Citrus limonin and its glucoside inhibit colon adenocarcinoma cell proliferation through apoptosis

Mechanism underlying the effect of Pulsatilla decoction in hepatocellular carcinoma treatment: a network pharmacology and in vitro analysis

BACKGROUND

Currently, hepatocellular carcinoma (HCC) is associated with a poor prognosis. Moreover, there exist limited strategies for treating HCC. Pulsatilla decoction (PD), a traditional Chinese medicine formula, has been used to treat inflammatory bowel disease and several cancer types. Accordingly, we explored the mechanism of PD in HCC treatment via network pharmacology and in vitro experiments.

METHODS

Online databases were searched for gene data, active components, and potential target genes associated with HCC development. Subsequently, bioinformatics analysis was performed using protein-protein interaction and Network Construction and Kyoto Encyclopedia of Genes and Genomes (KEGG) to screen for potential anticancer components and therapeutic targets of PD. Finally, the effect of PD on HCC was further verified by in vitro experiments.

RESULTS

Network pharmacological analysis revealed that 65 compounds and 180 possible target genes were associated with the effect of PD on HCC. These included PI3K, AKT, NF-κB, FOS, and NFKBIA. KEGG analysis demonstrated that PD exerted its effect on HCC mainly via the PI3K-AKT, IL-17, and TNF signaling pathways. Cell viability and cell cycle experiments revealed that PD could significantly inhibit cancer cell proliferation and kill HCC cells by inducing apoptosis. Furthermore, western blotting confirmed that apoptosis was mediated primarily via the PI3K-AKT, IL-17, and TNF signaling pathways.

CONCLUSION

To the best of our knowledge, this is the first study to elucidate the molecular mechanism and potential targets of PD in the treatment of HCC using network pharmacology.

Oral administration of Limonin (LM) exerts neuroprotective effects by inhibiting neuron autophagy and microglial activation in 6-OHDA-injected rats

Parkinson's disease (PD) is a neurodegenerative disorder that occurs most frequently in middle-aged and elderly people. It is characterized by an insidious onset and a complex etiology, and no effective treatment has been developed. The primary characteristic of PD is the degenerative death of midbrain dopaminergic neurons. The excessive autophagy of neurons and hyperactivation of microglia were shown to be involved in the apoptosis of dopaminergic neurons. Limonin (LM), a type of pure natural compound present in grapefruit or citrus fruits (e. g., lemon, orange) has been reported to inhibit apoptosis and inflammation. However, its role and mechanism of action in PD are unclear. In this study, we explored the effect and mechanism of action of LM in PD. In vivo experiments revealed that LM ameliorated 6-OHDA-induced reduced motor activity and PD-related pathological damage in rats. In vitro experiments revealed that LM inhibited the 6-OHDA-induced apoptosis of PC12 cells by inhibiting the excessive autophagy of neurons. In addition, LM inhibited microglial inflammation by activating the AKT/Nrf-2/HO-1 pathway and protected neurons against microglial inflammation-mediated neurotoxicity. In conclusion, the findings of this experiment demonstrated that LM exerted neuroprotective effects by inhibiting neuronal autophagy-mediated apoptosis and microglial activation in 6-OHDA-injected rats, thus indicating that LM can serve as a candidate for PD by targeting neuroinflammation and neuronal autophagy to inhibit neuronal apoptosis.

Limonin, a Component of Immature Citrus Fruits, Activates Anagen Signaling in Dermal Papilla Cells

Hair loss remains a significant problem that is difficult to treat; therefore, there is a need to identify safe natural materials that can help patients with hair loss. We evaluated the hair anagen activation effects of limonin, which is abundant in immature citrus fruits. Limonin increased the proliferation of rat dermal papilla cells (rDPC) by changing the levels of cyclin D1 and p27, and increasing the number of BrdU-positive cells. Limonin increased autophagy by decreasing phosphorylated mammalian target of rapamycin levels and increasing the phospho-Raptor, ATG7 and LC3B. Limonin also activated the Wnt/β-catenin pathway by increasing phospho-β-catenin levels. XAV939, a Wnt/β-catenin inhibitor, inhibited these limonin-induced changes, including induced autophagy, BrdU-positive cells, and cell proliferation. Limonin increased the phosphorylated AKT levels in both two-dimensional cultured rDPC and three-dimensional spheroids. Treatment with the PI3K inhibitor wortmannin inhibited limonin-induced proliferation, and disrupted other limonin-mediated changes, including decreased p27, increased BrdU-positive cells, induced autophagy, and increased ATG7 and LC3B levels. Wortmannin also inhibited limonin-induced cyclin D1 and LC3 expression in spheroids. Collectively, these results indicate that limonin can enhance anagen signaling by activating autophagy via targeting the Wnt/β-catenin and/or PI3K/AKT pathways in rDPC, highlighting a candidate nutrient for hair loss treatment.

Antiproliferative activity, cell-cycle arrest, apoptotic induction and LC-HRMS/MS analyses of extracts from two Linum species

CONTEXT

Linum is the largest genus of the Linaceae family; the species of this genus are known to have anticancer activity.

OBJECTIVE

In this study, ethyl acetate extracts of L. numidicum Murb. (EAELN) and L. trigynum L. (EAELT) were examined, for the first time, for their anticancer capacity. The secondary metabolites compositions were analysed by LC-HRMS/MS.

MATERIALS AND METHODS

The antiproliferative effect of EAELN and EAELT (0-10.000 μg/mL) against PC3 and MDA-MB-231 cell lines were  evaluated by the MTT assay after 72 h of treatment. Flow cytometer analysis of apoptosis (Annexin V-FITC/PI) and cell cycle (PI/RNase) was also performed after treatment with EAELN and EAELT at 250, 500, and 1000 μg/mL, for 24 h.

RESULTS

EAELN had the highest antiproliferative activity against PC3 (IC₅₀ 133.2 ± 5.73 μg/mL) and MDA-MB-231 (IC₅₀ 156.9 ± 2.83 μg/mL) lines, EAELN had also shown better apoptotic activity with 19 ± 2.47% (250 μg/mL), 87.5 ± 0.21% (500 μg/mL), and 92 ± 0.07% (1000 μg/mL), respectively, causing cell cycle arrest of PC3 cells in G2/M phase, whereas arrest in G0/G1 and G2/M phases was observed after treatment with EAELT. LC-HRMS/MS profiling of the extracts revealed the presence of known compounds that might be responsible for the observed anticancer activity such as chicoric acid, vicenin-2, vitexin and podophyllotoxin-β-d-glucoside.

DISCUSSION AND CONCLUSIONS

We have shown, for the first time, that EAELN and EAELT exert anticancer activity through cell cycle arrest and induction of apoptosis. EAELN can be considered as a source to treat cancer. Further studies will be required to evaluate the effect of the active compounds, once identified, on other cancer cell lines.

