Carob seeds as a source of bioactive flavonoid derivatives: isolation, network pharmacology-guided anti-cancer activity, and HPLC standardization.

INTRODUCTION:  Carob, Ceratonia siliqua L. (CS), is a legume well-known for its edible pod pulp. Its seeds are used almost exclusively as a source of the food additive E410. Although a variety of metabolites have been identified by HPLC and LC-MS analysis in CS, reports concerned with their isolation are scarce.   Methodology: In this study, two flavonoid derivatives were isolated from the methanolic extract of CS seeds, namely, quercetin-3-O-rhamnoside and 4'-p-hydroxybenzoylisorhamnetin-3,7-di-O-rhamnoside. Network pharmacology was unusually used as a guide for estimation of the biological potential of the isolated compounds. Finally, the methanolic extract of CS seeds and its ethyl acetate fraction were standardized for their 4'-p-hydroxybenzoylisorhamnetin-3,7-di-O-rhamnoside content by HPLC. RESULTS:  The identified isolates displayed the ability to interfere with the activity of several target proteins associated with renal and colon cancers. Their cytotoxic effect on renal and colorectal cancer cell lines was investigated in comparison to Doxorubicin. The selectivity of the isolated compounds was evaluated on normal human fetal fibroblast cell lines. The isolated 4'-p-hydroxybenzoylisorhamnetin-3,7-di-O-rhamnoside showed very potent cytotoxic activity against the tested cell lines with the highest selectivity. CONCLUSION:  CS seeds can be used as a source of bioactive flavonoid derivatives that can be incorporated in pharmaceutical industries.

Metabolome classification of olive by-products from different oil presses providing insights into its potential health benefits and valorization as analyzed via multiplex MS-based techniques coupled to chemometrics.

INTRODUCTION: The Olive (Olea europaea L.) is one of the most popular edible oil-producing fruits, consumed worldwide for its myriad nutritional and health benefits. Olive oil production generates huge quantities of by-products from the fruit, which are considered environmental hazards. Recently, more and more efforts have been made to valorize olive by-products as a source of low-cost, value-added food applications. OBJECTIVE: The main objective of this study was to globally assess the metabolome of olive fruit by-products, including olive mill wastewater, olive pomace, and olive seeds from fruits from two areas, Siwa and Anshas, Egypt. METHODS: Gas chromatography-mass spectrometry (GC-MS) and ultra-high-performance liquid chromatography with mass spectrometry (UPLC-MS) were used for profiling primary and secondary metabolites in olive by-products. Also, multivariate data analyses were used to assess variations between olive by-product samples. RESULTS: A total of 103 primary metabolites and 105 secondary metabolites were identified by GC-MS and UPLC-MS, respectively. Fatty acids amounted to a major class in the olive by-products at 53-91%, with oleic acid dominating, especially in the pomace of Siwa. Mill wastewater was discriminated from other by-products by the presence of phenolics mainly tyrosol, hydroxyl tyrosol, and α-tocopherol as analyzed by UPLC-MS indicating their potential antioxidant activity. Pomace and seeds were rich in fatty acids/esters and hydroxy fatty acids and not readily distinguishable from each other. CONCLUSION: The current work discusses the metabolome profile of olive waste products for valorization purposes. Pomace and seeds were enriched in fatty acids/esters, though not readily distinguishable from each other.

Identification of cyclooxygenase-II inhibitory saponins from fenugreek wastes: Insights from liquid chromatography-tandem mass spectrometry metabolomics, molecular networking, and molecular docking.

