Antifungal terpenoids from Hyalis argentea var. latisquama.

A detailed chemical study of the aerial parts and rhizomes of Hyalis argentea var. latisquama yielded a variety of sesqui- and diterpenes. In total, 26 compounds were isolated and identified, of which four are new, namely, two ent-kaurenes (1 and 2), a diterpene lactone (3), and a lindenanolide (4). The previously reported compounds included a series of lindenanolides, guaianolides, elemanolides, and additional diterpenes. The antifungal activity of the isolated compounds was tested against Cryptococcus neoformans and Candida albicans. Among the isolated compounds, the lindenanolides were the only structural class that showed strong antifungal activity, and onoseriolide acetate (5) was the most active. On the other hand, the isolated guaianolides were only moderately active, while the diterpenes did not show significant antifungal activity.