First report on essential oil composition and biological activities of five Strobilanthes species from Kumaun Region of Uttarakhand, India

In the present investigation the chemical composition and biological activities of essential oils (EOs) of the five Strobilanthes species viz., S. angustifrons C. B. Clarke, S. pentastemonoid M, (Nees) T. Anderson, S. tomentosa (Nees) J.R.I.Wood, S. attenuata (Wall. ex Nees) Jacq. ex Nees and S. glutinosa (Nees) collected from different locations of Kumaon region, Uttarakhand, India were examined and reported for the first time. The essential oils were analysed for their chemical composition by GC-MS. The yield of the hydro distilled essential oils was ranging from 0.2 to 0.3% (v/w). GC-MS results revealed a wide variability in the chemical composition among the studied Strobilanthes species. Among the biological activities, highest anti-inflammatory activity was recorded for S. angustifrons EO (IC50 = 9.6 +/- 0.57 mu L/mL). Highest antioxidant activity in terms of DPPH and metal chelating activity was shown by S. pentastemonoid EO (IC50 = 15.32 +/- 0.48 mu L/mL and 23.29 +/- 0.13 mu L/mL, respectively). Highest antioxidant activity in terms of H2O2 scavenging activity and highest antidiabetic activity was shown by S. attenuate EO (IC50 = 21.82 +/- 0.53 mu L/mL) and S. tomentosa EO (IC50 = 21.82 +/- 0.53 mu L/mL), respectively. The biological activity data revealed the significant antioxidant, anti-inflammatory and antidiabetic activities of the studied Strobilanthes species. Therefore, the essential oils of these species can be a good natural product to be used as ecofriendly antioxidant, anti-inflammatory and antidiabetic agents.