Preclinical Drug Pharmacokinetic, Tissue Distribution and Excretion Profiles of the Novel Limonin Derivate HY-071085 as an Anti-Inflammatory and Analgesic Candidate in Rats and Beagle Dogs

Limonin is one of the research hotspots in natural drug development. However, its low solubility in water leads to poor oral bioavailability, discouraging the further study of its potential as a candidate compound. In order to overcome this limitation, and to enhance its biological activities, a novel limonin derivative—HY-071085—was synthesized by structural modification, and has exhibited strong anti-inflammatory and analgesic activity. In order to achieve a thorough understanding of the biological actions of HY-071085 in vivo, this study evaluated the pharmacokinetics and bioavailability of HY-071085 in rats and beagle dogs, and the distribution and excretion in rats. Using ultra-high-performance liquid chromatography-tandem mass spectrometry, the kinetic profiles of HY-071085 in the plasma of healthy rats and beagle dogs after a single gavage, repeated gavages and the intravenous injection of HY-071085 were studied. The tissue distribution (heart, liver, spleen, lung, kidney, gastric tissue, intestine, brain, skin, testis, ovary and womb) and excretion of HY-071085 were also studied. These results showed that HY-071085 has nonlinear dynamic characteristics in rat and beagle dog plasma. It was found that the plasma concentrations of HY-071085 in female rats were significantly higher than those in male rats after a single oral administration. There were gender differences in the kinetic behavior of HY-071085 in rats; however, there was no difference identified in dogs. HY-071085 was mainly eliminated as metabolites in rats, and was distributed in most of the tissues except the brain, with the highest content being in the gastric tissue and intestinal arease, followed by the liver, spleen, fat, lung, kidney, ovary and heart. The bioavailability of HY-071085 in male and female rats was 2.8% and 10.8%, respectively, and was about 13.1% in beagle dogs. The plasma protein binding rate of HY-071085 in rats, beagle dogs and humans ranged from 32.9% to 100%, with obvious species differences. In conclusion, our study provides useful information regarding the absorption, distribution and excretion of HY-071085, which will provide a good base for the study of the mechanism of its biological effects.

Current Advances in Coptidis Rhizoma for Gastrointestinal and Other Cancers

Cancer is a serious disease with an increasing number of reported cases and high mortality worldwide. Gastrointestinal cancer defines a group of cancers in the digestive system, e.g., liver cancer, colorectal cancer, and gastric cancer. Coptidis Rhizoma (C. Rhizoma; Huanglian, in Chinese) is a classical Chinese medicinal botanical drug for the treatment of gastrointestinal disorders and has been shown to have a wide variety of pharmacological activity, including antifungal, antivirus, anticancer, antidiabetic, hypoglycemic, and cardioprotective effects. Recent studies on C. Rhizoma present significant progress on its anticancer effects and the corresponding mechanisms as well as its clinical applications. Herein, keywords related to C. Rhizoma, cancer, gastrointestinal cancer, and omics were searched in PubMed and the Web of Science databases, and more than three hundred recent publications were reviewed and discussed. C. Rhizoma extract along with its main components, berberine, palmatine, coptisine, magnoflorine, jatrorrhizine, epiberberine, oxyepiberberine, oxyberberine, dihydroberberine, columbamine, limonin, and derivatives, are reviewed. We describe novel and classic anticancer mechanisms from various perspectives of pharmacology, pharmaceutical chemistry, and pharmaceutics. Researchers have transformed the chemical structures and drug delivery systems of these components to obtain better efficacy and bioavailability of C. Rhizoma. Furthermore, C. Rhizoma in combination with other drugs and their clinical application are also summarized. Taken together, C. Rhizoma has broad prospects as a potential adjuvant candidate against cancers, making it reasonable to conduct additional preclinical studies and clinical trials in gastrointestinal cancer in the future.

Anticancer potential of limonoids from Swietenia macrophylla: Genotoxic, antiproliferative and proapoptotic effects towards human colorectal cancer

AIMS

Swietenia macrophylla have been considered for the treatment of various diseases, including anticancer activity. This study aimed to investigate the anticancer activity of S. macrophylla leaves extract and its isolated compound towards human colorectal cancer cell line.

MAIN METHODS

Hexanic extract of S. macrophylla leaves demonstrated relevant cytotoxicity only against colon cancer cell line HCT116.

KEY FINDINGS

Our results showed significant DNA damage and apoptosis after treatment with the hexanic extract of S. macrophylla. Moreover, no toxicity was noticed for the animal model. The isolated compound limonoid L1 showed potent cytotoxicity against cancer cell lines with IC₅₀ at 55.87 μg mL^-1. Limonoid L1 did not trigger any cell membrane rupture in the mice erythrocytes suggesting no toxicity. The antiproliferative effect of L1 was confirmed in colorectal cancer cells by clonogenic assay, inducing G2/M arrest, apoptosis, and DNA damage in cancer-type cells.

SIGNIFICANCE

L1 reduced BCL2 and increased ATM, CHK2, TP53, ARF, CDK1, CDKN1A, and CASP3 in the colorectal cancer cell line. These findings suggest that limonoid L1 isolated from S. macrophylla can be a promising anticancer agent in managing colorectal cancer.

Selective in vitro cytotoxicity effect of Drimia calcarata bulb extracts against p53 mutant HT-29 and p53 wild-type Caco-2 colorectal cancer cells through STAT5B regulation

Colorectal cancer is the fourth leading cause of oncological-related deaths and the third most diagnosed malignancy, worldwide. The emergence of chemoresistance is a fundamental drawback of colorectal cancer therapies and there is an urgent need for novel plant-derived therapeutics. In this regard, other compounds are needed to improve the efficacy of treatment against colorectal cancer. Medicinal plants have been effectively used by traditional doctors for decades to treat various ailments with little to no side effects. Drimia calcarata (D. calcarata) is one of the plants used by Pedi people in South Africa to treat a plethora of ailments. However, the anticancer therapeutic use of D. calcarata is less understood. Thus, this study was aimed at evaluating the potential anticancer activities of D. calcarata extracts against human colorectal cancer cells. The phytochemical analysis and antioxidant activity were analysed using LC-MS, DPPH, and FRAP. The inhibitory effects and IC50 values of D. calcarata extracts were determined using the MTT assay. Induction of cellular apoptosis was assessed using fluorescence microscopy, the Muse® Cell Analyser, and gene expression analysis by Polymerase Chain Reaction (PCR). Water extract (WE) demonstrated high phenolic, tannin, and flavonoid contents than the methanol extract (ME). LC-MS data demonstrated strong differences between the ME and WE. Moreover, WE showed the best antioxidant activity than ME. The MTT data showed that both ME and WE had no significant activity against human embryonic kidney Hek 293 cell line that served as non-cancer control cells. Caco-2 cells demonstrated high sensitivity to the ME and demonstrated resistance toward the WE, while HT-29 cells exhibited sensitivity to both D. calcarata extracts. The expression of apoptosis regulatory genes assessed by PCR revealed an upregulation of p53 by ME, accompanied by downregulation of Bcl-2 and high expression of Bax after treatment with curcumin. The Bax gene was undetected in HT-29 cells. The methanol extract induced mitochondrial-mediated apoptosis in colorectal Caco-2 and HT-29 cells and WE induced the extrinsic apoptotic pathway in HT-29 cells. ME downregulated STAT1, 3, and 5B in HT-29 cells. The D. calcarata bulb extracts, therefore, contain potential anticancer agents that can be further targeted for cancer therapeutics.

