Fig. 1

a Analytical HPLC chromatogram of methyl gallate showing single peaks at 10.994 min. b: Analytical HPLC chromatogram of catechin 3-O-gallate (CG) showing single peak at 11.15 min. Chromatographic conditions: Vision Ht C18 column (5 μm; 10 × 250 mm, Agilent USA). Mobile phase A (Millipore H₂O) and mobile phase B (acetonitrile) in gradients: 0–5 min; 15% B in A (isocratic run), 5–27 min; 15 to 100% B (Gradient mode), 27–32 min; 15% B in A (for column equilibration). Flow rate; 1 ml/min, injection volume 20 µl. Both compounds showed UV maxima at 280 nm (characteristic of polyphenolic compounds)