Arzanol, an Anti-inflammatory and Anti-HIV-1 Phloroglucinol α-Pyrone from Helichrysum italicum ssp. microphyllum

Abstract

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.

α-Pyrones and Yellow Pigments from the Sponge-Derived Fungus Paecilomyces lilacinus

“…Hence, the isolated methylene group was inserted at C-7 position connecting two partial structures, by comparison of the NMR data with those of phomapyrone B (3), 8 ascosalipyrone, 9 and micropyrone (4). 10 The only difference between 1 and micropyrone (4), isolated from the plant Helichrysum italicum, was the absence of the methyl group on C-7 in the linear side chain of 1. Therefore, the structure of paecilopyrone A (1) was established as 4-hydroxy-3,5-dimethyl-6-(3-methyl-2-oxo-pentyl)-pyran-2-one.…”

Chemical composition and biological activity of the essential oil from Helichrysum microphyllum Cambess. ssp. tyrrhenicum Bacch., Brullo e Giusso growing in La Maddalena Archipelago, Sardinia.

“…tyrrhenicum is less widespread with respect to the other subspecies, and its chemical composition is peculiar with respect to plants growing in the peninsula. In particular from this subspecies a heterodimeric phloroglucinol pyrone arzanol endowed with interesting biological activities as well as an unusual class of lipids named santinols have been recently characterized 7,8 .…”

An evaluation of a new approach to the regeneration of Helichrysum italicum (Roth) G. Don, and the molecular characterization of the variation among sets of differently derived regenerants

“…The ornamental value conferred by its distinctive yellow scented flowers, and the properties of its essential oils contribute to its popularity. Many researchers have pointed out the anti-inflammatory, anti-histamine, antimicrobial and anti-viral properties of these essential oils, which are employed in various industrial sectors [14][15][16][17][18]. The scarce availability of cultivated materials, lack of agronomic practices and extreme variability of spontaneous ecotypes justify the application of in vitro cultures to set up a platform for rapid multiplication in this plant species.…”