Effect of some soybean and bean phytoalexins and related isoflavonoids on growth of Candida albicans.
The influence of a series of related isoflavonoids on growth of the zoopathogenic yeast, Candida albicans, in liquid media was studied. The order of effectiveness was identical with that previously found for a range of phytopathogenic fungi. Minimum inhibitory concentration of phaseollinisoflavan, the most active test compound, was 250 microM for 3 days after inoculation. However, C. albicans resumed growth thereafter. Phaseollinisoflavan, 500 microM, did not inhibit but only delayed growth of the yeast. Tolerance of C. albicans to phaseollin and phaseollinisoflavan was based on nondegradative mechanism(s), while tolerance to glyceollin appeared to be based on detoxification.
Susceptibility of zoopathogenic fungi to phytoalexins
Phytoalexins are a group of low-molecular-weight antibiotics produced by higher plants in response to infection by relatively avirulent microorganisms. They are of relatively low toxicity for mammalian cells and have been reported to possess a broad spectrum of antimicrobial activity against bacteria and phytopathogenic fungi. Employing a broth dilution technique, we have found the zoopathogens Petriellidium boydii, Aspergillus flavus, A. fumigatus, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, Rhizopus oryzae, Sporothrix schenckii, and Trichophyton rubrum to be inhibited by one or more of the phytoalexins maackiain, medicarpin, phaseollin, phaseollin isoflavan, pisatin, sativan, and vestitol in concentrations of from 12.5 to 50 microgram/ml. Phaseollin isofalvan was the most effective of these. In agar cup diffusion tests growth of the yeast form of Blastomyces dermatitidis was inhibited by phaseollin at 50 microgram/ml and by phaseollin isoflavan at 25 microgram/ml. Susceptibility of the mycelial form of B. dermatitidis to these two compounds was demonstrated by inhibition of radial extension on agar plates.
Mineral element analyses of various tropical forages in Guatemala and their relationship to soil concentrations
Determination de la composition minerale de differents fourrages dans 3 regions d'elevage du Guatemala et etude des relations entre la chimie des sols et la composition minerale des fourrages