INTRODUCTION: This research explores sustainable applications for waste generated from fenugreek (Trigonella foenum-graecum), a plant with both nutritional and medicinal uses. The study specifically targets waste components as potential sources of nutrients and bioactive compounds. OBJECTIVES: The focus is to conduct detailed metabolic profiling of fenugreek waste, assess its anti-inflammatory properties by studying its cyclooxygenase (COX) inhibitory effect, and correlate this effect to the metabolite fingerprint. MATERIALS AND METHODS: Ethanolic extracts of fenugreek fruit pericarp and a combination of leaves and stems were subjected to untargeted metabolic profiling using liquid chromatography-mass spectrometry integrated with online database searches and molecular networking as an effective dereplication strategy. The study also scrutinized the COX inhibitory capabilities of these extracts and saponin-rich fractions prepared therefrom. Molecular docking was employed to investigate the specific interactions between the identified saponins and COX enzymes. RESULTS: The analysis led to the annotation of 81 metabolites, among which saponins were predominant. The saponin-rich fraction of the fruit pericarp extract displayed the strongest COX-II inhibitory activity in the in vitro inhibition assay (IC50 value of 81.64 ± 3.98 µg/mL). The molecular docking study supported the selectivity of the identified saponins towards COX-II. The two major identified saponins, namely, proto-yamogenin 3-O-[deoxyhexosyl (1 → 2)] [hexosyl (1 → 4)] hexoside 26-O-hexoside and trigofenoside A, were predicted to have the highest affinity to the COX-II receptor site. CONCLUSION: In the present study, we focused on the identification of COX-II inhibitory saponins in fenugreek waste through an integrated approach. The findings offer valuable insights into potential anti-inflammatory and cancer chemoprotective applications of fenugreek waste.

A multifunctional study of naturally occurring pyrazines in biological systems; formation mechanisms, metabolism, food applications and functional properties.

Natural pyrazines, mainly methyl- or ethyl-substituted forms, are commonly applied as flavor ingredients in raw and roasted food. Meanwhile alkylpyrazines are used as food preservatives due to their effective antimicrobial action. These natural pyrazines are widely distributed in several biological systems such as plants, animals, and insects; each with respective physiological role. Besides, pyrazines are formed in food via thermal treatment and fermentation. This review presents the most comprehensive overview of pyrazines with correlation to their chemical structures and different applications with emphasis on their food applications. The major part deals with pyrazines generated in thermally treated food, reaction mechanisms highlighting factors and optimum conditions affecting their production. Additionally, the several metabolic reactions mediating for pyrazines metabolism in humans and excretion via the kidney are discussed and on context to their effects. Lastly, a review of the different techniques applied for pyrazines isolation, detection and quantitation is presented. The study provides future considerations and direction of research on this important dietary component and their applications. Pyrazines multifunctional chemistry is of value to the food sector, by presenting the best practices for their production whilst the detrimental effects are minimized.

The Untargeted Phytochemical Profile of Three Meliaceae Species Related to In Vitro Cytotoxicity and Anti-Virulence Activity against MRSA Isolates.

BACKGROUND: A high mortality rate is associated with about 80% of all infections worldwide, mainly due to antimicrobial resistance. Various antimicrobial and cytotoxic activities have been proposed for Meliaceae species. This study aimed to evaluate the in vitro anti-virulence and cytotoxic effect of the leaf extracts of Aphanamixis polystachya, Toona ciliata and Melia azedarach against five MRSA strains and on three cancer cell lines, followed by biological correlation to their encompassed phytoconstituents. MATERIAL AND METHODS: We explored three plants of this family against a panel of Methicillin-resistant Staphylococcus aureus (MRSA) strains and several cancer cell lines to select the most promising candidates for further in vivo and preclinical studies. The phytochemical composition was evaluated by UHPLC-QTOF-MS untargeted profiling. Cell viability was assessed by SRB assay. Minimum Inhibitory Concentration was carried out by using the agar micro-dilution technique. Inhibition of biofilm formation and preformed biofilm disruption were assessed spectrophotomertically, according to the Sultan and Nabil method (2019). RESULTS: A total of 279 compounds were putatively annotated to include different phytochemical classes, such as flavonoids (108), limonoids/terpenoids (59), phenolic acids (49) and lower-molecular-weight phenolics (39). A. polystachya extract showed the most potent cytotoxic activity against Huh-7, DU-145 and MCF-7 cell lines (IC50 = 3, 3.5 and 13.4 µg mL-1, respectively), followed by M. azedarach, with no effect recorded for T. ciliata extract. Furthermore, both A. polystachya and M. azedarach extracts showed promising anti-virulence and antimicrobial activities, with A. polystachya being particularly active against MRSA. These two latter extracts could inhibit and disrupt the biofilm, formed by MRSA, at sub-lethal concentrations. Interestingly, the extracts inhibited hemolysin-α enzyme, thus protecting rabbit RBCs from lysis. A. polystachya extract reduced the pigmentation and catalase enzyme activity of tested pigmented strains better than M. azedarach at both tested sub-MICs. Consequently, susceptibility of the extract-treated cells to oxidant killing by 200 mM H2O2 increased, leading to faster killing of the cells within 120 min as compared to the extract-non-treated cells, likely due to the lower antioxidant-scavenging activity of cells exhibiting less staphyloxanthin production. CONCLUSION: These findings suggested that both A. polystachya and M. azedarach natural extracts are rich in bioactive compounds, mainly limonoids, phenolics and oxygenated triterpenoids, which can combat MRSA biofilm infections and could be considered as promising sources of therapeutic cytotoxic, antibiofilm and anti-virulence agents.

