Bioactive compounds in different citrus varieties. Discrimination among cultivars

Effects of mandarin peel powder on growth, biochemical, immune, and intestinal health in Oreochromis niloticus at suboptimal temperatures

This 60-day study aimed to examine the efficacy of a diet supplemented with mandarin peel powder (MP) in enhancing the health and survival of Oreochromis niloticus under suboptimal temperature conditions (21 ℃). One hundred and eighty Nile tilapia fish (22.51 ± 0.04 g) were randomly distributed into four experimental groups; each of 3 replicates (15 fish per replicate). The first group (CONT) received a basal diet without MP. The second (MP10%), third (MP15%), and fourth (MP20%) groups were fed diets containing 10, 15, and 20% MP powder, respectively. At the end of the feeding trail, growth performance, serum growth hormone, α-amylase enzyme, lysozyme activity, nitric oxide, protease activity, globulin, serum levels of IL-1ß, antioxidant status, and intestinal histology were measured. The results showed insignificant differences between CONT, MP15%, and MP20% groups in the final body weight and specific growth rate. The growth hormones in the MP15% and MP20% groups did not show a significant difference compared to fish fed a normal basal diet (CONT). However, the amylase enzymes were significantly greater in both groups. The MP20% and MP15% groups showed a significant increase in antioxidant, lysozyme, nitric oxide, and protease activities compared to CONT. The results also showed that fish that were fed a diet with MP had significantly less of the pro-inflammatory cytokine interleukin-1 beta, and their intestinal villi got wider, especially in the MP20% group. It could be concluded that feeding tilapia on a diet with 20% MP is an effective strategy to improve their health when the temperature is below 21 °C. This is because the fish exhibit higher levels of antioxidant activity, reduced pro-inflammatory responses, and improved intestinal health without difference in the growth performance in compared to control group.

Formation of Hesperetin-Methylglyoxal Adducts in Food and In Vivo, and Their Metabolism In Vivo and Potential Health Impacts

Polyphenols with a typical meta-phenol structure have been intensively investigated for scavenging of methylglyoxal (MGO) to reduce harmful substances in food. However, less attention has been paid to the formation level of polyphenol-MGO adducts in foods and in vivo and their absorption, metabolism, and health impacts. In this study, hesperitin (HPT) was found to scavenge MGO by forming two adducts, namely, 8-(1-hydroxyacetone)-hesperetin (HPT-mono-MGO) and 6-(1-hydroxyacetone)-8-(1-hydroxyacetone)-hesperetin (HPT-di-MGO). These two adducts were detected (1.6-15.9 mg/kg in total) in cookies incorporated with 0.01%-0.5% HPT. HPT-di-MGO was the main adduct detected in rat plasma after HPT consumption. The adducts were absorbed 8-30 times faster than HPT, and they underwent glucuronidation and sulfation in vivo. HPT-mono-MGO would continue to react with endogenous MGO in vivo to produce HPT-di-MGO, which effectively reduced the cytotoxicity of HPT and HPT-mono-MGO. This study provided data on the safety of employing HPT as a dietary supplement to scavenge MGO in foods.

Nutritional and volatile profiles of pulp and flavedo from four local pummelo cultivars grown in Fujian province of China

The nutritional and volatile profiles of pulp and flavedo samples from four distinct local pummelo landraces ("Siji," "Pingshan," "Wendan," and "Guanxi") cultivated in Fujian province of China were investigated. "Guanxi" pummelo exhibited relatively high contents of vitamin C (42.01 mg/100 mL) and phenols (360.61 mg/L) and displayed a robust antioxidant capacity (41.15 mg/100 mL). Conversely, the red pulp from "Pingshan" demonstrated relatively high values of carotenoids (55.96 µg/g) and flavonoids (79.79 mg/L). Considerable differences were observed in volatile compositions between the two fruit tissues and among the four genotypes. A total of 166 and 255 volatile compounds were detected in the pulp and flavedo samples, respectively. Notably, limonene and β-myrcene were identified as the principal volatile compounds in flavedo, whereas hexanal was highly abundant in the pulp of "Siji," "Pingshan," and "Guanxi." "Wendan" displayed distinct separation from the other three pummelo cultivars in principal component analysis based on the pulp volatile compositions. This distinction was attributed to the higher number and content of volatile compounds in "Wendan" pulp, particularly the remarkable enrichment of β-myrcene. The newly characterized pummelo landraces and genotype/tissue-dependent variations in volatiles provide essential information for the genetic improvement of pummelo aroma, as well as for fruit processing and utilization.

Quality evaluation of citrus varieties based on phytochemical profiles and nutritional properties

Introduction

China is one of the major producers and exporters of various kinds of citrus fruits. As one of China's major citrus planting bases, Sichuan has a citrus planting area that exceeds 400,000 hectares. Meanwhile, citrus cultivation has become one of the important agricultural pillar industries in the region. Citrus fruits are reported to show various health-promoting effects, especially antioxidant activity. However, reports on the functional, nutritional and qualitative characteristics of different citrus varieties in Sichuan are still scarce.

Methods

The quality attributes (color parameters, shape, and size), juice properties (titratable acids and total soluble sugar), mineral elements, and health-promoting nutritional and functional components (protein, carbohydrates, fat, dietary fiber, ascorbic acid, phenolic acids, and flavonoids), as well as antioxidant properties of 10 typical citrus varieties cultivated in Sichuan, were systematically investigated and analyzed.

Results and Discussion

Significant differences among different citrus varieties were found. In particular, the total soluble sugar content of Mingrijian was higher than that of other citrus, suggesting its potential for fresh consumption and food processing. Moreover, a total of five flavonoids and nine phenolic acids were identified and quantified. Yuanhong, with higher contents of ascorbic acid and phenolic acids, was considered to be a valuable variety with excellent antioxidant capacity and can be used for value-added processing in the food industry. Principal component analysis and hierarchical cluster heatmap analysis suggested that there were significant differences among the 10 citrus varieties. Correlation analysis confirmed the significant contribution of ascorbic acid and phenolic acids to antioxidant capacity in citrus. The results can provide some references for the cultivation and selection of nutritious citrus fruits.

