Comparative analysis of phytochemicals, antimicrobial and antioxidant activity of different species of Terminalia from Himachal Pradesh, India

The genus Terminalia (Family Combretaceae) is amongst the most widely used traditional medicinal plants worldwide. The present study aimed to investigate the phytochemical variation, and medicinal properties among three species of Terminalia, viz. Terminalia arjuna (TA), T. bellerica (TB) and T. chebula (TC) found in North western Himalayan Region, India. Phytochemical variation was done using spectrophotometric quantification of total phenolic and flavonoids. Gallic acid and Rutin were used as marker compounds. Quantification of phytocompounds was done using HPLC method. Total phenolic content (TPC) was highest in fruits of TC (350 ± 20.19 mg/g gallic acid equivalents, GAE) followed by bark of TA (233.64 ± 24.31 mg/g GAE), leaves of TC (200 ± 12.23 mg/g GAE), fruits of TB (186.5 ± 36.02 mg/g GAE), leaves of TB (170.36 ± 34.17 mg/g GAE) and leaves of TA (140.52 ± 36.19 mg/g GAE). Total flavonoid content (TFC) was highest in leaves of TC (212 ± 8.27 mg/g rutin equivalents, RE), followed by bark of TA (181.095 ± 13.87 mg/g RE), fruits of TC (153.8 ± 15.37 mg/g RE), leaves of TA (101.65 ± 6.21 mg/g RE), leaves of TB (93.65 ± 29.86 mg/g RE) and fruits of TB (84.71 ± 22.3 mg/g RE). Gallic acid was found to be higher in leaves of TB (74 µg/ml); whereas rutin was highest in leaves of TC (9.3 µg/ml). FTIR analysis showed the presence of several common peaks and some unique peaks in all the three species. Highest antioxidant potential was shown by TC (fruits) with IC50 value of 5.8 ± 1.4 µg/ml (DPPH), 4.35 ± 0.24 µM (FRAP), 4.55 ± 0.72 µg/ml (NO)] and TC (leaves) with IC50 value of 4.38 ± 1.25 µg/ml (DPPH), 8.6 ± 0.59 µM (FRAP), 5.95 ± 0.64 µg/ml (NO)]. Similarly, the antibacterial potency was also higher in fruits and leaves of TC as clearly visible with diameter of zone of inhibition and MIC value against all tested bacterial strains. The current study highlighted the medicinal importance of all the three members of Terminalia found in North-western Himalayas. T. chebula ranked higher among all the three species of Terminalia in biological activities, thereby validating its importance in therapeutics and food industry.