Phenolic and flavonoid contents, antioxidant and antimicrobial activities of leaf extracts from ten Algerian Ficus carica L. varieties

Abstract

Objective: To determine the total phenolic and flavonoid contents, antioxidant and antimicrobial activities of methanolic leaf extracts of ten Algerian fig (Ficus carica L.) varieties (uniferous, biferous and caprifig tree). Methods: Phenolics were extracted by Soxhlet method and analyzed by the Folin–Ciocalteu colorimetric method. Flavonoids were determined by aluminum trichloride assay and the antioxidant capacity was determined by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. The antimicrobial activity was studied with the disc diffusion method and a macrodilution broth method was used to determine the minimal inhibitory concentrations and minimal lethal concentrations. Results: The mean extract yield was 14.10% ± 0.66% (n = 10). Leaf extract of biferous followed by uniferous varieties had the highest total phenolic contents [(52.296 ± 5.232) and (48.973 ± 2.015) mg gallic acid equivalent/g of dry plant extract respectively], flavonoids [(14.388 ± 0.333) and (14.136 ± 1.082) mg quercetin equivalent/g of dry plant extract] and antioxidant capacity [IC50 (798.754 ± 108.590) and (825.004 ± 110.835) μg/mL]. Antioxidant capacity of fig leaves was significantly correlated with phenolic contents (r = 0.748). These extracts showed bactericidal activity and moderate antifungal activity, and the minimal inhibitory concentrations and minimal lethal concentrations were determined on Bacillus cereus and Staphylococcus aureus. Conclusions: All tested extracts contain phenolic compounds and exhibited an antioxidant activity and an antimicrobial effect against Gram-positive and Gram-negative bacteria. Further researches on identification and purification of phenolic compounds are required.

Keywords

• Fig leaves
• Phenolics
• Flavonoids
• Antioxidant activity
• Antimicrobial activity