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.