Citrus limonoids induce apoptosis and inhibit the proliferation of pancreatic cancer cells

In our recent study, we demonstrated that certain limonoids isolated from citrus seeds induced apoptosis in human pancreatic (Panc-28) cells. In this study, limonin, nomilin and limonexic acid (LNA) were investigated for understanding the possible mode of cytotoxicity in cultured pancreatic cancer (Panc-28) cells. All three limonoids inhibited Panc-28 cell proliferation, with IC50 values less than 50 μM after 72 h of incubation. The induction of apoptosis was confirmed through the cleavage of caspase-3, decreased mitochondrial membrane potential, and expression of apoptosis-related proteins. The Bax/Bcl2 expression ratio was increased up to 11-fold in cells pre-treated with 60 μM limonoids for 48 h. Apart from this, the limonoids also induced the expression of p21, and exhibited anti-inflammatory activity through decreasing the expression of cox-2, NF-κB and IL-6. Based on these results, we were interested in understanding the possible mode of inhibition by LNA, which exhibited the highest activity. The treatment of Panc-28 cells resulted in dose- and time-dependent induction of apoptosis-inducible proteins. In addition, treatment with 60 μM LNA resulted in the activation of Akt-associated signals to induce apoptosis, and the same was confirmed by the effects of the compounds on pAkt, p53, VEGF and caspase proteins. The results of this study demonstrated the cytotoxicity of limonoids to human pancreatic cancer cells through the modulation of genes involved in proliferation and survival.

Limonin modulated immune and inflammatory responses to suppress colorectal adenocarcinoma in mice model

Inflammation and compromised immune responses often increase colorectal cancer (CRC) risk. The immune-modulating effects of limonin on carcinogen/inflammation-induced colorectal cancer (CRC) were studied in mice. Male Balb/c mice were randomly assorted into three groups (n = 6): healthy control, non-treated CRC-induced (azoxymethane/dextran-sulfate-sodium AOM/DSS) control, and CRC-induced + 50 mg limonin/kg body weight. The CRC developments were monitored via macroscopic, histopathological, ELISA, and mRNA expression analyses. Limonin downregulated inflammation (TNF-α, tumor necrosis factor-α), enhanced the adaptive immune responses (CD8, CD4, and CD19), and upregulated antioxidant defense (Nrf2, SOD2) mRNA expressions. Limonin reduced serum malondialdehyde (MDA, lipid peroxidation biomarker), prostaglandin E2, and histopathology inflammation scores, while increasing reduced glutathione (GSH) in CRC-induced mice. Limonin significantly (p < 0.05) increased T cells (CD4 and CD8) and B cells (CD19) in spleen tissues. The CD335 (natural killer cells) were increased in the CRC-induced mice and limonin treatment restored them to normal levels suggesting reinstatement to normal colon conditions. Limonin apparently mitigated CRC development, by ameliorating adaptive immune responses (CD8, CD4, and CD19), reducing inflammation (serum prostaglandin E2; TNF-α, innate immune responses) and oxidative stress, and enhancing the endogenous anti-oxidation defense reactions (GSH) in CRC-induced mice.

The Use of Bio-Active Compounds of Citrus Fruits as Chemopreventive Agents and Inhibitor of Cancer Cells Viability

Common therapy of cancer, such as chemotherapy, has various side effects for the patients. In recent studies, new therapeutic approaches in cancer treatment are adjuvant therapy, along with a reduction in side effects of chemotherapy drugs. Treatment by herbal medicines may have some advantages over treatment with single purified chemicals, also in terms of side effects, the use of plants in cancer treatment is a more secure method. Citrus fruits are one of the most consumed natural products in the world due to the presence of various metabolites and bioactive compounds, such as phenols, flavonoids and, carotenoids. Bioactive compounds of citrus modulate signaling pathways and interact with signaling molecules such as apoptotic and cell cycle (P53, P21, etc.) and thus have a wide range of pharmacological activities, including anti-inflammatory, anti-cancer and oxidative stress. The findings discussed in this review strongly support their potential as anti-cancer agents. Therefore, the purpose of this review was to examine the effects of active compounds in citrus as a therapy agent in cancer treatment.

Limonin Enhances the Antifungal Activity of Eugenol Nanoemulsion against Penicillium Italicum In Vitro and In Vivo Tests

Penicillium italicum, the cause of citrus blue mold, is a pathogenic fungus that seriously affects the postharvest quality of citrus fruit and causes serious economic loss. In this study, a eugenol nanoemulsion containing limonin, an antimicrobial component from citrus seeds, was prepared using a high-pressure microfluidizer and the antifungal activity of the nanoemulsions against P. italicum was evaluated based on the conidial germination rate, mycelial growth, and scanning electron microscopy analysis. The results showed that the minimum inhibitory concentration and the inhibition rate of limonin-loaded eugenol nanoemulsion was 160 μg/mL and 59.21%, respectively, which was more potent than that of the limonin-free eugenol emulsion. After treatment with the nanoemulsions, the integrity of the P. italicum cell membrane was disrupted, the cell morphology was abnormal, and the leakage of nucleic acid and protein was observed. In addition, the challenge test on citrus fruits revealed that the limonin-loaded eugenol emulsion inhibited citrus infection for longer periods, with an infection rate of 29.2% after 5 days. The current research shows that nanoemulsions containing limonin and eugenol have effective antifungal activity against P. italicum, and may be used as a substitute for inhibiting blue mold in citrus fruits.

Virtual screening by targeting proteolytic sites of furin and TMPRSS2 to propose potential compounds obstructing the entry of SARS-CoV-2 virus into human host cells

Background and aim

The year 2020 begins with the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that cause the disease COVID-19, and continue till today. As of March 23, 2021, the outbreak has infected 124,313,054 worldwide with a total death of 2,735,707. The use of traditional medicines as an adjuvant therapy with western drugs can lower the fatality rate due to the COVID-19. Therefore, in silico molecular docking study was performed to search potential phytochemicals and drugs that can block the entry of SARS-CoV-2 into host cells by inhibiting the proteolytic cleavage activity of furin and TMPRSS2.

Experimental procedure

The protein-protein docking of the host proteases furin and TMPRSS2 was carried out with the virus spike (S) protein to examine the conformational details and residues involved in the complex formation. Subsequently, a library of 163 ligands containing phytochemicals and drugs was virtually screened to propose potential hits that can inhibit the proteolytic cleavage activity of furin and TMPRSS2.

Results and conclusion

The phytochemicals like limonin, gedunin, eribulin, pedunculagin, limonin glycoside and betunilic acid bind at the active site of both furin and TMPRSS2. Limonin and gedunin found mainly in the citrus fruits and neem showed the highest binding energy at the active site of furin and TMPRSS2, respectively. The polyphenols found in green tea can also be useful in suppressing the furin activity. Among the drugs, the drug nafamostat may be more beneficial than the camostat in suppressing the activity of TMPRSS2.

•

Protein-protein docking of the host proteases furin and TMPRSS2 with virus spike protein was performed.

•

A library of 163 phytochemicals and drugs was virtually screened to propose potential hits against SARS-CoV-2.

•

Limonin, gedunin, eribulin, pedunculagin, limonin glycoside and betunilic acid bind at the active site.

•

Drug nafamostat may be more beneficial than the camostat.

Limonin induces apoptosis of HL-60 cells by inhibiting NQO1 activity

Limonin is an important bioactive substance in citrus fruits, especially in seeds, which has great potential in cancer prevention and treatment. In order to explore the anticancer activity based on interaction between limonin and NQO1, Human promyelocytic leukemia cells (HL-60) were studied in vitro. We found that limonin could inhibit proliferation and promote apoptosis of HL-60 cells, and the effect was positively correlated with its dosage. Western blot results showed that limonin could activate the endogenous apoptosis pathway mediated by mitochondria via up-regulating pro-apoptotic proteins (Bax, cytochrome c, Caspase3, and Caspase9) and down-regulating anti-apoptotic proteins (Bcl-2), thus inhibiting the proliferation of HL-60 cells and promoting apoptosis, which further proved the anticancer activity of limonin from the molecular mechanism. At the same time, limonin down-regulated the expression of NQO1, indicating that limonin may indirectly act on the apoptosis pathway by regulating the expression activity of antioxidant enzymes in vivo, thus exerting its inhibitory effect on tumor cells, which provides an idea for the molecular mechanism that natural products can indirectly exert their anticancer effect by regulating the activity of antioxidant enzymes.

