EVALUATING ANTIOXIDANT CAPACITY, ALPHA-GLUCOSIDASE INHIBITORY POTENTIAL, AND BIOACTIVE COMPOUND QUANTIFICATION IN NOVEL HERBAL TEA BLENDS FEATURING CAMELLIA HAKODAE NINH FLOWERS

Camellia hakodae Ninh (C. hakodae Ninh) flowers, an endemic medicinal species in Vietnam, have attracted interest for their potential use in functional food and phytotherapy. This study evaluated the antioxidant and α-glucosidase inhibitory activities, as well as quantified total polyphenol and flavonoid contents, of herbal tea-bag formulations prepared from C. hakodae Ninh flowers combined with traditional medicinal herbs. Antioxidant capacity and α-glucosidase inhibition were determined using DPPH radical scavenging and in vitro enzymatic assays, respectively, while total polyphenol and flavonoid contents were measured spectrophotometrically using gallic acid and quercetin standards. Among the four formulations, CT1 (containing 50% C. hakodae Ninh flower) exhibited the strongest bioactivities, with IC₅₀ values of 288.41±5.84 µg/mL for DPPH and 86.15±2.45 µg/mL for α-glucosidase inhibition (p < 0.05). Its total polyphenol and flavonoid contents were 45.39±1.82 mg GAE/g and 10.35±0.48 mg QE/g, respectively. These results demonstrate that C. hakodae Ninh flowers, in combination with other herbal ingredients, contribute significantly to antioxidant and antidiabetic potential, supporting their development as functional herbal tea products for health promotion and glycemic control.