Anxiolytic and Peripheral Analgesic Effects of Myrianthus Arboreus Stem Bark Extract and its Fractions in Mice

Myrianthus arboreus stem bark is used as an anti-anxiety and pain reliever in traditional medicines. However, scanty scientific reports are available to corroborate these ethnomedicinal claims. Hence, this study investigated the anxiolytic and peripheral analgesic potentials of methanol stem bark extract and fractions of Myrianthus arboreus in mice. The anxiolytic potential was evaluated using elevated plus maze while the peripheral analgesic effect was investigated using mouse model of acetic acid induced writhing test. The Fourier-transform infrared analysis of the dichloromethane fraction was also carried out. The Myrianthus arboreus extract (125-500 mg/kg), dichloromethane and aqueous fractions at 250 mg/kg significantly (p<0.05) reduced the anxiety indices of mice compared to control, consistent with an anxiolytic effect. The crude extract and all the investigated fractions significantly (p<0.05) reduced the number of abdominal constrictions elicited by acetic acid compared to control, consistent with peripheral analgesic potentials. The Fourier-transform infrared analysis showed several functional groups in the dichloromethane fraction. The hydroxyl functionality in this fraction may be an integral part of some phenolic compounds such as flavonoid and tannins. This study concluded that Myrianthus arboreus may possess secondary plant metabolites responsible for its anxiolytic and peripheral analgesic potentials.