How do biocatalysis and biotransformation affect Citrus dietary flavonoids chemistry and bioactivity? A review.

Flavonoids, especially flavanones, flavones and polymethoxyflavones (PMFs) are distinctive bioactive compounds of Citrus fruits. Citrus peel and juice by-products potentially represent rich sources of these Citrus flavonoids that exhibit a myriad of biological activities both in in vitro and in vivo systems. Recently, much attention has been made toward biotransformation processes as a promising tool for the structural modification of natural products to be used in the drug and food industries along with its role in solving pollution problems related to Citrus by-products disposal. In this article, we present a state of the art review on both in vivo and in vitro biotransformation processes of Citrus juice and waste carried out by microorganisms, plant cell cultures, animal and human liver microsomes targeting its flavonoids composition. Such review highlights the main metabolic pathways for enzymatic and microbial reactions involved in these processes and suggest for reactions that need to be more capitalized for a wider application in industrial bioprocesses of Citrus by-products. Biotransformation and biocatalysis applications included employment of citrus by-products enriched in flavonoids as a low-cost, economical and natural sources of sugar substitutes, antifungal, anticancer drugs, hydrolyzable enzymes, probiotics and flavonoid aglycones. Further, biological effects of the biotransformed metabolites are discussed in relation to its parent compound highlighting potentials and or any limitations for each reaction type. Applications covered in Citrus biotransformation include for nutraceutical/food and cosmetics industries.

Uncovering the therapeutic potential of green pea waste in breast cancer: a multi-target approach utilizing LC-MS/MS metabolomics, molecular networking, and network pharmacology.

BACKGROUND PISUM SATIVUM: (PS) is a universal legume plant utilized for both human and animal consumption, particularly its seeds, known as green peas. The processing of PS in food industries and households produces a significant amount of waste that needs to be valorized. METHODS: In this study, the metabolite profiles of the 70% ethanolic extracts of PS wastes, namely peels (PSP) and a combination of leaves and stems (PSLS), were investigated by liquid chromatography-electrospray ionization-quadrupole time-of-flight tandem mass spectrometry (LC-ESI-QTOF-MS/MS) followed by molecular networking. RESULTS: Different classes of metabolites were identified, being flavonoids and their derivatives, along with phenolic acids, the most abundant categories. Additionally, a comprehensive network pharmacology strategy was applied to elucidate potentially active metabolites, key targets, and the pathways involved in cytotoxic activity against breast cancer. This cytotoxic activity was investigated in MCF-7 and MCF-10a cell lines. Results revealed that PSLS extract exhibited a potent cytotoxic activity with a good selectivity index (IC50 = 17.67 and selectivity index of 3.51), compared to the reference drug doxorubicin (IC50 = 2.69 µg/mL and selectivity index of 5.28). Whereas PSP extract appeared to be less potent and selective (IC50 = 32.92 µg/mL and selectivity index of 1.62). A similar performance was also observed for several polyphenolics isolated from the PSLS extract, including methyl cis p-coumarate, trans p-coumaric acid, and liquiritigenin/ 7-methyl liquiritigenin mixture. Methyl cis p-coumarate showed the most potent cytotoxic activity against MCF-7 cell line and the highest selectivity (IC50 = 1.18 µg/mL (6.91 µM) and selectivity index of 27.42). The network pharmacology study revealed that the isolated compounds could interact with several breast cancer-associated protein targets including carbonic anhydrases 1, 2, 4, 9, and 12, as well as aldo-keto reductase family 1 member B1, adenosine A3 receptor, protein tyrosine phosphatase non-receptor type 1, and estrogen receptor 2. CONCLUSION: The uncovered therapeutic potential of PSLS and its metabolite constituents pave the way for an efficient and mindful PS waste valorization, calling for further in-vitro and in-vivo research.

Effect of Light Quality and Media Components on Shoot Growth, Rutin, and Quercetin Production from Common Buckwheat.

