EFFECT OF HIGH-DOSE MORINDA CITRIFOLIA (MC) LEAF ETHANOLIC EXTRACT ON SWIMMING ENDURANCE IN FEMALE SPRAGUE DAWLEY RATS

Abstract

Morinda citrifolia (MC) is a herb that is famous for its various medicinal properties. However, there has been little research on its effect on increased stamina and physical fatigue reduction. The purpose of this study was to determine the effect of high-dose oral intake of 50% ethanol MC leaf extract on exercise performance and physical fatigue in an animal model. Thirty female Sprague-Dawley rats were divided into five groups; Control (C); Sedentary (S); Exercise (EX); MC leaf extract 1000 mg/kg/day (MC); MC leaf extract 1000 mg/kg/day with Exercise (MC+EX). The endurance test showed a significant difference in endurance time between EX and MC groups, whereby intake of MC leaf extract without daily exercise lowered endurance level by 68.75%. These findings correlated with serum fatigue indicator analysis whereby significant increases in CK levels of MC group, and LDH levels in MC and MC+EX groups were noted when compared to other groups. Electron microscopy analysis on cardiac muscle tissue showed ultrastructural injuries in muscle fibers of the EX, MC and MC+EX groups whereas injuries to the gastrocnemius myofibres were not so prominent. Based on the study findings, it can be concluded that the consumption of 1000 mg/kg/day 50% ethanol MC extract disturbed internal physiology and resulted in injury to the muscle tissues thus lowering rats endurance capability. This shows that a high dose has unfavourable effects on an animal model while a lower dose may be more appropriate.