Advances on multiclass pesticide residue determination in citrus fruits and citrus-derived products - A critical review.

The application of agrochemicals in citrus fruits is widely used to improve the quality of crops, increase production yields, and prolong post-harvest life. However, these substances are potentially toxic for humans and the ecosystem due to their widespread use, high stability, and bioaccumulation. Conventional techniques for determining pesticide residues in citrus fruits are chromatographic methods coupled with different detectors. However, in recent years, the need for analytical strategies that are less polluting for the environment has encouraged the appearance of new alternatives, such as sensors and biosensors, which allow selective and sensitive detection of pesticide residues in real time. A comprehensive overview of the analytical platforms used to determine pesticide residues in citrus fruits and citrus-derived products is presented herein. The review focuses on the evolution of these methods since 2015, their limitations, and possible future perspectives for improving pesticide residue determination and reducing environmental contamination.

Naringenin and Hesperidin as Promising Alternatives for Prevention and Co-Adjuvant Therapy for Breast Cancer.

Citrus (genus Citrus L.) fruits are essential sources of bioactive compounds with antioxidant properties, such as flavonoids. These polyphenolic compounds are divided into subclasses, in which flavanones are the most prominent. Among them, naringenin and hesperidin are emerging compounds with anticancer potential, especially for breast cancer (BC). Several mechanisms have been proposed, including the modulation of epigenetics, estrogen signaling, induction of cell death via regulation of apoptotic signaling pathways, and inhibition of tumor invasion and metastasis. However, this information is sparse in the literature and needs to be brought together to provide an overview of how naringenin and hesperidin can serve as therapeutic tools for drug development and as a successful co-adjuvant strategy against BC. This review detailed such mechanisms in this context and highlighted how naringenin and hesperidin could interfere in BC carcinogenesis and be helpful as potential alternative therapeutic sources for breast cancer treatment.

Insights on the Extraction and Analysis of Phenolic Compounds from Citrus Fruits: Green Perspectives and Current Status.

Citrus fruits (CF) are highly consumed worldwide, fresh, processed, or prepared as juices and pies. To illustrate the high economic importance of CF, the global production of these commodities in 2021 was around 98 million tons. CF's composition is considered an excellent source of phenolic compounds (PC) as they have a large amount and variety. Since ancient times, PC has been highlighted to promote several benefits related to oxidative stress disorders, such as chronic diseases and cancer. Recent studies suggest that consuming citrus fruits can prevent some of these diseases. However, due to the complexity of citrus matrices, extracting compounds of interest from these types of samples, and identifying and quantifying them effectively, is not a simple task. In this context, several extractive and analytical proposals have been used. This review discusses current research involving CF, focusing mainly on PC extraction and analysis methods, regarding advantages and disadvantages from the perspective of Green Chemistry.

Probiotics in Citrus Fruits Products: Health Benefits and Future Trends for the Production of Functional Foods-A Bibliometric Review.

The relationship between food and human health drives the search for knowledge of food components that are related to these benefits. The scientific community shows a growing interest in the knowledge of the interactions between components of citrus fruits and probiotics to develop ways to improve the quality of the food produced. In this bibliometric review, a study of scientific publications is carried out on the potential of probiotics in citrus fermentation, addressing the importance and future trends of plant-based products in the functional food group as an alternative to the dairy market. The review process of the articles initially took place with a bibliometric analysis and was followed by a literature review. The Scopus database was used in the search for articles, carried out in May 2021. The use of foods as carriers of probiotics is an alternative that has been growing and the surveys evaluated show the desire to diversify the probiotics available on the market. In addition, it was observed that citrus fruits have great potential for the development of functional foods due to their high acceptability and possibilities of development and application in various products.

Occurrence of citrus brown and black spot diseases and their control using pre-harvest approaches

Mild brown and black spot diseases symptoms were detected on citrus varieties, Valencia and Navel fruits during season 2018 in some citrus orchards at North Egypt. Collected diseased fruit samples revealed isolation of Alternaria alternata and Phyllosticta citricarpa (McAlpine) van der Aa. Some organic acids, salts and Saccharomyces cerevisiae were evaluated against the diseases incidents in vitro and in vivo. Complete growth inhibition was recorded for fungi tested at 2g/L of salicylic acid, Potassium dihydrogen phosphate, Tri-Sodium polyphosphate and 2.5 g/L of S. cerevisiae. All pre-harvest treated Valencia trees, inoculated fruits revealed no diseases symptoms up to 10 days of storage period. Meanwhile, S. cerevisiae and salicylic acid treatments had extended protective effect up to 20 days. Control strategy through spraying Valencia orange trees with yeast or some organic acids and salts as pre-harvest approaches should be taken in consideration especially these diseases began to occur in North region of Egypt.