Common buckwheat (Fagopyrum esculentum Moench) seeds are important nutritious grains that are widely spread in several human food products and livestock feed. Their health benefits are mainly due to their bioactive phenolic compounds, especially rutin and quercetin, which have a positive impact on heart health, weight loss, and diabetes management. In this study, we evaluated different media and light treatments for the in vitro cultures of common buckwheat (CB) in order to find the most optimum one producing the highest yield with the highest purity of these compounds. The subcultured treated samples included in this study were shoots, leaves, stems, hairy roots, and calli. From the several treated samples and under different light stress conditions, the best production was achieved by growing the shoots of common buckwheat in hormone-free media containing activated charcoal and exposing to blue light, attaining 4.3 mg and 7.0 mg/g of extracts of rutin and quercetin, respectively, compared to 3.7 mg of rutin/g of extract and traces of quercetin in the seeds of CB. Continuous multiplication of CB shoots in the media containing charcoal and different concentrations of kinetin produced an extract with 161 mg/g of rutin and 26 mg/g of quercetin with an almost 20-fold increase in rutin content. The rutin content under these conditions reached up to 16% w/w of the extract. The hairy root cultures of the leaves exposed to red light showed a significantly high yield of quercetin attaining 10 mg/g of extract. Large-scale production of CB shootlets under the best conditions were carried out, which enabled the isolation of pure quercetin and rutin using a simple chromatographic procedure. The identity and purity of the isolated compounds were confirmed through NMR and HPLC analyses.

Metabolome classification via GC/MS and UHPLC/MS of olive fruit varieties grown in Egypt reveal pickling process impact on their composition.

The role of variety and effects of pickling on Egyptian olive fruit metabolome was determined using mass spectrometry-based metabolomics targeting nutrients and bioactive metabolities. The analyzed fresh olive fruit varieties included Manzanilo, Picual, Koroneiki, and Coratina, while the pickled samples included the Manzanilo and Picual varieties. Profiling of primary and secondary metabolites resulted in the detection of 201 metabolites. Variation between varieties was mostly observed among sugars, sugar alcohols, secoiridoids, and flavonoids. An abundance of carbohydrates and O-glycosides in Picual and Manzanilo versus enrichment of secoiridoids in Picual and Coratina olives viz. dehyro-oleuropein could account for the difference in palatability and health benefits among varieties. Herein, 13 new compounds are reported in the tested varieties, of which 10 appeared exclusively in pickled samples. Generally, pickled samples were characterized by the relative abundance of secoiridoids regarded as important markers for the pickling process. Metabolites profiling provided greater insight into the pickling process as a preservation method and accounted for the improved organoleptic characters in pickled fruits.

UPLC-MS Metabolome-Based Seed Classification of 16 Vicia Species: A Prospect for Phyto-Equivalency and Chemotaxonomy of Different Accessions.

Seeds of domesticated Vicia (vetch) species (family Fabaceae-Faboideae) are produced and consumed worldwide for their nutritional value. Seed accessions belonging to 16 different species of Vicia-both domesticated and wild taxa-were subjected to a chemotaxonomic study using ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) analyzed by chemometrics. A total of 89 metabolites were observed in the examined Vicia accessions. Seventy-eight out of the 89 detected metabolites were annotated. Metabolites quantified belonged to several classes, viz., flavonoids, procyanidins, prodelphinidins, anthocyanins, stilbenes, dihydrochalcones, phenolic acids, coumarins, alkaloids, jasmonates, fatty acids, terpenoids, and cyanogenics, with flavonoids and fatty acids amounting to the major classes. Flavonoids, fatty acids, and anthocyanins showed up as potential chemotaxonomic markers in Vicia species discrimination. Fatty acids were more enriched in Vicia faba specimens, while the abundance of flavonoids was the highest in Vicia parviflora. Anthocyanins allowed for discrimination between Vicia hirsuta and Vicia sepium. To the best of our knowledge, this is the first report on employing UPLC-MS metabolomics to discern the diversity of metabolites at the intrageneric level among Vicia species.

Exploring the Antivirulence Activity of Pulverulentone A, a Phloroglucinol-Derivative from Callistemon citrinus Leaf Extract, against Multi-Drug Resistant Pseudomonas aeruginosa.

