LC-MS/MS Profiling, Antioxidant Potential and Cytotoxicity Evaluation of Citrus reticulata Albedo

Abstract

Background: The massive production of agro-industrial waste has become a global concern. Approximately 3.6 million tons of citrus waste are disposed of annually after processing, despite most bioactive molecules being found in fruit peels. Objectives/methodology: This work explored the biochemical and carbohydrate polymer profile of methanolic extract of the soft, spongy Citrus reticulata (C. reticulata) albedo through proximate analysis, antioxidant and scavenging potential analysis, carbohydrate analysis, antioxidant enzyme and genotoxicity analysis, which were further quantified by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and Fourier transform infrared spectroscopy (FTIR) analysis. Results: The results revealed that the citrus albedo comprised an ample amount of ash (3.30 g/100−g of fresh weight (FW), moisture (52.67 g/100−g FW), fiber (30.80 g/100−g FW), lipid (5.58 g/100−g FW), protein (9.62 Kcal/ 100−g FW) and carbohydrate contents, ie, pectin (18.5 mg/g of dry weight (DW), glucosamine (5.05 mg/g DW), maltose (6.5 mg/g DW), D-xylose (35.5 mg/g DW), cellulose (12.2 mg/g DW), total soluble sugars (13.5 mg/g DW), starch (29% w/w). The antioxidant enzyme exhibited excellent activities (23.06 IU/mL for superoxide dismutase, 37.10 IU/mL for catalase and 1.27 IU/mL for peroxidase). The bioactive molecules of the citrus albedo showed maximum total phenolic content (TPC) (2.30 mg gallic acid equivalent (GAE)/ g DW), total flavonoid contents (TFC) (1.71 mg quercetin equivalent (QE)/ g DW) and scavenging potential (50.67% inhibition) when used at a higher concentration of 100 mg/mL. FTIR and liquid chromatography-mass spectrometry (LC-MS) findings concluded that the citrus albedo was rich in polysaccharides including pectin, glucosamine and antioxidants like caffeic acid, quercitin, naringenin, hesperidin and resveratrol. Moreover, the MTT assay showed that the hepatoblastoma cell line (HepG2) underwent apoptosis after 72-h exposure to C. reticulata albedo extract at varied concentrations. Conclusion: These findings suggest that citrus albedo can be a potential chemotherapeutic agent against hepatocellular carcinoma.