In vitro antioxidant,anti-diabetic,cholinesterase and tyrosinase inhibitory potential of fresh juice from Citrus hystrix and C.maxima fruits

In the present study,antioxidant potential,α-amylase,α-glucosidase,cholinesterase and tyrosinase inhibitory activity of fresh juice from indigenous fruits of Citrus hystrix and C.maxima(Red&White var.)were investigated using an in vitro model.The contents of total phenolics,tannins,and total flavonoids ranged between 836.90 and 909.52 mg gallic acid equivalent(GAE)/L,333.33 and 523.21 mg gallic acid equivalent(GAE)/L and 224.88 and 262.22 mg rutin equivalent/L,respectively.The antioxidant activity of fresh juice was evaluated by employing different in vitro assays such as reducing power assay,DPPH•,ABTS•+and•OH radical scavenging capacities,peroxidation inhibition activity,antihemolytic assay.In addition,75.55%–79.75%ofα-amylase and 70.68%–72.83%ofα-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay.Also,all the juice samples exhibited excellent tyrosinase(76.95%–80.79%),acetylcholinesterase(75.71%–79.74%)andβ-glucuronidase inhibitory activity(68.13%–69.38%).These results indicated that fresh juice of C.hystrix and C.maxima(Red&White var.)could be used as a source of antioxidant agents,functional food and nutraceuticals.©2014 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Effects of maturity of citrus fruits on their stalks cutting force

When the citrus harvesting robot harvests citruses,the mechanical properties of citrus stalks have an important influence on the success rate of the citrus harvesting robot.During the harvesting,the maturity of citrus fruits not only determined the harvesting time of citrus fruits but also affected the mechanical properties of citrus fruit stalks.In this study,the changes in the cutting force of citrus fruit stalks were described during the maturity of citrus fruits,and the effect of the maturity on the cutting force of stalks was clarified,so as to determine the harvesting time with the minimum cutting force required for harvesting citrus fruits by the harvesting robot.During the maturity,the relevant parameters of fruit maturity,such as the hardness,pH,and solid solution content of citrus fruits,were monitored.The results showed that there is a significant correlation between the hardness,pH,the solid solution content of citrus fruits,and the cutting force of citrus fruit stalks during maturity.The single-factor mechanical model of hardness,pH,solid solution content of citrus fruits,and the cutting force of citrus fruit stalks were established based on the data of 2019,which were verified through tests in 2020.The test results are as follows:during the ripening period of citrus fruits,the fruit hardness varies in the range of 0.13-0.31 MPa,the hardness changes by 0.02 MPa,and the cutting force changes by about 2.0-6.0 N;the pH of the citrus fruits changes in the range of 2.8-4.0,and the cutting force changes by about 1.5-2.2 N for every 0.1 change in the pH;the variation range of fruit solid solution content is 6.5%-9.0%,and for every 0.2%change in solid solution,the cutting force of citrus fruit stalks changes by about 1.25-2.0 N.The mechanical models can predict the cutting force required to cut off citrus fruit stalks according to the relevant parameters of citrus fruit maturity and can provide a reference for effectively evaluating the required cutting force.

Effects of edible whole citrus fruits on endogenous antioxidant enzymes of HepG2 cells

The effects of eating fresh citrus fruits including two varieties of mandarins,one of sweet oranges,one of grapefruit,two of pomelo,and one of kumquat cultivated in China on endogenous antioxidant enzymes were investigated by in vitro digestion and HepG2 cells.The correlations between enzyme activity and cell uptake of phytochemicals and cellular antioxidant capacities were analyzed.The results showed that most fresh citrus fruits increased the endogenous antioxidant activity.Bairoumiyou,Hongroumiyou,Ponkan,and Jinju after digestion significantly increased the activity of catalase(P<0.05).Hongroumiyou,Bairoumiyou,Ponkan navel orange,and Jinju after digestion significantly increased glutathione peroxidases(GPxs)activity(P<0.05),while Huyou and satsuma could not increase the activity of GPxs after digestion.Thioredoxin oxidoreductase activity was improved significantly by most of the digested whole citrus fruits except Ponkan(P<0.05)and thioredoxin oxidoreductase added whole citrus fruits had a higher increase than added citrus fruits extracts.The results indicated that edible whole citrus fruits had similar effects as extracts on enzymes.

