Mohammad Hojjati; Behrooz Alizadeh Behbahani
Abstract
Introduction: There is a remarkable interest in developing natural antimicrobial compounds of essential oils and plant extracts origin, due to the increase of bacterial resistance to common antibiotics. On the other hand, lipid oxidation in raw or processed materials leads to food rancidity and deterioration. ...
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Introduction: There is a remarkable interest in developing natural antimicrobial compounds of essential oils and plant extracts origin, due to the increase of bacterial resistance to common antibiotics. On the other hand, lipid oxidation in raw or processed materials leads to food rancidity and deterioration. In this way, synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are used to prolong the storage stability of food products. Nevertheless, the toxicologists and nutritionists have documented the side effects and potential toxic effects of synthetic antioxidants. Herbs contain a wide variety of phenolic compounds such as phenolic acids, flavonoid, tannins and so forth. These bioactive compounds could be therefore used as natural antioxidants and antimicrobial agents to suppress lipid oxidation and food spoilage. In this context, Allium jesdianum extracts were obtained and their antioxidant and antimicrobial activities were investigated. Materials and methods: A. jesdianum was exposed to methanolic and aqueous maceration-based extraction methods to extract its bioactive compounds with positive biological activity. The extraction yield, total phenolic compounds, antioxidant activity (based on DPPH and ABTS radical scavenging activity), and antimicrobial activity (based on disc diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods) of the methanolic and aqueous extracts were evaluated and compared to each otherr. Results and discussion: The methanolic extract of A. jesdianum had higher extraction yield of 7.1±0.2% compared to the aqueous extract with 4.6±0.28% extraction yield, mainly due to the ability of methanol to extract both nonpolar and semi-polar compounds. The total phenolic compounds of the methanolic extract were also remarkably higher than the aqueous counterpart (88.28% vs. 68.29% mg gallic acid/g dried extract), indicating that the solvent type plays a significant role in extracting bioactive compounds. However, the aqueous extract was able to significantly scavenge DPPH and ABTS radicals compared to the methanolic extract. This means that the presence of phenolic compounds is not the only factor affecting the antioxidant activity of plant extracts. The bioactive extracts of A. jesdianum were able to suppress the growth of or kill the examined bacteria P. aeruginosa, E. coli, E. aerogenes, L. innocua, and S. pyogenes; and this effect was more pronounced in the methanolic extract. Therefore, A. jesdianum methanolic and aqueous extracts could be used as natural preservatives to improve the oxidative stability of food products rich in unsaturated fatty acids, and to inhibit the growth of spoilage and pathogenic microorganisms, treat infections, and increase the safety of food products.