Comparative Study on Physicochemical and Nutritional Qualities of Kiwifruit Varieties

In order to study the physicochemical and nutritional characteristics of kiwifruit varieties, 14 kiwifruits from different species with different flesh colors were selected for research. The pectin content was significantly higher in green-fleshed kiwifruits than those in red-fleshed and yellow-fleshed kiwifruits. Red-fleshed kiwifruits had the highest total flavonoid content, and green-fleshed kiwifruits in A. eriantha had the highest chlorophyll a content, chlorophyll b content and total carotenoid content. The energy and carbohydrate contents of yellow-fleshed kiwifruits were significantly lower than those of red-fleshed kiwifruit. Moreover, the protein contents in A. chinensis and A. chinensis var. deliciosa were higher than those in other species. The content of vitamin C in A. eriantha was far higher than in other kiwifruits. Red-fleshed kiwifruits had a significantly higher vitamin E and vitamin B1 content than green-fleshed kiwifruits. In addition, 1-pentanol, trans-2-hexen-1-ol, n-hexane and styrene presented only in red-fleshed kiwifruits. Therefore, these could be used as a characteristic fragrance for red-fleshed kiwifruits. Moreover, the varieties were ranked comprehensively by principal component analysis (PCA), among which the top four highest-ranking kiwifruits among the 14 varieties were 'Huate', 'MHYX', 'Jinkui' and 'Xuxiang', respectively. This study provides a reference for consumers and markets on quality improvement and processing.

Fermentation of Clementine Juice with Lactobacillus salivarius spp. salivarius CECT 4063: Effect of Trehalose Addition and High-Pressure Homogenization on Antioxidant Properties, Mucin Adhesion, and Shelf Life

Fermentation of fruit juices with lactic acid bacteria enhances their antioxidant properties to a different extent depending on the microbial strain and the growing media composition, which can be modified by adding certain ingredients or applying a homogenization step. This study analyzed the effect of trehalose addition (10%, w/w) and homogenization at 100 MPa before or after Lactobacillus salivarius spp. salivarius CECT 4063 inoculation on the antioxidant profile and the microbiological properties of commercial clementine juice during 96 h fermentation. Antioxidant properties and viable cell count of 24 h-fermented juices during refrigerated storage (30 days at 4 °C) were also evaluated. Fermentation over 24 h reduced the microbial population and antioxidant content of clementine juice. Homogenizing the juice before inoculation enhanced the microbial growth but favored antioxidant degradation. Adding trehalose (10%, w/w) to the juice formulation and/or homogenizing at the fermented juice at 100 MPa for 24 h had a negative impact on viable counts and did not improve the microbial adhesion to intestinal mucosa. However, both techniques prevented antioxidant oxidation and cell decay during the storage of fermented juice under refrigeration, which should not last more than 15 days.

Characterization and Differentiation of Fresh Orange Juice Variety Based on Conventional Physicochemical Parameters, Flavonoids, and Volatile Compounds Using Chemometrics

The present study focused on the possibility of differentiating fresh-unprocessed orange juice according to botanical origin (variety), based on the use of conventional physico-chemical parameters, flavonoids, and volatile compounds, in combination with chemometrics. For this purpose, oranges from seven different varieties were collected during the harvest years of 2013−2014 and 2014−2015 from central and southern Greece. The physico-chemical parameters that were determined included: electrical conductivity, acidity, pH, and total soluble solids. The flavonoids: hesperidin, neohespseridin, quercetin, naringin, and naringenin were determined using high-performance liquid chromatography (HPLC-DAD). Finally, volatile compounds were determined using headspace solid-phase micro-extraction in combination with gas chromatography-mass spectrometry (HS-SPME/GC-MS). Statistical treatment of data by multivariate techniques showed that orange juice variety had a significant (p < 0.05) impact on the above analytical parameters. The classification rate for the differentiation of orange juice according to orange variety using multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) was 89.3%, based on the cross-validation method.

Evaluation of antibacterial activity of compounds isolated from the peel of Newhall navel orange

Fifteen compounds including one flavanone hesperitin (1), two cinnamic acid derivatives as (E)-4-hydroxycinnamic acid (2) and (E)-ferulic acid (3), eight polymethoxyflavones (PMFs) (4-11), and four hydroxylated PMFs (12-15) isolated from orange peel were subjected to antibacterial evaluation. Compounds 1-3 exhibited wide-spectrum antibacterial effects against four test strains involving Bacillus subtilis, Staphylococcus aureus, Xanthomonas citri subsp. citri (Xcc), and Meticillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentrations (MICs) ranging from 0.0312 to 0.125 mg/mL. In contrast, all PMFs showed weak antibacterial activity against these four strains with MICs being equal to or more than 0.125 mg/mL. Hydroxylated PMFs demonstrated better antibacterial effect against Xcc relative to PMFs. In addition, the synergistic effect against Xcc was obtained when compounds 1 and 3 were combined. Furthermore, the scanning electron microscopy (SEM) results of Xcc treated with both compounds 2 and 3 showed shrunken and rough surface morphologies, indicative of the cell membrane damage.

Review of phytochemical and nutritional characteristics and food applications of Citrus L. fruits

Since the dietary regimen rich in fruits is being widely recognized and encouraged, Citrus L. fruits have been growing in popularity worldwide due to their high amounts of health-promoting phytonutrients and bioactive compounds, such as flavonoids, phenolic acids, vitamins, carotenoids, pectins, and fatty acids. The diverse physicochemical properties and multiple utilization of citrus fruits in food industry are associated with their unique chemical compositions. Throughout the world, citrus has been used for producing various value-added and nutritionally enhanced products, including juices, wines, jams, canned citrus, and dried citrus. However, the current studies regarding the phytochemical and nutritional characteristics and food applications of citrus are scattered. This review systematically summarizes the existing bibliography on the chemical characteristics, functional and nutraceutical benefits, processing, and potential applications of citrus. A thorough understanding of this information may provide scientific guidance for better utilizing citrus as a functional fruit and benefit the extension of citrus value chain.

