Synthesis and biological activity of fungal metabolite, 4-hydroxy-3-(3′-methyl-2′-butenyl)-benzoic acid

4-Hydroxy-3-(3′-methyl-2′-butenyl)-benzoic acid (HMBA) was previously isolated from Curvularia sp. KF119 as a cell-cycle inhibitor. However, the present study used a novel and practical synthetic method to prepare a large quantity of HMBA. The synthetic HMBA was found to inhibit the cell-cycle progression of HeLa cells with a comparable potency to the natural fungal metabolite. The inhibition of the cell-cycle progression by the synthetic HMBA involved both the activation of p21_WAF1 and the inhibition of cyclin D1 expression in the cells. Consequently, this new synthetic procedure provides an easy and convenient way to produce or manipulate the original fungal metabolite.