Efficacious anti-cancer property of flavonoids from citrus peels

Application of deep eutectic solvents on extraction of flavonoids

Deep eutectic solvents (DESs), as a new type of eco-friendly solvent, have attracted increasing attention on the extraction and separation of flavonoid compounds from various samples, owing to their excellent properties such as biodegradability and ease of handling with very low toxicity. This article provides a status review of the applications of DESs in the extraction of flavonoids, including the introduction of flavonoid compounds, the properties and superiority of DESs, and extraction methods (ultrasonic-assisted extraction, heating reflux extraction, matrix solid-phase dispersion, and solid-phase extraction). Finally, prospects and challenges in the application of DESs on extraction and separation are extensively elucidated and critically reviewed.

Antioxidants from different citrus peels provide protection against cancer

Cancer is one of the leading causes of death. Despite significant advancements in the discovery of medications for the treatment of cancer, these drugs are hindered by applicability and efficacy issues and frequently exhibit major side effects that can further impair patients 'quality of life. Therefore, the development of therapeutically sound anti-cancer medicines derived from natural products has gained prominence in the field of functional foods. Some of these compounds have shown efficacy in the prevention and treatment of cancer as well as low toxicity. Additionally, many recent studies have explored the recycling of agro-industrial waste to create bioactive chemicals. Citrus peels are produced in vast quantities in the food processing sector; due to their abundance of flavonoids, they may be inexpensive sources of protection against several cancers. Citrus is a common type of fruit that contains a variety of nutrients. In particular, the antioxidant chemicals found in citrus peel have been identified as potential cancer-fighting agents. Antioxidant substances such as flavonoids prevent the development of cancer by inhibiting the metastatic cascade, decreasing the mobility of cancer cells in the circulatory system, promoting apoptosis, and suppressing angiogenesis. To explore the most effective uses of citrus peel-derived antioxidants, this review presents background information, an overview of the role of citrus antioxidants in cancer therapy, and a discussion of the key underlying molecular mechanisms.

Flavones: The Apoptosis in Prostate Cancer of Three Flavones Selected as Therapeutic Candidate Models

Cancer is a widespread but dangerous disease that can strike anyone and is the second 1leading cause of death worldwide. Prostate cancer, in particular, is a prevalent cancer that occurs in men, and much research is being done on its treatment. Although chemical drugs are effective, they have various side effects, and accordingly, anticancer drugs using natural products are emerging. To date, many natural candidates have been discovered, and new drugs are being developed as drugs to treat prostate cancer. Representative candidate compounds that have been studied to be effective in prostate cancer include apigenin, acacetin and tangeretin of the flavone family among flavonoids. In this review, we look at the effects of these three flavones on prostate cancer cells via apoptosis in vitro and in vivo. Furthermore, in addition to the existing drugs, we suggest the three flavones and their effectiveness as natural anticancer agents, a treatment model for prostate cancer.

Citrus Waste as Source of Bioactive Compounds: Extraction and Utilization in Health and Food Industry

The current research was conducted to extract the bioactive compounds from citrus waste and assess their role in the development of functional foods to treat different disorders. The scientific name of citrus is Citrus L. and it belongs to the Rutaceae family. It is one of the most important fruit crops that is grown throughout the world. During processing, a large amount of waste is produced from citrus fruits in the form of peel, seeds, and pomace. Every year, the citrus processing industry creates a large amount of waste. The citrus waste is composed of highly bioactive substances and phytochemicals, including essential oils (EOs), ascorbic acid, sugars, carotenoids, flavonoids, dietary fiber, polyphenols, and a range of trace elements. These valuable compounds are used to develop functional foods, including baked products, beverages, meat products, and dairy products. Moreover, these functional foods play an important role in treating various disorders, including anti-aging, anti-mutagenic, antidiabetic, anti-carcinogenic, anti-allergenic, anti-oxidative, anti-inflammatory, neuroprotective, and cardiovascular-protective activity. EOs are complex and contain several naturally occurring bioactive compounds that are frequently used as the best substitutes in the food industry. Citrus essential oils have many uses in the packaging and food safety industries. They can also be used as an alternative preservative to extend the shelf lives of different food products.

Recent Progress in the Hesperetin Delivery Regimes: Significance of Pleiotropic Actions and Synergistic Anticancer Efficacy

BACKGROUND

In the plant kingdom, flavonoids are widely distributed with multifunctional immunomodulatory actions. Hesperetin (HST) remains one of the well-studied compounds in this domain, initially perceived in citrus plants as an aglycone derivative of hesperidin (HDN).

