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The aim of this study was to investigate the antioxidant potentials, subacute toxicity, and beneficiary effects of methanolic extract of pomelo (Citrus grandis L. Osbeck) in rats. Long Evans rats were divided into four groups of eight animals each. The rats were orally treated with three doses of pomelo (250, 500, and 1000 mg/kg) once daily for 21 days. Pomelo extract contained high concentrations of polyphenols, flavonoids, and ascorbic acid while exhibiting high 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power values. There was no significant change in the body weight, percentage water content, and relative organ weight at any administered doses. In addition, no significant alterations in the hematological parameters were also observed. However, rats which received 1000 mg/kg dose had a significant reduction in some serum parameters, including alanine transaminase (15.29%), alkaline phosphatase (2.5%), lactate dehydrogenase (15.5%), γ-glutamyltransferase (20%), creatinine (14.47%), urea (18.50%), uric acid (27.14%), total cholesterol (5.78%), triglyceride (21.44%), low-density lipoprotein cholesterol (40.74%), glucose (2.48%), and all atherogenic indices including cardiac risk ratio (24.30%), Castelli’s risk index-2 (45.71%), atherogenic coefficient (42%), and atherogenic index of plasma (25%) compared to control. In addition, the highest dose (1000 mg/kg) caused a significant increase in iron (12.07%) and high-density lipoprotein cholesterol (8.87%) levels. Histopathological findings of the vital organs did not indicate any pathological changes indicating that pomelo is nontoxic, safe, and serves as an important source of natural antioxidants. In addition, the fruit extract has the potential to ameliorate hepato- and nephrotoxicities and cardiovascular diseases as well as iron deficiency anemia.

A comparative study of the extraction efficiency of nine known polyphenols [phenolic acids (benzoic acid, dihydroxybenzoic acid, gallic acid, trans-cinnamic acid, and vanillic acid) and flavonoids (naringenin, naringin, quercetin, and rutin)] was conducted by deliberately adding the polyphenols to an artificial honey solution and performing solid phase extraction (SPE). Two SPE methods were compared: one using Amberlite XAD-2 resin and another one using a C18 cartridge. A gradient high performance liquid chromatography system with an RP18 column and photodiode array detector was utilized to analyze the extracted polyphenols. The mean percent of recovery from the C18 cartridges was 74.2%, while that from the Amberlite XAD-2 resin was 43.7%. The recoveries of vanillic acid, naringin, and rutin were excellent (>90%); however, gallic acid was not obtained when C18 cartridges were used. Additionally, the reusability of Amberlite XAD-2 resin was investigated, revealing that the mean recovery of polyphenols decreased from 43.7% (1st extraction) to 29.3% (3rd extraction). It was concluded that although Amberlite XAD-2 resin yielded a higher number of compounds, C18 cartridges gave a better extraction recovery. The lower recovery seen for the Amberlite XAD-2 resin also cannot be compensated by repeated extractions due to the gradual decrease of extraction recovery when reused.