The impact of regional locality on chemical composition, anti-oxidant and biological activities of Thymelaea hirsuta L. extracts

Abstract

Background: Thymelaea hirsuta L. is a medicinal plant endemic to Tunisia, commonly used for its biological properties in traditional medicinal.

Purpose: This study reports, to the best of our knowledge for the first time, the effect of regional location on the chemical composition, anti-oxidant and biological activities of organics extracts obtained from aerial parts of T. hirsuta.

Methods/study design: The aerial parts collected from different locations were prepared by sequential method with solvents of increasing polarity namely hexane, ethyl acetate, ethanol and methanol. An assessment of the anti-oxidant properties of all extracts was performed using DPPH and ABTS⁺ assays. We also investigated the anti-cholinesterase, anti-xanthine oxidase and cytotoxic (against MCF-7 and OVCAR) activities.

Results: The study of the phytochemical composition showed that the extracts are rich in phenolics (5.38-315.65 mg GAE/g dw) and tannin (0.7-73.8 mg CE/g dw). Also, the results showed that the chemical composition as well as the biological activities varies considerably between regions. The DPPH and ABTS⁺ assays revealed that the highest important antioxidant activity was in the methanolic extract for all localities (IC50: 14.8-16.5 mg/l and 6.4-22.23 mg/l, respectively). However, the various extracts had moderate anti-cholinesterase activity (7.52-45.36%) at 50 mg/l. Regarding the xanthine oxidase inhibitory activity, ethyl acetate extract exhibited a moderate activity at a 50 mg/l. The highest cytotoxic activity against MCF-7 and OVCAR was recorded in the ethyl acetate extract of Fernana region (70.1% and 70.8% inhibition at 50 mg/l, respectively). The analysis of HPLC-UV indicates the presence of several phenolic compounds in different extracts of T. hirsuta, possibly accounting for its biological properties.

Conclusion: The phenolic contents were highly correlated to anti-oxidant activity with very high correlation coefficient (R²) values. The findings show that the extracts are rich in antioxidant compounds and this plant may be used as a natural source of bioactive compounds with high anti-oxidant and potential anticancer activities.

Keywords: Anti-oxidant activity; Biological activities; Cytotoxic activity; HPLC-UV; Phytochemical composition; Thymelaea hirsuta L.