Influence of Harvest Age, Extraction Method and Solvent Polarity on the Enzyme Inhibitory Activity of Orthosiphon aristatus Extracts.

<b>Background and Objective:</b> The rising prevalence of diabetes mellitus in Indonesia highlights the urgent need for effective, natural therapeutic options. This study evaluates the antidiabetic potential of <i>Orthosiphon aristatus </i>(Blume) Miq. (cat's whiskers) by analyzing the effects of harvest age, extraction method and solvent polarity on its ability to inhibit α-amylase and α-glucosidase enzymes-key targets in diabetes management. <b>Materials and Methods:</b> Tissue-cultured <i>O. aristatus</i> plants harvested at 6 and 9 months were subjected to three extraction methods: Ultrasonic-assisted, maceration and infusion, using solvents of varying polarity (water, 30 and 70% ethanol). Extract yields and inhibitory activities were assessed and IC values were determined using standard <i>in vitro</i> enzyme inhibition assays. Data were analyzed statistically to compare extraction efficiency and biological activity. <b>Results:</b> Ultrasonic extraction with 30% ethanol from 9-month-old plants produced the most effective extract, yielding 10% extract with strong inhibitory activity: IC values of 64.35 ppm (α-amylase) and 64.68 ppm (α-glucosidase). Both harvest age and extraction parameters significantly influenced extract potency. <b>Conclusion:</b> The study demonstrates that harvest age and extraction strategy critically affect the antidiabetic efficacy of <i>O. aristatus</i> extracts. These findings support its potential as a complementary therapy in diabetes management and provide direction for optimized extraction protocols in future pharmacological applications.