Citrus Fruit Peel Research Articles

Headspace volatolome of peel flours from citrus fruits grown in Brazil

Citrus fruit peel comprises a pleasant mix of volatile compounds together with fibers, nutrients, and bioactive compounds. Therefore, it has great potential for use as a food ingredient. Studies evaluating the volatile composition of citrus peel flours are limited for most citruses. The goal of this study was to characterize, by HS-SPME/GC–MS, the volatile profile of citrus peel flours made from fruits commonly grown in Brazil. Two composite samples of ten types of citrus peel flours from consecutive harvests were evaluated. 69 volatile compounds were assigned, 49 in Tahiti acid lime, 49 in Sicilian lemon, 37 in Persian lime, 34 in Italian tangerine and oval kumquat, 33 in Valencia orange, 32 in Baia orange and round kumquat, 28 in Blood-of-Mombuca orange and 26 in Lima orange. 26 major compounds represented 93–99% of the total chromatogram peak area. Terpenic compounds were predominant in all samples, especially monoterpenes (about 48–97% of the total chromatogram peak area), while lower proportions of aldehydes (0.2–16.1%), monoterpene alcohols (0.4–11.8%) and esters (0.0–7.7%) were observed. Even though a few compounds like limonene, β-myrcene, linalool, α-pinene and valencene were detected in all citrus, volatile compounds followed specific patterns in the different citruses, with a clear distinction among them, especially between lemon flours and the remaining flours. The variety of volatile profiles and singular specific volatolomic signatures in citrus peels can be explored for different applications related to food flavoring and preservation, and promotion of good health. These aspects should be thoroughly investigated in future studies.

The Doxorubicin-Induced G2/M Arrest in Breast Cancer Cells Modulated by Natural Compounds Naringenin and Hesperidin

Doxorubicin as the common drug for breast cancer has been widely proposed to use in combine with a natural compound in order to overcome its side effects such as cardiotoxicity and resistance. Previously, we reported that naringenin and hesperidin, the abundant flavanons in citrus fruit peel, increased cytotoxic and apoptosis activities of doxorubicin in doxorubicin resistant breast cancer cells (T47D and MCF-7 cells). Since doxorubicin arrests G2/M phase in most cancer cells, both flavanons are speculated to affect the similar phase in breast cancer cells. Cell cycle distributions were determined by flowcytometry using propidium iodide (PI) to stain DNA of the cells. Combination of naringenin or hesperidin with doxorubicin increased accumulation of T47D cells in G2/M phase, while in MCF-7 cells, accumulated cells in G2/M phase were decreased, accompanying with slightly increased in G1 phase. Naringenin itself had no effect on cell cycle of both cells. Whereas, hesperidin arrested G2/M and G1 phases in T47D and MCF-7 cells, respectively. The different effect of naringenin and hesperidin in T47D and MCF-7 cells is most likely caused by difference of p53 status. In p53 mutant, T47D cells, naringenin and hesperidin supported mechanism of doxorubicin to arrest at G2/M that to be considered via p53-independent pathway. Whereas, in p53 wild-type MCF-7 cells, naringenin and hesperidin decreased G2/M arrest, suggesting that both flavanons do not utilize cell cycle arrest for their anticancer activity with doxorucibin. This study revealed that potential co-chemoterapeutic agents, naringenin and hesperidin distinctly modulated cell cycle arrest induced by doxorubicin according to the characteristic of breast cancer cells.Keywords: naringenin, hesperidin, doxorubicin, cell cycle, breast cancer cells.

CsMYB96 confers resistance to water loss in citrus fruit by simultaneous regulation of water transport and wax biosynthesis.

A Citrus sinensis R2R3 MYB transcription factor (CsMYB96) has previously been shown to be strongly associated with the expression of many genes related to wax biosynthesis in the fruit. In this study, CsMYB96 was found to alleviate water loss by simultaneously regulating the expression of genes encoding plasma membrane intrinsic proteins (CsPIPs) and wax-related genes. Expression profiling indicated that CsPIP1;1 and CsPIP2;4 had high expression that was representative of other aquaporins, and they were down-regulated in the peel of post-harvest citrus fruit. CsPIP2;4 was further characterized as the predominant CsPIP, with high expression and high-water channel activity. Transient overexpression of CsPIP2;4 accelerated water loss in citrus fruit. In silico analysis further indicated that the expression of CsMYB96 had a significant negative correlation with that of CsPIPs. In vivo and in vitro experiments confirmed that CsMYB96 was able to directly repress the expression of CsPIPs. In addition, CsMYB96 was able to activate wax-related genes and promote wax biosynthesis for defense against water loss. Transient and stable overexpression of CsMYB96 reduced water loss from both citrus fruit and Arabidopsis.