OBSERVATIONS

Natural origin, low in vivo toxicity, and pleiotropic functional essence are the foremost fascinations for HST use as an anticancer drug. However, low aqueous solubility accompanied with a prompt degradation by intestinal and hepatocellular enzymes impairs HST physiological absorption.

MOTIVATION

Remedies attempted herein comprise the synthesis of derivatives and nanocarrier (NC)-mediated delivery. As the derivative synthesis aggravates the structural complexity, NC-driven HST delivery has emerged as a sustainable approach for its sustained release. Recent interest in HST has been due to its significant anticancer potential, characterized via inhibited cell division (proliferation), new blood vessel formation (angiogenesis), forceful occupation of neighboring cell's space (invasion), migration to erstwhile physiological locations (metastasis) and apoptotic induction. The sensitization of chemotherapeutic drugs (CDs) by HST is driven via stoichiometrically regulated synergistic actions. Purpose and Conclusion: This article sheds light on HST structure-function correlation and pleiotropic anticancer mechanisms, in unaided and NC-administered delivery in singular and with CDs synergy. The discussion could streamline the HST usefulness and long-term anticancer efficacy.

Natural Products as Cancer Chemo Preventive Agents: Where We Stand

This work briefly reviews cancer chemoprevention. This is a very challenging field, as products with a high level of toxicity such as chemotherapeutic agents may be proposed and accepted only under life-threatening conditions. Cancer chemoprevention is otherwise limited to completely safe substances, preferably having neither toxic nor side effects, administered in relatively low amounts. Phases of clinical trials, therapeutic end-points, and biomarkers of chemoprevention are difficult to be defined. The clinical trials needed to prove the efficacy of chemopreventive agents must be very long and extremely widespread to achieve significance, with many variables difficult to control, and therefore subjected to many confounding factors. This makes them almost impossible. It is, therefore, no surprise, if the progress of chemoprevention has been so far very limited. There are only a few examples of direct use of chemopreventive agents, under investigation, but with anything but established protocols, in addition to indirect uses such as general supplementation with antioxidant, anti-inflammatory, and immune-supportive agents. Cancer chemoprevention remains a potentially very rewarding approach, certainly worth further study, but extremely difficult to pursue, in need of different methodological approaches to producing valuable chemopreventive compounds of clear dosages and benefits.

Protective Effects of Naringenin from Citrus sinensis (var. Valencia) Peels against CCl4-Induced Hepatic and Renal Injuries in Rats Assessed by Metabolomics, Histological and Biochemical Analyses

Citrus fruits are grown worldwide for their special nutritive and several health benefits. Among citrus bioactives, naringenin, a major flavanone, exhibits a potential hepatoprotective effect that is not fully elucidated. Herein, serum biochemical parameters and histopathological assays were used to estimate the hepatoprotective activity of naringenin, isolated from Citrus sinensis (var. Valencia) peels, in CCl4-induced injury in a rat model. Further, GC-MS-based untargeted metabolomics was used to characterize the potential metabolite biomarkers associated with its activity. Present results revealed that naringenin could ameliorate the increases in liver enzymes (ALT and AST) induced by CCl4 and attenuate the pathological changes in liver tissue. Naringenin decreased urea, creatinine and uric acid levels and improved the kidney tissue architecture, suggesting its role in treating renal disorders. In addition, naringenin increased the expression of the antiapoptoic cell marker, Bcl-2. Significant changes in serum metabolic profiling were noticed in the naringenin-treated group compared to the CCl4 group, exemplified by increases in palmitic acid, stearic acid, myristic acid and lauric acids and decrease levels of alanine, tryptophan, lactic acid, glucosamine and glucose in CCl4 model rats. The results suggested that naringenin's potential hepato- and renoprotective effects could be related to its ability to regulate fatty acids (FAs), amino acids and energy metabolism, which may become effective targets for liver and kidney toxicity management. In conclusion, the current study presents new insights into the hepato- and renoprotective mechanisms of naringenin against CCl4-induced toxicity.

Antioxidant and antibacterial activities of Artemisia absinthium and Citrus paradisi extracts repress viability of aggressive liver cancer cell line

BACKGROUND

Numerous reports show that herbal medicines can be utilized in the treatment of different liver disorders. In this study, antioxidant, antibacterial, and anticancer activities of individual as well as combined 80% ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels were investigated.