Citrus fruit intake and lung cancer risk: A meta-analysis of observational studies

OBJECTIVE

To explore the hypothesis that Citrus intake may reduce the risk of lung cancer.

DESIGN

Meta-analyses of Dichotomy and dose-response relationship.

DATA SOURCES

We searched online literature databases including PubMed, Embase, and Cochrane Library to screen relevant articles available up to 27 July 2020. Search terms included (i) Citrus, Fruit, Diet, Dietary; (ii) cancer, neoplasm, tumor (iii)lung; (iv)case-control, cohort, prospective.

STUDY SELECTION

The selection of studies and the meta-analysis were carried out by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The following inclusion criteria were chosen: (i) epidemiological studies with case-control or cohort design; (ii) human participants; (iii) studies investigated the relationship between Citrus fruit intake and lung cancer risk; (iv) if data were duplicated in more than two studies, we brought the most recent or all-sided study into this analysis. We collected all full-text articles that met the inclusion criteria. We applied the following exclusion criteria to the full-text articles, including possible articles listed by manual search: (i) there was no represented odds ratio (OR) or relative risk (RR) estimate and its corresponding 95 % confidence interval (95 % CI) (or data to calculate them) for the highest versus lowest levels of Citrus fruit consumption (ii) reviews, systematic reviews and meta-analyses; (iii) there was no data of Citrus fruit intake at the individual level.

DATA EXTRACTION

Two reviewers independently performed the extraction of data from eligible studies.

STATISTICAL METHODS

Adjusted odds ratios (ORs) and 95 % CIs were combined and weighted by the method of "Dersimonian and Laird" to produce pooled ORs using a random-effects model. Moreover, we utilized the method reported by "Longnecker and Greenland" to evaluate linear trends and 95 % CIs by the ORs' natural logs and corresponding CIs from categories of Citrus intake. Finally, we evaluated the risk of publication bias and selection bias by inspecting for asymmetry in the pre-specified funnel plots of the study OR against the standard error of the OR's logarithm and by "Egger's test".

RESULTS

We included twenty-one studies in the final review. Pooled analyses suggested that those with the highest Citrus fruit intake compared to the lowest intake had a 9% reduction in lung cancer risk [OR 0.91 (95 % CI 0.84-0.98)]. We found a nonlinear association between Citrus intake and lung cancer risk in the dose-response analysis (p = 0.0054) and that the risk reached the minimum (OR = 0.91) around 60 g/d. However, no obvious dose-response association was observed with intakes above 80 g/d.

CONCLUSION

We found that Citrus fruit intake was negatively associated with the risk of lung cancer. Besides, there was a nonlinear dose-response relationship between Citrus intake and lung cancer risk within a certain range.

Phenolic Compounds Impact on Rheumatoid Arthritis, Inflammatory Bowel Disease and Microbiota Modulation

Non-communicable chronic diseases (NCDs) are nowadays the principal cause of death, especially in most industrialized nations. These illnesses have increased exponentially with the consumption of diets very high in fat and sugar, not to mention stress and physical inactivity among other factors. The potential impact of suboptimal diets on NCDs’ morbidity and mortality rates brings to the forefront the necessity for a new way of improving dietary habits. The literature provides extensive scientific work that presents evidence that phenolic compounds from diets have antioxidant, anti-inflammatory and antiproliferative activities that impact human health. Gut microbiota modulation by some phenolic compounds leads to favorable changes in abundance, diversity, and in the immune system. However, polyphenol’s limited bioavailability needs to be overcome, highlighting their application in new delivery systems and providing their health benefits in well-established ways such as health maintenance, treatment or adjuvant to conventional pharmacological treatments. In this context, novel dietary approaches, including new food supplements, have emerged to prevent diseases and preserve health.

CYP3A4 inducer aggravates big flower Evodiae Fructus-induced hepatotoxicity whereas limonin attenuates its hepatotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Evodiae Fructus (EF), the traditional Chinese medicine, has been typically used to treat headache, abdominal pain, hernias, and menorrhagia for thousands of years. It is a mild toxicity herb-medicine listed in Sheng Nong's Herbal Classic. Recently, EF was reported to have toxicity or no toxicity in some investigations. Toxicity and approaches to reducing toxicity of EF are of great interest. Limonin (LIM), a major triterpenoid component of EF, also had various pharmacological activities such as anti-inflammatory, anticancer, and antioxidant effects. However, little attention was paid to the role of LIM in EF-induced hepatotoxicity.

AIM OF STUDY

The study aimed to address the problem of controversial hepatotoxicity of EF, evaluate the role of CYP3A4 inducer/inhibitor in EF-induced hepatotoxicity and disclose the effect of LIM in EF-induced hepatotoxicity.

MATERIALS AND METHODS

The chemical compositions and hepatotoxicity of small flower EF (SEF), medium flower EF (MEF), big flower EF (BEF) and the "organ knock-out" samples (the shell and seed part of BEF) were investigated. Simultaneously, C57BL-6 mice were randomly divided into four groups, which were given orally administered BEF, BEF in combination with dexamethasone (DEX), BEF in combination with ketoconazole (KTC), and BEF in combination with LIM, respectively.

RESULTS

In this study, more alkaloids and less LIM were detected in BEF compared with the compounds in SEF and MEF. Furthermore, we found that BEF group induced hepatotoxicity whereas no hepatotoxicity was observed in SEF and MEF groups. In addition, no LIM was detected in the shell part of BEF and five alkaloids were not detected in the seed part of BEF. Correspondingly, the shell part of BEF group induced hepatotoxicity whereas no hepatotoxicity was observed in the seed part of BEF group. It was also found that the BEF-induced hepatotoxicity was remarkably exacerbated when the mice were pretreated with DEX whereas the BEF-induced hepatotoxicity could be reversed by pretreatment with KTC or LIM.

CONCLUSIONS

Based on the results in this study, the misuse of BEF but not SEF and MEF could produce hepatotoxicity. The hepatotoxicity difference of different categories of EF might be associated with the relative contents of alkaloids and LIM. In addition, the results demonstrated that CYP3A4 inducer aggravated BEF-induced hepatotoxicity and LIM attenuated its hepatotoxicity.

Limonin ameliorates dextran sulfate sodium-induced chronic colitis in mice by inhibiting PERK-ATF4-CHOP pathway of ER stress and NF-κB signaling

Inflammatory bowel disease (IBD) is a chronic gastrointestinal inflammation regulated by intricate mechanisms. Limonin, a natural tetracyclic triterpenoid compound, possesses multiple bioactivities including anti-inflammation, anti-cancer and so on. However, the therapeutic potential and the underlying mechanism of limonin on IBD remain unclear. Here, we probe into the effect of limonin on chronic colitis induced by dextran sulfate sodium (DSS) and illustrated the potential mechanisms. We found that limonin relieved the risk and severity of DSS-induced chronic colitis in mice through various aspects including increasing body weight and colon length, decreasing the mortality rate, inhibiting MPO activity and improving colon pathology. Limonin also decreased the production of proinflammatory cytokines TNF-α, IL-1β, IL-6 and the expression of inflammatory proteins COX-2, iNOS in colon tissues from DSS-induced colitis mice. Moreover, limonin attenuated DSS-induced chronic colitis by inhibiting PERK-ATF4-CHOP pathway of endoplasmic reticulum (ER) stress and NF-κB signaling. In vitro, limonin not only decreased LPS-induced higher production of pro-inflammatory cytokines and inflammatory proteins mentioned above by inhibiting NF-κB signaling in macrophage cells RAW264.7, but also suppressed PERK-ATF4-CHOP pathway of ER stress. In summary, our study demonstrated that limonin mitigated DSS-induced chronic colitis via inhibiting PERK-ATF4-CHOP pathway of ER stress and NF-κB signaling. All of this study provides the possibility for limonin as an effective drug for chronic colitis of IBD in the future.