Impact of citrus fruit and hesperidin intake on multiple health outcomes:An umbrella review

Citrus fruits are rich sources of several biologically active flavonoids such as hesperidin,naringin,and polymethoxylated flavones.We evaluated the evidence of associations between citrus fruit or hesperidin intake and multiple health outcomes.An umbrella review was conducted for studies performed in humans.Overall,246 articles were initially identified by searching in 4 databases.Twenty-two meta-analyses and systematic reviews with 28 health outcomes met the inclusion criteria.Citrus fruit intake had beneficial effects on all-cause mortality(relative risk[RR].0.90;95%confidence interval[95%CI],0.86 to 0.94),cardiovascular diseases(RR,0.78;95%CI,0.66 to 0.92),coronary heart disease(RR,0.91;95%CI,0.86 to 0.96),stroke(RR,0.74;95%CI,0.65 to 0.84),type 2 diabetes mellitus(RR,0.85;95%CI,0.78 to 0.92),and several cancers.Dose-response analyses indicated that each 100-g/d increase in citrus fruit intake could reduce the risks of all-cause mortality by 6%(RR,0.94;95%CI,0.88 to 1.00),stroke by 22%(RR,0.78;95%CI,0.69 to 0.90),and cardia gastric cancer by 40%(RR,0.60;95%CI,0.44 to 0.83).Citrus fruit intake also had beneficial effects on the lipid profile and body weight control(weighted mean difference,−1.28;95%CI,−1.82 to−0.74).Grapefruits could reduce the systolic blood pressure(weighted mean difference,−2.43,95%CI,−4.77 to−0.09).Hesperidin supplementation significantly improved inflammation.Citrus fruit intake was generally safe and beneficial for multiple health outcomes in humans.However,grapefruit and pomelo juice may affect the bioavailability of various medications,so care should be exercised before increasing the intake of these fruits or their juices.

Two Lycopene β-Cyclases Genes from Sweet Orange (Citrus sinensis L. Osbeck) Encode Enzymes With Different Functional Efficiency During the Conversion of Lycopene-to-Provitamin A

Citrus fruits are rich in carotenoids.In the carotenoid biosynthetic pathway,lycopene β-cyclase（LCYb,EC：1.14.-.-） is a key regulatory enzyme in the catalysis of lycopene to β-carotene,an important dietary precursor of vitamin A for human nutrition.Two closely related lycopene β-cyclase cDNAs,designated CsLCYb1 and CsLCYb2,were isolated from the pulp of orange fruits（Citrus sinensis）.The expression level of CsLCYb genes is lower in the flavedo and juice sacs of a lycopeneaccumulating genotype Cara Cara than that in common genotype Washington,and this might be correlated with lycopene accumulation in Cara Cara fruit.The CsLCYb1 efficiently converted lycopene into the bicyclic β-carotene in an Escherichia coli expression system,but the CsLCYb2 exhibited a lower enzyme activity and converted lycopene into the β-carotene and the monocyclic γ-carotene.In tomato transformation studies,expression of CsLCYb1 under the control of the cauliflower mosaic virus（CaMV） 35S constitutive promoter resulted in a virtually complete conversion of lycopene into β-carotene,and the ripe fruits displayed a bright orange colour.However,the CsLCYb2 transgenic tomato plants did not show an altered fruit colour during development and maturation.In fruits of the CsLCYb1 transgenic plants,most of the lycopene was converted into β-carotene with provitamin A levels reaching about 700 μg g-1DW.Unexpectedly,most transgenic tomatoes showed a reduction in total carotenoid accumulation,and this is consistent with the decrease in expression of endogenous carotenogenic genes in transgenic fruits.Collectively,these results suggested that the cloned CsLCYb1 and CsLCYb2 genes encoded two functional lycopene β-cyclases with different catalytic efficiency,and they may have potential for metabolite engineering toward altering pigmentation and enhancing nutritional value of food crops.

