Chemical composition, antioxidant, antimicrobial and cytotoxic activities of bioactive compounds extracted from Opuntia dillenii cladodes

Opuntia dillenii has been used in folk medicine as a natural remedy for its diverse biological activities and bioactive compounds. The present study aimed to quantify the bioactive substances of cladode extracts (aqueous and ethanolic) of O. dillenii from Djerba Island, Tunisia and evaluate their antioxidant, antimicrobial and cytotoxic potentials. The results showed that O. dillenii cladodes had a high amount of total phenolic content (TPC) and total flavonoid content (TFC). Interestingly, by LC-MS analysis, we found that most of the phenolic and volatile compounds were present in the ethanolic extract. Indeed, quinic acid (58.78 µg/g), quercetin (11.5 µg/g), rutin (7.02 µg/g), luteolin (4.93 µg/g), cirsiliol (3.22 µg/g) were the major phenolic compounds in O. dillenii ECE. GC-MS analysis of O. dillenii ACE and ECE revealed that n-hexadecanoic acid (13.08%), and stigmastan-3, 5-diene (6.97%) were the main volatile compounds detected in ECE. Correlation analysis showed that the TPC and TFC were significantly correlated with the antioxidant, antimicrobial and cytotoxic activities. Staphylococcus aureus, Micrococcus luteus, and Fusarium oxysporum were found to be the most sensitive strains. Finally, the human colon carcinoma cell line Caco-2 was more sensitive to aqueous and ethanolic extracts with an IC50 = 50.89 ± 0.01 µg/mL and IC50 = 40 ± 0.01 µg/mL, respectively than K-562 cell line.