Development of a functional ingredient rich in hesperidin from citrus fruit wastes

The peels of citrus fruits contain a high concentration of bioactive compounds. Among these compounds, hesperidin stands out for its beneficial health effects. This study had the objective of evaluating the hesperidin content in peel samples of different citrus fruit and to propose the development of a functional product obtained from these peels. The peels were lyophilized and had the total flavonoids analyzed by high-performance liquid chromatography. The peels of several fruits were dried in a microwave oven and ground in a blender to obtain a homogeneous powder. This material was submitted to extraction and quantification of hesperidin. The highest concentrations were found in the ‘Ponkan’ tangerine, ‘Murcott’ tangerine and ‘Navel’ orange, while the lowest were found in the ‘Sicilian’ lemon and ‘Lima’ orange. The functional ingredient obtained from the ground peels after microwave drying can be used for direct consumption or to enrich food preparations.

Selective degradation of AR-V7 to overcome castration resistance of prostate cancer

Androgen receptor splice variant 7 (AR-V7), a form of ligand-independent and constitutively activating variant of androgen receptor (AR), is considered as the key driver to initiate castration-resistant prostate cancer (CRPC). Because AR-V7 lacks ligand-binding domain, the AR-targeted therapies that aim to inactivate AR signaling through disrupting the interaction between AR and androgen are limited in CRPC. Thus, the emergence of AR-V7 has become the greatest challenge for treating CRPC. Targeting protein degradation is a recently proposed novel avenue for cancer treatment. Our previous studies have been shown that the oncoprotein AR-V7 is a substrate of the proteasome. Identifying novel drugs that can trigger the degradation of AR-V7 is therefore critical to cure CRPC. Here we show that nobiletin, a polymethoxylated flavonoid derived from the peel of Citrus fruits, exerts a potent anticancer activity via inducing G0/G1 phase arrest and enhancing the sensitivity of cells to enzalutamide in AR-V7 positive PC cells. Mechanically, we unravel that nobiletin selectively induces proteasomal degradation of AR-V7 (but not AR). This effect relies on its selective inhibition of the interactions between AR-V7 and two deubiquitinases USP14 and USP22. These findings not only enrich our understanding on the mechanism of AR-V7 degradation, but also provide an efficient and druggable target for overcoming CRPC through interfering the stability of AR-V7 mediated by the interaction between AR-V7 and deubiquitinase.

08 Edible fruit and nuts; peel of citrus fruit or melons: United States

08 Edible fruit and nuts; peel of citrus fruit or melons: United States

08 Edible fruit and nuts; peel of citrus fruit or melons: United Kingdom

08 Edible fruit and nuts; peel of citrus fruit or melons: United Kingdom

08 Edible fruit and nuts; peel of citrus fruit or melons: Iceland

08 Edible fruit and nuts; peel of citrus fruit or melons: Iceland

A review: Antimicrobial activity and toxicity analysis of the peel of banana, pomegranate, papaya, and citrus fruits (lemon and orange)

A review: Antimicrobial activity and toxicity analysis of the peel of banana, pomegranate, papaya, and citrus fruits (lemon and orange)

P-PN031. Medicinal importance and health beneficial effect of tangeretin: Therapeutic role in neurodegeneration and inflammatory responses

Introduction. Citrus flavonoids are important polyphenolic compounds having huge biological potential. Therapeutic potential of various flavonoidal compounds in obesity, cancer, diabetes and Alzheimer’s has been well documented in the scientific literature. Demand of natural products and their derived products including dietary supplements has been increased in the medical field. Alzheimer’s and Parkinson's disease are most common Neurodegenerative disorders affecting huge population in the world. Prevention and treatment of neurodegenerative disorders by use of natural products is warranted. Tangeretin is important polymethoxylated flavonoids derived from the peel and other parts of Citrus fruits. Tangeretin has been proven for their antiinflammatory and neuroprotective effects in several disorders. Methods. To know the therapeutic importance of tangeretin in the medicine, various scientific databases have been searched and evaluated for their role in neurodegeneration and inflammatory responses. Medicinal importance and therapeutic effect of tangeretin in neurodegeneration and related disorders have been analyzed through different scientific database. Therapeutic importance of tangeretin in neurodegeneration and inflammatory disorders has been analyzed in the present study and correlated with other biological potential. Results. From the analysis of the scientific databases of tangeretin it was found to have chemopreventive and neuroprotective potential. Scientific data analysis revealed that tangeretin reduced expression of inflammatory mediators. Experimental databases suggest that tangeretin is an effective candidate for prevention and treatment of neuroinflammation and dementia. Other experimental study suggests that tangeretin decreased nitric oxide. Tangeretin is also effective in colitis through suppression of IL12 and TNF-α expression and nuclear factor kappa-B activation. Conclusion. From the analysis of the scientific research work it was found that tangeretin have potential medicinal value for the treatment of neurodegeneration and inflammatory medicated disorders.