METHODS AND RESULTS

Values of total phenolic contents (TPC), total flavonoid contents (TFC), DPPH-radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured to explore the antioxidant capacity. To assess antibacterial activity, four bacterial strains (Escherichia coli, Staphylococcus aureus, Salmonella enterica, and Klebsiella pneumoniae) were used. Anticancer activity was assessed on Huh-7 (liver cancer) and Vero (non-cancerous) cell lines. FRAP activity of combined plants extract was higher as compared to their individual effect; the trend did not hold in the case of DPPH-radical scavenging activity. Antibacterial activity of combined extracts by disk diffusion method was observed only against E.coli. MTT results indicated that both plants had a cytotoxic effect on Huh-7 cell line but did not show any effect on Vero cell line. Our data showed a strong negative correlation between the amount of TPC, TFC, & DPPH radicals-scavenging activity and viability of Huh-7 cell line.However, no effect was shown on the non-cancerous cell line.

CONCLUSION

The ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels can be used against liver cancer because of their antioxidant, antibacterial, and anticancer activities.

An Up-to-Date Review on Citrus Flavonoids: Chemistry and Benefits in Health and Diseases

Flavonoids, the main class of polyphenols, are characterized by the presence of 2-phenyl-benzo-pyrane nucleus. They are found in rich quantities in citrus fruits. Citrus flavonoids are classified into flavanones, flavones, flavonols, polymethoxyflavones and anthocyanins (found only in blood oranges). Flavanones are the most abundant flavonoids in citrus fruits. In many situations, there are structure-function relationships. Due to their especial structures and presence of many hydroxyls, polymethoxies and glycoside moiety, the flavonoids have an array of multiple biological and pharmacological activities. This article provides an updated overview of the differences in chemical structures of the classes and members of citrus flavonoids and their benefits in health and diseases. The review article also sheds light on the mechanisms of actions of citrus flavonoids in the treatment of different diseases, including arthritis, diabetes mellitus, cancer and neurodegenerative disorders as well as liver, kidney and heart diseases. The accumulated and updated knowledge in this review may provide useful information and ideas in the discovery of new strategies for the use of citrus flavonoids in the protection, prevention and therapy of diseases.

Anti-estrogenic and anti-aromatase activities of citrus peels major compounds in breast cancer

Estrogen signaling is crucial for breast cancer initiation and progression. Endocrine-based therapies comprising estrogen receptor (ER) modulators and aromatase inhibitors remain the mainstay of treatment. This study aimed at investigating the antitumor potential of the most potent compounds in citrus peels on breast cancer by exploring their anti-estrogenic and anti-aromatase activities. The ethanolic extract of different varieties of citrus peels along with eight isolated flavonoids were screened against estrogen-dependent breast cancer cell lines besides normal cells for evaluating their safety profile. Naringenin, naringin and quercetin demonstrated the lowest IC_50s and were therefore selected for further assays. In silico molecular modeling against ER and aromatase was performed for the three compounds. In vivo estrogenic and anti-estrogenic assays confirmed an anti-estrogenic activity for the isolates. Moreover, naringenin, naringin and quercetin demonstrated in vitro inhibitory potential against aromatase enzyme along with anticancer potential in vivo, as evidenced by decreased tumor volumes. Reduction in aromatase levels in solid tumors was also observed in treated groups. Overall, this study suggests an antitumor potential for naringenin, naringin and quercetin isolated from citrus peels in breast cancer via possible modulation of estrogen signaling and aromatase inhibition suggesting their use in pre- and post-menopausal breast cancer patients, respectively.

Incorporation of natural assumption to deal with cancer

The current state of the art for the use of natural ingredients for cancer therapy is by reviewing the publications and findings associated with cancer research with the employment of flavonoids. Cancer is the most furious disease making fear in the eyes of mankind. Though various treatment methods are prevalent, the patient's choices are shifting from synthetic treatment strategy to the natural ones. The plant-based metabolites are used very often in our life as a food additive and also as a medicine for primary health care. The safety profile and its efficacy add on advantage for the incorporation of the natural products separately or in combination as a remedy for cancer. Flavonoids, the plant-based metabolites are proven for their anti-inflammatory, anti-oxidant, and anti-cancer properties. Their chemotherapeutic and chemosensitizing power had made it interesting for the researchers to dig more on the health benefits of the flavonoids and incorporating it in a holistic approach, with its natural benefits to relieve the pain and the symptoms of the patient suffering from various medical conditions. The predominant approach for the management of cancer is by following safe and effective treatment modality. In this review, we mentioned the benefits of the flavonoids for the management of various cancers and its potency as a chemotherapeutic agent and as the chemosensitizer. Our mother nature had given remedies to cure various diseases in both human beings and animals by it; we just need to find out the sources and access to them.

