Abstract

In recent years, research on medicinal plants has engrossed a lot of interest worldwide. Large body of proof has been accumulated to reveal promising potential of medicinal plants used in different traditional, complementary and alternative systems. Keeping this in mind, the present study was carried out to scrutinize the antinociceptive and central nervous system (CNS) depressant activity of the methanol extracts of seed (MNLS) and peel (MNLP) of Nephelium longan in young Long-Evans rats. Both types of tests were conducted after oral administration at doses of 250 and 500 mg/kg body weight of rats. CNS activity was evaluated by watching the fall of rats in locomotor and exploratory activities. We also used open field and hole cross tests. The analgesic activity was examined using acetic acid-induced writhing and formalin tests. The results of the statistical analysis showed that the experimental extracts had significant (P < 0.01 and 0.05,) dose dependent CNS depressant and antinociceptive activities. In the acetic acid-induced writhing model, MNLP at dose of 500 mg/kg exerted a maximum of 54.43% inhibition of writhing response, whereas MNLS gave 52.531% inhibition which are comparable to 58.86% inhibition of writhing by standard drug, indomethacin (10 mg/kg). In case of CNS depressant activity, both extracts displayed dose dependent suppression of motor activity and exploratory behavior in the tested models. The results of the study indicate that the plant possesses strong analgesic and central nervous system depressant activity.

Key words: Nephelium longan, antinociceptive, indomethacin, CNS depressant activity.