Anti-hyperlipidemic effects of citrus fruit peel extracts against high fat diet-induced hyperlipidemia in rats

The effects of extracts of orange, , lime, citron and sour orange fruit peels (250 and 500 mg kg-1, i.p) were tested in high fat diet-fed rats. The extracts of lime and sour orange peels (250 and 500 mg kg-1, i.p) showed potent effects, as evident by the decreases in total cholesterol (TC), triglycerides (TG), LDL-C, and VLDL-C, in addition to the increases in HDL-C levels. Besides, lime and sour orange peels (250 and 500 mg kg-1) extract significantly decreased LDL-C/HDL-C ratio, while lime, sour orange and peel extracts markedly decreased index. Remarkably, lime peel extract followed by sour orange and orange at 500 mg kg-1 improved hepatic architecture to near normal with less deposition of fat globules and fewer. Altogether, lime and sour orange peel extracts were found to be effective against parameters such as TC, TG, LDL-C, VLDL-C, and TC/HDL-C and LDL-C/HDL-C ratios, and index, in addition to the increased levels of HDL-C. Thus, lime and sour orange peel extracts could be natural supplement in the management of and associated diseases.

Nobiletin Inhibits Inflammatory Reaction in Interleukin-1β-Stimulated Human Periodontal Ligament Cells.

The immune response in periodontal lesions is involved in the progression of periodontal disease. Therefore, it is important to find a bioactive substance that has anti-inflammatory effects in periodontal lesions. This study aimed to examine if nobiletin, which is found in the peel of citrus fruits, could inhibit inflammatory responses in interleukin (IL)-1β-stimulated human periodontal ligament cells (HPDLCs). The release of cytokines (IL-6, IL-8, CXCL10, CCL20, and CCL2) and matrix metalloproteinases (MMP-1 and MMP-3) was assessed by ELISA. The expression of cell adhesion molecules (ICAM-1and VCAM-1) and the activation of signal transduction pathways (nuclear factor (NF)-κB, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt)) in HPDLCs were detected by Western blot analysis. Our experiments revealed that nobiletin decreased the expression of inflammatory cytokines, cell adhesion molecules, and MMPs in IL-1β-stimulated HPDLCs. Moreover, we revealed that nobiletin treatment could suppress the activation of the NF-κB, MAPKs, and Akt pathways. These findings indicate that nobiletin could inhibit inflammatory reactions in IL-1β-stimulated HPDLCs by inhibiting multiple signal transduction pathways, including NF-κB, MAPKs, and Akt.

EXTRACTION OF PECTIN FROM VARIOUS BANANA FRUIT PEELS AND ITS FAT REDUCTION ACTIVITY

The pectin a hetero polysaccharide which is mainly accumulated in fruit peels and used as food gelling purposes. Pectin is also needed in medicines, stabilizer in confectionery and main source of dietary fiber. This pectin can be used as dietary fiber supplement which helps for constipation and impaired digestive issues. It reduces the cholesterol naturally anti- diabetic activity and weight reduction. The present study was focused on the potential benefits of the non-citrus fruit peel as a source of pectin. This research emphasized on the pectin which was extracted from three different fruits namely Yellow banana (Musa balbisiana); Green banana (Plantains); and Apple peel powder using three different pH (2.0, 2.2, 2,5) respectively. This study has been distributed as effect on yield of pectin at physical parameters and characterization of the fat reduction activity. The output of the work reflected that the fiber rich non citrus fruit peels are good source of pectin and showing benefits of jelly for industrial use and it’s commercially binder for pharmaceutics and also a source of weight reduction naturally.