Fruit Juice Industry Wastes as a Source of Bioactives

Food processing sustainability, as well as waste minimization, are key concerns for the modern food industry. A significant amount of waste is generated by the fruit juice industry each year. In addition to the economic losses caused by the removal of these wastes, its impact on the environment is undeniable. Therefore, researchers have focused on recovering the bioactive components from fruit juice processing, in which a great number of phytochemicals still exist in the agro-industrial wastes, to help minimize the waste burden as well as provide new sources of bioactive compounds, which are believed to be protective agents against certain diseases such as cardiovascular diseases, cancer, and diabetes. Although these wastes contain non-negligible amounts of bioactive compounds, information on the utilization of these byproducts in functional ingredient/food production and their impact on the sensory quality of food products is still scarce. In this regard, this review summarizes the most recent literature on bioactive compounds present in the wastes of apple, citrus fruits, berries, stoned fruits, melons, and tropical fruit juices, together with their extraction techniques and valorization approaches. Besides, on the one hand, examples of different current food applications with the use of these wastes are provided. On the other hand, the challenges with respect to economic, sensory, and safety issues are also discussed.

Differentiation of juice of mandarin-like hybrids based on physicochemical characteristics, bioactive compounds, and antioxidant capacity

In this study, samples of mandarin-like hybrids (Clemenvilla, Nadorcott and Ortanique) from two harvesting seasons (2017−2018 and 2018−2019) were analyzed, to evaluate its differences in physicochemical characteristics and nutritional properties and establish the parameters that allow classify these citrus cultivars. Results showed that Clemenvilla juice had the highest concentration of total phenolic and ascorbic acid and are strongly correlated to its higher antioxidant capacity. Flavonoids were higher in Nadorcott samples. Large differences of total carotenoids were observed in juice analyzed. Varieties and harvesting seasons significantly influenced (p < 0.05) the physicochemical properties, bioactive compounds content and antioxidant capacity of samples. The pH, flavonoids, ascorbic acid, DPPH and TEAC values were determined as predictor parameters to classify the groups according to the varieties, concluding that Nadorcott samples were clearly different. The data presented in this research will currently provide information about the physicochemical evaluation of mandarin-like hybrid varieties and their potential as source of bioactive compounds and antioxidant capacity.

Impact of drying methods on natural antioxidants, phenols and flavanones of immature dropped Citrus sinensis L. Osbeck fruits

Citrus fruits are famous for nutritional value and studies are there for extraction of secondary metabolites from citrus waste. An attempt was made to quantify antioxidants, flavonoids and phenols from dropped fruits of 8–24 mm size, to find the impact of freeze and hot-air oven drying techniques on extraction. Flavonoids (hesperidin, narirutin/isonaringin, diosmin and didymin/neoponcirin) were quantified through high performance liquid chromatography (HPLC) and total phenols (TPC) were estimated by Folin-Ciocalteu method. Antioxidant capacity was adjudged by azino-bis [3-ethylbenzthiazoline-6-sulfonic acid] (ABTS), 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). Freeze dried fruits of 10 mm and 12 mm retained maximum hesperidin content (22.383% and 21.560%) in comparison to hot-air oven counterparts (18.377% and 15.090%). Narirutin/isonaringin (1.343% and 1.191%), diosmin (5.293% and 3.234%) and didymin/neoponcirin (1.187% and 1.113%) content were found higher in 8 mm and 10 mm freeze dried fruits. The antioxidant capacity (7.548–11.643 mmol L⁻¹ Trolox, 8.164–14.710 mmol L⁻¹ Trolox, 4.008–5.863 mmol L⁻¹ Trolox by ABTS, DPPH and FRAP assays) and TPC were found higher in freeze dried samples. Significant correlation was found between antioxidant capacity, TPC and flavonoids at p < 0.01. Freeze drying technique can be adopted for retaining and quality extraction of bioactive compounds from immature dropped fruits for further use in nutraceutical industries.

Optimization of Naringin and Naringenin Extraction from Citrus × paradisi L. Using Hydrolysis and Excipients as Adsorbent

While flavanones exist in a variety of chemical forms, their favorable health effects are most prominent in their free form—aglycones. Their concentrations in grapefruit (Citrus × paradisi L.) extracts vary according to the extraction and hydrolysis methods used. The primary aim of this work was to maximize the yields of naringin and naringenin from various parts of fresh grapefruit fruits (flavedo, albedo, and segmental) using different extraction and hydrolysis methods. In addition, we aimed to evaluate the excipient—magnesium aluminometasilicate—and determine its influence on the qualitative composition of grapefruit extracts. Extracts were obtained by heat reflux extraction (HRE), ultrasound-assisted extraction with an ultrasonic homogenizer (UAE*), and ultrasound-assisted extraction with a bath (UAE). Ultrasound-assisted extraction using a bath (UAE) was modulated using acidic, thermal, and alkaline hydrolysis. The highest yield of naringin 8A (17.45 ± 0.872 mg/g) was obtained from an albedo sample under optimal conditions using ultrasound-assisted extraction; a high yield of naringenin 23-SHR (35.80 ± 1.79 µg/g) was produced using the heat reflux method from the segmental part. Meanwhile, ultrasonic combined with thermal hydrolysis significantly increased flavanone extraction from the albedo and segmental parts: naringin from sample 9-A (from 17.45 ± 0.872 mg/g to 25.05 ± 1.25 mg/g) and naringenin from sample 15-S (from 0 to 4.21 ± 0.55 µg/g). Additionally, magnesium aluminometasilicate demonstrated significant increases of naringenin from all treated grapefruit parts. To our knowledge, this is the first report of magnesium aluminometasilicate used as an adsorbent in flavanone extractions.

