Antioxidant and immunomodulatory constituents of henna leaves.

The immunomodulatory bioassay-guided fractionation of the methanolic extract of henna (Lawsonia inermis L.; syn. Lawsonia alba L.) leaves resulted in the isolation of seven compounds; three have been isolated for the first time from the genus, namely p-coumaric acid, 2-methoxy-3-methyl-1,4-naphthoquinone and apiin, along with the previously isolated compounds: lawsone, apigenin, luteolin, and cosmosiin. Structural elucidation of the isolated compounds was based upon their physical, chemical as well as spectroscopic characters. Their immuomodulatory profile was studied using an in vitro immunoassay, the lymphocyte transformation assay. The ABTS [2,2'-azino-bis (3-ethyl benzthiazoline-6-sulfonic acid)], free radical scavenging assay depicted that all isolated compounds exhibited antioxidant activity comparable to that of ascorbic acid.