Innovative Technologies for Extraction and Microencapsulation of Bioactives from Plant-Based Food Waste and their Applications in Functional Food Development

The by-products generated from the processing of fruits and vegetables (F&V) largely are underutilized and discarded as organic waste. These organic wastes that include seeds, pulp, skin, rinds, etc., are potential sources of bioactive compounds that have health imparting benefits. The recovery of bioactive compounds from agro-waste by recycling them to generate functional food products is of increasing interest. However, the sensitivity of these compounds to external factors restricts their utility and bioavailability. In this regard, the current review analyses various emerging technologies for the extraction of bioactives from organic wastes. The review mainly aims to discuss the basic principle of extraction for extraction techniques viz. supercritical fluid extraction, subcritical water extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and pulsed electric field extraction. It provides insights into the strengths of microencapsulation techniques adopted for protecting sensitive compounds. Additionally, it outlines the possible functional food products that could be developed by utilizing components of agricultural by-products. The valorization of wastes can be an effective driver for accomplishing food security goals.

Anti-quorum Sensing and Protective Efficacies of Naringin Against Aeromonas hydrophila Infection in Danio rerio

It is now well known that the quorum sensing (QS) mechanism coordinates the production of several virulence factors and biofilm formation in most pathogenic microorganisms. Aeromonas hydrophila is a prime pathogen responsible for frequent outbreaks in aquaculture settings. Recent studies have also continuously reported that A. hydrophila regulates virulence factor production and biofilm formation through the QS system. In addition to the presence of antibiotic resistance genes, biofilm-mediated antibiotic resistance increases the severity of A. hydrophila infections. To control the bacterial pathogenesis and subsequent infections, targeting the QS mechanism has become one of the best alternative methods. Though very few compounds were identified as QS inhibitors against A. hydrophila, to date, the screening and identification of new and effective natural QS inhibitors is a dire necessity to control the infectious A. hydrophila. The present study endorses naringin (NA) as an anti-QS and anti-infective agent against A. hydrophila. Initially, the NA showed a concentration-dependent biofilm reduction against A. hydrophila. Furthermore, the results of microscopic analyses and quantitative virulence assays displayed the promise of NA as a potential anti-QS agent. Subsequently, the downregulation of ahh1, aerA, lip and ahyB validate the interference of NA in virulence gene expression. Furthermore, the in vivo assays were carried out in zebrafish model system to evaluate the anti-infective potential of NA. The outcome of the immersion challenge assay showed that the recovery rate of the zebrafish has substantially increased upon treatment with NA. Furthermore, the quantification of the bacterial load upon NA treatment showed a decreased level of bacterial counts in zebrafish when compared to the untreated control. Moreover, the NA treatment averts the pathogen-induced histoarchitecture damages in vital organs of zebrafish, compared to their respective controls. The current study has thus analyzed the anti-QS and anti-infective capabilities of NA and could be employed to formulate effective treatment measures against A. hydrophila infections.

Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry

BACKGROUND

Hepatitis C virus genotype 3a (HCV G3a) is highly prevalent in Pakistan. Due to the elevated cost of available Food and Drug Administration-approved drugs against HCV, medicinal natural products of potent antiviral activity should be screened for the cost-effective treatment of the disease. Furthermore, from natural products, active compounds against vital HCV proteins like non-structural protein 3 (NS3) protease could be identified to prevent viral proliferation in the host.

AIM

To develop cost-effective HCV genotype 3a NS3 protease inhibitors from citrus fruit extracts.

METHODS

Full-length NS3 without co-factor non-structural protein 4A (NS4A) and codon optimized NS3 protease in fusion with NS4A were expressed in Escherichia coli. The expressed protein was purified by metal ion affinity chromatography and gel filtration. Citrus fruit extracts were screened using fluorescence resonance energy transfer (FRET) assay against the protease and polyphenols were identified as potential inhibitors using electrospray ionization-mass spectrometry (MS)/MS technique. Among different polyphenols, highly potent compounds were screened using molecular modeling approaches and consequently the most active compound was further evaluated against HCV NS4A-NS3 protease domain using FRET assay.

RESULTS

NS4A fused with NS3 protease domain gene was overexpressed and the purified protein yield was high in comparison to the lower yield of the full-length NS3 protein. Furthermore, in enzyme kinetic studies, NS4A fused with NS3 protease proved to be functionally active compared to full-length NS3. So it was concluded that co-factor NS4A fusion is essential for the purification of functionally active protease. FRET assay was developed and validated by the half maximal inhibitory concentration (IC₅₀) values of commercially available inhibitors. Screening of citrus fruit extracts against the native purified fused NS4A-NS3 protease domain showed that the grapefruit mesocarp extract exhibits the highest percentage inhibition 91% of protease activity. Among the compounds identified by LCMS analysis, hesperidin showed strong binding affinity with the protease catalytic triad having S-score value of -10.98.