Metabolic Diversity of Flavonoids and Antioxidant Potential for Characterization of Underutilized Citrus Species for Nutritional Security

Citrus fruits are grown commercially throughout the world. They are widely consumed due to their nutrients, use in energy supplements, and numerous health benefits. There is significant interest among consumers about this naturally available source, rich in flavonoids and antioxidants. However, underutilized citrus varieties remain unexplored due to the lack of information about the pool of nutritive properties they confer. Ten underutilized citrus varieties were collected from Nokrek Biosphere Reserve, West Garo Hills, Meghalaya, India, identified by UNESCO as a Biosphere reserve, to study the diversity in terms of limonin, ascorbic acid, carotenoids, browning, flavonoids, total phenol, and antioxidant activity, the contents of which varied significantly among different citrus cultivars. The results indicated that Citron and Pomelo were good sources of ascorbic acid (29.50 and 45.09 mg/100 mL), and that Khasi papeda was found to contain lower limonin content (9.21 ppm). However, in terms of flavonoids, Khasi papeda and Pomelo were found to exhibit a higher naringin content (189.13 ppm and 32.15 ppm), whereas the hesperidin content was highest in Kachai lemon, Khasi papeda, and Chinotto, at 199.51 ppm, 148.04 ppm, and 135.88 ppm, respectively. Antioxidant activity was assessed by three antioxidant assays (ABTS+ (radical cation azino-bis [3-ethylbenzthiazoline-6-sulfonic acid]) (ABTS), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), and Ferric Reducing Antioxidant Power (FRAP)). Khasi papeda (7.48 mM L−1 Trolox), Chinotto (7.48 mM L−1 Trolox), and Pomelo (7.48 mM L−1 Trolox) exhibited the highest reducing power with DPPH radical scavenging activity, and Khasi papeda (15.41 mg GAE L−1) possessed a higher phenolic content, whereas the antioxidant activity when assessed with ABTS and FRAP assays was highest among the underutilized species of Khasi papeda (4.84 mM L−1 Trolox, 1.93 mM L−1 Trolox) and Ada Jamir (4.96 mM L−1 Trolox, 2.03 mM L−1 Trolox), respectively. To the best of our knowledge, this is among the very few papers presenting comprehensive data on the metabolic diversity of flavonoids and antioxidant potential to characterize the underutilized citrus species. This study also demonstrated that Khasi papeda, Pomelo, Chinotto, and Kachai lemon can serve as potential sources of functional components, bioactive compounds, and antioxidants, which can be explored for further application in the processing industry for nutritional security.

Ascorbic Acid Content and Transcriptional Profiling of Genes Involved in Its Metabolism during Development of Petals, Leaves, and Fruits of Orange (Citrus sinensis cv. Valencia Late)

Citrus fruit is one of the most important contributors to the ascorbic acid (AsA) intake in humans. Here, we report a comparative analysis of AsA content and transcriptional changes of genes related to its metabolism during development of petals, leaves and fruits of Valencia Late oranges (Citrus sinensis). Petals of close flowers and at anthesis contained the highest concentration of AsA. In fruits, AsA content in the flavedo reached a maximum at color break, whereas the pulp accumulated lower levels and experienced minor fluctuations during development. AsA levels in leaves were similar to those in the flavedo at breaker stage. The transcriptional profiling of AsA biosynthetic, degradation, and recycling genes revealed a complex and specific interplay of the different pathways for each tissue. The D-galacturonic acid pathway appeared to be relevant in petals, whereas in leaves the L-galactose pathway (GGP and GME) also contributed to AsA accumulation. In the flavedo, AsA content was positively correlated with the expression of GGP of the L-galactose pathway and negatively with DHAR1 gene of the recycling pathway. In the pulp, AsA appeared to be mainly controlled by the coordination among the D-galacturonic acid pathway and the MIOX and GalDH genes. Analysis of the promoters of AsA metabolism genes revealed a number of cis-acting elements related to developmental signals, but their functionalities remain to be investigated.

Regulation of Tocopherol Biosynthesis During Fruit Maturation of Different Citrus Species

Tocopherols are plant-derived isoprenoids with vitamin E activity, which are involved in diverse physiological processes in plants. Although their biosynthesis has been extensively investigated in model plants, their synthesis in important fruit crops as Citrus has scarcely been studied. Therefore, the aim of this work was to initiate a physiological and molecular characterization of tocopherol synthesis and accumulation in Citrus fruits during maturation. For that purpose, we selected fruit of the four main commercial species: grapefruit (Citrus paradisi), lemon (Citrus limon), sweet orange (Citrus sinensis), and mandarin (Citrus clementina), and analyzed tocopherol content and the expression profile of 14 genes involved in tocopherol synthesis during fruit maturation in both the flavedo and pulp. The selected genes covered the pathways supplying the tocopherol precursors homogentisate (HGA) (TAT1 and HPPD) and phytyl pyrophosphate (PPP) (VTE5, VTE6, DXS1 and 2, GGPPS1 and 6, and GGDR) and the tocopherol-core pathway (VTE2, VTE3a, VTE3b, VTE1, and VTE4). Tocopherols accumulated mainly as α- and γ-tocopherol, and α-tocopherol was the predominant form in both tissues. Moreover, differences were detected between tissues, among maturation stages and genotypes. Contents were higher in the flavedo than in the pulp during maturation, and while they increased in the flavedo they decreased or were maintained in the pulp. Among genotypes, mature fruit of lemon accumulated the highest tocopherol content in both the flavedo and the pulp, whereas mandarin fruit accumulated the lowest concentrations, and grapefruit and orange had intermediate levels. Higher concentrations in the flavedo were associated with a higher expression of all the genes evaluated, and different genes are suitable candidates to explain the temporal changes in each tissue: (1) in the flavedo, the increase in tocopherols was concomitant with the up-regulation of TAT1 and VTE4, involved in the supply of HGA and the shift of γ- into α-tocopherol, respectively; and (2) in the pulp, changes paralleled the expression of VTE6, DXS2, and GGDR, which regulate PPP availability. Also, certain genes (i.e., VTE6, DXS2, and GGDR) were co-regulated and shared a similar pattern during maturation in both tissues, suggesting they are developmentally modulated.

