Antifungal bioassay

The S. lividam sn s SorAB, SorABRCDFE, and SorABRCDFE+BL were fermented in the presence of thiostrepton to induce the expression of the soraphen biosynthetic genes, but no production of soraphen A, or any other soraphen congener was found by LC-MS analyses (Table I). As there is no evidence that S. lividam has the capacity to biosynthesize the soraphen starter unit benzoyl-CoA as part of its normal metabolism (3S), we tried to ferment these strains while feeding benzoate SorABRCDFE+BL, but not the other two strains, produced soraphen A as shown by antifungal bioassay and LC-MS analysis (Figure 2C and D, Table I). In conclusion, both an external source of benzoate and the introduction of a suitable benzoyl-CoA ligase [the BadA entyme of R palustris (37)] were necessaiy for soraphen A production in S. lividam. 

Antifungal bioassay. Known amounts of the pure test compounds were dissolved in DMSO and serial dilutions prepared in the same solvent. A 20 1 aliquot of each solution was mixed with 2 ml of Emmons liquid medium seeded with ca. 2 X 10 CFU/ml of the test organism. The inoculated tubes were vortexed and incubated at 26 C. Similarly, inoculated tubes without test compounds served as controls. Depending on the growth characteristics of the test species, results were recorded after 2-4 days. The lowest concentration of the test compound that totally inhibited growth of test organism was recorded as the minimum inhibitory concentration (MIC) for that species. 

Temeyer tested the toxicity of miconazole and six other antifungal agents and solvents for use in horn fly larval rearing or bioassays. Each of which appeared to be potentially useful in bovine fecal medium [99],... 

Hoeprich and Huston [117] assessed the stability of miconazole and three other antifungal agents under conditions encountered in bioassay and susceptibility testing in vitro. Although the amphotericins were labile as compared with other drugs, tests should be reliable with all four drugs in view of the rapid action of the polyenes and the relatively slow action of miconazole and 5-fluorocytosines. 

Bioassay-directed isolation of antifungal compounds from the bark of Macaranga monandrayie ( eA. two clerodane-type diterpenes, kolavenic acid and 2-oxo-kolavenic acid, with moderate activity against Phomopsis viticola... 

Ouf, S.A., Hady, RK., Abdel, E.M.H., Shaker, K.H. Isolation of antifungal compounds from some Zygophyllum species and their bioassay against two soil-borne plant pathogens. Folia Microbiol 1994 39 215-221. 

The structure of Cypridina luciferin was established by analysis of spectroscopic data, chemical degradations, extensive MS analysis, and total synthesis [41—44]. Cypridina luciferin is biosynthesized from L-tryptophan, L-arginine, and L-isoleudne [45,46]. Distomadines A (24) and B (25) have been isolated from the asddian Pseudodistoma aureum and were not adive in antifungal, antiviral, anti-inflammatory, and anti-mycobacterial bioassays [47]. 

The bioassay-guided fractionation of the antifungal dichloromethane extract from the roots of Vernonanthora tweedieana (Baker) H. Rob. allowed the isolation of one active sesquiterpene, identified as 6-cinnamoyloxy-l-hydroxyeudesm-4-en-3-one, Fig. (9) [162]. MIC values of this eompound showed Trichophyton mentagrophytes as the most sensitive strain. 

Flavonoids are natural polyphenolic substances widely distributed in the different parts of plants such as fruits, bark, stems, roots, leaves and flowers. Structurally they are characterized by a pyran ring or a similar structure of three carbons. These polyphenolic compounds are well known for displaying a remarkable spectrum of biological activities, including antibacterial and antifungal properties. In the Anthemideae tribe, some of these compounds were isolated by bioassay-guided fractionation, after previously detecting antimicrobial activity on the part of the plant. 

Extracts of Cribrochalina sp, a marine sponge, displayed antifungal activity. Bioassay guided fractionation led to the isolation of cribrochalinamine /V-oxides A and B (21a,b). Structures of these compounds were determined using HRFABMS, and one- and two-dimensional JH and 13CNMR[118],... 

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