Phytochemical profile, antioxidant, antimicrobial and antipancreatic lipase activities of fermented Camellia japonica L leaf extracts

Abstract

Purpose: To investigate the probable antioxidant, antimicrobial and  antipancreatic lipase effects of fermented Camellia japonica leaf extracts.
Methods: Camellia japonica leaves fermented with Nuruk were extracted using methanol and ethanol. Total phenolic, flavonoid, carotenoid and L-ascorbic acid contents were determined by UV-visible spectrophotometry. The antioxidant activities of these extracts were determined by free radical scavenging, ferrous ion chelating and reducing power assays. Their  antimicrobial properties against Gram-positive Staphylococcus epidermidis and Bacillus subtilis, and Gram-negative Klebsiella pneumonia and Escherichia coli bacteria were evaluated by disc diffusion method. Inhibition of pancreatic lipase was measured based on the hydrolytic reaction of p-nitrophenyl butyrate with pancreatic lipase.
Results: The ethanol extracts of fermented Camellia japonica leaves exhibited higher phenolic (32274mg GAE/100 g) and flavonoid (20519 mg RE/100 g) contents with higher superoxide (IC₅₀ = 0.23  mg/mL), hydrogen peroxide (IC₅₀ = 0.28 mg/mL) radical scavenging and ferrous ion chelating (IC₅₀ = 0.21 mg/mL) activities than those of methanol. These ethanol extracts also showed higher antimicrobial activities against all bacterial strains tested with higher inhibitory effects on pancreatic lipase than methanol extracts.
Conclusion: The results highlight the possible use of fermented Camellia japonica leaf extracts as a source of antioxidant, antibacterial and antiobesity agents. Ethanol is recommended as solvent for extracting antioxidants, antibacterial and antiobesity agents from this plant.

Keywords: Antioxidant activity, Antimicrobial activity, Fermented Camellia japonica extracts, Pancreatic lipase inhibition