Antifungal activity of chitooligosaccharides against the dermatophyte Trichophyton rubrum.

Antifungal activity against the dermatophytic fungus Trichophyton rubrum by a well-characterized chitooligosaccharides (COS) sample, hydrolyzed using a recombinant chitosanase, was investigated in vitro and in vivo. The minimum inhibitory concentration (MIC) of COS ranged between 0.25 and 0.50%, which was measured using a microdilution method. Analysis of inhibition rates using an agar diffusion method showed that treatment with 0.5% and 1% COS significantly suppressed T. rubrum cell growth (p<0.05 and p<0.01, respectively, in comparison with untreated control). Morphological changes and structural alterations of cells were observed by TEM. In vivo efficacy of COS in treatment of T. rubrum dermatophytosis was evaluated using a guinea pig model. Skin lesion scores revealed a strong, dose-dependent therapeutic effect of COS. The 5% COS group showed a reduction of skin lesions even greater than that of the positive control group treated with 1% fluconazole (FCZ). Histological analysis revealed no inflammation or tissue destruction in the groups treated with 5% COS or 1% FCZ. Hyperkeratosis was also observed, perhaps resulting from a defensive response of the tissue cells to COS. The findings indicate that COS has excellent potential for development of novel antifungal drugs for clinical treatment/remission of dermatophytoses.

Isolation, characterization, and antitumor activity of a novel heteroglycan from cultured mycelia of Cordyceps sinensis.

A novel heteroglycan, Cordyceps sinensis polysaccharide 1 (molecular weight 1 17 × 10(5) Da), was isolated and purified from mycelia of the fungus C. sinensis obtained by solid-state culture. Structural characterization by chemical analysis, GC-MS, FTIR, and NMR spectroscopy showed that C. sinensis polysaccharide 1 was mainly composed of (1 → 6)-linked α-D-Glc and α-D-Gal, with minor ß-(1 → 4)-D-Xyl and ß-(1 → 4)-D-Man residues probably located in the side chains with a trace amount of α-(1 → 3)-L-Rha residue. In biological assays, C. sinensis polysaccharide 1 significantly inhibited proliferation of sarcoma 180 cells and induced apoptosis in a dose-dependent manner. Further studies will elucidate the antitumor mechanism of C. sinensis polysaccharide 1 and promote its utilization for the development of novel, effective anticancer drugs.

Protective effect of chitooligosaccharides against cyclophosphamide-induced immunosuppression in mice.

Chitooligosaccharides (COS) display a variety of important biological activities, including antimicrobial, antitumor, anti-inflammatory, and immunoenhancing. In the present study, a COS sample (degree of polymerization 4-11, analyzed by FTIR and MALDI-TOF-MS) prepared by hydrolysis with a recombinant chitosanase was orally administered to mice for evaluation of its effect on cyclophosphamide (Cy)-induced immunosuppression. Thymus and spleen indices, delayed-type hypersensitivity (DTH) reaction, macrophage phagocytosis, and certain enzyme activities were significantly higher in mice treated with COS+Cy than in mice treated with Cy alone. ELISA experiments showed that COS treatment enhanced production of the cytokines IL-2, IL-12, and IFN-γ but decreased production of IL-10 in sera of Cy-treated mice. The well-defined COS product studied displayed strong immunoenhancing activity and a protective effect against Cy-induced immunosuppression. COS-derived products should be further investigated for possible immunostimulatory applications in the food and pharmaceutical industries.