New Diphenol and Isocoumarins from the Aerial Part of Lawsonia inermis and Their Inhibitory Activities against NO Production

Lawsonia inermis Linn (Lythraceae), also known as henna, is a small shrub or tree distributed throughout Taiwan’s Lanyu Island, in North Africa, and in Australia. Its leaves are used as a folk medicine for the treatment of external hemorrhage and fingernail abscesses. Investigation of the ethyl acetate (EtOAc)-soluble fractions from methanol extract of the aerial part of Lawsonia inermis has led to the isolation of a new diphenol, (Z)-4,4′-(prop-1-ene-1,3-diyl)diphenol (1), two new isocoumarin carbonates, inermiscarbonates A (2) and B (3), and six known compounds, 4′-hydroxyflavanone (4), apigenine (5), kampferol (6), luteolin (7), quercetin (8), and (-)-catechin (9). Their structures were determined by detailed analysis of spectroscopic data and comparison with the data of known analogues. Compounds 1 and 4–9 were evaluated for the inhibition of nitric oxide production in lipopolysaccharide (LPS)-stimulated product of nitrite in RAW 264.7 cells with IC(50) values of 5.63, 15.72, 8.67, 6.67, 6.17, 7.61, and 14.52 μg/mL, respectively.