1,5-Diphenylpent-3-en-1-ynes and methyl naphthalene carboxylates from Lawsonia inermis and their anti-inflammatory activity

Lawsonia inermis (Lythraceae) known as henna is one of the most popular and ancient plants used in cosmetics and hair dying. It is cultivated for its leaves but other parts such as seeds, flowers, stem bark and roots are also used in traditional medicine for millennia. Henna tattoo paste also proved to be beneficial for wound healing and in several skin diseases suggesting potent anti-inflammatory activity. To evaluate henna anti-inflammatory activity, 31 compounds, including three 1,5-diphenylpent-3-en-1-yne derivatives, lawsochylin A-C and three methyl naphthalene carboxylates, lawsonaphthoate A-C, were isolated from the stems and leaves of henna utilizing a bioassay-guided fractionation. The structures of the compounds were elucidated by spectroscopic data. Two compounds, lawsochylin A and lawsonaphthoate A showed potent anti-inflammatory activity by inhibition of superoxide anion generation (IC ₅₀ = 1.80 and 1.90 μg/ml) and elastase release (IC₅₀ = 1.58 and 3.17 μg/ml) of human neutrophils in response to fMLP or cytochalasin B. Moreover, the known compounds, luteolin, apigenin, 4S-4-hydroxy-α- tetralone, and 2-butoxysuccinic acid, also showed potent inhibition of superoxide anion generation (IC₅₀ = 0.75-1.78 μg/ml) and elastase release (IC₅₀ = 1.62-3.61 μg/ml).