Antifungal metabolite with a new carbon skeleton from Keissleriella sp. YS4108, a marine filamentous fungus.

In addition to four known metabolites (4-acetyl-6,8-dihydroxy-5-methylisocoumarin, 6,8-dihydroxy-3-methylisocoumarin, 6,8-dihydroxy-3,5,7-trimethylisocoumarin and 3,3'-oxy-(5-methyl)-phenol), bioassay-guided fractionation of the culture of Keissleriella sp., a marine filamentous fungus (strain number: YS 4108), afforded an antifungal metabolite with a new carbon skeleton whose structure was elucidated spectrometrically as 3,6,8-trihydroxy-3-[3,5-dimethyl-2-oxo-3(E)-heptenyl]-2,3-dihydronaphthalen-1(4H)-one. In vitro antifungal assays of all isolates revealed that the new metabolite and 3,3'-oxybis[5-methylphenol] were inhibitory to the growth of the human pathogenic fungi Candida albicans, Tricophyton rubrum and Aspergillus niger with MICs of the former being 40, 20 and 80 microg/ml, and those of the latter 10, 30 and 50 microg/ml, respectively.

Terpenoids and flavonoids from Artemisia species.

A phytochemical reinvestigation of the aerial parts of Artemisia sieversiana gave a new guaianolide and two known flavones (chrysosplenetin and 5-hydroxy-3',4',6,7-tetramethoxyflavone). Antifungal fractions derived from the chloroform extract of A. annua afforded two cadinane derivatives (arteannuin B and artemisinin), oleanolic acid, beta-sitosterol, stigmasterol, and the four flavones artemetin, bonanzin, eupalitin and chrysosplenetin. Their structures were elucidated by spectral methods. All isolates from the two species were tested in vitro for antifungal activity. Arteannuin B, a main sesquiterpenoid in A. annua, showed antifungal activity against one human (Candida albicans, MIC: 100 micrograms/ml) and four plant pathogenic fungi (Gaeumannomyces graminis var. tritici, Rhizoctonia cerealis, Gerlachia nivalis and Verticillium dahliae, MICs: 150, 100, 150 and 100 micrograms/ml, respectively) whereas others showed no antifungal activity. The MIC value of ketoconazole to C. albicans was 1.0 microgram/ml, and those of triadimefon to G. graminis var. tritici and R. cerealis 150 and 100 micrograms/ml.

Lignans and sesquiterpene lactones from Artemisia sieversiana and Inula racemosa.

The aerial parts of Artemisia sieversiana afforded, in addition to beta-sitosterol, stigmasterol and daucosterol, two novel lignans as well as one known and three new guaianolides. The roots of Inula racemosa gave beta-sitosterol, daucosterol and isoalantolactone. The structures were determined by a combination of spectral methods (IR, EIMS, 1H and 13C NMR, DEPT, COSY, NOESY and HETCOR). All isolates were subjected to antifungal tests. Isoalantolactone, a major sesquiterpene lactone of I. racemosa, was found to be active against the human pathogenic fungi. Aspergillus flavus, A. niger, Geotrichum candidum, Candida tropicalis and C. albicans at concentrations of 50, 50, 25, 25 and 25 micrograms/ml, respectively. The taxonomic significance of the characterized constituents is discussed briefly.

Biologically active substances from the genus Artemisia.

Artemisia species, widespread in nature, are frequently utilized for the treatment of diseases such as malaria, hepatitis, cancer, inflammation, and infections by fungi, bacteria, and viruses. Furthermore, some Artemisia constituents were found to be potential insecticides and allelopathic chemicals. This genus is receiving growing attention presumably due to: (i) the diversified biology and chemistry of the constituents, (ii) the frequent application in traditional medical practice, and (iii) the rich source of the plant material. This review summarizes mainly the biological results obtained in the past decade. The significance and trends in this field are briefly discussed.