Quantification of total polyphenols, catechin, caffeine, L-theanine, determination of antioxidant activity and effect on antileishmanial drugs of ethiopian tea leaves extracts

Abstract

Objective:In this study four tea samples Gumero black, Wushwush black and Wushwush green from Agri- Ceft Plc and East Africa black tea leaves from East African Agribusiness Plc were investigated for total polyphenols, caffeine, catechin and L-theanine content.Materials and Methods:The aqueous extracts were investigated for their antioxidant and antileishmanial property and effect on amphotericin B, miltefocine and sodium stibogluconate, the commonly used antileishmanial drugs. Antileishmanial studies were conducted on L. aethiopica.Results:Wushwush green tea had the highest content of polyphenol (19.98 ± 1.15 mg gallic acid equivalent /100 g dry leaf weight), catechin (37.06 mg/g) and L-theanine (48.54 mg/g but the lowest caffeine content). It exhibited the highest antioxidant activity. The highest antioxidant effect of Wushwush green tea may be attributed to the highest polyphenol content. East African black tea had the lowest L-theanine (20.72 mg/g) and antioxidant activity but the highest caffeine (16.60 mg/g) content.Conclusion:Wushwush green tea showed slight inhibitory effect on L. aethiopica while the lack tea extracts (Gumero, East Africa and Wushwush) exhibited no antileishmanial activity. Wushwush green tea did not show any synergistic or antagonistic effect on the antileishmanial drugs used in this study while Gumero, East Africa and Wushwush black tea extracts exhibited dose dependant inhibitory activity to the commonly used antileishmanial drugs included in this study.

Synergisms in alpha-glucosidase inhibition and antioxidant activity of Camellia sinensis L. Kuntze and Eugenia uniflora L. Ethanolic Extracts

“…[ 3 ] Since then, several studies have been performed in different species aiming to find new sources of inhibitors of this enzyme due to increase cases of T2DM in the world. Researchers have proposed different species as natural sources of alpha-glucosidase inhibitors including Camellia sinensis L. Kuntze (green tea), the most consumed and popular beverages worldwide,[ 4 ] and Eugenia uniflora L. (Brazilian Pitanga), a Brazilian native species that, shows in recent years an interesting potential as source of bioactive compounds. Both species have been already confirmed to have beneficial effects in the treatment of diabetes mellitus.…”