CONCLUSION

Fused NS4A-NS3 protease is functionally more active, which is effectively inhibited by hesperidin from the grapefruit mesocarp extract with an IC₅₀ value of 23.32 µmol/L.

Clinical Evaluation of the Safety and Effectiveness of Heptonica: A Ghanaian Hepatorestorative Polyherbal Product

The incidence of liver diseases is increasing globally, and many patients in developing countries are resorting to the use of herbal products as treatment. This study was aimed at establishing the safety and effectiveness outcomes for patients with deranged liver panel treated with a Ghanaian finished polyherbal product. The product Heptonica is prepared by CPMR from three medicinal plants: Bidens pilosa, Citrus aurantifolia, and Trema orientalis. Fifty (50) participants with clinical and biochemical signs of liver impairment were purposively recruited and treated for a period of 28 days. Participants received Heptonica at a dose of 30 mL 8 hourly after meals for the treatment period. Clinical and biochemical evaluation (liver panel test, renal function test, haematology, and urinalysis) of subjects for the safety and effectiveness of the product was undertaken at days 0 (baseline), 14, and 28. Compared to the baseline values, Heptonica did not have any untoward effect on renal function, haematological parameters, and urine parameters of subjects. Clinical and liver panel results of the participants also improved compared to the baseline: serum aspartate transaminase (AST) (p < 0.0001), alanine transaminase (ALT) (p < 0.0001), gamma-glutamyltransferase (GGT) (p- 0.0013), total bilirubin (p-0.0136), direct bilirubin (p < 0.0001), total proteins (p-0.0409), and alkaline phosphates (p- 0.0284). Level of albumin showed no significant difference within the study period. The outcome of this study indicates Heptonica has hepatorestorative action with no observable toxicity and can be used with confidence as indicated as a liver tonic.

Citrus Peel Flavonoids as Potential Cancer Prevention Agents

Citrus fruit and in particular flavonoid compounds from citrus peel have been identified as agents with utility in the treatment of cancer. This review provides a background and overview regarding the compounds found within citrus peel with putative anticancer potential as well as the associated in vitro and in vivo studies. Historical studies have identified a number of cellular processes that can be modulated by citrus peel flavonoids including cell proliferation, cell cycle regulation, apoptosis, metastasis, and angiogenesis. More recently, molecular studies have started to elucidate the underlying cell signaling pathways that are responsible for the flavonoids' mechanism of action. These growing data support further research into the chemopreventative potential of citrus peel extracts, and purified flavonoids in particular. This critical review highlights new research in the field and synthesizes the pathways modulated by flavonoids and other polyphenolic compounds into a generalized schema.

Effect of citrus peel extracts on the cellular quiescence of prostate cancer cells

The re-entry of quiescent cancer cells to the cell cycle plays a key role in cancer recurrence, which can pose a high risk after primary treatment. Citrus peel extracts (CPEs) contain compounds that can potentially impair tumour growth; however the mechanism of action and effects on cell cycle regulation remain unclear. In this study, the capacity of an ethyl acetate : hexane extract (CPE/hexane) and water extract (CPE/water) to modulate the cell cycle re-entry of quiescent (PC-3 and LNCaP) prostate cancer cells was tested in an in vitro culture system. Cell cycle analysis showed that the quiescent PC-3 and LNCaP cancer cells in the presence of CPE/water were impaired in their ability to enter the S phase where only 2-3% reduction of G0/G1 cells was noted compared to 12-18% reduction of control cells. In contrast, the CPE/hexane did not show any cell cycle inhibition activity in both cell lines. A low DNA synthesis rate and weak apoptosis were observed in quiescent cancer cells treated with CPEs. Hesperidin and narirutin, the predominant flavonoids found in citrus fruits, were not responsible for the observed biological activity, implicating alternative bioactive compounds. Notably, citric acid was identified as one of the compounds present in CPEs that acts as a cell cycle re-entry inhibitor. Citric acid exhibited a higher cell toxicity effect on PC-3 prostate cancer cells than non-cancerous RWPE-1 prostate cells, suggesting specific benefits for cancer treatment. In conclusion, CPE containing citric acid together with various bioactive compounds may be used as a chemopreventive agent for post-therapy cancer patients.

