Abstract
Background:
Currently, research is focused on therapeutic plants which are regarded as a supply of several phytotherapeutic compounds with several activities; among these plants we find cacti.

Aim:
The purpose of this work is to reveal the phytochemical composition and the antioxidant and antimicrobial properties of fruit peel from Opuntia stricta.

Methods:
The phenolics profile has been obtained by LC-ESI-MS analysis, antioxidant capacity has been evaluated by DPPH, FRAP, CAT, and ABTS• + free radical, the antimicrobial activity was tested against 7 bacteria and 3 fungi.

Results:
The results reveal that EFOS has a high content in polyphenols, flavonoids, quinic acid and hyperoside which were the most dominant. Moreover, the observed antioxidant capacity of extract was remarkable. In addition, a high antimicrobial capacity especially against Staphylococcus aureus and Pythium catenulatum. These results indicate that fruits peels of O. stricta have potential applications as a natural preservative in cosmetics and in food formulations, and also as a natural remedy.

Conclusion:
The finding proved that EFOS is characterized firstly by a wide variability of polyphenols and flavonoids and secondly by a good potential antioxidant and antibacterial activities.

Key words: Opuntia stricta, Phytochemical composition, LC-ESI-MS analysis, Antioxidant, Antimicrobial activities