Phenolic Content, Antioxidant and Antimicrobial Properties of Hawthorn (Crataegus orientalis) Fruit Extracts Obtained via Carbohydrase-Assisted Extraction

Abstract

The enzyme-assisted approaches for plant phenolics extraction are more eco-friendly methods compared to acid or alkaline hydrolysis. Carbohydrase enzymes can release free phenolics from plant materials by cleaving the glycosidic bonds between phenolic compounds and cell wall polymers. In this study, the efficiency of carbohydrase-assisted treatment approaches was evaluated to extract bioactive phenolics from hawthorn (Crataegus orientalis) fruit residues. Enzymatic treatment of the fruits was operated by using a crude cellulolytic enzyme cocktail from Rhizomucor miehei NRRL 5282 and a pectinase preparate from Aspergillus niger. Both cellulase and combined cellulase–pectinase treatments improved the total phenolic content (TPC) and antioxidant activity of extracts. The TPC increased to 1899 ± 27 mg gallic acid equivalents/100 g dry matter during the combined enzyme treatment, showing a strong correlation with the average antioxidant capacity determined by ferric-reducing antioxidant power (1.7-fold increment) and 2,2-diphenyl-1-picrylhydrazyl (1.15-fold increment) reagents. The major phenolics in enzyme-treated extracts were vanillic and ferulic acids, the concentrations of which increased 115.6-fold and 93.9-fold, respectively, during carbohydrase treatment. The planktonic growth of Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Chromobacterium violaceum was slightly inhibited by the extracts with minimum inhibitory concentration values between 15.0 and 77.9 mg/mL, while the yeasts tested were quite resistant to the samples. B. subtilis and yeast biofilms were sensitive to the enzyme-treated extracts, which also showed quorum-sensing inhibitory effects against C. violaceum. The obtained bioactive hawthorn extracts hold potential as a natural source of antioxidants and antimicrobials.