VETERINARY AND SANITARY AND PHYTOSANITARY CONTROL OF CITRUS FRUIT

The modern Russian market is represented by a wide range of exotic types of plant products imported from different countries. Currently, there are more frequent cases when in fruits and vegetables there is an increased content of nitrates and toxic elements. Exotic types of plant products sold on food markets are allowed for sale only after passing veterinary and sanitary control in the State laboratories of veterinary and sanitary examination. The aim of the research was the veterinary and phytosanitary control of citrus fruits sold on the commodity market of the Chelyabinsk region. As the objects of research used fresh tangerines, oranges and pomelo, sold in the «Central Market» of Troitsk, Chelyabinsk region. It was found that only the labeling of the studied mandarin samples was complete and in accordance with the regulated requirements of the State Standard 51074–2003, Technical Regulations of the Customs Union 022/2011 and 005/2011. The organoleptic and physical characteristics of the tested samples were in accordance with the rules of the Rules for Veterinary Sanitary Expertise of Plant Food Products in the Veterinary Sanitary Expertise Laboratories of the Markets and the applicable State Standards – 4428–82, 4427–82, 34307–2017. Fresh tangerines, oranges and pomelo were safe for the content of lead, cadmium and nitrates in accordance with the norms of the Sanitary Rules and Norms 2.3.2.1078–01 and Technical Regulation of the Customs Union 021/2011. However, the amounts of lead and cadmium were more detected in the pulp, and the amount of nitrates was the same in the pulp and in the peel of citrus fruits.

Bioactive Substances, Heavy Metals, and Antioxidant Activity in Whole Fruit, Peel, and Pulp of Citrus Fruits.

The use of whole citrus fruits in the food industry means that the valuable peel is used, but this may raise palatability or health concerns among consumers. The content of sugars, dietary fibre, redox compounds, lead, and cadmium was compared in citrus fruits (orange; pomelo; mandarin; lemon; key lime; and red, yellow, and green grapefruit). The pulp of all fruits contained significantly less fibre, tannins, and phenolic compounds than the peel. Whole citrus fruits had significantly lower content of sugars and higher content of dietary fibre and phenolic compounds, including ferulic acid, than their pulps. Whole grapefruits had higher concentrations of ascorbic acid. Whole lemons, limes, and mandarins had higher antioxidant potential than their pulp, due to their higher content of ascorbic acid, tannins, and phenolic compounds. Lead and cadmium content in whole fruits, while higher than in the pulps, was well below the acceptable daily intake.

Comparative study of phytochemical profile and antioxidant activity of flavedo from two Iranian citron fruit (Citrus medica L.)

The citrus fruit peel essential oils (EO) can be considered a valuable by-product of citrus production and processing and the main product of some specific citrus cultivars. The EO contents of two citron fruits including Citrus medica L. var. ‘medica’ Proper. (small citron) and C. medica L. var. ‘macrocarpa’ Risso. (big citron), as well as their constituents and antioxidant activity (IC50), were analyzed by GC/MS. Some biochemical properties of flavedo extract (total flavonoide and total phenol) and polyphenol compounds (HPLC methods) including rutin, quersetin, hesperidin, hesperetin and trans-ferrulic acid are determined. The EO percentage and yield were 0.71% (v/w) and 0.09 ml/fruit in the big citron while 1.86% and 0.20 ml/fruit in the small citron, respectively. The main constituent of EO in macrocarpa variety was limonene (89.39%). While in medica variety, limonene (48.59%), linalool (22.98%) and linalyl acetate (8.21%) were detected as the major components. The antioxidant activity of the EO in the big citron was higher than that in the small citron. All polyphenol compounds, with the exception of rutin, have a higher value in big citron as compare with small citron. In general, limonene was identified as the main compound in both citron trees. These varieties are seemingly divided into two chemotypes: limonene chemotype (macrocarpa variety) and limonene-linalool chemotype (medica variety).

LC-MS-Based Profiling Provides New Insights into Apocarotenoid Biosynthesis and Modifications in Citrus Fruits.

Apocarotenoids contribute to fruit color and aroma, which are critical quality and marketability attributes. Previously, we reported that the red peels of citrus fruits, which are characterized by higher expression levels of a carotenoid cleavage dioxygenase 4b (CitCCD4b) gene, accumulate higher levels of β-citraurin and β-citraurinene than yellow peels. Here, we identified and quantified 12 apocarotenoids, either volatile or nonvolatile, in citrus peel using liquid chromatography-mass spectrometry (LC-MS). Our results show that red peels contain also dramatically higher amounts of β-apo-8'-carotenal, crocetin dialdehyde known from saffron, β-citraurol, β-cyclocitral, and 3-OH-β-cyclocitral and up to about 17-fold higher levels of 3-OH-β-cyclocitral glucoside (picrocrocin isomer). The content of these apocarotenoids was also significantly increased in different CitCCD4b-overexpressing transgenic callus lines, compared with corresponding controls. Transient expression of CitCCD4b in Nicotiana benthamiana leaves resulted in a striking increase in the 3-OH-β-cyclocitral level and the accumulation of picrocrocin. Thus, our work reinforces the specific function of CitCCD4b in producing C10 apocarotenoid volatiles and C30 pigments in citrus peel and uncovers its involvement in the biosynthesis of picrocrocin, C20 dialdehyde, and C30 alcohol apocarotenoids, suggesting the potential of this enzyme in metabolic engineering of apocarotenoids and their derivatives.

