The therapeutic potential of plant extracts has attracted significant interest, especially regarding indigenous species with health-promoting properties. Gymnema inodorum, native to Northern Thailand, is recognized for its rich phytochemical profile; however, the impact of various extraction techniques on its phenolic composition and bioactivity remains underexplored. Optimizing extraction methods is essential to enhance the pharmacological efficacy of this plant’s bioactive compounds. This study investigated the influence of four extraction methods—ethanol maceration, ethanol reflux, aqueous decoction, and microwave-assisted extraction—on the bioactive profile of G. inodorum leaves, with a focus on the phenolic content and biological activities. Antioxidant activities were evaluated using DPPH, ABTS, and FRAP assays, while the total phenolic and flavonoid contents were quantified by colorimetric methods. High-Performance Liquid Chromatography (HPLC) quantified gymnemic acid and key phenolic compounds. Among the methods, ethanol reflux yielded the highest antioxidant activities (DPPH and ABTS scavenging), with a total phenolic content of 82.54 mg GAE/g and flavonoid content of 31.90 mg QE/g. HPLC analysis identified sinapic acid, myricetin, and p-hydroxybenzoic acid as major phenolics. Furthermore, the ethanol reflux extract displayed potent anti-diabetic activity, with IC₅₀ values of 13.36 mg/mL for α-amylase and 7.39 mg/mL for α-glucosidase, as well as strong anti-inflammatory activity (IC₅₀ of 1.6 mg/mL) and acetylcholinesterase inhibition (IC₅₀ of 1.2 mg/mL). These findings suggest that ethanol reflux extraction is a highly effective method for producing bioactive-rich G. inodorum extracts, with substantial pharmacological potential for developing herbal remedies and nutraceuticals, particularly in enhancing therapeutic approaches for diabetes and other health-related conditions.

Cocoa husk tea has gained attention as a value-added beverage from cocoa processing by-products, due to its potential content of bioactive compounds associated with health benefits. However, rapid and reliable analytical methods for the simultaneous determination of methylxanthines and flavanols in this matrix remain limited. This study aimed to develop and validate a rapid HPLC–PDA method for the simultaneous determination of methylxanthines and selected flavanols in cocoa husk tea. Separation was performed using a Zorbax 300SB-C18 with a gradient system of acetic acid, water and acetonitrile, and detection at 280 nm. The method enabled separation of theobromine, caffeine, catechin, epicatechin, procyanidin B1, and procyanidin B2 within 15 min. Validation followed ICH Q2(R2) guidelines, demonstrating satisfactory linearity, sensitivity, accuracy, and precision. The method was applied to ten commercial cocoa husk tea products from Thailand. Theobromine was the predominant methylxanthine (10.483–16.027 mg g⁻¹), whereas caffeine was lower (0.923–1.909 mg g⁻¹), while flavanol contents varied among samples. These findings demonstrate that the developed method provides a rapid and reliable approach for the analysis and quality assessment of cocoa husk tea products and may support the further utilization of cocoa by-products in the functional beverage industry.