Rind Of Citrus Fruits Research Articles

A review of the hepatoprotective effects of hesperidin, a flavanon glycoside in citrus fruits, against natural and chemical toxicities.

Liver is the most important and functional organ in the body to metabolize and detoxify endogenous compounds and xenobiotics. The major goal of the present narrative review is to assess the hepatoprotective properties of hesperidin against a variety of natural and chemical hepatotoxins via different mechanisms. Scientific databases such as Scopus, Medline, Web of Science and Google scholar were thoroughly searched, based on different keywords. A variety of natural hepatotoxins such as lipopolysaccharide, concanavalin A and microcystins, and chemical hepatotoxins such as ethanol, acrylamide and carbon tetrachloride have been shown to damage hepatocytes as well as other liver cells. In addition to hepatocytes, ethanol can also damage liver hepatic stellate cells, Kupffer cells and sinusoidal endothelial cells. In this regard, the flavanone hesperidin, occur in the rind of citrus fruits, had been demonstrated to possess widespread pharmacological properties. Hesperidin exerts its hepatoprotective properties via different mechanisms including elevation in the activities of nuclear factor-like 2/antioxidant response element and heme oxygenase 1 as well as the levels of enzymatic and non-enzymatic antioxidants. Furthermore, reduction in the levels of high-mobility group box1 protein, inhibitor of kappa B protein-alpha, matrix metalloproteinase-9 and C-reactive protein are some other important hesperidin-derived hepatoprotective mechanisms. Based on several research papers, it could be concluded that hesperidin is able to protect against liver damage from inflammation and/or oxidative stress-mediated natural and chemical toxins.

Limonene inhibits streptococcal biofilm formation by targeting surface-associated virulence factors.

The present study explores the efficacy of limonene, a cyclic terpene found in the rind of citrus fruits, for antibiofilm potential against species of the genus Streptococcus, which have been deeply studied worldwide owing to their multiple pathogenic efficacy. Limonene showed a concentration-dependent reduction in the biofilm formation of Streptococcus pyogenes (SF370), with minimal biofilm inhibitory concentration (MBIC) of 400 μg ml - 1. Limonene was found to possess about 75-95 % antibiofilm activity against all the pathogens tested, viz. Streptococcus pyogenes (SF370 and 5 clinical isolates), Streptococcus mutans (UA159) and Streptococcus mitis (ATCC 6249) at 400 μg ml - 1 concentration. Microscopic analysis of biofilm architecture revealed a quantitative breach in biofilm formation. Results of a surface-coating assay suggested that the possible mode of action of limonene could be by inhibiting bacterial adhesion to surfaces, thereby preventing the biofilm formation cascade. Susceptibility of limonene-treated Streptococcus pyogenes to healthy human blood goes in unison with gene expression studies in which the mga gene was found to be downregulated. Anti-cariogenic efficacy of limonene against Streptococcus mutans was confirmed, with inhibition of acid production and downregulation of the vicR gene. Downregulation of the covR, mga and vicR genes, which play a critical role in regulating surface-associated proteins in Streptococcus pyogenes and Streptococcus mutans, respectively, is yet further evidence to show that limonene targets surface-associated proteins. The results of physiological assays and gene expression studies clearly show that the surface-associated antagonistic mechanism of limonene also reduces surface-mediated virulence factors.

CITRUS FRUITS AND THE MEDITERRANEAN FRUIT FLY

The Mediterranean fruit fly (medfly), Ceratitis capitata (Diptera: Tephritidae) is considered one of the most important pests for citrus fruits. Recent and older studies demonstrate a variable degree of sensitivity of citrus species to medfly infestations. It seems that the chemical properties of the citrus fruit rind are the most important barrier prohibiting survival and development of medfly immature stages. The toxic properties of rind vary a lot among different citrus species as a result of quantitative and qualitative (composition) aspects of citrus essential oils. Effects of fruit flesh on biological traits of larvae do not vary much among different citrus species. On the other hand, citrus essential oils affect, in a variable manner among different fruit species, a range of adult behavioral traits. For example, male medflies are attracted to citrus essential oils while exposure to them increases mating competitiveness over non-exposed males. Likewise, citrus oils regulate female ovipositional decisions. The current paper provides a comprehensive account on the complex interactions between medfly and citrus plants. Practical and theoretical implications are discussed.

Nobiletin, a polymethoxyflavone in citrus fruits, reduces TAFI expression in HepG2 cells through transcriptional inhibition

Thrombin-activatable fibrinolysis inhibitor (TAFI, carboxypeptidase B2) is a 58-kDa plasma glycoprotein secreted by hepatocytes as an inactive form. TAFI is activated by the thrombin-thrombomodulin complex, and activated TAFI (TAFIa) plays an important role in regulating the balance between coagulation and fibrinolysis through inhibition of fibrinolysis. It has been suggested that high levels of TAFI in circulating plasma increase the risks of cardiovascular death and acute phase in ischaemic stroke. However, the mechanisms of regulating TAFI expression have been unclear. The present study investigated the effects of nobiletin (a polymethoxy flavonoid contained in the rind of citrus fruits) on TAFI gene (CPB2) and TAFI antigen expression in cultured human hepatoma HepG2 cells. Nobiletin decreased the release of TAFI antigen from HepG2 cells into conditioned medium in parallel with decreased levels of CPB2 mRNA and antigen. The half-life time of CPB2 mRNA in nobiletin-treated cells was unchanged compared to that of untreated control cells. Using nobiletin-treated cells that were transfected with a luciferase CPB2 promoter reporter plasmid, activity decreased to half of that in untreated control cells. A series of luciferase reporter constructs containing 5´-flanking region deletions of the human CPB2 gene showed that the sequences from -150 bp to -50 bp were essential for transcription of CPB2 and contained an AP-1 binding sequence at ~ -119 bp to - 99 bp in the CPB2 promoter. The amount of complexed nuclear protein and sequences from ~ -119 bp to -99 bp was decreased in nobiletin-treated cells. ChIP assays showed that c-Jun bound to the ~ -119 bp to -99 bp region of the CPB2 promoter and that the amount of the immunocomplex decreased after nobiletin treatment. Therefore, nobiletin-induced repression of CPB2 transcription might involve AP-1 inhibition and/or prevention of AP-1 binding in a specific region on the CPB2 gene in HepG2 cells.

