Screening of Alpha Amylase Inhibitory Activity and Antioxidant Activity of Selected Sri Lankan Medicinal Plants and Development of Herbal Tea

Aims: Herbal medicines are widely used because of its health benefits and minimum side effects. There are many underutilized medicinal herbs in Sri Lanka which are not subjected to any scientific study to prove their health benefits. The present study attempted to identify the health benefits and possibility to develop herbal teas from selected herbs; Solanum trilobatum, Ocimum tenuiflorum, Cardiospermum halicacabum, Acalypha indica and Plectranthus amboinicus.

Study Design: Complete Randomized Design was employed.

Place and Duration of Study: The study was carried out in Agricultural Chemistry Laboratory of Uva Wellassa University, Badulla, Sri Lanka From November 2018 to March 2019.

Methodology: Leaf samples of these herbs were oven dried for 12 hours at 50 . Infusions were prepared by boiling varying amounts of leaf samples from 1g to 5g in 100 ml of distilled water and tested for antioxidant activity with DPPH (1, 1-diphenyl-2-picrylhydrazyl) assay and α-amylase inhibition activity using Dinitrosalicylic acid method. Sensory evaluation was conducted for the same infusions with ISO-3103 specifications to select the best amounts of samples for consumption. The selected amounts were subjected to chemical analysis.

Results: The best antioxidant activity and α-amylase inhibition activity were observed in C.halicacabum with 7.71 mg ml-1 and 45.51 mg ml-1 IC50 values respectively. Results confirmed that all leaf infusions contain Anthocyanin (4.20-0.11mg dm-3), Polyphenols (120.49-32.93 mg dm-3 and Free Sugar (262.95-24.67mg dm-3).

Conclusion: Selected herbs show positive responses towards selected biochemical properties and there is a very good potential to develop herbal teas with interesting health benefits with high customer attraction. C. halicacabum shows the best potential among selected herbs. However, it is suggested to carry out further studies to confirm these results and find out any adverse effects of overconsumption.