Nutrients and bioactives in citrus fruits: Different citrus varieties, fruit parts, and growth stages

Citrus fruits are consumed in large quantities worldwide due to their attractive aromas and taste, as well as their high nutritional values and various health-promoting effects, which are due to their abundance of nutrients and bioactives. In addition to water, carbohydrates, vitamins, minerals, and dietary fibers are important nutrients in citrus, providing them with high nutritional values. Citrus fruits are also rich in various bioactives such as flavonoids, essential oils, carotenoids, limonoids, and synephrines, which protect from various ailments, including cancer and inflammatory, digestive, and cardiovascular diseases. The composition and content of nutrients and bioactives differ significantly among citrus varieties, fruit parts, and growth stages. To better understand the nutrient and bioactive profiles of citrus fruits and provide guidance for the utilization of high-value citrus resources, this review systematically summarizes the nutrients and bioactives in citrus fruit, including their contents, structural characteristics, and potential health benefits. We also explore the composition variation in different citrus varieties, fruits parts, and growth stages, as well as their health-promoting effects and applications.

Orange fruit (Citrus sinensis) peel extract attenuates chemotherapy-induced toxicity in male rats

Background: Cyclophosphamide (CYP) is a chemotherapy drug widely used in the treatment of several types of cancers and autoimmune disorders. Unfortunately, it causes severe side effects on many organs due to its oxidative stress effect. Objective: The present study aims to tentatively identify the phytochemical constituents of orange fruit (Citrus sinensis) peel extract (OFPE) and elucidate the chemopreventive effects of OFPE on CYP drug induced organ toxicity. Methods: The high performance liquid chromatography coupled with mass spectroscopy (HPLC-MS/MS) technique was used to identify the compounds. Thirty-five male rats were divided into five groups (GP; n = 7): GP1: normal control, GP2: OFPE 0.5 only, GP3: CYP-only, GP4: OFPE 0.25 + CYP, and GP5: OFPE 0.5 + CYP. Results: Twenty-nine compounds of polyphenolic nature, mainly flavonoids, anthocyanidins, phenolic acids and limonoids were characterized by HPLC-MS/MS analysis. Among these compounds, naringin, hesperidin, diosmin, rutin, neohesperidin and limonin were the predominant compounds in the examined extract. Serum cellular markers were found to be decreased significantly upon treatment with OFPE (especially high dose). Also, a significant prophylactic effect against liver, kidney, and heart injuries induced by CYP via decreasing inflammation (serum TNF-α, IL-1β & IL-6) and lipid peroxidation (MDA) was also revealed. Also, an increase in antioxidant levels (serum TAO, and cellular GSH & CAT in tissue homogenates) confirmed the protective efficacy of OFPE against CYP toxicity. Conclusions: The present study reveals some chemopreventive properties and beneficial effects of OFPE on CYP-induced organ toxicity via its antioxidant status and immunoregulatory activities.

Quantification of Flavonoids, Phenols and Antioxidant Potential from Dropped Citrus reticulata Blanco Fruits Influenced by Drying Techniques

Physiologically dropped immature Citrus reticulata Blanco fruits are regarded as waste and discarded in the citrus orchard but are a good source of bioactive compounds including flavonoids, antioxidants and total phenols. A study was undertaken to identify and quantify these bioactive compounds and to investigate the influence of different drying techniques, namely freeze drying and hot air oven drying, on flavonoids namely flavanone glycosides, antioxidant potential and total phenol content in immature dropped fruits of Citrus reticulata Blanco. Flavonoids were quantified in high-performance liquid chromatography (HPLC). The antioxidant activity were investigated with three assays azino-bis [3-ethylbenzthiazoline-6-sulfonic acid]) (ABTS), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), Ferric Reducing Ability of Plasma (FRAP) and total phenol content was determined. Freeze dried samples of 12 and 14 mm size retained maximum hesperidin flavonoid content (27.03% and 27.20%) as compared to the hot air dried samples (17.99%) and retained higher phenolic content ranged from 50.54-54.19 mg GAEL^-1. The antioxidant activity in freeze dried fruits was from 12.21-13.55 mM L^-1 Trolox and 15.27-16.72 mM L^-1 Trolox with ABTS, DPPH assay and FRAP values ranging from 7.31-9.07 mM L^-1 Trolox. Significant positive correlation was found between the flavonoid hesperidin with antioxidant assays and total phenolic content (TPC). The results showed that waste citrus fruits can act as potential source of bioflavonoids, especially hesperidin, and antioxidants for pharmaceutical as well as nutraceutical industry.

Insights of Phenolic Pathway in Fruits: Transcriptional and Metabolic Profiling in Apricot (Prunus armeniaca)

There is an increasing interest in polyphenols, plant secondary metabolites, in terms of fruit quality and diet, mainly due to their antioxidant effect. However, the identification of key gene enzymes and their roles in the phenylpropanoid pathway in temperate fruits species remains uncertain. Apricot (Prunus armeniaca) is a Mediterranean fruit with high diversity and fruit quality properties, being an excellent source of polyphenol compounds. For a better understanding of the phenolic pathway in these fruits, we selected a set of accessions with genetic-based differences in phenolic compounds accumulation. HPLC analysis of the main phenolic compounds and transcriptional analysis of the genes involved in key steps of the polyphenol network were carried out. Phenylalanine ammonia-lyase (PAL), dihydroflavonol-4-reductase (DFR) and flavonol synthase (FLS) were the key enzymes selected. Orthologous of the genes involved in transcription of these enzymes were identified in apricot: ParPAL1, ParPAL2, ParDFR, ParFLS1 and ParFLS2. Transcriptional data of the genes involved in those critical points and their relationships with the polyphenol compounds were analyzed. Higher expression of ParDFR and ParPAL2 has been associated with red-blushed accessions. Differences in expression between paralogues could be related to the presence of a BOXCOREDCPAL cis-acting element related to the genes involved in anthocyanin synthesis ParFLS2, ParDFR and ParPAL2.