Molecular Phylogeny of the “True Citrus Fruit Trees” Group (Aurantioideae, Rutaceae) as Inferred from Chloroplast DNA Sequence

The genus Citrus L. has a long controversial taxonomy history, and a well-resolved molecular phylogeny of the ＂true citrus fruit trees＂ group in the future will provide new information for advancing breeding techniques and developing better conservation strategies. In the present study, three cpDNA fragments （TrnL-TrnF, PsbH-PetB, and TrnS-TrnG） of 30 genotypes chosen from the six genera of the ＂true citrus fruit trees＂ group were analyzed. A molecular phylogenetic tree of the ＂true citrus fruit trees＂ group ＂~as reconstructed based on plastid DNA sequences. The results confirmed that the ＂true citrus fruit trees＂ group was monophyletic, and thereby the group was divided into genera as previously suggested based on morphological characters. The cpDNA data also suggested that Poncirus might be the first genus separated from the other five genera in the group. The genus Fortunella were of hybrid origin and Citrus might be as its putative paternal parent. The genera Microcitrus, Eremocitrus, and Clymenia were possibly monophyletic and their common ancestor might branch out from Citrus. Furthermore, the phylogenetic relationships within the Citrus genus were discussed.

Integrative cytology and proteome alterations unravel the multitarget effect of a novel alkaloid antofine against Penicillium italicum

Penicillium italicum is the causal agent of citrus blue mold,which is a major threat to the global citrus fruit industry.Antofine,a natural phenanthroindolizidine alkaloid,is water-soluble and exhibits a broad range of biological activities.However,whether it can inhibit P italicum growth and the potential inhibitory mechanism remains to be elucidated.This study aimed to investigate the antifungal mechanism of antofine against P italicum using scanning electron microscopy,transmission electron microscopy(TEM),propidium iodide staining,and tandem mass tag-labeled quantitative proteomic analysis.Antofine was found to exhibit its preeminent antifungal activity against P italicum with a minimum inhibitory concentration of 1.56 mg/L and a minimum fungicidal concentration of 6.25 mg/L.The challenge test revealed that antofine inhibited the development of citrus blue mold during a 6-d P italicum-infected period.Antofine acted on its potential multitargets to inhibit P italicum growth by synergistically activating oxidative stress through accumulating excess reactive oxygen species,impairing membrane integrity.inducing membrane lipid peroxidation,and disrupting mitochondrial function,thereby disrupting the membrane system and reducing cell via-bility.Moreover,antofine treatment downregulated most differentially expressed proteins involved in carbon metabolism,pyruvate metabolism,and the tricarboxylic acid cycle(TCA)in P italicum mycelia,which may explain the mitochondrial decomposition observed by TEM and the de-clines in ATP levels as well as the activities of TCA-related enzymes.These results indicate that antofine treatment inhibited P italicum growth by targeting the cell membrane and mitochondria.

Identification and expression profiles of gustatory receptor genes in Bactrocera minax larvae(Diptera:Tephritidae):Role of BminGR59f in larval growth

Insects employ various types of gustatory receptors(GRs)to identify nutrient-rich food and avoid toxic substances.The larval gustatory system is the critical checkpoint for food acceptance or rejection.As a specialist herbivore,the larvae of Bactrocera minax feed only on unripe citrus fruits.However,how larvae use GRs to check and adapt to the secondary metabolites in unripe citrus fruits remains unknown.In this study,we first performed developmental expression profiles showing that most BminGRs genes were highly expressed in 1st and 2nd instar larvae and that tissue-specific expression indicated high expression of most BminGRs genes in the mouthparts of 2nd instar larvae.Furthermore,we found that silencing BminGR59f by RNA interference(RNAi)affected the growth of 2nd instar B.minax larvae.Hesperidin and naringin were screened as ligands of BminGR59f via RNAi and cell calcium imaging,and the combination of these two flavones increased the body weight of larvae.In summary,we identified a novel gustatory perception pattern in B.minax for detecting hesperidin and naringin,which boosted the growth of B.minax larvae.These results shed light on how specialist herbivores detect and adapt to host metbolites in adverse environments depending on larval GRs.