Polymethoxylated Flavones Target Cancer Stemness and Improve the Antiproliferative Effect of 5-Fluorouracil in a 3D Cell Model of Colorectal Cancer

Polymethoxylated flavones (PMFs) from citrus fruits are reported to present anticancer potential. However, there is a lack of information regarding their effect on cancer stem cell (CSC) populations, which has been recognized as responsible for tumor initiation, relapse, and chemoresistance. In this study, we evaluated the effect of an orange peel extract (OPE) and its main PMFs, namely, nobiletin, sinensetin, tangeretin, and scutellarein tetramethylether in targeting cell proliferation and stemness using a 3D cell model of colorectal cancer composed of HT29 cell spheroids cultured for 7 days in stirred conditions. Soft agar assay, ALDH1 activity, and relative quantitative gene expression analysis of specific biomarkers were carried out to characterize the stemness, self-renewal, and mesenchymal features of HT29 cell spheroids. Then, the impact of OPE and PMFs in reducing cell proliferation and modulating cancer stemness and self-renewal was assessed. Results showed that, when compared with monolayer cultures, HT29 cell spheroids presented higher ALDH1 activity (81.97% ± 5.27% compared to 63.55% ± 17.49% for 2D), upregulation of CD44, PROM1, SOX9, and SNAI1 genes (1.83 ± 0.34, 2.54 ± 0.51, 2.03 ± 0.15, and 6.12 ± 1.59 times) and high self-renewal capability (352 ± 55 colonies compared to 253 ± 42 for 2D). Incubation with OPE (1 mg/mL) significantly inhibited cell proliferation and modulated cancer stemness and self-renewal ability: colony formation, ALDH1 activity, and the expression of cancer stemness biomarkers PROM1 and LGR5 were significantly reduced (0.66 ± 0.15 and 0.51 ± 0.14 times, respectively). Among all PMFs, tangeretin was the most efficient in targeting the CSC population by decreasing colony formation and the expression of PROM1 and LGR5. Scutellarein tetramethylether was shown to modulate markers of mesenchymal/metastatic transition (increasing CDH1 and reducing ZEB1 and SNAI1) and nobiletin was capable of downregulating PROM1 and SNAI1 expression. Importantly, all PMFs and OPE were shown to synergistically interact with 5-fluorouracil, improving the antiproliferative response of this drug.

Extraction of diverse polyphenols in relation with storage periods of Citrus paradisi CV. Shamber through HPLC-DAD technique using different solvent

In this article, Citrus paradisi, (Shamber) an exceptional source of Vitamins A and C and full of nutrients, selected for extraction of diverse polyphenols including dietary flavonoids and essential flavonoids by HPLC-DAD technique using various solvents. These essential targeted compounds also analyze after keeping different storage periods and compare with fresh fruits for better efficacy of these compounds. The highest number of phenolic compounds including gallic acid, chlorogenic acid sinapic acid, ferulic acid, myricetin, quercetin, and kaempferol extracted in methanol solvent leading to the new compounds of tetra-O-methylscutellar and heptamethoxy flavone. The essential flavonoids determined by polyethersulfone filter and insoluble precipitation separated by the dimethyl sulfoxide. The results showed that the methanolic extraction exhibited higher essential flavonoids including nobiletin, sinensetin, tangeritin, and tetra-O-methylscutellarein and heptamethoxy flavone. The RP-HPLC analysis exposed the maximum number of nutritional flavonoids like naringin, hesperidin, total flavones, glycosyl. Moreover, it observed that dietary flavonoids and phenolic compounds of stored fruits were unaffected in 30 days of storage periods while minor variations were pragmatic during 60-90 days storage. The investigation revealed that C. paradisi proves to be the valuable resource of different phenolic compounds and flavonoids which are effective against various oxidative stresses in the human body.

Phytochemical composition and in vitro antioxidant activities of Citrus sinensis peel extracts

BACKGROUND

Citrus sinensis peels are usually discarded as wastes; however, they are rich sources of Vitamin C, fibre, and many nutrients, including phenolics and flavonoids which are also good antioxidant agents. This study aimed to examine phytochemical composition and antioxidant capabilities of C. sinensis peel extracted conventionally with different methanol/water, ethanol/water, and acetone/water solvents.

METHODS

C. sinensis peels were subjected to extraction with 100%, 70% and 50% of methanol, ethanol, and acetone, respectively, as well as hot water extraction. Antioxidant activities of the peel extracts were examined via the 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging activity, ferric reducing antioxidant power (FRAP) assay, and oxygen radical absorbance capacity (ORAC) assay. Total phenolic content and total flavonoid content of the extracts were measured via the Folin-Ciocalteau method and the aluminium chloride colorimetric method, respectively. Phenolic acid and organic acid composition of the peel extracts were further determined via high performance liquid chromatography (HPLC) while flavonoid content was identified via ultra performance liquid chromatography (UPLC).