Strategies to Produce Grapefruit-Like Citrus Varieties With a Low Furanocoumarin Content and Distinctive Flavonoid Profiles

Pummelos and hybrids, such as grapefruits, have high furanocoumarin and low flavonoid contents. Furanocoumarins interact negatively with certain drugs, while flavonoids are antioxidant compounds with health benefits. To obtain new grapefruit-like varieties with low furanocoumarin and high flavonoid contents, diploid and triploid hybrid populations from crosses between diploid and tetraploid "Clemenules" clementine and diploid "Pink" pummelo were recovered and analyzed. With regard to furanocoumarins, triploids produce less bergapten, bergamottin and 6,7-DHB than diploids. Regarding flavonoids, triploids yielded more eriocitrin, narirutin, hesperidin and neohesperidin than diploids, whereas no differences were observed in neoeriocitrin and naringin. These results indicate that, the strategy to recover triploid hybrids by 4x × 2x crosses is more appropriate than the recovery of diploid hybrids by 2x × 2x crosses for obtaining grapefruit-like varieties of citrus with lower furanocoumarin and higher flavonoid contents.

Secondary Metabolic Profile as a Tool for Distinction and Characterization of Cultivars of Black Pepper (Piper nigrum L.) Cultivated in Pará State, Brazil

This study evaluated the chemical compositions of the leaves and fruits of eight black pepper cultivars cultivated in Pará State (Amazon, Brazil). Hydrodistillation and gas chromatography-mass spectrometry were employed to extract and analyze the volatile compounds, respectively. Sesquiterpene hydrocarbons were predominant (58.5-90.9%) in the cultivars "Cingapura", "Equador", "Guajarina", "Iaçará", and "Kottanadan", and "Bragantina", "Clonada", and "Uthirankota" displayed oxygenated sesquiterpenoids (50.6-75.0%). The multivariate statistical analysis applied using volatile composition grouped the samples into four groups: γ-Elemene, curzerene, and δ-elemene ("Equador"/"Guajarina", I); δ-elemene ("Iaçará"/"Kottanadan"/"Cingapura", II); elemol ("Clonada"/"Uthirankota", III) and α-muurolol, bicyclogermacrene, and cubebol ("Bragantina", IV). The major compounds in all fruit samples were monoterpene hydrocarbons such as α-pinene, β-pinene, and limonene. Among the cultivar leaves, phenolics content (44.75-140.53 mg GAE·g^-1 FW), the enzymatic activity of phenylalanine-ammonia lyase (20.19-57.22 µU·mL^-1), and carotenoids (0.21-2.31 µg·mL^-1) displayed significant variations. Due to black pepper's susceptibility to Fusarium infection, a molecular docking analysis was carried out on Fusarium protein targets using each cultivar's volatile components. F. oxysporum endoglucanase was identified as the preferential protein target of the compounds. These results can be used to identify chemical markers related to the susceptibility degree of black pepper cultivars to plant diseases prevalent in Pará State.

Antioxidant capacity in fruit of Citrus cultivars with marked differences in pulp coloration: Contribution of carotenoids and vitamin C

The purpose of this study was to evaluate the specific contribution of carotenoids and vitamin C to the lipophilic and hydrophilic antioxidant capacity, respectively, of the pulp of citrus fruits using the genetic diversity in pigmentation and in the carotenoid complement. To this end, six citrus varieties were selected: two mandarins, Clemenules (Citrus clementina) and Nadorcott (C. reticulata); two grapefruits (C. paradisi), Marsh and Star Ruby; and two sweet oranges (C. sinensis), Valencia late and Valencia Ruby. Total carotenoid content and composition in the pulp of fruits were very different, in relation to their color singularities. Valencia Ruby and Nadorcott had the highest carotenoid content, accumulating the former large amounts of linear carotenes (phytoene, phytofluene, and lycopene) and Nadorcott of β-cryptoxanthin. Orange fruits contained the highest amount of vitamin C while in Nadorcott mandarin it was substantially lower. Analysis of antioxidant capacity, evaluated by 2,2'-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, in the pulp of the different fruit varieties indicated a high and positive correlation between vitamin C content and hydrophilic antioxidant capacity. Nevertheless, a weak correlation was observed between carotenoids content and lipophilic antioxidant capacity in the pulp extracts assayed by ABTS. Overall, vitamin C in the pulp of citrus fruit had an important contribution to the hydrophilic antioxidant capacity, whereas that of carotenoids to lipophilic antioxidant capacity was very variable, being the highest that of Valencia Ruby orange, with large concentrations of lycopene and phytoene, followed by Nadorcott mandarin, with high β-cryptoxanthin content.

Comparative Metabolites and Citrate-Degrading Enzymes Activities in Citrus Fruits Reveal the Role of Balance between ACL and Cyt-ACO in Metabolite Conversions

Citric acid metabolism is considered to be the central cellular process of metabolite conversions. ATP-citrate lyase (ACL) and cytosolic aconitase (cyt-ACO) are the two citrate-degrading enzymes that decide the carbon flux towards different metabolite biosynthesis pathways. However, the correlation of their activities with metabolite concentrations in citrus fruits is still unclear. Here, the concentrations of soluble sugars, organic acids, acetyl-CoA, flavonoids, carotenoids, and γ-aminobutyric acid, as well as the activities of ACL, cyt-ACO, acetyl-CoA C-acetyltransferase, and acetyl-CoA carboxylase, were compared among the fruits of six citrus cultivars during fruit development and ripening. The results showed that the correlation between citrate concentration and cyt-ACO or ACL activity varied greatly among cultivars, while the activities of cyt-ACO and ACL had a significantly negative correlation (r = −0.4431). Moreover, ACL overexpression and RNA interference in the Citrus callus indicated that increasing and decreasing the ACL activity could reduce and induce cyt-ACO activity, respectively. In addition, significant correlation was only observed between the ACL activity and the concentration of acetyl-CoA (r = 0.4333). Taken together, the present study suggested that ACL and cyt-ACO synergistically control the citrate fate for the biosynthesis of other metabolites, but they are not the key determinants for the accumulation of citrate, as well as other metabolites in citrus fruits.