Water extract of sporoderm-broken spores of Ganoderma lucidum enhanced pd-l1 antibody efficiency through downregulation and relieved complications of pd-l1 monoclonal antibody

PURPOSE

Osteosarcoma is a malignant musculoskeletal tumor with early metastasis and a poor prognosis, especially in adolescents. Ganoderma lucidum (Leyss. Ex Fr.) Karst (G. lucidum), a traditional East Asian medicine, has been reported to play a critical role in antitumor and immunomodulatory activity. The aim of this study was to investigate the effects and molecular mechanisms of water extract of sporoderm-broken spores of G. lucidum (BSGWE) on osteosarcoma PD-L1 (programmed cell death-ligand 1) transcriptional regulation, efficacy enhancement, and side effect remission.

METHODS

The antitumor effects on cell proliferation of BSGWE in osteosarcoma cells were detected by apoptosis flow cytometry, and the migration ability of HOS and K7M2 cells were evaluated by cell scratch assay. Potential signaling regulation of PD-L1 was detected by western blotting. To confirm the signaling pathway of BSGWE-related PD-L1 downregulation, a pho-STAT3 turnover experiment was carried out. Colivelin was administered as a pho-STAT3 activator to rescue the BSGWE-induced PD-L1 inhibition. To further study in vivo signaling, in a Balb/c osteosarcoma allograft model, tumor volume was measured using an in vivo bioluminescence imaging system. The body weight curve and tumor volume curve were analyzed to reveal the remission effects of BSGWE on PD-L1 antibody-related body weight loss and its immunomodulatory effects on the osteosarcoma and spleen. The PD-L1 expression level and expression of related transcription-factor pho-STAT3 in tumor cells and spleens were assessed by IHC analysis.

RESULTS

BSGWE suppressed the proliferation and migration of osteosarcoma cells in vitro via induction of apoptosis. In addition, BSGWE downregulated PD-L1 expression and related STAT3 (signal transducers and activators of transcription) phosphorylation levels in a dose-dependent manner. Western blotting and qRT-PCR assay revealed that BSGWE downregulated PD-L1 expression by inhibiting STAT3 phosphorylation. A turnover experiment showed that colivelin administration could rescue PD-L1 inhibition via pho-STAT3 activation. BSGWE not only downregulated PD-L1 expression via the STAT3 pathway in an allograft Balb/c mouse model, but also relieved complications including weight loss and spleen atrophy in a mouse monoclonal antibody therapy model on the basis of its traditional advantages in immune enhancement.

CONCLUSION

BSGWE downregulated PD-L1 expression via pho-STAT3 inhibition of protein and RNA levels. BSGWE enhanced PD-L1 antibody efficacy via phosphorylated STAT3 downregulation in vitro and in vivo. BSGWE also relieved complications of weight loss and spleen atrophy in a murine allograft osteosarcoma immune checkpoint blockade therapy model.

In silico ADMET and molecular docking study on searching potential inhibitors from limonoids and triterpenoids for COVID-19

Virtual screening of phytochemicals was performed through molecular docking, simulations, in silico ADMET and drug-likeness prediction to identify the potential hits that can inhibit the effects of SARS-CoV-2. Considering the published literature on medicinal importance, 154 phytochemicals with analogous structure from limonoids and triterpenoids were selected to search potential inhibitors for the five therapeutic protein targets of SARS-CoV-2, i.e., 3CLpro (main protease), PLpro (papain-like protease), SGp-RBD (spike glycoprotein-receptor binding domain), RdRp (RNA dependent RNA polymerase) and ACE2 (angiotensin-converting enzyme 2). The in silico computational results revealed that the phytochemicals such as glycyrrhizic acid, limonin, 7-deacetyl-7-benzoylgedunin, maslinic acid, corosolic acid, obacunone and ursolic acid were found to be effective against the target proteins of SARS-CoV-2. The protein-ligand interaction study revealed that these phytochemicals bind with the amino acid residues at the active site of the target proteins. Therefore, the core structure of these potential hits can be used for further lead optimization to design drugs for SARS-CoV-2. Also, the medicinal plants containing these phytochemicals like licorice, neem, tulsi, citrus and olives can be used to formulate suitable therapeutic approaches in traditional medicines.

•

154 limonoids and triterpenoids were screened computationally to search potential inhibitors for COVID-19.

•

Phytochemicals were screened by molecular docking, in silico ADMET and drug-likeness prediction.

•

Docking studies of phytochemicals were performed with five therapeutic protein targets of SARS-CoV-2.

•

7 potential phytochemicals were proposed as potential hits against the SARS-CoV-2.

•

Proposed phytochemicals are found mainly in neem, tulsi, citrus, licorice and olives.

A practical synthesis of amino limonin/deoxylimonin derivatives as effective mitigators against inflammation and nociception

A practical synthetic route, consisting of 5 steps, has been developed and applied successfully for converting limonin/deoxylimonin into the corresponding amino derivatives I- 5a-I- 5e and II- 5a-II- 5e. Deoxylimonin analogs II- 5a and II- 5b bearing an open A ring structure underwent ring closure reaction by employing the Mitsunobu procedure to afford II- 6a and II- 6b. All of the 12 newly synthesized compounds were subjected to preliminary screening for evaluating their inflammation and nociception inhibition efficacy. The most promising compounds, I- 5b and II- 5d, were selected for further investigation by a carrageenan-induced mouse paw edema model, both of which displayed a dose-response dependent manner and demonstrated superior anti inflammation capacity to that of indomethacin in the first 2 hours.

Exploiting Citrus aurantium seeds and their secondary metabolites in the management of Alzheimer disease

Fruit by-products are considered nature’s golden gift for human health and a good starting point to discover new drugs depending on the fact that they contain millions of bio-active compounds that are responsible for therapeutic activities. In this context, the main goal of this study is to recycle Citrus aurantium (C. aurantium) seeds to produce pharmaceutical molecules to be used in the prevention of the progressive neurological damage associated with Alzheimer disease (AD). Donepezil (0.75 mg/kg), hesperidin (125 and 250 mg/kg) and limonoids (50 and 100 mg/kg) were used for treatment of rats for 2 weeks prior to concomitant administration of AlCl₃ for three successive weeks. Protection against cognitive deterioration was observed among study group with insignificant difference from normal control group and significant difference from positive control group in the Y-Maze test. On the other hand, treatment with both doses of hesperidin (125 and 250 mg/kg) and high dose of limonoids only (100 mg/kg) produced improvement in psychological state, observed by significant increase in ambulation frequency in comparison to positive control group, however it was not as frequent as normal group, as it was significantly less than normal group in the open field test. Regarding acetylcholine esterase (AChE) and beta-amyloid (β amyloid) levels, the effect of limonoids low dose was the best as it didn’t have a significant effect when compared to normal control, also hesperidin in both doses showed insignificant effects on β amyloid levels when compared to normal control group. Our results encourage the use of C. aurantium seeds which are wasted in huge amounts, as Alzheimer prophylactic food additives.

