An acetone extract of Helichrysum italicum ssp. microphyllum afforded the phloroglucinol alpha-pyrone arzanol (1a) as a potent NF-kappaB inhibitor. Arzanol is identical with homoarenol (2a), whose structure should be revised. The phloroglucinol-type structure of arzanol and the 1,2,4-trihydroxyphenyl-type structure of the base-induced fragmentation product of homoarenol could be reconciled in light of a retro-Fries-type fragmentation that triggers a change of the hydroxylation pattern of the aromatic moiety. On the basis of these findings, the structure of arenol, the major constituent of the clinically useful antibiotic arenarin, should be revised from 2b to 1b, solving a long-standing puzzle over its biogenetic derivation. An alpha-pyrone (micropyrone, 7), the monoterpene rac-E-omega-oleoyloxylinalol (10), four known tremetones (9a-d), and the dimeric pyrone helipyrone (8) were also obtained. Arzanol inhibited HIV-1 replication in T cells and the release of pro-inflammatory cytokines in LPS-stimulated primary monocytes, qualifying as a novel plant-derived anti-inflammatory and antiviral chemotype worth further investigation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.