Seasonal assessment of the best harvesting months of Bangladeshi Piper betle L. (Piperaceae) leaves: Insights into polyphenols and antioxidant activity using multivariate techniques

This study evaluated monthly and maturity stage variations in polyphenols [total phenol (TP) and total flavonoid (TF)] and antioxidant activity (AA) in Piper betle L. leaves collected between 2021 and 2024. TP and TF were quantified using the Folin-Ciocalteu and aluminum chloride methods, respectively, while AA was measured by DPPH and ABTS assays. TP and TF ranged from 23.56 ± 3.51 to 58.81 ± 26.15 mg GAE/g and 8.93 ± 0.29 to 35.55 ± 0.14 mg QE/g, respectively. IC50 values for DPPH and ABTS varied from 0.45 ± 0.010 to 1.70 ± 0.000 and 0.24 ± 0.001 to 0.87 ± 0.001 (mg AAE/mL), subsequently. The highest TP, TF, and AA were found in March, corresponding to low rainfall (18 mm), moderate temperature (25.35 °C), and humidity (70.5%). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) identified three seasonal clusters. March is recommended as the optimal harvest month to maximize bioactive potential for food, pharmaceutical, and cosmetic applications.