In-Vitro Bioactivity Evaluation of Hydrangenol Extracted from Hydrangea macrophylla (Thunb.) Ser. Leaves

Abstract

Hydrangea macrophylla plant, native to Japan and Korea, has been attracting scientific attention due to its potential applications in both food science and health-related research. In this investigation, dry Hydrangea leaves were utilized as the source material. Subsequent to comminution and thermal treatment at 70 °C for an 18-hour duration, followed by a 30-minute ultrasonic bath extraction and a 5-minute centrifugation at 5000 rpm, hydrangenol was isolated through preparative HPLC. The investigation involved assessing the antioxidant capacity of hydrangenol, its impact on the activity of α-amylase and α-glucosidase enzymes, and its ability to prevent enzymatic browning. Quantification of antioxidant capacity, determined through TEAC (Trolox Equivalent Antioxidant Capacity), showed values from 1.8 to 3.2 mmol TE/mmol. Likewise, the ORAC (Oxygen Radical Absorbance Capacity) values were in the range of 16.5-27.0 mmol TE/mmol. Total phenolics content (Folin-Ciocalteu test) yielded a range of 7.1-11.2 g GAE (Gallic Acid Equivalents) per 100 g. Examining α-amylase inhibition, hydrangenol demonstrated a 52% inhibition (IC50: 3.6 mg/mL), whereas acarbose (positive control) displayed a higher inhibition of 99 % (IC50: 0.51 mg/mL). Regarding α-glucosidase inhibition, hydrangenol exhibited a 51% inhibition (IC50: 0.97 mg/mL), while acarbose displayed a 46% inhibition (IC50: 2.1 mg/mL). Additionally, the activity of PPO was suppressed by 61% at hydrangenol concentrations of 1 mg/mL and 2 mg/mL, and by 46% at a concentration of 4 mg/mL.