Novel isonahocol E3 exhibits anti-inflammatory and anti-angiogenic effects in endothelin-1-stimulated human keratinocytes

Endothelin-1 (ET-1) is reported to be a potent mitogenic and pro-angiogenic factor that plays a vital role in both physiological and pathological processes. ET-1 is implicated in dermal cell proliferation and skin disorders, such as psoriasis and atopic dermatitis. ET-1, endothelin ETA receptor, and endothelin ETB receptor could be potential targets for developing specific therapeutics to treat such disorders. Here, we provide the first report that an isonahocol [2,-5-dihydroxy-3-(13-hydroxy-3,-7,-11,-15-tetramethyl-12-oxo-hexadeca-2,-6,-14-trienyl)-phenyl]-acetic acid methyl ester (isonahocol E3) from the brown algae Sargassum siliquastrum has functional antagonistic activities against ET-1 induced inflammatory and pro-angiogenic effects. Isonahocol E3 significantly inhibited ET-1-induced cell proliferation, as well as inflammatory mediators, such as interleukin-6 (IL-6) and interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α), and pro-angiogenic factors including metalloproteinases in immortalized human keratinocytes. We also found that isonahocol E3 reduced expression level of endothelin ETA receptor, and endothelin ETB receptor as well as suppressed ET-1-induced extracellular signal-regulated kinase (ERK) phosphorylation. Taken together, our results suggest that isonahocol E3 can exert anti-inflammatory and anti-angiogenic activities at least by regulating the expression of ET-1 receptors and ERK signaling pathway.