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Problem statement: Dermatophytes have developed resistance to the existing antifungal antibiotics. As a part of our continuous search we had isolated, identified and characterized actinomycetes from the halophilic environment having antagonistic activity against the dermatophytes namely Trichophyton, Microsporum and Epidermophyton. Approach: Actinomycetes were isolated from the soil sample collected from the Ennore saltpan region, Chennai, India and screened for antidermatophytic secondary metabolite production by well diffusion method. [MTCC 7880] were used to study its susceptibility to the isolated actinomycetes. Actinomycetes which showed antidermatophytic activity were subjected to cultural characterization with respect to aerial and substrate mycelia color, diffusible and melanin pigment production and the growth of the organisms on different media. Further the micro morphological characteristics such as spore surface ornamentation and spore chain morphology determined by Scanning Electron Microscopic (SEM) analysis also suggested that the isolates belonged to the genus Streptomyces. The isolates were also tested for utilization of various carbon and nitrogen sources, degradation of complex compounds, sensitivity to antibiotics and inhibitory compounds. Results: All the 3 isolates exhibited different cultural and morphological characteristics. Based on the cultural characters and morphology they were assigned to the genus Streptomyces. The three isolates produced an inhibition zone of 30-31 mm on an average, utilized a wide range of carbon and nitrogen sources, degraded almost all the complex compounds and exhibited a broad spectrum of antibiotic resistance. They were designated as Streptomyces sp. DKDVIT1, Streptomyces sp. DKDVIT2 and Streptomyces sp., DKDVIT3. Conclusion: The Streptomyces sp. isolated from the Ennore saltpan of Bay of Bengal exhibited potential antidermatophytic activity. The extraction and characterization of secondary metabolites from these Streptomyces may be used as a lead compound/therapeutic agent for dermatophytosis.

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Diastereomeric conduramine derivatives, i.e., (1R,2S,3R/S,6S)-6-(N-carbomethoxyamino) 1,2-O-isopropylidenecyclohex-4-ene-1,2,3-triol (1 and 2) and their O-acetyl derivatives (3 and 4), were studied using gas chromatography (GC) with electron ionization (EI) and chemical ionization (CI). The EI mass spectra of diastereomeric pairs show consistent differences in the relative abundances of characteristic ions. The EI fragmentation patterns are based on precursor/product ion spectra, high-resolution mass spectrometry (HRMS) and deuterium labelling. The CI spectra show differences from the EI spectra, and the isobutane/CI spectra are much simpler than the methane/CI spectra. The differences shown in the CI spectra are similar to those shown in the product ion spectra of [M+H](+) ions generated under electrospray ionization (ESI) conditions. Theoretical calculations are performed to understand the observed differences. The differences in the relative stabilities of molecular ions, or protonated molecules at different sites, can explain the observed differences in the spectra.

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