Irina Ioannou

Extraction Methods of Citrus Peel Phenolic Compounds

Several extraction methods have been reported in the literature for the extraction of phenols from citrus peel. Extraction methods may cause a degradation of phenolic compounds due to high applied temperature and pressure or long extraction times (conventional solvent extraction, high-pressure extraction). However, other extraction methods are limited by the polarity of phenolic compounds (supercritical CO2 extraction). Novel techniques of extraction of bioactive compounds have been developed in order to shorten the extraction time, increase the extraction yield, and prevent the degradation of the phenolic compounds. This review provides a critical comparison of the different extraction methods of citrus peel phenolic compounds. The review compiles valuable data that could be useful for the choice of an appropriate extraction method for bioactive compounds from vegetables sources. The main parameters influencing the extraction yield are also discussed.

Phytochemical characteristics of citrus peel and effect of conventional and nonconventional processing on phenolic compounds: A review

ABSTRACT Citrus peel is rich in functional ingredients such as essential oils (0.6–1%), fibers (6.30–42.13 g/100 g db), phenols (0.67–19.62 g/100 g db), and vitamin C (0.109–1.150 g/100 g db). Flavanones (hesperidin: 0.002–80.90 mg/g db, neohesperidin: 0.05–11.70 mg/g db, narirutin: 0.03–26.90 mg/g db; naringin: 0.08–14.40 mg/g db), and polymethoxylated flavones (sinensetin: 0.08–0.29 mg/g db, nobiletin: 0.20–14.05 mg/g db, tangeretin: 0.16–7.99 mg/g db) are the main phenolic compounds (PCs) of citrus peel. Due to their antioxidant activity, PCs are used in various applications such as formulation of healthy food, cosmetic, and pharmaceutical products. PCs present sensitivity to process operating conditions (during juice processing and further thermal and nonthermal processing). This review summarizes the main publications dealing with the proximate chemical composition, the functional properties, and the potential applications of the main citrus peel compounds. The effects of conventional and nonconventional processing on PCs of citrus fruits and their derived and coproducts are analyzed. The information provided in this review allows a better choice of appropriate processes and their optimal operating conditions for a better retention of antioxidants in citrus products.

Heat treatment improves the immunomodulatory and cellular antioxidant behavior of a natural flavanone: Eriodictyol

&NA; Plants and natural molecules are generally consumed not in raw state but after different processing conditions (heating, mechanical agitation or cooking). The understanding of the chemistry and biological outcome of thermal treatment is still scarce. In the current study, Eriodictyol, a natural flavanone, has undergone heat treatment, generating hence three different products ((3‐(3,4‐dihydroxyphenyl)‐3‐hydroxypropanoic acid, (3‐(3,4‐dihydroxyphenyl) propanal) and an unidentified component). The consequences of aforementioned treatment on the immunomodulatory behavior of resulted molecules were evaluated. The amount of nitric oxide production and the lysosomal enzyme activity were determined in vitro on mouse peritoneal macrophages. The kinetic of cellular antioxidant activity in splenocytes and macrophages was measured. The present investigation demonstrates that heat‐processed eriodictyol significantly enhanced the proliferation of lymphocytes B and T compared to native eriodictyol. Indeed, this compound showed an important improvement on cytotoxic T lymphocyte (CTL) and natural killer (NK) activities. In addition, the production of nitric oxide (NO) and suppression of phagocytic activity of activated macrophages have been increasingly important after thermal processing. Furthermore, it was also revealed that heat‐treated Erio in comparison with the native (non heat‐treated) molecule has a highest cellular anti‐oxidant activity in splenocytes and macrophages cells. These findings highlight the importance of heat‐process as feasible and effective strategy to improve the immunomodulatory and the antioxidant efficiency of an known flavanone Eriodictyol. Graphical abstract: Figure. No caption available. HighlightsHeated and native eriodictyol showed non cytotoxic effect against splenocytes and macrophages.Heat‐treated eriodictyol increased the proliferation of both lymphocytes B and T and improved CTLs and NK activities.Heated eriodictyol revealed an efficient anti‐inflammatory effect.Heated eriodictyol improved the cellular anti‐oxidant activity in splenocytes and macrophages cells compared to native one.

Heated naringin mitigate the genotoxicity effect of Mitomycin C in BALB/c mice through enhancing the antioxidant status

A major problem with cancer chemotherapy is its severe toxic effects on non-target tissues. Assessment of natural products for their protective effect against anticancer drugs induced toxicity is gaining importance in cancer biology. The aim of the present study was to evaluate the effect of native and thermal treated naringin on the protective effect against mitomycin C (MMC) induced genotoxicity. The genotoxicity in liver kidney and brain cells isolated from Balb/C mice were evaluated by performing the comet assay. Antioxidant and lipid peroxidation assays were carried out to understand the protective effects of these compounds. The comet assay showed that heated and native naringin were not genotoxic at the tested dose (40 mg/kg b.w) on liver, kidney and brain cells. A significant decrease in DNA damages was observed, at the tested doses (20 mg/kg b.w and 40 mg/kg b.w) suggesting a protective role of these molecules against the genotoxicity induced by mitomycin C on liver, kidney and brain cells. Moreover, administration of MMC (6 mg/kg b.w.) altered the activities of glutathione peroxidase and superoxide dismutase accompanied by a significant increase of lipid peroxidation. Pretreatment of mouse with heated and native naringin before MMC administration significantly raised the glutathione peroxidase and superoxide dismutase activities followed by a reduced MMC-induced lipid peroxidation. Our study demonstrated that heat treatment of naringin preserve activities of native naringin. The genoprotective properties of heated and native naringin against MMC could be attributed to its antioxidant activities and its inhibitory effect on lipid peroxidation.