(1) Background: Bacterial resistance to antibiotics is a global life-threatening issue. Antivirulence therapy is a promising approach to combat bacterial infections as it disarms the bacteria from their virulence factors with reduced selective pressure and a lower chance of resistance. (2) Methods: Callistemon citrinus leaf extract and its major constituent, Pulverulentone A, were tested for their ability to inhibit biofilm, exopolysaccharides, pyocyanin and proteases produced by MDR P. aeruginosa. In addition, a Galleria mellonella larvae model was employed to evaluate the in vivo cytotoxicity of Pulverulentone A and its ability to combat Pseudomonas infection. Docking study was further performed to investigate Pulverulentone A druggability against main quorum sensing (QS) targets expressed by P. aeruginosa; (3) Results: Both C. citrinus extract and the isolated compound could inhibit biofilm formation, extracellular polymeric substances (EPS) and pigment production by the tested isolates. Unexpectedly, no significant inhibition was observed on proteases production. The in silico docking analysis revealed good interactions of Pulverulentone A with all QS targets examined (LasR, MyfR/PqsR, QscR). Pulverulentone A was safe up to 400 µg·mL-1 in Galleria caterpillars. Moreover, pre-treatment of P. aeruginosa with Pulverulentone A slightly enhanced the survival of the infected larvae. (4) Conclusions: The present study proves Pulverulentone A safety with significant in vitro and in silico antivirulence potential against P. aeruginosa.

Comparative Metabolite Profiling of Four Citrus Peel Cultivars via Ultra-Performance Liquid Chromatography Coupled with Quadrupole-Time-of-Flight-Mass Spectrometry and Multivariate Data Analyses.

Citrus plants are one of the most economical fruit bearing trees grown worldwide for their medicinal use as well as for the flavor and food industry. This study attempts to characterize the metabolome difference in polyphenols of four Citrus species fruit peels; C. reticulata Blanco cv. Egyptian, C. sinensis (L.) Osbeck cv. Olinda Valencia, C. aurantiifolia Swingle cv. Mexican and C. paradisi Macfad. cv. Duncan via ultra-performance liquid chromatography coupled with quadrupole-time-of-flight-mass spectrometry platform. A total of 163 metabolites were characterized of which 28 were detected for the first time in Citrus cultivars including eight coumarin derivatives, three cinnamic acids conjugates, one polymethoxyflavone, 5 O-glycosides, 2 C-glycosides, three flavone-di-O-glucosides and six acetyl sugar derivatives of luteolin and kaempferol in addition to oxygenated and methylated fatty acids. Flavonoids amounted for the most abundant secondary metabolites class in the studied Citrus peels. The relative variability among these Citrus peels was estimated using clustering analysis with flavonoids accounting for cvs. segregation. Hierarchical clustering analysis revealed the chemical similarity of C. reticulata, C. sinensis and C. paradise peels and being distant them from that of C. aurantiifolia. To the best of our knowledge, this study provides the first report for metabolite compositional differences in these four Citrus peels.

Volatile profiling in Rhus coriaria fruit (sumac) from three different geographical origins and upon roasting as analyzed via solid-phase microextraction.

Rhus coriaria (sumac) is a fruit grown worldwide for its culinary use as a flavoring agent and for its health benefits. Despite several studies on R. coriaria non-volatile metabolites, much less is recognized concerning volatile composition within that genus. In an effort to expand on flavor profile sumac and its food products, we report on volatile profiling from three accessions of different origins including Palestine, Jordan and Egypt in addition to its cold tea and post roasting via headspace solid-phase microextraction (SPME). Under optimized conditions, 74 volatile components were identified belonging to alcohols, aromatics, esters, ethers, furan/aldehyde, hydrocarbons, ketones, monoterpenes, oxides and sesquiterpene hydrocarbons. Major identified components included α-pinene, naphthalene and o-cymene in Palestinian, Jordanian and Egyptian sumac, respectively. Whereas sesquiterpenes amounted for the major volatile class in fresh R. coriaria at ca. 40-58%, furan/aldehydes were the predominant classes in roasted fruits (58%). Volatile abundance data was further subjected to multivariate data analyses revealing furfural and nonanal enrichment in roasted compared to fresh fruits and their cold tea preparation. Seeds exhibited no aroma components which justified their removal in R. coriaria prior to its use as a food flavor. Such knowledge is expected to be the key for understanding the olfactory and taste properties of R. coriaria and its several food products.

