New CuCl2-induced glucoside esters and other constituents from Portucala oleracea.

Two new glucoside esters 1 and 2 were produced as stress metabolites in the fresh leaves of Portulaca oleracea, in response to abiotic stress elicitation by CuCl(2). A new sugar ester (3) and two known compounds (4 and 5) were also isolated. Their structures were established by spectroscopic means. The antioxidative activities of stress metabolites and the related isolates were evaluated by DPPH assay. The results showed that new stress-driven adducts of monolignans and monoterpenes with a glucose bridge exhibited much stronger antioxidative activities than other compounds.