BACKGROUND: Mitragyna speciosa (MS) or ketum is primarily found in Southeast Asia, particularly in northern Malaysia and Thailand. The medicinal value of this plant has attracted significant attention from both herbal medicine practitioners and scientists worldwide. Despite having illegal consumption status, the plant merits study. We conducted a series of experiments to test our hypothesis that ketum impairs both learning and memory in rats.
METHODS: Ketum leaves were extracted using methanol and standardised for the amount of its pure compound, mitragynine. Rats were divided into groups for a passive avoidance task and long-term potentiation (LTP) extracellular recording. In the extracellular recording condition, rats were grouped into control, MS100 (100 mg/kg of ketum extract), MS200 (200 mg/kg of ketum extract), and MS500 (500 mg/kg of ketum extract) groups. An additional group that received morphine was included in the passive avoidance task (10 mg/kg), and there were six animals per group. Rats received daily treatments orally for 28 days for both experiments.
RESULT: Using a passive avoidance task, our data revealed that the rats' memory significantly increased with increasing doses of MS compared to the morphine-treated group. Our findings from LTP recordings showed that LTP was fully blocked by the higher doses of MS.
CONCLUSION: We speculate on the possibility that additional factors were involved in the passive avoidance task because it was an in vivo animal study, while the LTP experiment solely involved brain slices.
Mitragyna speciosa Korth, or better known as ketum, has long been used by traditional folk around Southeast Asia to prevent fatigue from working under hot tropical weather and as a replacement of opium, which can then cause addiction. To date, no findings have been reported of the toxic effect of ketum subchronically (28 days). Hence, the aim of this study was to investigate the toxicity of subchronic effect of standardized methanolic extract of ketum (SMEMS) in Sprague-Dawley rats. Rats were orally administered with 100, 200, and 500 mg/kg of SMEMS for 28 days. Body weights were recorded daily. They were terminated at day 28 to obtain data for hematology, biochemistry, and histopathology of the brain, liver, kidney, lung, heart, sciatic nerve, and spinal cord. The SMEMS affected body weight compared to control group. Biochemistry findings showed that liver and kidney were affected with the abnormal values in AST, creatinine, globulin, glucose, total protein, and urea. However, SMEMS produced toxic effect more to liver, kidney, and lung than other organs as observed histopathologically. The results suggested subchronic exposure of ketum is toxic to the physiology of the animals.