Effect of Post-Harvest LED and UV Light Irradiation on the Accumulation of Flavonoids and Limonoids in the Segments of Newhall Navel Oranges (Citrus sinensis Osbeck)

To investigate the effect of post-harvest light irradiation on the accumulation of flavonoids and limonoids, harvested Newhall navel oranges were continuously exposed to light-emitting diode (LED) and ultraviolet (UV) light irradiation for 6 days, and the composition and content of flavonoids and limonoids in the segments were determined using UPLC-qTOF-MS at 0, 6, and 15 days after harvest. In total, six polymethoxylated flavonoids (PMFs), five flavone-O/C-glycosides, seven flavanone-O-glycosides, and three limonoids were identified in the segments. The accumulation of these components was altered by light irradiation. Red and blue light resulted in higher levels of PMFs during exposure periods. The accumulation of PMFs was also significantly induced after white light, UVB and UVC irradiation were removed. Red and UVC irradiation induced the accumulation of flavone and flavanone glycosides throughout the entire experimental period. Single light induced limonoid accumulation during exposure periods, but limonoid levels decreased significantly when irradiation was removed. Principal component analysis showed a clear correlation between PMFs and white light, between flavonoid glycosides and red light and UVC, and between limonoids and UVC. These results suggest that the accumulation of flavonoids and limonoids in citrus is regulated by light irradiation. White light, red light and UVC irradiation might be a good potential method for improving the nutrition and flavor quality of post-harvest citrus.

Optimization of a polyphenol extraction method for sweet orange pulp (Citrus sinensis L.) to identify phenolic compounds consumed from sweet oranges

The consumption of sweet oranges has been linked to several health benefits, many of which are attributed to hesperidin, a flavanone that is present in high amounts in these fruits. However, other phenolic compounds can contribute to the bioactivity of sweet orange. To link those effects to their phenolic profile, the complete characterization of the phenolic profile is mandatory. Although many studies have profiled the phenolic composition of orange juices, their pulps, which retain phenolic compounds, are overlooked. This fact is particularly relevant because dietary guidelines recommend the consumption of whole fruits. Therefore, this study aimed to develop a specific method for the optimal extraction of phenolics from orange pulp and to use this method to characterize these fruits grown at different locations by HPLC-ESI-MS/MS. The extraction conditions that reported the highest total polyphenol content (TPC) and hesperidin contents were 20 mL/g, 55 °C, and 90% methanol. The extraction time and number of sequential steps were further evaluated and optimized as 20 min and two extraction steps, respectively. Although lower extraction rates were achieved when using ethanol as the extraction solvent, high TPC and hesperidin yields were obtained, suggesting the potential use of this methodology to produce phenolic-rich extracts for the food industry. By applying the optimized methodology and analyzing the extracts by HPLC-ESI-MS/MS, geographic cultivation regions were demonstrated to affect the phenolic profiles of oranges. In short, we developed a quick, easy-to-perform methodology that can be used to extract orange phenolics from pulp for their identification and quantification and to evaluate the factors that affect the phenolic profile in sweet orange pulps.

Impact of in vitro digestion phases on the stability and bioaccessibility of carotenoids and their esters in mandarin pulps

The composition of carotenoids (carotenes and free and acylated xanthophylls) and their bioaccessibilities were determined for the first time in pulps of mandarins cultivated in Brazil. Two cultivars of mandarin, Citrus reticulata Blanco cv. 'Ponkan' and Citrus reticulata × C. sinensis cv. 'Murcott', showed higher contents of most carotenoids compared to those found in C. deliciosa Tenore cv. 'Rio'. The major carotenoids in mandarin cv. 'Ponkan' and 'Murcott' were (all-E)-β-cryptoxanthin laurate (19-21%), (all-E)-β-cryptoxanthin myristate (15-17%) and (Z)-ζ-carotene (7-12%), followed by (all-E)-β-cryptoxanthin palmitate (4-7%), free (all-E)-β-cryptoxanthin (5-6%) and (all-E)-β-carotene (4-5%), while in mandarin cv. 'Rio' (all-E)-β-cryptoxanthin myristate (22%) was the major compound, followed by (all-E)-β-cryptoxanthin laurate (16%), (all-E)-β-cryptoxanthin palmitate (11%), (all-E)-β-cryptoxanthin (9%) and (all-E)-β-carotene (6%). After in vitro digestion, the qualitative carotenoid profile of the supernatant containing the micellarized carotenoids was similar to that of fresh fruits, but the contents were significantly lower. Carotenoid and mandarin physico-chemical properties influenced the bioaccessibility of carotenoids. Free (all-E)-β-cryptoxanthin showed the highest bioaccessibility in all mandarin cultivars (33-42%), while the bioaccessibilities of β-carotene (16-36%) and the major carotenoid esters (18-33%) were lower. The overall recovery of carotenoids during in vitro digestion was around 98% after the oral phase, 79% after oral + gastric phases and 77% after oral + gastric + duodenal phases, with free (all-E)-β-cryptoxanthin and (all-E)-β-carotene being the most stable ones. Besides possible E-Z isomerization and ester hydrolysis, evident losses occurred in total carotenoid contents and also in the most individual carotenoids and they were not compensated for by the former reactions.

Targeted Analysis of the Concentration Changes of Phenolic Compounds in Persian Lime (Citrus latifolia) during Fruit Growth

Citrus fruits possess a high content of phenolic compounds; however, few studies have focused on the changes occurring during fruit growth. In this study, the changes in the concentration of 20 flavonoids, 4 phenolic acids, and their biosynthetic precursors phenylalanine and tyrosine have been evaluated during fruit maturation (14 weeks). Extracts from all samples, obtained by ultrasound assistance, were analyzed by liquid chromatography coupled to tandem mass spectrometry with a triple quad system (LC-QqQ MS/MS). In general, the concentration of flavanones, which represented over 70% of the studied phenols, and flavones increased during fruit growth, reaching their maximum concentration around week 12. In general, flavanols and phenolic acids exhibited their maximum concentration at week 5 and then decreasing significantly during the rest of maturation. Phenylalanine and tyrosine showed a sinuous behavior during fruit growth. Partial least-squares showed a clear differentiation among fruits belonging to different maturation stages, coumaric acid derivatives being the most influential variables on the projection.

