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02243 EVALUATION OF ANTIMICROBIAL AND CONTRACEPTIVE ACTIVITIES OF NISIN: IN VITRO AND IN VIVO STUDIES Reddy,K.V.R A number of vaginal microbicides are currently undergoing preclinical or clinical trials to assess their acceptability, safety and efficacy in protecting women from STI/HIV infections and unintended pregnancies. Since the best known microbicide, Nonoxynol-9 causes vaginal toxicity, a major challenge is to design mechanism based microbicides that are highly effective against infections and unwanted pregnancies while lacking detergent-type effects. Therefore, we evaluated Nisin, a known naturally occuring antimicrobial peptide. Nisin is a 34 amino acid peptide having a molecular weight of ~3.5 kDa. The peptide is produced by bacteria, Lactococcus lactis and is being used as a food preservative. Nisin (400 ?g)is found to inhibit sperm motility in a dose and time dependent manner. Intravaginal administration of a single dose of Nisin blocked conception in rats (200 ?g) and rabbits (1 mg/ml). Repeated intravaginal application of Nisin (50 mg/day/14 consecutive days) was found to be safe and did not cause local, systemic or reproductive toxicity. In addition, Nisin inhibits the growth of STI causing pathogens at a concentration of 200 ?g. In conclusion, under the conditions of its intended to use as a dual function spermicidal microbicide, Nisin has a unique advantage that may greatly enhance its prophylactic capability against conventional STIs. Reddy Venkata Rami Kudumula |
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