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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.

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The dimeric nonprenylated acylphloroglucinol semimyrtucommulone (6) was obtained from the leaves of myrtle (Myrtus communis) as a 2:1 mixture of two rotamers. The known trimeric phloroglucinol myrtucommulone A (1) was also isolated and characterized spectroscopically as a silylated cyclized derivative (5). Myrtucommulone A showed significant antibacterial activity against multidrug-resistant (MDR) clinically relevant bacteria, while semimyrtucommulone was less active.

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Original PaperRetention indices in the analysis of food aroma volatile compounds in temperature-programmed gas chromatography: Database creation and evaluation of precision and robustness A retention index (RI) database containing 250 volatile compounds was created on a polar stationary phase column and validated for food aroma characterisation. Precision of the retention indices (RIs) was assessed by performing replicated injections of a representative number of volatiles under the same experimental conditions: differences lower than 1 U were observed for all the compounds. Robustness was evaluated by carrying out injections of the same set of volatile compounds under different experimental conditions, i. e. program temperature, column batches and instrumentation. Excellent results were obtained with a maximum difference in the RI values of 10 U. The capabilities of the created database for food aroma characterisation were finally evaluated by analysing the volatile fractions of different food matrices such as dry sausages, cheese and bread. A great number of volatile compounds were identified in the analysed samples on the basis of their RI, thus proving the usefulness of the RI collections in the field of food analysis.

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[formula: see text] The Mitsunobu reaction can distinguish between alcohol and phenol hydroxyls in esterification reactions, providing an expeditious and broadly applicable entry into various phenolics and polyphenolics of biomedical and nutritional relevance.