New triterpenoid acyl derivatives and biological study of Manilkara zapota (L.) Van Royen fruits.

ß-amyrin-3-(3'-dimethyl) butyrate, a new natural compound was isolated from the fruits of Manilkara zapota (L.) Van Royen, in addition to lupeol-3-acetate and 4-caffeoylquinic acid (cryptochlorogenic acid). The structures of these compounds were identified using different spectral methods (IR, MS, UV, (1)H-NMR, (13)C-NMR and 2D-NMR). The alcoholic and aqueous extracts of the unripe fruits, in addition to their aqueous homogenate exhibited antioxidant, antihyperglycemic and hypocholesterolemic activities.

Chemical and biological study of Manilkara zapota (L.) Van Royen leaves (Sapotaceae) cultivated in Egypt.

BACKGROUND: Manilkara zapota (L.) Van Royen is an evergreen tree, native to the tropical Americas and introduced to Egypt as a fruiting tree in 2002. No previous study was reported on the plant cultivated in Egypt. MATERIALS AND METHODS: In this study, the leaves of the plant cultivated in Egypt were subjected to phytochemical and biological investigations. The lipoidal matter was analyzed by GLC. Five compounds were isolated from the petroleum ether and ethyl acetate fractions of the alcoholic extract of the leaves by chromatographic fractionation on silica gel and sephadex, the structures of these compounds were identified using IR, UV, MS, (1)H-NMR and (13)C-NMR. The LD(50) of the alcoholic and aqueous extracts of the leaves was determined and their antihyperglycemic, hypocholesterolemic and antioxidant activities were tested by enzymatic colorimetric methods using specific kits. RESULTS: Unsaturated fatty acids represent 32.32 % of the total fatty acids, oleic acid (13.95%), linoleidic acid (10.18 %) and linoleic acid (5.96 %) were the major ones. The isolated compounds were identified as lupeol acetate, oleanolic acid, apigenin-7-O-α-L-rhamnoside, myricetin-3-O-α-L-rhamnoside and caffeic acid. This is the first report about isolation of these compounds from Manilkara zapota except myricetin-3-O-α-L-rhamnoside, which was previously isolated from the plant growing abroad. The LD(50) recorded 80 g/Kg b. wt. for both the tested extracts, so they could be considered to be safe. They exhibited antihyperglycemic, hypocholesterolemic and antioxidant activities. CONCLUSION: The observed biological activities were attributed to the different chemical constituents present in the plant mainly its phenolic constituents.

Comparative study of the hypocholesterolemic, antidiabetic effects of four agro-waste Citrus peels cultivars and their HPLC standardization

ABSTRACT Citrus is an economically important fruit for Egypt, but its peel also is one of the major sources of agricultural waste. Due to its fermentation, this waste causes many economic and environmental problems. Therefore it is worthwhile to investigate ways to make use of this citrus waste generated by the juice industry. This study was aimed to explore the hypocholesterolemic, antidiabetic activities of four varieties of citrus peels agrowastes, to isolate the main flavonoids in the active fractions and to quantify them by HPLC method for nutraceutical purposes. All the tested samples of the agro-waste Citrus fruits peels showed significant decrease in cholesterol, triacylglyceride and glucose. The most decrease in cholesterol level was observed by mandarin peels aqueous homogenate and its hexane fraction (59.3% and 56.8%, respectively) reaching the same effect as the reference drug used (54.7%). Mostly, all samples decrease triacylglyceride (by 36%-80.6%) better than the reference drug used (by 35%), while, glucose was decreased (by 71.1%-82.8 and 68.6%-79.6%, respectively) mostly by the aqueous homogenates (except lime) and alcoholic extracts (except mandarin) of Citrus fruits peels better than the reference drug used (by 68.3%). All the isolated pectin, from the four cultivars, has significant effect on the three parameters. The comparative HPLC rapid quantification of nobiletin in the different by-product citrus varieties hexane fractions revealed that nobiletin is present in higher concentration in mandarin (10.14%) than the other species. Nobiletin and 4′,5,7,8-tetramethoxy flavone were isolated from mandarin peels hexane fraction by chromatographic fractionation. This is the first report of the comparative HPLC quantification of nobiletin and biological studies of different citrus peels species as agro-waste products. Based on these results, we suggest the possibility that Citrus fruits peels may be considered as an antidiabetic and hypocholesterolemic nutraceutical product.