triterpene saponin, 3-O-[α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl]-hedragenin (1) along with two known saponins, 3-O-[α-L-arabinopyranosyl]-hedragenin (2) and 3-O-[α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl]-hedragenin (3), two fatty acid esters, methyl (Z,Z) 9,12-octadecadienoate (methyl linoleate) (4) and methyl (Z,Z,Z) 9,12,15-octadecatrienoate (methyl linolineate) (5) and two long chain hydrocarbons, octadecane (6) and heneicosane (7). The structures were established on the basis of IR, 1D- and 2D-NMR (HMQC and HMBC) spectroscopic and ESI-QTOF-MS/MS analysis. Simultaneously, the volatile composition of fresh flowers of L. japonica, analyzed by GC/MS, indicated the presence of two long chain hydrocarbons, heneicosane (37.5%) and octadecane (34.5%) as major constituents. Other metabolites characterized were fatty acids and their esters, such as palmitic acid (1.7%), linolenic acid (2.5 %), linoleic acid (1.3%), methyl palmitate (2.3%), methyl 9,12-octadecadienoate (4.5%) and methyl (Z,Z,Z)-9,12,15-octadecatrienoate, along with oxygenated monoterpenes and sesquiterpenes, namely linalool, cis-linalool oxide, terpine-4-ol and trans-nerolidol.