Discovery of deoxylimonin δ-lactam derivative with favorable anti-inflammation and antinociception efficacy from chemical modified limonin/deoxylimonin analogs

Chemical modifications on the A ring of limonin (1) and deoxylimonin (2) afforded 28 structural characterized derivatives, which were firstly subjected to preliminary in vivo analgesic and anti-inflammatory screen by mice model. The most promising candidate, deoxylimonin analog II-B-2 (70 mg/kg) with 3,4-dimethoxyphenylethyl moiety substitued δ-lactam in the A ring, exhibited better analgesic activity than aspirin (200 mg/kg) and stronger anti-inflammatory efficacy than naproxen (150 mg/kg). Further in vivo evaluation confirmed its advantage over limonin and showed dose-response dependent manner, and follow-up research suggested that the anti-inflammatory effect of compound II-B-2 may be attributed to the downregulation of cyclooxygenase 2 expression and the suppression of prostaglandin E₂ formation.

Synthesis of Limonin Derivatives with Improved Anti-inflammatory and Analgesic Properties

Background:

Limonoids represent an important class of natural products which possess a broad range of biological activities. Albeit their enormous potentials as therapeutic candidates, they usually suffer from low bioavailability, poor aqueous solubility and relatively weak biological activities which result in significant challenges in the clinic applications. Therefore, the exploration and development of novel limonin derivatives with improved drug-like properties through the structural modifications recently have attracted great attention in the biological and medicinal chemistry field.

Methods:

Based on the structural modifications of C17-furan ring in limonin, a series of limonin derivatives was designed, synthesized and screened for their anti-inflammatory and analgesic activities in vivo.

Results and Conclusion:

Preliminary pharmacological studies revealed that most tested compounds exhibited more potent anti-inflammatory and analgesic efficacies than lead molecule limonin. Especially, for compound 3f, it exhibited a stronger anti-inflammatory effect than that of naproxen and comparable analgesic potency with aspirin. In the formalin test, 3f showed an obviously attenuated phase-II pain response which indicated that it may produce an anti-inflammatory effect in the periphery. Furthermore, the significantly low hERG inhibition (IC50 >100 μM) and high LD50 value of target molecule 3f further demonstrated it as a promising analgesic/anti-inflammatory candidate with excellent drug-like profiles.

Role of limonin in anticancer effects of Evodia rutaecarpa on ovarian cancer cells

Background

Ovarian cancer therapy generally involves systemic chemotherapy with anticancer drugs; however, chemotherapy with a platinum-based drug has often been shown to cause adverse reactions and drug resistance in ovarian cancer patients. Evodia rutaecarpa (ER) reportedly shows anticancer activity against various types of cancer cells. However, the effects of ER have not yet been fully uncovered in ovarian cancer.

Methods

In the present study, we investigated the anticancer effects of an ER extract and its components against the ovarian cancer cell lines SKOV-33, A2780, RMUG-S and a cisplatin-resistant SKOV-3 cell line (Cis^R SKOV-3). Cell viability and colony formation assays along with subcellular fractionation analysis, immunoblotting, and immunofluorescence staining were performed.

Results

ER treatment led to a significant reduction in the viability of SKOV-3 cells. Moreover, limonin, a compound found in ER, reduced the viability of both serous-type (SKOV-3 and A2780) and mucinous-type (RMUG-S) ovarian cancer cells by inducing apoptosis via activation of the p53 signaling pathway. Furthermore, limonin reversed the drug resistance through activation of apoptosis in Cis^R SKOV-3.

Conclusion

Taken together, our findings suggest that limonin contributes to the anti-ovarian cancer effects of ER by inducing apoptosis via activation of the p53 signaling pathway.

On the use of microwave pretreatment to assist zero-waste chemical-free production process of nanofibrillated cellulose from lime residue

Microwave (MW) pretreatment as an energy-efficient method to enhance the production of nanofibrillated cellulose (NFC) from lime (Citrus aurantifolia Swingle) residue after juice extraction is proposed. NFC was prepared by subjecting lime residue to MW pretreatment for up to 3 rounds; this was followed by high-shear and high-pressure homogenization. Repeated application of MW pretreatment helped remove non-cellulosic components and resulted in an increased cellulose content and crystallinity index but a decrease in fiber diameter. Freshly prepared NFC sample exhibited gel-like behavior. G' and G″ of suspension prepared from dried NFC markedly decreased, indicating the loss of gel-like property upon drying. Proper pectin molecular weight as well as pectin content were noted to play an important role in controlling aggregation of NFC during drying and hence water redispersibility of dried NFC. Significant amounts of pectin and limonin could be recovered and utilized as co-products after the first round of MW pretreatment.

Limonin: A Review of Its Pharmacology, Toxicity, and Pharmacokinetics

Limonin is a natural tetracyclic triterpenoid compound, which widely exists in Euodia rutaecarpa (Juss.) Benth., Phellodendron chinense Schneid., and Coptis chinensis Franch. Its extensive pharmacological effects have attracted considerable attention in recent years. However, there is no systematic review focusing on the pharmacology, toxicity, and pharmacokinetics of limonin. Therefore, this review aimed to provide the latest information on the pharmacology, toxicity, and pharmacokinetics of limonin, exploring the therapeutic potential of this compound and looking for ways to improve efficacy and bioavailability. Limonin has a wide spectrum of pharmacological effects, including anti-cancer, anti-inflammatory and analgesic, anti-bacterial and anti-virus, anti-oxidation, liver protection properties. However, limonin has also been shown to lead to hepatotoxicity, renal toxicity, and genetic damage. Moreover, limonin also has complex impacts on hepatic metabolic enzyme. Pharmacokinetic studies have demonstrated that limonin has poor bioavailability, and the reduction, hydrolysis, and methylation are the main metabolic pathways of limonin. We also found that the position and group of the substituents of limonin are key in affecting pharmacological activity and bioavailability. However, some issues still exist, such as the mechanism of antioxidant activity of limonin not being clear. In addition, there are few studies on the toxicity mechanism of limonin, and the effects of limonin concentration on pharmacological effects and toxicity are not clear, and no researchers have reported any ways in which to reduce the toxicity of limonin. Therefore, future research directions include the mechanism of antioxidant activity of limonin, how the concentration of limonin affects pharmacological effects and toxicity, finding ways to reduce the toxicity of limonin, and structural modification of limonin—one of the key methods necessary to enhance pharmacological activity and bioavailability.

The gastrointestinal fate of limonin and its effect on gut microbiota in mice

The gut microbiota plays a critical role in human health. Diets could modulate the gut microbiota, which in turn may contribute to altered health outcomes by way of changing the relative risk of chronic diseases. Limonin, widely found in citrus fruits, has been reported to possess multiple beneficial health effects. However, the gastrointestinal fate of limonin and its effect on gut microbiota remain unknown. Herein, mice were fed a diet containing 0.05% limonin (w/w) for 9 weeks. Liquid chromatography-mass spectrum analysis showed that limonin was concentrated along the gastrointestinal tract and reached 523.14 nmol g^-1 in the colon lumen. Compared to control mice, colonic microbiota richness was significantly increased by limonin. Gut microbiota community was also clearly distinct from the control group as shown by Principle Coordinate Analysis. Additionally, the relative abundance of 22 genera (relative abundance >0.1%) was altered significantly. Among these, generally regarded probiotics (Lactobacillus and Bifidobacterium) were reduced, which was not due to direct inhibitory effect of limonin. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, amino acid metabolism, lipid, metabolism and immune system function were predicted to be upregulated, and immune system disease and infectious disease markers were predicted to be suppressed dramatically by limonin based on gut microbiota composition. Within the infectious disease category, bacterial toxin and Staphylococcus aureus infection markers were suppressed significantly with limonin treatment. Collectively, our study provides the first line of evidence that oral intake of limonin could shift gut microbiota composition and its functions, which warrants further investigation to determine its implication in human health.