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, ß-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.

Screening Methods for Isolation of Biocontrol Epiphytic Yeasts against Penicillium digitatum in Lemons.

Worldwide, the green rot caused by Penicillium digitatum is one of the most aggressive postharvest diseases of lemons. Searching for sustainable alternatives to chemical fungicides, epiphytic yeasts as potential biocontrol agents were isolated from citrus fruits using a tailor-made selective medium. For disclosing their antagonistic potential against P. digitatum, obtained isolates were subjected to direct screening methods, both in vitro and in vivo. In the course of the primary in vitro screening that comprised dual culture assays, 43 yeast strains displaying antagonistic activities against the pathogen were selected. Subsequently, such strains were subjected to an in vivo screening that consisted of a microscale test, allowing the selection of six yeast strains for further analysis. In the final screening using macroscale in vivo tests, three strains (AcL2, AgL21, and AgL2) displaying the highest efficiencies to control P. digitatum were identified. The protection efficiencies in lemons were 80 (AcL2), 76.7 (AgL21), and 75% (AgL2). Based on sequence analysis of the PCR amplified D1/D2 domains of the 26S rRNA genes, they were identified as representatives of the species Clavispora lusitaniae. Interestingly, the strains exhibited a broad action spectrum among citrus fruits as they were also able to combat the green mold disease in grapefruit and two orange varieties. The direct screening methods applied in this study favored the recovery of efficient candidates for application as biological control agents to combat fungal infestations of citrus fruits.

Visualization of Carotenoid-Storage Structures in Fruits by Transmission Electron Microscopy.

Plastids are cell organelles that, beside other functions, have the capability to store carotenoids in specialized structures, which may vary among the different plant species, tissues or according to the carotenoid complement. Fruits are an important source of carotenoids, and during ripening, chloroplasts differentiate into chromoplasts that are able to accumulate large amounts of carotenoids, rendering then the characteristic fruit coloration. Whereas lycopene or ß-carotene may accumulate as crystal in the chromoplasts of some fruit, other xanthophyll-accumulating fruits differentiate plastoglobuli as a preferred system to enhance carotenoids stability and storage. Visualization of plastid ultrastructure and their transformation during ripening or in fruit of contrasting coloration are fundamental objectives within carotenoids research in fruits. Therefore, in this chapter, we describe a protocol for the visualization and analysis of plastid ultrastructure by transmission electron microscopy (TEM), specially designed and adapted to fruit tissues.

Coumarins from the peel of citrus grown in Colombia: composition, elicitation and antifungal activity.

The present work analyses the chromatographic profile of the peels from fruits of different citrus cultivated in Colombia: sweet orange (Citrus sinensis [L.] Osbeck var. Valencia), mandarins (Citrus reticulata L. var. Arrayana and Oneco), Key lime (Citrus aurantifolia [Christ.] Swingle var. Pajarito), Mandarine lime (Citrus x limonia, a hybrid between Citrus reticulata and Citrus x limon) and Tahitian lime (C. latifolia Tanaka, syn. Persian lime). Coumarins, furanocoumarins and polymethoxylated flavones are the major compounds. Then, six coumarins were isolated and identified from fruits of Tahitian and Key lime corresponding to 5-geranyloxy-7-methoxycoumarin; 5,7-dimethoxycoumarin (syn. limettin); 5,8-dimethoxypsoralen (syn. isopimpinellin); 5-methoxypsoralen (syn. bergaptene); 5-geranoxypsoralen (syn. bergamottin) and 5-(2,3-dihydroxy-3-methylbutoxy) psoralen (syn. oxypeucedanin hydrate). Coumarins and furanocoumarins were quantified by liquid chromatography (HPLC-DAD). Results show that the prenylated compounds were present in high concentrations in Tahitian and Key lime but in very low amounts in mandarins and sweet orange. Subsequently, the antifungal activity (inhibition of mycelial growth and germination of spores) of the coumarins against the fungus causing the anthracnose, Colletotrichum sp. (isolated from aerial parts of Tahitian lime) was determined. The compounds limettin and bergaptene, as well as mixtures of them, showed significant inhibitory effect (radial growth and spore germination) when compared to the control. Finally, the effect of some recognized elicitors to induce the coumarin production in fruits of C. latifolia was evaluated. The results showed that the chemical profiles are dependent on the applied elicitor and the post-induction time. As a result of the induction, a high concentration of some coumarins and furanocoumarins was maintained in the course of time for the Tahitian lime. In conclusion, isolated coumarins could be involved in the defense mechanisms of C. latifolia, C. aurantifolia and C. limonia and their accumulation may be modulated by the application of elicitors.

