Lemon wastes as a resource of antioxidant agents and their toxicological profiles in multiple models

TAPIA PABLO; SILVA AM; DELERUE-MATOS C; MOREIRA M; RODRIGUES F; CARTAGENA, ELENA; ARENA MARIO; ALBERTO, MARÍA ROSA

Workshop; Workshop on Redox Nutrition and Toxicology; 2023

Lemon production in the northwest represents 95.6% of Argentine production. Citrus limon wastes consists mainly of peels and pressed pulp (seeds and membranes), which represent ~50% of the fruit weight after industrial processing. From an environmental point of view, it is essential to take advantage of these residues. In this work, we determined the chemical composition of peel (C), liquid effluent (LE) and solid effluent (SE) extracts and their antioxidant, eco-toxic, cytotoxic and acute toxic effects. The extracts were obtained by consecutive extractions with a hydro-alcoholic solution.Phenolic compounds resulted for SE: 61.11, LE: 40.81 and C: 32.73 mg EAG/g PS (Gallic Acid Equivalent). From HPLC-DAD the following main compounds were identified: Caftaric acid ˃ 4,5-di-O-caffeoylquinic acid ˃ (-)-Epicatechin ˃ Naringin ˃ Vanillic acid in C; Ellagic acid ˃ 4,5-di-O-caffeoylquinic acid ˃ Naringin ˃ (+)-Catechin ˃ Caftaric acid in EL, and finally in ES: Ellagic acid ˃ 4,5-di-O-caffeoylquinic acid ˃ Caftaric acid ˃ Naringin ˃ Kaempferol-3-O-ruthinoside.SE showed the best antioxidant capacity (71.19 mg EAG/g PS), the free radical scavenging capacity were for: ABTS•+ SC50 45.15 μg/ml, nitric oxide SC50 217 μg/ml, superoxide anion SC50 611.14 μg/ml, and hypochlorite SC50 10.30 μg/ml; while the iron chelating, Fe3+ ion reducing, and cupric ion reducing capacities resulted CC50 917.98 μg/ml, RC50 44.63 μg/ml, and 56.80 mg EAG/g PS, respectively.In the toxicity tests, all extracts (1000 μg/ml) did not affect the HT29-MTX and Caco-2 cell viability by the MTT assay, nor the aquatic bioindicator Lemna minor. Only C (250 μg/g) reduced the viability of terrestrial isopod Armadidillium vulgare, and SE (500 μg/ml) stopped bacterial growth of Bacillus subtilis. Extracts had a moderate toxicity against salt-water crustacean Artemia salina (LD50 100-500 μg/ml). In conclusion, the biological potential of lemon residue extracts justifies future in vivo studies for its sustainable and healthy applications