RESULTS

DPPH radical scavenging activity of C. sinensis peel extracts varied from 8.35 to 18.20 mg TE/g, FRAP ranged from 95.00 to 296.61 mmol Fe(II)/g, while ORAC value ranged from 0.31 to 0.92 mol TE/g. Significant level of association between the assays was observed especially between TPC and FRAP (R-square = 0.95, P < 0.0001). TPC of various C. sinensis peel extracts ranged from 12.08 to 38.24 mg GAE/g, with 70% acetone/water extract (AEC) showing the highest TPC. TFC ranged from 1.90 to 5.51 mg CE/g. Extraction yield ranged from 0.33 to 0.54 g/g DW and tended to increase with increasing water concentration in the solvent. In the phytochemical investigation, five phenolic acids were identified using HPLC, including gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, caffeic acid and ferulic acid. A total of five organic acids including lactic acid, citric acid, L-mallic acid, kojic acid and ascorbic acid were quantified via HPLC. In addition, concentrations of six flavonoids including catechin, epigallocatechin, vitexin, rutin, luteolin and apigenin were determined via UPLC.

DISCUSSION AND CONCLUSION

Phytochemicals including phenolics and flavonoids in C. sinensis peel extracts exhibited good antioxidant properties. Among the extracts, 70% AEC with highest TPC and high TFC content showed greatest antioxidant activity in all three assays. Different phenolic acids, organic acids and flavonoids were also identified from the extracts. This study indicated that C. sinensis peels contained potential antioxidant compounds which could be exploited as value added products in the food industry.

A review on flavonoid-based scaffolds as multi-target-directed ligands (MTDLs) for Alzheimer's disease

Alzheimer's disease (AD), the most common form of dementia, is a multifactorial neurodegenerative disease. The target enzymes inhibition including cholinesterase, beta-secretase, monoamine oxidase and inhibition of amyloid-β aggregation as well as oxidative stress and metal chelation play an important role in the pathogenesis of AD. Chroman-4-one scaffold with benzo-γ-pyrone network is a privileged structure in organic synthesis and drug design. A large number of research has been carried out on modified naturally occurring chromanone scaffolds and/or synthesized new analogues, to obtain effective drugs for AD management. The present review summarizes aspects related to the multi-target-directed ligands (MTDLs) strategy in enzyme targets modulation performed with natural and synthesized chroman-4-one-based structures to look at their potential in the management of multifactorial Alzheimer's disease.

Flavonoids Effects on Hepatocellular Carcinoma in Murine Models: A Systematic Review

The hepatocellular carcinoma (HCC) is the second most common cause of cancer deaths worldwide. It occurs primarily as manifestation of other pathological processes, such as viral hepatitis, cirrhosis, and toxin exposure that affect directly the cellular process. Studies were selected from PubMed and Scopus databases according to the PRISMA statement. The research filters were constructed using three parameters: flavonoids, hepatocellular carcinoma, and animal model. The bias analysis of the 34 selected works was done using the ARRIVE guidelines. The most widely used flavonoid in the studies was epigallocatechin gallate extracted from green tea. In general, the treatment with different flavonoids presented inhibition of tumor growth and antiangiogenic, antimetastatic, antioxidant, and anti-inflammatory activities. The bias analysis evidenced the absence of methodological processes in all studies, such as the age or weight of the animals, the method of flavonoids' extraction, or the experimental designs, analytical methods, and outcome measures. It has been known that flavonoids have a protective effect against HCC. However, the absence or incomplete characterization of the animal models, treatment protocols, and phytochemical and toxicity analyses impaired the internal validity of the individual studies, making it difficult to determine the effectiveness of plant-derived products in the treatment of HCC.

Polymethoxylated Flavones from Orange Peels Inhibit Cell Proliferation in a 3D Cell Model of Human Colorectal Cancer

Polymethoxylated flavones (PMFs) have been recognized to inhibit colorectal cancer proliferation through various mechanisms, however most of these studies have been performed on cells grown as monolayers that present limitations in mimicking the 3D tumor architecture and microenvironment. The main aim of this study was to investigate the anticancer potential of an orange peel extract (OPE) enriched in PMFs in a 3D cell model of colorectal cancer. The OPE was developed by supercritical fluid extraction and the anticancer effect was evaluated in HT29 spheroids cultures in a stirred-tank based system. Results showed that OPE inhibited cell proliferation, induced cell cycle arrest (G2/M phase), promoted apoptosis, and reduced ALDH⁺ population on HT29 spheroids. The antiproliferative activity was significantly lower than that obtained for 2D model (EC50 value of 0.43 ± 0.02 mg/mL) and this effect was dependent on diameter and cell composition/phenotype of spheroids derived from different culture days (day 3 - 0.53 ± 0.05 mg/mL; day 5 - 0.55 ± 0.03 mg/mL; day 7 - 1.24 ± 0.15 mg/mL). HT29 spheroids collected at day 7 presented typical characteristics of in vivo solid tumors including a necrotic/apoptotic core, hypoxia regions, presence of cancer stem cells, and a less differentiated invasive front. Nobiletin, sinesentin, and tangeretin were identified as the main compounds responsible for the anticancer activity.