Induction of NAD (P)H: Quinone reductase 1 (QR1) and antioxidant activities in vitro of 'Toranja Burarama' (Citrus maxima [Burm.] Merr.).

Toranja 'Burarama', Citrus maxima (Burm.) Merr. (Citrus grandis), is a new citrus discovered in the State of Espírito Santo, Brazil. As several varieties of citrus are known to possess antioxidant and cancer chemopreventive properties, the aim of the study was to evaluate in vitro if this Toranja possess these properties. The antioxidant activity, the potential to induce quinone reductase 1, and the influence on cell viability were measured. ESI(-)FT-ICR MS analysis was also performed and identified flavonoids, coumarins, and fatty acids in the extract. The ethyl acetate and methanolic extracts of the peels presented the highest antioxidant activity in vitro by DPPH (IC50  = 298.3 ± 2.6 µg/ml and 303.8 ± 0.4 µg/ml), ABTS assay (IC50  = 298.2 ± 6.4 µg/ml and 296.4 ± 2.5 µg/ml), and FRAP (IC50  = 234.6 ± 1.8 µg/ml and 398.1 ± 3.8 µg/ml). The ethyl acetate extract of the peel induced quinone reductase 1 activity in Hepa1c1c7 cells, indicating that C. maxima exhibited cancer chemopreventive properties.

Actividad antioxidante in vitro y toxicidad de extractos hidroalcohólicos de hojas de Citrus spp. (Rutaceae) / Antioxidant activity in vitro and toxicity of hydroalcoholic extracts from Citrus spp. (Rutaceae) leaves

Introducción: los cítricos constituyen un género de plantas rico en contenido de fenoles y flavonoides, metabolitos secundarios que debido a su efecto antioxidante y baja toxicidad, han recibido en los últimos años mucha atención como potenciales fármacos. Objetivos: determinar la actividad antioxidante in vitro y la toxicidad frente a Artemia salina L. de extractos hidroalcohólicos de hojas de Citrus aurantium L. var. sinensis L.; Citrus aurantium L.; Citrus aurantiifolia (Christm.) Swingle; Citrus latifolia (Tanaka ex Yu. Tanaka) Tanaka; Citrus reticulata Blanco (Rutaceae). Métodos: los extractos etanólicos y metanólicos se obtuvieron mediante extracción por ultrasonido y se caracterizaron fitoquímicamente; se determinó la concentración total de fenoles y flavonoides. La actividad antioxidante se halló mediante la capacidad atrapadora de radicales libre y el poder reductor. La toxicidad se evaluó mediante el bioensayo de letalidad sobre Artemia salina. Resultados: en los extractos etanólicos se encontró mayor presencia de compuestos químicos que en los extractos metanólicos. La mayor concentración de fenoles totales se obtuvo en el extracto metanólico de Citrus reticulata y de flavonoides totales en el extracto etanólico de Citrus aurantifolia y Citrus reticulata, en ambos solventes. Todos los extractos mostraron actividad antioxidante mediante las 2 pruebas ensayadas. Los extractos presentaron toxicidad moderada frente Artemia salina, siendo el extracto metanólico de Citrus latifolia el de menor toxicidad (LC50 = 464,24 µg/mL). Conclusiones: se evidenció la presencia de fenoles y clases de flavonoides, la actividad antioxidante de los extractos hidroalcohólicos de Citrus spp. y su moderada toxicidad frente a Artemia salina(AU)

