Impact of brief exposure to antifungal agents on the post-antifungal effect and hemolysin activity of oral Candida albicans

AbstractPost-antifungal effect (PAFE) of Candida and its production of hemolysin are determinants of candidal pathogenicity. Candida albicans is the foremost aetiological agent of oral candidosis, which can be treated with polyene, azole, and echinocandin antifungals. However, once administered, the intraoral concentrations of these drugs tend to be subtherapeutic and transient due to the diluent effect of saliva and cleansing effect of the oral musculature. Hence, intra-orally, Candidamay undergo a brief exposure to antifungal drugs.Objective Therefore, the PAFE and hemolysin production of oral C. albicans isolates following brief exposure to sublethal concentrations of the foregoing antifungals were evaluated.Material and Methods A total of 50 C. albicans oral isolates obtained from smokers, diabetics, asthmatics using steroid inhalers, partial denture wearers and healthy individuals were exposed to sublethal concentrations of nystatin, amphotericin B, caspofungin, ketoconazole and fluconazole for 60 min. Thereafter, the drugs were removed and the PAFE and hemolysin production were determined by previously described turbidometric and plate assays, respectively.Results Nystatin, amphotericin B, caspofungin and ketoconazole induced mean PAFE (hours) of 2.2, 2.18, 2.2 and 0.62, respectively. Fluconazole failed to produce a PAFE. Hemolysin production of these isolates was suppressed with a percentage reduction of 12.27, 13.47, 13.33, 8.53 and 4.93 following exposure to nystatin, amphotericin B, caspofungin, ketoconazole and fluconazole, respectively.Conclusions Brief exposure to sublethal concentrations of antifungal drugs appears to exert an antifungal effect by interfering with the growth as well as hemolysin production of C. albicans.

Assessment of biomedical and pharmacological activities of sea anemones Stichodactyla mertensii and Stichodactyla gigantea from Gulf of Mannar Biosphere Reserve, southeast coast of India

Cnidarians comprise an old and diverse animal phylum, and possess a wide variety of biologically active substances. Sea anemones contain a diversity of interesting biologically active compounds including some potent toxins. In the present work, the sea anemones Stichodactyla mertensii and Stichodactyla gigantea, collected from the Mandapam coast, are characterized biomedically and pharmacologically. The crude protein was obtained by using methanol and aqueous extracts. The respective protein contents of S. mertensii and S. gigantea were found to be 2.10 µg/mL and 1.87 µg/mL. The methanol and aqueous extracts of S. mertensii and S. gigantea yielded six and nine bands by SDS-PAGE on 12 percent gel. In the hemolytic assay, both extracts exhibited hemolytic effect on chicken, goat, cow and human erythrocytes ('A', 'B' and 'O'). The neurotoxic effects of these crude extracts were determined in vivo using the sea shore crab Ocypode macrocera and mortality was observed. The mouse bioassay for lethality was performed on male albino mice. The crude extract of S. mertensii showed higher lethality (58 seconds at 1 mL-dose) than that of S. gigantea (2 minutes and 10 seconds at 0.75 mL-dose). The analgesic activity test was also carried out on albino mice by Eddy's hot plate and tail-flick methods. The extracts showed moderate analgesic effect by both hot-plate and tail-flick methods. These characteristics emphasize the need for the isolation and molecular characterization of new active toxins in S. mertensii and S. gigantea.(AU)