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

Dynamic changes in volatile and non-volatile components of Jinggang honey pomelo (Citrus maxima (L.) Osbeck) during growth revealed through an untargeted metabolomics approach

We adopted HS-SPME-GC-MS and UPLC-Q-TOF/MS in our study to analyze changes in volatile components (VOCs) and non-VOCs during the growth of Citrus maxima cv. Jinggang honey pomelo. In total, 75 VOCs and 65 non-VOCs were identified. Terpenes were the most important components of the VOCs, D-limonene and germacrene D were the most representative. The contents of organic acids, flavonoids, coumarins, and amino acids gradually decreased throughout the growth process, while delayed bitter compounds (limonin and nomilin) continued accumulating. According to variable importance in the projection >1 and p < 0.05, 25 non-volatile differential metabolites were selected. KEGG pathway analysis indicated that phenylpropanoid biosynthesis was the main pathway around which a sophisticated metabolic network was formed. The flavor of Jinggang honey pomelo evolved with changes in its components, ultimately presenting flavor characteristics of citrus and green aromas, balanced sweet and sour flavors, and a hint of bitterness in the aftertaste.

Discovery of Quality by Design-Based Extraction Technology and the Quality Standard of Jinhua Finger Citron Essential Oil

Jinhua finger citron is one of the traditional specialties of Jinhua with a long history of cultivation. The current study highlighted the advantages of using the quality by design approach to optimize the ultrasonic-assisted distillation extraction of Jinhua finger citron essential oil. The yield of Jinhua finger citron essential oil was regarded as a potential critical quality attribute. Potential critical process parameters were screened by the definitive screening design. Finally, the design space of the essential oil extraction process was constructed. The optimal operating space included an auxiliary NaCl concentration range of 9-12.00%, a soak temperature range of 30-50 °C, a distillation time range of 3.5-4.00 h, an ultrasonic power range of 200-300 W, a solid-liquid ratio range of 1:3-1:3.5, and a soak time range of 40-80 min. On this basis, the relative density, refractive index, and pH values of different batches of Jinhua finger citron essential oil were checked. The involved batches were analyzed by gas chromatography (GC), and gas chromatographic fingerprints were established by identifying major compounds, including d-limonene, γ-terpinene, and 5,7-dimethoxycoumarin. Based on the "quality by design" strategy, the extraction process of Jinhua finger citron essential oil established in this study was robust, reliable, and flexible.

Unlocking the Potential of Citrus medica L.: Antioxidant Capacity and Phenolic Profile across Peel, Pulp, and Seeds

Citrus medica L. is a traditional citrus fruit that is rich in bioactive compounds and has the potential to be used as a natural source of food additives. This study aims to evaluate the antioxidant capacity and characterize the phenolic compounds present in the peels (including flavedo and albedo), pulp, and seeds of citron. The results showed that, compared to the other parts, the pulp had a substantially higher Antioxidant Activity Coefficient (AAC) of 168.2. The albedo and the seeds had significantly lower AAC values, while the green and yellow flavedo showed noteworthy results. O-coumaric acid was the predominant phenolic acid in all of the citron fractions; it was found in the highest concentration in albedo (37.54 µg/g FW). Flavanones and flavanols were the primary flavonoids in the pulp, peel, and seeds, with total flavonoid concentration ranging from ~9 µg/g FW in seeds to 508 µg/g FW in the pulp. This research offers significant insights into the antioxidant properties of this ancient fruit, emphasizing its potential applications as a natural source of antioxidants to be used in different applications.

Essential oil composition and antioxidant activity of citron fruit (Citrus medica var. macrocarpa Risso.) peel as relation to ripening stages

Stages of maturity have decisive roles in determining the quality and quantity of essential oil (EO). In this regard, EO yield and composition and their antioxidant activity of citron fruit at four fruit maturity stages, i.e. the green mature (GM), intermediate (INT), yellow ripe (MAT) and overripe stage (OR) were studied. Obtained results showed significant effect of fruit maturity on most measured properties. The concentration of EO varied between 0.60 and 0.77% (v/w). The highest amount of limonene was 89.39% related to GM stage. The limonene decreased significantly during maturity. The highest antioxidant activity (76.08%) was measured at the OR stage, which is probably due to the presence of specific compounds in the EO and their synergistic effects. The phytochemical behaviors of this citron variety were different as relation to stages of fruit maturity. We can determine the ideal harvest period for maximum bioactive substances by recognizing these actions.

