PHYTOCHEMICAL COMPOSITION AND EVALUATION OF ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF TUNISIAN OPUNTIA DILLENII PEEL FRUITS

Sabrine Ben Lataief, Mohamed-Nizar Zourgui, Wissal Affi, Amal Daoud, Néji Gharsallah and
Lazhar Zourgui*

ABSTRACT

Considering that the chemical additives are generally toxic, Opuntia dillenii is known by their natural bioactive compounds useful as an added ingredient in drug and cosmetic product preservatives. The purpose of this study was to analyze the phytochemical composition, antioxidant and antimicrobial activities of peel fruit extracts (aqueous and ethanolic) from O.dillenii growing in southern Tunisia, especially in Djerba Island. The effect of two solvents (water and ethanol) on the phenolic composition of O.dillenii peel fruits and their biological activities were studied. The results showed that the ethanolic extract was the most effective solvent for the polyphenolic extraction, as confirmed by HPLC-MS. The quinic acid was the major compound in both extracts. GC-MS analysis revealed the presence of 9 bioactive compounds identified in the ethanolic extract. The little mean values of IC50 were recorded by ethanolic extract (IC50 DPPH= 0.32 ±0.001 mg/mL and IC50 NO=0.1±0.0006 mg/mL) and the highest mean values of FRAP (optical density= 1.84±0.002) and TAC (91.81±0.92 mg EAA/g) were observed also in this extract (p<0.05). S. aureus, M. luteus, and P. Catenulatum were found to be the most sensitive strains. The Pearson’s coefficient revealed a strong correlation between the TPC, TFC and the parameters of antioxidant activity. The finding suggested that Opuntia dillenii is an edible plant that could improve the proprieties of drug and cosmetic products as a natural additive.

Keywords: Opuntia dillenii, peel extracts, HPLC-ESI-MS, GC-MS, antioxidant activity, antimicrobial activity.