Antimycobacterial Scalarane-Based Sesterterpenes from the Red Sea Sponge <i>Hyrtios </i><i>e</i><i>recta</i>

Abstract

A new scalarane-type pentacyclic sesterterpene, sesterstatin 7 (1), was isolated from the Red Sea sponge Hyrtios erecta, together with 16-epi-scalarolbutenolide (2), 25-dehydroxy-12-epi-deacetylscalarin (3), 3-acetylsesterstatin 1 (4), and 21-acetoxydeoxyscalarin. The structure of 1 was elucidated by spectroscopic data interpretation. Sesterstatin 7 (1) showed 63% inhibition of Mycobacterium tuberculosis (H(37)Rv) at a concentration of 6.25 microg/mL. Compound 2 displayed moderate inhibitory activity, while 3 and 4 were weakly active against the same biological target.