Discovery of novel limonin derivatives as potent anti-inflammatory and analgesic agents

Novel series of limonin derivatives (V-A-1-V-A-8, V-B-1-V-B-8) were synthesized by adding various tertiary amines onto the C (7)-position of limonin. The synthesized compounds possessed favorable physicochemical property, and the intrinsic solubility of the novel compounds were significantly improved, compared with limonin. Different pharmacological models were used to evaluate the analgesic and anti-inflammatory activities of the target compounds. Compound V-A-8 exhibited the strongest in vivo activity among the novel limonin analogs; its analgesic activity was more potent than aspirin and its anti-inflammatory activity was stronger than naproxen under our testing conditions.

By blocking hexokinase-2 phosphorylation, limonin suppresses tumor glycolysis and induces cell apoptosis in hepatocellular carcinoma

Introduction

The purpose of present study was to investigate the effect of limonin on tumor glycolysis and the underlying mechanisms in hepatocellular carcinoma (HCC).

Methods

Cell proliferation and colony formation assays were performed to evaluate the potency of limonin against HCC cells in vitro. The glucose consumption and lactate production after limonin treatment was determined. The effect of limonin on hexokinase-2 (HK-2) activity was assessed and the mitochondrial location of HK-2 was studied by immunoprecipitation. Cell apoptosis and protein expression were detected by flow cytometry and western blotting respectively. Protein overexpression by plasmid transfection was adopted to investigate the molecular mechanisms.

Results

HCC proliferation and colony formation were inhibited by limonin in vitro. With the suppression of HK-2 activity, the glycolytic level in HCC cells was substantially reduced, which was evidenced by the decrease of glucose consumption and lactate production. The phosphorylation of HK-2 was substantially inhibited by limonin, which resulted in the disassociation of HK-2 from mitochondria. Due to the reduction of HK-2 in mitochondria, increasing Bax were shifted to the mitochondria and gave rise to the release of cytochrome C, which induced HCC cells to subject to mitochondria-mediated apoptosis. Mechanism investigations revealed that the decrease of HK-2 phosphorylation was mainly due to the inhibition of Akt activity. In Akt exogenously overexpressed HCC cells, limonin-mediated cell proliferation inhibition, glycolysis suppression and apoptosis induction were significantly impaired.

Conclusion

Limonin inhibited the tumor glycolysis in hepatocellular carcinoma by suppressing HK-2 activity, and the suppression of HK-2 was closely related to the decrease of Akt activity.

Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation

PURPOSE

Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms.

MATERIALS AND METHODS

Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin.

RESULTS

Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation.

CONCLUSION

Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation.

Beneficial effects of naringenin in liver diseases: Molecular mechanisms

Liver diseases are caused by different etiological agents, mainly alcohol consumption, viruses, drug intoxication or malnutrition. Frequently, liver diseases are initiated by oxidative stress and inflammation that lead to the excessive production of extracellular matrix (ECM), followed by a progression to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). It has been reported that some natural products display hepatoprotective properties. Naringenin is a flavonoid with antioxidant, antifibrogenic, anti-inflammatory and anticancer properties that is capable of preventing liver damage caused by different agents. The main protective effects of naringenin in liver diseases are the inhibition of oxidative stress, transforming growth factor (TGF-β) pathway and the prevention of the transdifferentiation of hepatic stellate cells (HSC), leading to decreased collagen synthesis. Other effects include the inhibition of the mitogen activated protein kinase (MAPK), toll-like receptor (TLR) and TGF-β non-canonical pathways, the inhibition of which further results in a strong reduction in ECM synthesis and deposition. In addition, naringenin has shown beneficial effects on nonalcoholic fatty liver disease (NAFLD) through the regulation of lipid metabolism, modulating the synthesis and oxidation of lipids and cholesterol. Moreover, naringenin protects from HCC, since it inhibits growth factors such as TGF-β and vascular endothelial growth factor (VEGF), inducing apoptosis and regulating MAPK pathways. Naringenin is safe and acts by targeting multiple proteins. However, it possesses low bioavailability and high intestinal metabolism. In this regard, formulations, such as nanoparticles or liposomes, have been developed to improve naringenin bioavailability. We conclude that naringenin should be considered in the future as an important candidate in the treatment of different liver diseases.

Characterisation of nutraceutical compounds from different parts of particular species of Citrus sinensis 'Ovale Calabrese' by UHPLC-UV-ESI-HRMS

Consumers are aware of diet causing health problems and therefore there is an increased demand for natural ingredients that are expected to be safe and health-promoting. Many of these compounds belong to the class of flavonoids and can be divided into these five groups: flavanones, flavones, flavonols, flavanols, isoflavones and anthocyanidins. Extracts from citrus fruits are usually used as functional ingredients for several products. The aim of this paper was to develop an UHPLC-UV-ESI-HRMS method to define the metabolite profile of different parts of citrus fruit, of a particular cultivar called 'Ovale Calabrese', and in its main by-products. The high resolution mass spectrometry analysis allowed the identification of 27 compounds belonging to the classes of flavonoids and terpenoids. The high contents of phytochemical compounds, reveal the potential use of the 'Ovale Calabrese' as a rich source of nutraceutical compounds.

Citrus nomilin down-regulates TNF-α-induced proliferation of aortic smooth muscle cells via apoptosis and inhibition of IκB

Nomilin is a bitter compound present in citrus and has been demonstrated as useful for various disease preventions through anti-proliferative, anti-inflammatory, and pro-apoptotic activities. Although in vitro disease models have shown that certain limonoids in the p38 mitogen-activated protein kinase signal cascade, the downstream signaling pathways remain unclear. In this study, the effects of nomilin on the proliferation and apoptotic pathways of human aortic smooth muscle cells (HASMCs) that forms the basis of progression of atherosclerotic diseases and restenosis was tested for the first time. The cellular uptake level and stability of nomilin were determined by high-performance liquid chromatography and high-resolution mass spectra. Pretreatment of HASMCs with nomilin stimulated extrinsic caspase-8, intrinsic caspase-9, and apoptotic caspase-3 and resulted in significant inhibition of TNF-α-induced proliferation. Additionally, results showed a decreased ratio of anti-apoptotic Bcl-2 protein to pro-apoptotic Bax (Bcl2/Bax), indicating mitochondrial dysfunction consistent with apoptosis. Furthermore, nomilin significantly decreased the phosphorylation of IκBα, an inhibitor of NF-κB and subsequently, reduced the downstream inflammatory signaling in TNF-α treated HASMCs. Our findings indicate that the anti-proliferative activity of nomilin on TNF-α-induced HASMCs results from apoptosis through a mitochondrial-dependent pathway and suppression of inflammatory signaling mediated through NF-κB.