Seasonal Fluctuations of the Firmness and Cell Wall Polysaccharides of Citrus Fruit Rind

To compare to two types of Citrus fruit rind [i.e., soft type (satsuma mandarin, Citrus unshiu Marc.) and firm type (Hassaku, C. Hassaku Hort. Tanaka)], rind firmness and contents of cell wall polysaccharides were measured from August to January. In August, firmness was measured by a puncture test and found to be ≈3000g in both species. Firmness of satsuma mandarin decreased drastically with time from August to September and decreased slightly thereafter. In contrast, Hassaku firmness increased slightly from August to September, decreased from September to November, and fluctuated. Hassaku firmness, therefore, was significantly higher than satsuma mandarin firmness after September. We measured sugar content in each fraction after fractionalizing cell wall polysaccharides. In flavedo tissue, sugar content in cellulose fraction was the highest, followed by hot-water and EDTA fraction; hemicellulose fraction was the lowest. Although both species were almost the same in sugar content in cellulose and EDTA fraction in August, satsuma mandarin was significantly higher than Hassaku in January. These data showed that changing of rind firmness in citrus was related to the sugar content of cellulose and EDTA fraction in flavedo tissue. In albedo tissue, sugar content in the cellulose fraction was the highest, followed by hemicellulose and hot-water fraction, and EDTA fraction was the lowest. However the extent of seasonal fluctuation in albedo tissue was smaller than that of flavedo tissue, not having any relation to the changing of the firmness.

The effect of chlorpyrifos on flower and fruit development in grapefruit, Citrus paradisi Macfayden

Deformations consisting of longitudinal ridges in the rind of Citrus fruits have recently been found in Southern California Citrus groves. Here, we report the correlation between ridge formation and applications of chlorpyrifos (Lorsban, Dow Chemical Company, Midland, MI) during the ‘feather-growth’ stage of bud break when flower buds become visible. All chlorpyrifos formulations resulted in significant ridging. The addition of agricultural oil and 2,4-dichlorophenoxyacetic acid (2,4-D) to chlorpyrifos resulted in the greatest ridging damage, and widened the window of susceptibility by 2 weeks in 1988. In 1989, no significant difference was seen between treatments of chlorpyrifos, although all were significantly greater than the control. The susceptible stages of bud growth are described, as are the non-susceptible stages which precede and follow it. Floral buds in which organs are just initiating are susceptible to fruit ridging upon application of chlorpyrifos. These ridges are the result of an increase in cell size of the flavedo tissue. A degree-day model which can be used to predict the timing of the susceptible stages is described.

THE EFFECT OF CHLORPYRIFOS ON FRUIT DEVELOPMENT IN GRAPEFRUIT, CITRUS PARADISI MACFAYDEN.

Deformations consisting of longitudinal ridges in the rind of Citrus fruits have recently been found in Southern California Citrus groves. Here, we report the correlation between ridge formation and applications of chlorpyrifos (Lorsban, Dow Chemical Company, Midland, MI) during the feather-growth stage of bud break. All chlorpyrifos formulations resulted in significant ridging. Addition of agricultural oil and 2,4-D (2,4-dichlorophenoxyacetic acid (2,4-D) to chlorpyrifos resulted in the greatest ridging damage and widened the window of susceptibility by 2 weeks in 1988. In 1989, no significant difference was seen between treatments of chlorpyrifos, although all were significantly greater than the control. The susceptible stages of bud growth are described, as are the non-susceptible stages which precede and follow it. Floral buds in which carpels are initiating are susceptible to fruit ridging upon application with chlorpyrifos. These ridges are the result of an increase in cell size of the flavedo tissue which may be the result of a polyploid chimera.

Carotenoids of the rind of citrus fruits

Carotenoids of the rind of citrus fruits

Rapid automated determination of biphenyl in citrus fruit rind.

A totally automated analytical procedure for determining the fungistat biphenyl in citrus fruit rind has been developed. Small pieces of hand-peeled rind are automatically homogenised in water and steam-distilled to liberate the biphenyl, which is trapped in cyclohexane solution; this solution is exhaustively extracted to remove interfering steam volatiles, and the biphenyl remaining is read at 246 mµ in a continuous flow recording spectrophotometer. Time required from the introduction of rind samples to read out of biphenyl present is 9 minutes, with about 15 minutes for the first sample. The useful range is from 1 to about 150 p.p.m. on a whole-fruit basis with a reproducibility of about 3 per cent. The method has been applied most extensively to Valencia oranges.