nystatin-a1 and propionic-acid

Bioassay-guided fractionation of antibacterial extracts from cultures of a basidiomycete from Northern Thailand, which represents a new species of the genus Deconica, yielded the terpenoid deconin A (1), whose structure was elucidated by spectral methods (NMR, HRMS) as a cuparenic/mevalonic acid conjugate. The absolute configuration of 1 was determined after saponification and comparison of specific rotations of the resulting cuparenic acid and mevalonolactone with authentic standards and literature data. Six minor congeners (2-7) were isolated and identified, and their antimicrobial and cytotoxic effects are reported. Compounds 1-4 are the first natural products featuring an unmodified mevalonic acid residue as a building block.

Topics: Anti-Bacterial Agents; Basidiomycota; Mevalonic Acid; Microbial Sensitivity Tests; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Propionates; Stereoisomerism; Terpenes; Thailand

Intracellular pH (pHi) was monitored during pH-regulated dimorphism of Candida albicans using two different methods: (1) by steady-state distribution of propionic acid and (2) by use of polyene antibiotic, nystatin. There was no significant change in pHi during the first 120 min in either bud- or germ tube-forming populations. However, there was a rapid increase around 135 min which also coincided with the time of evagination. The magnitude of increase in pHi was different in the two populations; being 0.44 and 0.14 pH units in bud- and germ tube-forming populations, respectively. In the two diverging populations, the transient increase in pHi was followed by a rapid drop. The sharp rise in pHi of the population destined to form buds was sensitive to orthovanadate and to the depletion of K+ from the medium while this was not the case with germ tube-forming cells. The results suggest that pHi may play an important role in the phenotypic divergence of C. albicans.

Topics: Candida albicans; Cell Membrane; Cytoplasm; Electrochemistry; Hydrogen-Ion Concentration; Kinetics; Nystatin; Phenotype; Potassium; Propionates; Proton-Translocating ATPases; Vanadates