Polysaccharides from the peels of Citrus aurantifolia induce apoptosis in transplanted H22 cells in mice

In this study, an acidic polysaccharide (CAs) was extracted and purified from the peels of Citrus aurantifolia by Sephadex G-150. HPGPC showed the molecular weight of CAs was about 7.94×10⁶Da. Ion chromatography (IC) analysis showed CAs was mainly composed of rhamnose (Rha), arabinose (Ara), galactose (Gal), glucose (Glu), mannose (Man) and galacturonic acid (GalA), with the molar ratio of 0.67: 7.67: 10.83: 3.83: 4.00: 1.00. ¹H and ¹³C NMR spectra of CAs also identified the presence of five kinds of monosaccharides and galacturonic acid. Moreover, the antitumor activity of CAs was evaluated in mice transplanted H22 hepatoma cells. It was shown that CAs dose-dependently suppressed tumor cells growth with few toxic effects on host. Further investigations revealed that CAs increased the levels of tumor infiltrating CD8⁺ T lymphocytes, blocked tumor cell cycle in S phase, down-regulated anti-apoptotic protein Bcl-xL and Mcl-1 expression, and led to the activation of caspase 3. These results suggested that CAs had capacity of inducing tumor cells apoptosis in vivo, and it supported considering CAs as an adjuvant reagent in hepatocellular carcinoma treatment.

Enhancing the Total Phenolic Content and Antioxidants of Lemon Pomace Aqueous Extracts by Applying UV-C Irradiation to the Dried Powder

Several studies have shown that UV-C (ultraviolet C) irradiation promotes the bioactive compounds and antioxidants of fresh fruits and vegetables. The aim of this study was to apply UV irradiation in dried lemon pomace powder for enhancing its phenolic content and antioxidant properties, thus more bioactive compounds should be available for extraction and utilization. Lemon pomace dried powder was placed under a UV lamp and treated with dosages of 4, 19, 80 and 185 kJ·m⁻², while untreated powder was used as a control. UV-C irradiation significantly affected the total phenolic content, total flavonoid content, proanthocyanidins, and antioxidant capacity measured by cupric reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) of the lemon pomace dried powder, while it did not affect the vitamin C content. UV-C irradiation of 19 kJ·m⁻² resulted in 19% higher total phenolic content than the control, while UV-C irradiation of 180 kJ·m⁻² resulted in 28% higher total flavonoid content than the control. The antioxidant capacity was reduced when UV-C irradiation more than 4 kJ·m⁻² was applied. The results of this study indicate that UV-C treatment has the potential to increase the extraction of bioactive compounds of dried lemon pomace at relatively high dosages.

Identification of differentially expressed genes implicated in peel color (red and green) of Dimocarpus confinis

Nowadays, there are few reports about regulatory genes implicated in peel color of longan. The basic genetic research of longan has been in stagnation for a long time as a lack of transcriptomic and genetic information. To predict candidate genes associated with peel color, Gene Functional Annotation and Coding Sequence prediction were used to perform functional annotation for our assembled unigenes and investigate differentially expressed genes (DEGs) of fruitlet peels from Longli (Dimocarpus confinis). Finally, a total of 24,044 (44.19 %) unigenes were annotated at least in one database after BLAST search to NCBI non-redundant protein sequence, NCBI non-redundant nucleotide sequences, Kyoto Encyclopedia of Genes and Genomes (KEGG) Ortholog, manually annotated and reviewed protein sequence database (Swiss-Prot), Protein family, Gene Ontology, euKaryotic Ortholog Groups databases. After searching against the KEGG-GENE protein database, a result of 6228 (11.45 %) unigenes were assigned to 245 KEGG pathways. Via comparing the distributions of expression value of all corresponding unigenes from red peel and green peel fruit, it could be intuitively concluded that high similarity was existed in the two distributions; however, on the whole, between two distributions of log RPKM expression value, some differences indicated that expression level in green-peel fruit group is slightly higher than values in red-peel fruit group. Finally, a total of 1349 unigenes were identified as DEGs after blasting the DEGs to public sequence databases, and 32 peel-color-related genes were identified in longan. Our results suggest that a number of unigenes involved in longan metabolic process, including anthocyanin biosynthesis. In addition, DRF, F3H, ANS, CYP75A1 and C1 may be the key ones. The study on key genes related to peel color will be contributed to revealing the molecular mechanisms of regulating peel color in woody plants.