Untargeted Phytochemical Profiling, Antioxidant, and Antimicrobial Activities of a Tunisian Capsicum annuum Cultivar

Peppers are among the spices possessing a wide plethora of biological properties due to their excellent supply of health-related metabolites. Capsicum annuum L. (Solanaceae) is cultivated throughout Tunisia, and there is a shortage of information on the identification of the secondary metabolites in the seeds of this species as well as on their biological activities. In the present work, we intended to undertake a chemical characterization of the bioactive compounds from the hydromethanolic seed extract of C. annuum as well as an evaluation of its broad spectrum of antimicrobial and antioxidant activities. The chemical profile was evaluated by RP-HPLC-DAD-QTOF-MS/MS, whereas the total phenol and flavonoid content, antioxidant, and antimicrobial activities were determined in in vitro assays. In this work, 45 compounds belonging to various phytochemical classes, such as organic acids (2), phenolic compounds (4 phenolic acids and 5 flavonoids), capsaicinoids (3), capsianosides (5), fatty acids (13), amino acids (1), sphingolipids (10), and steroids (2) were identified in the hydro-methanolic seed extract of C. annuum. The phenolic and flavonoid content (193.7 mg GAE/g DW and 25.1 mg QE/g DW, respectively) of the C. annuum extract correlated with the high antiradical activity (IC50 = 45.0 mu g/mL), reducing power (EC50 = 61.3 mu g/mL) and chelating power (IC50 = 79.0 mu g/mL) activities. The hydro-methanolic seed extract showed an important antimicrobial activity against seven bacterial and four fungal strains. In fact, the inhibition zones (IZs) for bacteria ranged from 9.00 +/- 1.00 mm to 12.00 +/- 0.00 mm; for fungi, the IZs ranged from 12.66 +/- 0.57 mm to 13.66 +/- 0.57 mm. The minimal inhibition concentration and minimal bactericidal concentration values showed that the extract was more effective against fungi than bacteria.

Automated summary

This study characterized the bioactive compounds in the seed extract of Capsicum annuum L. and evaluated its antimicrobial and antioxidant activities. The extract was found to contain various phytochemical classes, including phenolic compounds and flavonoids. The phenolic and flavonoid content correlated with the extract's high antiradical, reducing power, and chelating power activities. The extract also exhibited significant antimicrobial activity against both bacteria and fungi.