An Insight into Citrus medica Linn.: A Systematic Review on Phytochemical Profile and Biological Activities

Plant species are a reservoir of natural compounds that can potentially be used to treat different diseases. Citrus medica Linn. belonging to the Rutaceae family, has been used for centuries in medicine for its antioxidant, anti-inflammatory, antimicrobial, antiviral, and antihyperglycemic properties. These activities are ascribable not only to the presence of health-promoting macronutrients and micronutrients, such as carbohydrates, minerals, amino acids, and vitamins, but also to specialized metabolites, such as flavonoids (apigenin, hesperetin, hesperidin, naringin, naringenin, rutin, quercetin, and diosmin), coumarins (citropten, scoparone, and bergapten), terpenes (limonene, γ-terpinene, limonin, and nomilin), and phenolic acids (p-coumaric acid, trans-ferulic acid, and chlorogenic acid). In recent years, particular attention has been focused on the antioxidant, anti-inflammatory, antimicrobial activity, antidiabetic, anticancer, and neuroprotective activity of C. medica. However, although many studies have reported this species' chemical and biological properties, the literature has never been analyzed via a systematic approach. For this reason, using PubMed and Scopus as databases, we performed a systematic review of C. medica's chemical composition and biological properties to inspire new research approaches and increase its curative application.

A comparative metabolomic investigation in fruit sections of Citrus medica L. and Citrus maxima L. detecting potential bioactive metabolites using UHPLC-QTOF-IMS

The current study focused on targeted and non-targeted metabolomics of Citrus fruit parts (exocarp, mesocarp, endocarp, and seeds) to gain a comprehensive metabolomic insight. Sections of the Citrus fruit were preliminarily examined for proximate compositions (moisture, ash, fibre, fat, and protein). Whereas ultrasonication-assisted solvent extraction revealed a higher phenolic and flavonoid content at 80% (v/v) ethanolic medium, with the highest amount in the exocarp. Using targeted metabolomics, hesperidin (3307.25 mg/100 g), naringin (4803.73 mg/100 g) were detected in C. medica and C. maxima at greater levels, respectively. Further quantitative analysis revealed the presence of phenolic acids (gallic acid, trans-ferulic acid, p-coumaric acid, trans-cinnamic acid), and polymethoxyflavones (nobiletin, and tangeretin) and detected in the order of exocarp > mesocarp > endocarp > seeds. Using an untargeted metabolomics approach, metabolite discriminations among Citrus fruit sections were illustrated by Venn-diagram, heatmap, PCA, o-PLSDA, correlation matrices, and S-plot. UHPLC-QTOF-IMS revealed 48 metabolites including phenolics, vitamins, and amino acids. Furthermore, the METLIN database leads to the identification of 202 unknown metabolites. The metabolite biosynthesis and corresponding metabolite presence in Citrus fruit sections were confirmed using pathway enrichment and mass fragmentation analysis. Finally, potential biological activities were determined using in silico PASS software approach, and free radical scavenging potential was confirmed using in vitro assays for future preventive and therapeutic applications of the identified metabolites.

Edible plant by-products as source of polyphenols: prebiotic effect and analytical methods

Polyphenols with high chemical diversity are present in vegetables both in the edible parts and by-products. A large proportion of them remains unabsorbed along the gastrointestinal tract, being accumulated in the colon, where they are metabolized by the intestinal microbiota. These polyphenols have been found to have "prebiotic-like" effects. The edible plant industry generates tons of residues called by-products, which consist of unutilized plant tissues (peels, husks, calyxes and seeds). Their disposal requires special and costly treatments to avoid environmental complications. Reintroducing these by-products into the value chain using technological and biotechnological practices is highly appealing since many of them contain nutrients and bioactive compounds, such as polyphenols, with many health-promoting properties. Edible plant by-products as a source of polyphenols highlights the need for analytical methods. Analytical methods are becoming increasingly selective, sensitive and precise, but the great breakthrough lies in the pretreatment of the sample and in particular in the extraction methods. This review shows the importance of edible plant by-products as a source of polyphenols, due to their prebiotic effect, and to compile the most appropriate analytical methods for the determination of the total content of phenolic compounds as well as the detection and quantification of individual polyphenols.