Exceptional Antioxidant, Non-Cytotoxic Activity of Integral Lemon Pectin from Hydrodynamic Cavitation

Abstract

Lemon pectin extracted along with water-soluble flavonoids and other phytochemicals from citrus industry’s waste lemon peel via hydrodynamic cavitation in water, directly at pre-industrial scale and further isolated via freeze drying, shows exceptionally high antioxidant and non-cytotoxic activity. Preliminary investigation indicates also significant antimicrobial activity. These findings open the route to the development of new nutraceutical and healthcare application of a versatile biopolymer endowed with new functionality, rapidly and conveniently obtained from an abundant by-product of the agrofood industry.

Towards a new treatment against polymicrobial infections: high antibacterial activity of lemon IntegroPectin against Pseudomonas aeruginosa and Escherichia coli

“…[12] Easily dissolved in water, the resulting yellow pectin flakes obtained after freeze drying have a pleasant lemon smell and are completely devoid of cytotoxic activity against human pulmonary cells up to high concentration (1 mg/mL). [13] Furthermore, lemon IntPec has an extremely high content of polyphenols adsorbed at its surface: 0.88 mg GAE/g (in terms of gallic acid equivalents, or GAE, per dry gram of pectin) versus 8.3×10 -3 mg GAE/g for the lemon peel of the cultivar with the highest biophenol concentration.…”

“…[23] We make the hypothesis that the antibacterial action of lemon IntegroPectin is due to a synergistic combination of i) the pectic polymer, ii) the lemon oil adsorbed at its surface (the citrus essential oil is present in the form of a highly stable nanoemulsion in the aqueous phase after the hydrocavitation process), [12] and iii) the lemon flavonoids highly concentrated (with respect to the citrus peel) at the surface of lyophilized IntPec. [13] Likewise to other citrus oils, lemon oil is particularly active against Gram-positive bacteria, even though selected Gramnegative bacteria such as E. coli and Campylobacter jejuni are inhibited by lemon oil due to the presence of oxygenated monoterpenes exhibiting much stronger antimicrobial activity than hydrocarbon monoterpenes present in the essential oil. [24] These results were subsequently confirmed for the fungicidal action of lemon oil against Candida albicans pathogenic yeasts, wherein the most active antimicrobial was found to be citral.…”

“…Taking into account the complete lack of cytotoxicity of citrus IntPec against human lung cells at the aforementioned concentration (1 mg mL -1 ), [13] and the antibacterial activity of lemon IntPec against Gram-positive S. aureus, [11] these results may open the route to the industrial development a new antibacterial treatment against polymicrobial infections based on a new bioproduct reproducibly and economically obtained in large amounts from the main citrus industry's by-product.…”

Hydrodynamic Cavitation-based Rapid Expansion of Hesperidin-rich Products from Waste Citrus Peel as a Potential Tool Against COVID-19

“…The HC-based integral extraction of waste citrus peel in water, without any other additive, was demonstrated directly on the semi-industrial scale using waste orange peels (WOP) [49], and waste lemon peels (WLP) [50], from citrus fruits organically grown in Sicily. No other processes allowed to extract in just 10 minutes around 60% (w/w) of the overall polyphenol content in fresh WOP [49].…”

“…In the case of the HC-based processing of WLP, the IntegroPectin showed exceptional antioxidant properties and complete lack of cytotoxicity against pulmonary epithelial cells up to very high doses (1 mg/mL) [50]. IntegroPectin also showed a strong antibacterial activity against the Gram-positive Staphylococcus aureus [51].…”