Ravenic Acid, a New Tetramic Acid Isolated from a Cultured Microfungus, Penicillium sp.

Abstract

A new antibiotic polyene tetramic acid, ravenic acid (2), has been isolated from the mycelia of a cultured fungus, Penicillium sp. The structure of ravenic acid was determined by detailed spectroscopic analysis and the major isomer identified as possessing (3Z, 7E, 9E, 11E, 13E) stereochemistry.

Penicillenols from Penicillium sp. GQ-7, an Endophytic Fungus Associated with Aegiceras corniculatum

“…21) All the 3-acyl tetramic acids can be considered as the results from the substitution of the hydrogens of C-5 with other functional groups and the substitution of the methyl group of C-7. 22) To date, hundreds of tetramic acids have been isolated, and to the best of our knowledge, among them neither 2-isooctyl nor oct-6-en-2-yl substituent at C-7 has been reported prior to our new penicillenols A 1 , A 2 , B 1 , B 2 , C 1 , and C 2 (1)(2)(3)(4)(5)(6). In this paper we report the isolation, structure elucidation, and cytotoxic activities of the six penicillenols (1-6).…”

“…GQ-7, exhibiting cytotoxicity against the P388 cell line. Studies on the active constituents of this fungus led to the isolation of six new tetramic acids derivatives (1)(2)(3)(4)(5)(6) (Fig. 1), together with citrinin, phenol A acid, phenol A, and dihydrocitrinin.…”

“…The naturally occurring tetramic acids were isolated from bacteria, 1,2) molds, 3) fungi 4,5) and sponges. 6) These isolated compounds exhibit a wide range of biological and pharmaceutical activities 7,8) (including potent antibiotic 6,9) and antiviral 10,11) properties, mycotoxicity, 12) and cytotoxicity [13][14][15][16][17][18] ) and have attracted much attention of chemists, physicians, and biologists.…”

“…The cell lines were grown in RPMI-1640 supplemented with 10% FBS under a humidified atmosphere of 5% CO 2 and 95% air at 37°C. Those cell suspensions (200 ml) at a density of 5ϫ10 4 cell ml Ϫ1 were plated in 96-well microtiter plates and incubated for 24 h at the above condition. The test compound solution (2 ml in DMSO) at different concentrations was added to each well and further incubated for 72 h in the same condition.…”

Functional Operons in Secondary Metabolic Gene Clusters in Glarea lozoyensis (Fungi, Ascomycota, Leotiomycetes)

“…It belongs to the tetramic acid class of metabolites, such as ravenic acid (15), militarinone C (16), and pretenellin A (17), which are common in fungi. Its structure is similar to those of other tetramic acids but not identical due to having a different polyketide side chain and substituents on the 2,4-pyrrolidinedione ring.…”