Antioxidant and antibacterial activities of Opuntia ficus indica seed oil fractions and their bioactive compounds identification

Abstract

Abstract Aim The two Opuntia ficus indica seed oil fractions (glyceridic and unsaponifiable) were compared to their biological activities and then assessed with their bioactive compounds. Methods Based on the inhibition concentration at 50 percent (IC50) values, the antioxidant activity of the two fractions was compared with three different tests. The antibacterial activity was assessed by the agar disk diffusion assay against five human pathogenic bacteria. Moreover, the main fatty acids composition and unsaponifiable compounds in Opuntia ficus indica seed oil were identified by gas chromatography/mass spectrometryand (GC/MS) and NP-HPLC. Results Results showed that antioxidant and antibacterial activities considerably varied depending on the fraction. In fact, unsaponifiable fraction has higher biological activities than the glyceridic ones. The unsaponifiable fraction has stronger effects of scavenging 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical and it is more efficient against bleaching of β-carotene than the saponifiable extract, unlike the experimental results of 2,2′-azino-bis3-ethylbenzthiazoline-6- sulfonic acid (ABTS) scavenging test. Furthermore, the unsaponifiable fraction was more efficient against all pathogenic strains specially Escherichia coli. The major fatty acids identified were: linoleic (61.42%), oleic (20.55%) and palmitic acids (11.88%). Such a difference in biological capacities between the two fractions can be explained by the high content of some bioactive compounds in the unsaponifiable fraction. Low level of squalene was present in the seed oil. But high levels of terpenic alcohols (3169 mg/kg) and of coenzyme Q9 (75.3 mg/kg) were detected in the Opuntia seed oil. Conclusion Informations provided through this work are important for the valorization and use of this cactus vegetable oil in cosmetic, pharmaceutical and nutraceutical industries.