Screening of Chemical Composition, Antimicrobial and Antioxidant Activities in Pomegranate, Quince, and Persimmon Leaf, Peel, and Seed: Valorization of Autumn Fruits By-Products for a One Health Perspective

Abstract

Antimicrobial resistance is increasing globally and is now one of the major public health problems. Therefore, there is a need to search for new antimicrobial agents. The food industry generates large amounts of by-products that are rich in bioactive compounds, such as phenolic compounds, which are known to have several health benefits, including antioxidant and antimicrobial properties. Thus, we aimed to characterize the phenolic compounds present in pomegranate, quince, and persimmon by-products, as well as their antioxidant and antimicrobial activities. Phenolic compounds were extracted from pomegranate, quince, and persimmon leaves, seeds, and peels using a mixture of ethanol/water (80/20). The polyphenol profile of the extracts was determined by high-performance liquid chromatography. The antioxidant activity of the extracts was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and cupric reducing antioxidant capacity (CUPRAC) methods. Antimicrobial susceptibility was evaluated using the Kirby–Bauer disk diffusion method. In general, leaves showed higher concentrations of phenolics than the peel and seeds of fruits. In total, 23 phenolic compounds were identified and quantified, with sanguiin and apigenin-3-O-galactoside being present in the highest concentrations. Leaf extracts of pomegranate showed higher antioxidant activities than the other components in all methods used. In general, all extracts had a greater antimicrobial activity against Gram-positive bacteria. Persimmon leaf and seed extracts inhibited a greater number of bacteria, both Gram-positive and -negative. The lowest minimum inhibitory concentration (MIC) detected among Gram-positive and -negative bacteria was 10 mg/mL for pomegranate peel and leaf extracts against Staphylococcus aureus and S. pseudintermedius and for pomegranate leaf extract against Escherichia coli. Our results reinforce the need to value food industry by-products that could be used as food preservatives and antibiotic adjuvants against multiresistant bacteria.

Green Synthesis of Cocos nucifera-Based Nanomaterials and Mechanistic Basis of Their Antimicrobial Action

“…Furthermore, the antimicrobial activity of nanoparticles has been attributed to three main mechanisms of action, including (i) adhesion onto the outer membrane, accumulation in the inner membrane, increase in membrane permeability, leakage of cell content followed by cell death; (ii) interaction with sulfur and phosphate groups of the DNA (deoxyribonucleic acid) and proteins to alter their functions; and (iii) interaction with cellular components to alter the metabolic pathways, membranes, and genetic material, among others [39,40,64,65].…”

“…Furthermore, there is evidence that antioxidant compounds, such as phenolics, flavonoids, alkaloids, fatty acids, tannins, terpenoids, and steroids are accountable for the antimicrobial activity of plant extracts [32,33]. Indeed, a variety of antioxidant metabolites, including flavonoids [19,34], terpenoids [19,35], and phenolic compounds [36], were reported in Cocos nucifera L. These compounds are well known to exert antimicrobial activity via a number of mechanisms, including bacterial or fungal membrane damage, inhibition of virulence factors (enzymes and toxins) and nucleic acid synthesis, leakage of cellular components, and inhibition and eradication of bacterial biofilm formation, among others [37][38][39][40].…”