New α-glucosidase inhibitors and antibacterial compounds from Myrtus communis L.

Three new acylphloroglucinols - myrtucommulone D (1), myrtucommulone E (2), and myrtucommulone C (3) - and a new usnic acid derivative usnone A (4) have been isolated from Myrtus communis L., along with the known acylphloroglucinol myrtucommulone B (5), one sterol 8 and six triterpenes 10-15, two flavonoids 6 and 9, and 2,5-dihydroxy-4methoxybenzophenone (cearoin; 7). The structures of compounds 1, 2, 4, and 5 were also unambiguously determined by single-crystal X-ray diffraction analysis, The compounds 1-3 and 5 were found to be more potent a-glucosidase inhibitors than the clinically used standard acarbose. Compound 3 exhibited the highest activity among all the acylphloroglucinols, with an IC50 (inhibition concentration) = 35.4 +/- 1.15 mu m. Compounds 1, 2, 4, 7, and 11-15 also exhibited antibacterial activities. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)