Morphology Characterization, Molecular Phylogeny, and Pathogenicity of Diaporthe passifloricola on Citrus reticulata cv. Nanfengmiju in Jiangxi Province, China.

The Nanfengmiju (Citrus reticulata cv. Nanfengmiju), a high-quality local variety of mandarin, is one of the major fruit crops in Jiangxi Province, China. Citrus melanose and stem-end rot, two common fungal diseases of Nanfengmiju, are both caused by Diaporthe spp. (syn. Phomopsis spp.). Identification of the Diaporthe species is essential for epidemiological studies, quarantine measures, and management of diseases caused by these fungi. Melanose disease was observed on Nanfengmiju fruit in Jiangxi Province of China in 2016. Based on morphological characterization and multi-locus phylogenetic analyses, three out of 39 isolates from diseased samples were identified as D. passifloricola. Since these three isolates did not cause melanose on citrus fruit in the pathogenicity tests, they were presumed to be endophytic fungi present in the diseased tissues. However, our results indicate that D. passifloricola may persist as a symptom-less endophyte in the peel of citrus fruit, yet it may cause stem-end if it invades the stem end during fruit storage. To the best of our knowledge, this is the first report of D. passifloricola as the causal agent of the stem-end rot disease in Citrus reticulata cv. Nanfengmiju.

Citrus peel flavonoid nobiletin alleviates lipopolysaccharide-induced inflammation by activating IL-6/STAT3/FOXO3a-mediated autophagy.

Nobiletin, a polymethoxyflavone widely present in the peel of citrus fruits, has significant anti-inflammatory activity. Autophagy plays a critical role in maintaining cell homeostasis by promoting the degradation of intracellular structures in response to various stress. Recent research suggests the involvement of autophagy in the inflammatory process and therefore some inflammation-related diseases. However, the "cross-talk" between autophagy and nobiletin's anti-inflammation response remains not well elucidated. Therefore, this study was initiated with the aim of investigating the role of autophagy in nobiletin's protective effect against inflammation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Results showed that nobiletin significantly (P < 0.05) inhibited the release of nitric oxide (NO) and decreased the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner. Moreover, nobiletin significantly (P < 0.05) promoted autophagy as evidenced by the appearance of more autophagosomes, up-regulated LC3II protein, low-regulated p62 protein, and increased autophagy-related (Atg) genes' expression compared with the control treated with LPS alone. Addition of chloroquine, an autophagy inhibitor, alleviated nobiletin's anti-inflammatory effect, further supporting the requirement of an active autophagy process for the citrus peel flavonoid's biological activity. Mechanistically, we found that nobiletin treatment leads to activation of the IL-6/STAT3/FOXO3a signal pathway through the down-regulation of IL-6 and STAT3 phosphorylation and the upregulation of FOXO3a phosphorylation in the cell nucleus, which is responsible for induction of macrophage autophagy. Taken together, our study provides evidence that nobiletin suppresses inflammatory response through enhancing autophagy through activating the IL-6/STAT3/FOXO3a pathway in macrophage cells.

Polymethoxyflavones in orange peel extract prevent skeletal muscle damage induced by eccentric exercise in rats.

Polymethoxyflavones (PMFs) contained in the peel of citrus fruits have anti-inflammatory, anticancer, and antidepressant effects. However, their effects on skeletal muscle are unknown. We investigated whether PMFs could prevent skeletal muscle damage induced by eccentric exercise in rats. Downhill running for 90 min increased the levels of the inflammatory cytokines, monocyte chemotactic protein-1 (MCP-1), and interleukin-1β (IL-1β) in skeletal muscles, especially in vastus lateralis, and the plasma creatine kinase levels. These increases were attenuated by a single oral administration of orange peel extract (OPE) 30 min before downhill running. A mixture of nobiletin, sinensetin, 3,5,6,7,8,3',4'-heptamethoxyflavone, and tangeretin, which are the major PMFs of OPE, also showed similar effects on muscle damage. These results suggest that OPE has a protective effect against eccentric exercise-induced skeletal muscle damage, and that the effects may be attributed to the 4 major PMFs.