Introduction: citrus fruits constitute an important source of flavonoids and phenols. The latter are secondary metabolites extensively studied in the last few years on account of their antioxidant effect and low toxicity and of their potentialities as pharmaceuticals. Objectives: to determine the in vitro antioxidant activity and toxicity against Artemia salina of hydroalcoholic extracts obtained from leaves of Citrus aurantium L. var. sinensis L.; Citrus aurantium L.; Citrus aurantiifolia (Christm.) Swingle; Citrus latifolia (Tanaka ex Yu. Tanaka) Tanaka, Citrus reticulata Blanco (Rutaceae). Methods: the ethanol and methanol extracts were obtained by ultrasound-assisted extraction method, and characterized using phytochemistry assays; the total amount of phenols and flavonoids was also determined. The antioxidant activity was estimated by the free radical scavenging activity and reducing power. The toxicity of the extracts was evaluated against Artemia salina. Results: the amount of chemical compounds was higher in ethanol than in methanol extracts. The highest concentration of total phenols was found in methanol extract from Citrus reticulate where that of total flavonoids was seen in the ethanolic extracts from Citrus aurantiifolia and Citrus reticulate, in both solvents. The extracts showed antioxidant activity after the two tests. All the extracts presented moderate toxicity against Artemia salina, being the methanol extract from Citrus latifolia the least toxic (LC50= 464.24 µg/mL). Conclusions: this study showed the existence of phenols and flavonoids, the antioxidant activity of hydroalcoholic extracts from Citrus spp. leaves and their moderate toxicity against Artemia salina(AU)

Actividad antioxidante in vitro y toxicidad de extractos hidroalcohólicos de hojas de Citrus spp. (Rutaceae) / Antioxidant activity in vitro and toxicity of hydroalcoholic extracts from Citrus spp. (Rutaceae) leaves

Introducción: los cítricos constituyen un género de plantas rico en contenido de fenoles y flavonoides, metabolitos secundarios que debido a su efecto antioxidante y baja toxicidad, han recibido en los últimos años mucha atención como potenciales fármacos. Objetivos: determinar la actividad antioxidante in vitro y la toxicidad frente a Artemia salina L. de extractos hidroalcohólicos de hojas de Citrus aurantium L. var. sinensis L.; Citrus aurantium L.; Citrus aurantiifolia (Christm.) Swingle; Citrus latifolia (Tanaka ex Yu. Tanaka) Tanaka; Citrus reticulata Blanco (Rutaceae). Métodos: los extractos etanólicos y metanólicos se obtuvieron mediante extracción por ultrasonido y se caracterizaron fitoquímicamente; se determinó la concentración total de fenoles y flavonoides. La actividad antioxidante se halló mediante la capacidad atrapadora de radicales libre y el poder reductor. La toxicidad se evaluó mediante el bioensayo de letalidad sobre Artemia salina. Resultados: en los extractos etanólicos se encontró mayor presencia de compuestos químicos que en los extractos metanólicos. La mayor concentración de fenoles totales se obtuvo en el extracto metanólico de Citrus reticulata y de flavonoides totales en el extracto etanólico de Citrus aurantifolia y Citrus reticulata, en ambos solventes. Todos los extractos mostraron actividad antioxidante mediante las 2 pruebas ensayadas. Los extractos presentaron toxicidad moderada frente Artemia salina, siendo el extracto metanólico de Citrus latifolia el de menor toxicidad (LC50 = 464,24 µg/mL). Conclusiones: se evidenció la presencia de fenoles y clases de flavonoides, la actividad antioxidante de los extractos hidroalcohólicos de Citrus spp. y su moderada toxicidad frente a Artemia salina

Introduction: citrus fruits constitute an important source of flavonoids and phenols. The latter are secondary metabolites extensively studied in the last few years on account of their antioxidant effect and low toxicity and of their potentialities as pharmaceuticals. Objectives: to determine the in vitro antioxidant activity and toxicity against Artemia salina of hydroalcoholic extracts obtained from leaves of Citrus aurantium L. var. sinensis L.; Citrus aurantium L.; Citrus aurantiifolia (Christm.) Swingle; Citrus latifolia (Tanaka ex Yu. Tanaka) Tanaka, Citrus reticulata Blanco (Rutaceae). Methods: the ethanol and methanol extracts were obtained by ultrasound-assisted extraction method, and characterized using phytochemistry assays; the total amount of phenols and flavonoids was also determined. The antioxidant activity was estimated by the free radical scavenging activity and reducing power. The toxicity of the extracts was evaluated against Artemia salina. Results: the amount of chemical compounds was higher in ethanol than in methanol extracts. The highest concentration of total phenols was found in methanol extract from Citrus reticulate where that of total flavonoids was seen in the ethanolic extracts from Citrus aurantiifolia and Citrus reticulate, in both solvents. The extracts showed antioxidant activity after the two tests. All the extracts presented moderate toxicity against Artemia salina, being the methanol extract from Citrus latifolia the least toxic (LC50= 464.24 µg/mL). Conclusions: this study showed the existence of phenols and flavonoids, the antioxidant activity of hydroalcoholic extracts from Citrus spp. leaves and their moderate toxicity against Artemia salina