Development of safer molecules through chirality.

Many of the drugs currently used in medical practice are mixtures of enantiomers (racemates). Many a times, the two enantiomers differ in their pharmacokinetic and pharmacodynamic properties. Replacing existing racemates with single isomers has resulted in improved safety and/or efficacy profile of various racemates. In this review, pharmacokinetic and pharmacodynamic implications of chirality are discussed in brief, followed by an overview of some important chiral switches that have yielded safer alternatives. These include levosalbutamol, S-ketamine, levobupivacaine, S-zopiclone, levocetirizine, S-amlodipine, S-atenolol, S-metoprolol, S-omeprazole, S-pantoprazole and R-ondansetron. Few potential chiral switches under evaluation and some chiral switches that have not been successful are also discussed.

Study of anti-fertility effect of lemon seeds (Citrus limonum) in female albino mice.

Among the citrus species, Citrus-limonum is native of North West region of India. The petroleum ether, alcoholic and aqueous extracts of Citrus-limonum (lemon) seeds were investigated for anti-fertility effect in female albino mice. The extracts were administered orally for 7 days after insemination (i.e. post-ovulatory test). The control group received 4% gum acacia. The animals were examined for implantation sites on 10th day of pregnancy and the number of pups delivered at term for each group was recorded. The alcoholic extract showed significant anti-fertility effect as compared to petroleum ether and aqueous extracts. The alcoholic extract was subjected for fractionation and the fractions were again tested for their anti-fertility effect. The fraction of ethyl-acetate (12-25 fractions) showed most encouraging anti-fertility activity. In second part of the study, the alcoholic extract and its ethyl-acetate fraction (12-25 fractions) were subjected to evaluation of their mechanism of action and it was found that their principal mode of action is as an anti-zygotic agent. Withdrawal of the test drug, resulted in complete restoration of fertility. Thus the ethyl-acetate fraction (12-25 fractions) of alcoholic extract of lemon seeds exerted reversible anti-fertility effect in female mice by virtue of its anti-zygotic action.