Statistical optimisation of Mitragyna speciosa leaves extract via central composite design and its phytochemical characterisation

The demand for natural-based remedies is rising due to their safety and efficiency compared to synthetic-based medicine. In view of this, the unique bioactive properties of Mitragyna speciosa (M. speciosa) have attracted high interest for its potential application in the pharmacological industry. Therefore, this study aimed to optimise the Ultrasound-Assisted Extraction (UAE) method using Response Surface Methodology (RSM) for the production of crude methanolic extract from M. speciosa leaves. Statistical optimisation was performed to evaluate the effect of temperature, extraction time, and volume of solvent. The phenolic and flavonoid contents of crude methanolic extract were analysed through Total Phenolic Content (TPC) and Total Flavonoid Content (TPC), respectively. Furthermore, Gas Chromatography-Mass Spectrometry (GC-MS) was carried out to determine the characteristic of the crude methanolic extract. The optimal conditions at a temperature of 34 °C, extraction time of 25 min, and volume of the solvent of 166 mL resulted in a maximum yield of 49.72% of the crude methanolic extract with TPC and TFC recorded at 137.3±15.7 mg GAE/g and 90.3±15.3 mg RE/g, respectively. The GC-MS analysis identified the presence of 18 phytochemical compounds in the crude extract including glycerine, phytol, and stigmasterol. These identified compounds could exhibit certain therapeutic effects, such as anti-inflammatory, antioxidant, and antibacterial effects. Therefore, the findings in this study support the suggestion that the various available bioactive compounds besides alkaloid contributed to the bioactive properties in M. speciosa, making it an effective traditional herbal medicine to treat various illnesses.