Mandarin fruit quality: a review

During the last decade, there has been a continuous rise in consumption and global marketing of fresh, easy-to-peel mandarins, with current annual production of nearly 29 million tons. Nevertheless, most of the existing knowledge on quality traits of citrus fruit comes from research conducted on oranges and grapefruit, which are the main products for the citrus juice manufacturing industry; relatively little is yet known regarding the unique fruit quality traits of mandarins, nor about the great diversity in these traits among the various natural sub-groups and varieties of mandarins. In the present review we discuss the physiological, biochemical, and molecular factors governing key fruit quality attributes of mandarins, including fruit colour, size and shape, ease of peeling, seedlessness, flavour, and nutritional quality. Fruit colour, size, and shape contribute to external appearance; peelability and seedlessness to ease of consumption; and flavour and nutritional quality to internal quality. © 2017 Society of Chemical Industry.

Flavanones: Citrus phytochemical with health-promoting properties

Citrus fruit and juices represent one of the main sources of compounds with a high potential for health promoting properties. Among these compounds, flavanones (such as hesperetin, naringenin, eriodictyol, isosakuranetin, and their respective glycosides), which occur in quantities ranging from ∼180 to 740 mg/L (depending on the Citrus species and cultivar) are responsible for many biological activities. These compounds support and enhance the body's defenses against oxidative stress and help the organism in the prevention of cardiovascular diseases, atherosclerosis, and cancer. Moreover, among other properties, they also show anti-inflammatory, antiviral, and antimicrobial activities. This review analyzes the biochemistry, pharmacology, and biology of Citrus flavanones, emphasizing the occurrence in Citrus fruits and juices and their bioavailability, structure-function correlations and ability to modulate signal cascades both in vitro and in vivo. © 2017 BioFactors, 43(4):495-506, 2017.

Antioxidant and antiplatelet activities of flavonoid-rich fractions of three citrus fruits from Korea

Three different fractional (methanol, ethyl acetate and hexane) extracts from yuzu (Citrus junos Sieb ex Tanaka), hallabong [(C. unshiu Marcov × C. sinensis Osbeck) × C. reticulata Blanco] and orange (C. sinensis) were evaluated for their antioxidant activity and antiplatelet effects. 2,2-Diphenyl-1-Picrylhydrazyl (DPPH), cupric reducing antioxidant capacity (CUPRAC) and ferric-reducing antioxidant power (FRAP) methods were used for the antioxidant activity tests. Total flavonoids and total phenolics were also evaluated spectrophotometrically. The ethyl acetate fraction contained the highest total flavonoid and total phenolic content and exhibited the highest antioxidant activities (185.2 ± 14.5 and 208.7 ± 17.5 mg/g dry extract for FRAP and CUPRAC values, respectively). The total phenolic and total flavonoid content ranged from 58.2 ± 1.4 to 102.4 ± 8.6 and 19.6 ± 0.5 to 64.3 ± 0.8 mg/g dry extract, respectively. The results of DPPH assay showed that ethyl acetate fractions had the least IC50 values (0.12 ± 0.002, 0.04 ± 0.0006, in mg/mL for orange and hallabong samples, respectively) followed by the hexane fraction (0.19 ± 0.007 mg/mL) of the orange sample. For all fractions, the antioxidant activity and contents of total phenolics and total flavonoids correlated well with each other. In vitro investigation of the antiplatelet effect showed that ethyl acetate fraction has the highest inhibition (84.3 ± 5.8 to 96.1 ± 1.8 %). Hexane and MeOH fractions of hallabong and orange samples inhibited platelet aggregations by less than or equal to 41 %.

Phenolic compositions and antioxidant activities of grapefruit (Citrus paradisi Macfadyen) varieties cultivated in China

The phenolic compounds in different fruit parts including the flavedos, albedos, segment membranes, juice vesicles and seeds of nine grapefruit varieties cultivated in China were determined and their antioxidant capacities were evaluated using three methods. Naringin and neohesperedin were the dominant flavonoids in all grapefruit tested. Fenghongtangmuxun and Jiwei flavedo had the highest contents of naringin (5666.82 μg/g DW) and neohesperedin (1022 μg/g DW), respectively. Gallic acid was the major phenolic acid in all grapefruit tested, and Jiwei juice vesicles had the highest content of gallic acid (343.7 μg/g DW). Fenghongtangmuxun juice vesicles were rich in chlorogenic acid (110.23 μg/g DW), caffeic acid (53.86 μg/g DW) and ferulic acid (23.12 μg/g DW). Overall, the flavedo was rich in flavonoid, while juice vesicle had high amounts of phenolic acid. The Jiwei, Fenghongtangmuxun, Maxu, Huoyan and Hongmaxu grapefruit cultivars contained more phenolics and exhibited higher antioxidant capacities than Shatianyou and Liangpingyou pummelos, and were good sources of natural phytochemical antioxidants.

In vitro antioxidative and binding properties of phenolics in traditional, citrus and exotic fruits

Many polyphenols bind proteins, therefore our research was focused on the potential of protein binding to polyphenols of investigated fruits and their health-related effects. The contents of polyphenols and related antioxidant activities of traditional, citrus and exotic fruits were compared. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples and their interaction with human serum albumin (HSA) was studied by HPLC, Fourier Transform Infrared (FT-IR) and three dimensional fluorescence spectroscopy (3D-FL). The highest levels of polyphenols, antioxidant and binding capacities were found in red and blond grapefruits (citrus group), followed by strawberries and apples (traditional group) and mangosteen and kiwi fruit (exotic fruit), which also contained the highest levels of protocatechuic, p-coumaric, ferulic acids and quercetin. In conclusion, for the first time, the interaction of the polyphenols with human serum albumin was evaluated by fluorometry/FTIR. The obtained binding profiles allowed the comparison of three different groups of fruits. A mixture of these fruits can be recommended for consumption.