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Highlights: [•] China is rich in pummelo germplasm which were underutilised. [•] The flavonoids and antioxidant activities of peels and pulps in 29 Chinese local pummelos and three grapefruits were reported. [•] Some Chinese local pummelos and three grapefruits were rich in flavonoid and exhibited high antioxidant capacity. [•] Remarkable variation was observed in flavonoids contents and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compared OA metabolism and mineral nutrient status between normal and granulated juice sacs. [•] Granulation decreased citrate and isocitrate levels, thus lowering juice sac acidity. [•] The reduction in citrate concentration might be caused by increased degradation. [•] Granulation increased the levels of mineral elements (i.e. P, Mg, S, Zn and Cu) in juice sacs. [ABSTRACT FROM AUTHOR]

Abstract: The flavonoid composition of flavedos and juices from four Chinese pummelo cultivars (Citrus grandis ‘Shatianyu’, C. grandis ‘Guanximiyu’, C. grandis ‘Yuhuanyu’, and C. grandis ‘Cuixiangtianyu’) and one grapefruit cultivar (Citrus paradisi ‘Changshanhuyu’), was investigated using high-performance liquid chromatography diode array detection electrospray ionisation mass spectrometry (HPLC-DAD-ESI MS/MS). Twenty-eight flavonoids were identified. Naringin was the predominant flavanone in these pummelo varieties, whereas naringin and neohesperidin were the principal flavanones found in C. paradisi ‘Changshanhuyu’. The four pummelo cultivars had higher levels of flavones when compared with the grapefruit. Based on the flavonoid profiles in flavedos and juices, four pummelo cultivars and one grapefruit cultivar were well separated. [Copyright &y& Elsevier]

[Display omitted] • Four new flavonoid compounds were isolated from Citrus grandis Shatianyu pulp. • A HMG and a 4′-glucose substitution decreased the ORAC activity of flavonoids. • Melitidin, bergamjuicin and naringin contributed most to ORAC value of SPFEs. • Bergamjuicin, melitidin and cigranoside E contributed most to CAA value of SPFEs. The Citrus genus is a good source of dietary flavonoids, which have many health benefits. As a representative citrus fruit, the flavonoids composition in Shatianyu (Citrus grandis L. Osbeck) pulp remains to be investigated. In the present study, 11 flavonoids were isolated and identified from Shatianyu pulp flavonoid extracts (SPFEs). Among them, 4 flavonoids were previously undescribed and 2 flavonoids were firstly isolated from pummelo. The cellular antioxidant activity (CAA) and oxygen radical absorbance capacity (ORAC) of isolated compounds were evaluated. Naringin and rhoifolin showed the highest ORAC activity, and the presence of a 3-hydroxy-3-methylglutaryl or a 4′-glucose decreased the ORAC activity of flavonoids. The contribution of isolated flavonoids to the holistic antioxidant activity of SPFEs was determined by an online knockout method. Melitidin, bergamjuicin and naringin contributed most to ORAC activity, while bergamjuicin, melitidin and apigenin-4′- O - β - d -glucopyranosyl-7- O - α - l -rhamnopyranosyl-(1 → 2)-[6″- O -(3- hydroxy-3-methylgltaryl)]- β - d -glucopyranoside contributed most to CAA activity. [ABSTRACT FROM AUTHOR]

• This is the first ELISA for naringenin using monoclonal antibodies. • Hapten of naringenin has been successfully prepared. • The developed icELISA offers an advantage for detecting naringenin in herb samples. Naringenin, a flavonoid compound found in pummelo, is a key biological active compound in some traditional Chinese medicines, including Citri reticulatae pericarpium , Citri reticulatae pericarpium viride , Aurantii fructus immaturus , and Aurantii fructus. These Chinese medicinal preparations are the peels or immature fruits of certain citrus species. Aiming at detecting naringenin in complex matrices such as pummelo and traditional Chinese medicines, we put forward a sensitive and practical indirect competitive enzyme-linked immunosorbent assay (icELISA) based on anti-naringenin monoclonal antibodies (anti-Nar-mAbs). The median inhibitory concentration (IC 50) was 4.43 ng/mL, and the working range was 1.15–15.81 ng/mL. The findings of the icELISA for the analysis of naringenin in pummelo and herb samples had a good correlation with the ultra performance liquid chromatography (UPLC) methodology and showed good accuracy and reproducibility. These data demonstrated that the developed icELISA is reliable, accurate, and suitable for detecting naringenin in pummelo and traditional Chinese medicines. [ABSTRACT FROM AUTHOR]

• 1.5% chitosan coating suppressed juicy sac granulation of harvested pummelo through maintaining cell wall modification. • Chitosan reduced the deposition of lignin and cellulose in pummelo fruit. • Chitosan reduced the activities and down-regulated the expression levels of lignin synthesis-related enzyme. • Chitosan increased the activities and up-regulated the expression levels of cell wall degrading enzymes. Deposition of both lignin and cellulose accompanied by juice sac granulation is widespread in harvested citrus fruit. Hence, measures to suppress postharvest granulation of 'Majiayou' pummelo is of great importance. The fruit was treated with 1.5% chitosan and then stored at room temperature (20 ± 2 °C) for 150 d. As compared to the control fruits, chitosan coating significantly suppressed granulation index and maintained good quality. Chitosan coating inhibited lignification by suppressing the activities and expression levels of lignin synthesis-related enzymes (PAL, CAD and POD). By contrast, chitosan treatment enhanced the activities and expression levels of cell wall degrading enzymes, including PME, PG, Cx, XTH and β-Gal, which might contribute to the decrease in cellulose. In a nutshell, chitosan coating can effectively suppress juice sac granulation and fruit senescence of pummelo fruits, and play a crucial role in maintaining the cell wall modification. [ABSTRACT FROM AUTHOR]

• A sensitive and rapid analytical method was developed based on UHPLC-QqQ-MS/MS. • 47 analytes including 13 groups of isomers could be simultaneously quantitated. • Good separation of the 47 analytes was achieved during a 13 min chromatographic run. • Furocoumarins and polymethoxylated flavonoids were included in the analytes. • The 47 analytes in flavedo, albedo and pulp of pummelo fruits were determined. The impact of secondary metabolites on fruit quality, plant growth and human health has led to an increased demand for analytical methods to characterize and quantify these metabolites in recent years. A versatile, sensitive and rapid method based on UHPLC-QqQ-MS/MS was developed for simultaneous qualitation and quantitation of coumarins, furocoumarins, flavonoids and phenolic acids. The chromatographic elution and multiple reaction monitoring mode transitions were optimized to achieve good separation and accurate quantitation of 47 analytes, including 13 groups of isomers, during a single 13 min chromatographic run. This method was validated with good precision and recoveries, wide linear ranges and low limits of detection and quantitation (0.014–1.50 μg L−1). The validated method was further applied to quantify the analytes in flavedo, albedo and pulp from two pummelo varieties, C. grandis 'Shatianyu' and C. grandis 'Guanximiyu'. This method combines high sensitivity, good selectivity, and short chromatographic run time. [ABSTRACT FROM AUTHOR]