Anticancer efficacy of the ethyl acetate extract from the traditional Chinese medicine herb Celastrus orbiculatus against human gastric cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) herb Celastrus orbiculatus is an important folk medicinal plant in China that has been used as an anti-inflammatory, antitumor, and analgesic in various diseases. The ethyl acetate extract of C. orbiculatus (C. orbiculatus extract, COE) was reported to show significant antitumor effects. However, no study in China or abroad has reported the effect and mechanism of COE in triggering apoptosis of gastric cancer (GC) cells.

AIM OF STUDY

To further uncover the molecular mechanism underlying COE's apoptotic and anti-proliferative effects and lay a foundation for the development of novel, effective antitumor TCM agents.

MATERIALS AND METHODS

The effect of COE on AGS and BGC-823 GC cell viability was examined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis of AGS and BGC-823 cells induced by COE was analyzed using flow cytometry and a mitochondrial membrane potential assay kit (JC-1). The proliferating GC cells were identified and examined using a 5-bromo-2'-deoxyuridine (BrdU) staining kit and flow cytometric analysis. A western blot assay was used to detect the effect of COE on apoptosis-related proteins, B-cell lymphoma-2 (Bcl-2), Bcl-extra-large (Bcl-xL), Bcl-2-like protein 12 (Bcl-L12), Bcl-2-associated X protein (Bax), and caspase as well as proliferation-related proteins, phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR)/p70s6k. Transmission electron microscopy (TEM) and an animal imaging technique were used to evaluate the microstructure of apoptotic GC cells and the effect of COE on tumor cell growth in vivo, respectively.

RESULTS

The results indicate that COE significantly inhibited proliferation and induced apoptosis of GC AGS and BGC-823 cell lines both in vivo and in vitro. COE significantly decreased the cell mitochondrial membrane potential. Moreover, COE downregulated the levels of Bcl-2, Bcl-xL, and PI3K/Akt/mTOR/p70s6k while those of Bax and caspase were upregulated. More interestingly, COE altered the microstructure of the mitochondria.

CONCLUSION

All these data collectively indicate that COE not only has significant antiproliferative effects but also has both in vivo and in vitro apoptotic effects. In addition, COE altered the structure and function of the mitochondria, which is another potential pathway for the antitumor activity of COE. These findings may provide a basis for the development of new anticancer TCM candidates.

Ethyl acetate extract from Selaginella doederleinii Hieron inhibits the growth of human lung cancer cells A549 via caspase-dependent apoptosis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella doederleinii Hieron has been used as a folk medicine for the treatment of different cancers, especially for nasopharyngeal carcinoma, lung cancer and trophoblastic tumor in China. Previously, the ethyl acetate extract from S. doederleinii (SDEA extract) showed favorable anti-cancer potentials. However, the main chemical composition and anticancer mechanism of the SDEA extract were still not very clear. Until now, there are no reports available about the oral toxicity of the extract.

AIM OF STUDY

The present study was to further elucidate the chemical composition and anti-lung cancer mechanism of the SDEA extract, and evaluate the acute oral toxicity of the extract.

MATERIALS AND METHODS

The SDEA extract was separated and analysed by HPLC to disclose its main chemicals. The effects of the extract were then investigated in vitro on cell viability, apoptosis and cell cycle using fluorescence microscopy and flow cytometry, and the molecular mechanism against human lung cancer cells A549 was further studied by western blot assays. The in vivo anti-cancer effect of the extract was evaluated in A549 xenograft mice model by histochemical assay, and tumor growth, microvascular density (MVD) and Ki67 expression were also measured. In addition, acute oral toxicity test of the extract was executed in mice.

RESULTS

SDEA extract mainly contained eight biflavonoids. The extract caused the loss of mitochondrial membrane potential and induced cell apoptosis by upregulating Bax, downregulating Bcl-2, activating caspase-9 and caspase-3 and blocked the cell cycle in S phase. The extract reduced expression of antigen Ki67, decreased MVD, and significantly inhibited the tumor growth. The extract did not show apparent oral acute toxicity in healthy mice.

CONCLUSION

The SDEA extract exerted anti-tumor effect through activating mitochondrial pathways and reducing Ki67 expression and MVD. Low oral acute toxicity suggested it a promising chemotherapy agent.

Enhanced colon cancer chemoprevention of curcumin by nanoencapsulation with whey protein

To improve bioavailability and enhance colon cancer prevention ability of curcumin, whey protein was used to nanoencapsulate at three different ratios such as 70:30, 50:50 and 35:65 for the first time. The drug loading, entrapment efficiency and structural changes of curcumin was confirmed by quantitative NMR spectroscopy. The nanoparticles prepared using the three ratios had an average diameters of 236.5±8.8, 212±3.4, and 187±11.4nm, as well as zeta (ζ) potentials of -13.1,-9.26, and -4.63mV, respectively, at pH 7.0. The cytotoxicity assay was performed for human colon and prostate cancer (SW480 and LNCap) by MTT assay and results showed significantly higher cytotoxicity of nanoencapsulated curcumin (NEC) (equivalent to 30.91, 20.70 and 16.86µM of NEC-1, 2 and 3 respectively), as compared to plain curcumin at 50µM after 72h of treatment. Cytotoxicity was also confirmed by microscopy of treated cells stained with acridine orange and propidium iodide. The cells treated with 50µM of curcumin, 30.91µM (NEC-1), 20.70µM (NEC-2) and 16.86µM (NEC-3) showed enhanced activation of p53 and elevated bax/Bcl2 expression (NEC-3), increased cytochrome-c in cytosol (NEC-2) confirming the enhanced cytotoxicity. To confirm the increased bioavailability, the intracellular curcumin was measured using fluorescence intensity. The fluorescent signal for intracellular curcumin was increased by 12, 30, and 21% for NEC-1, NEC-2, and NEC-3 respectively as compared to plain curcumin at 4h. Based on these results, we conclude that nanoencapsulated curcumin with whey protein will have potential to be considered for clinical applications for future studies.

Inhibitory effects and molecular mechanisms of tetrahydrocurcumin against human breast cancer MCF-7 cells

BACKGROUND

Tetrahydrocurcumin (THC), an active metabolite of curcumin, has been reported to have similar biological effects to curcumin, but the mechanism of the antitumor activity of THC is still unclear.

METHODS

The present study was to investigate the antitumor effects and mechanism of THC in human breast cancer MCF-7 cells using the methods of MTT assay, LDH assay, flow cytometry analysis, and western blot assay.

RESULTS

THC was found to have markedly cytotoxic effect and antiproliferative activity against MCF-7 cells in a dose-dependent manner with the IC50 for 24 h of 107.8 μM. Flow cytometry analysis revealed that THC mediated the cell-cycle arrest at G0/G1 phase, and 32.8% of MCF-7 cells entered the early phase of apoptosis at 100 μM for 24 h. THC also dose-dependently led to apoptosis in MCF-7 cells via the mitochondrial pathway, as evidenced by the activation of caspase-3 and caspase-9, the elevation of intracellular ROS, a decrease in Bcl-2 and PARP expression, and an increase in Bax expression. Meanwhile, cytochrome C was released to cytosol and the loss of mitochondria membrane potential (Δψm) was observed after THC treatment.

CONCLUSION

THC is an excellent source of chemopreventive agents in the treatment of breast cancer and has excellent potential to be explored as antitumor precursor compound.

Comparative metabolism of four limonoids in human liver microsomes using ultra-high-performance liquid chromatography coupled with high-resolution LTQ-Orbitrap mass spectrometry

RATIONALE

Limonoids, characterized by a triterpenoid skeleton with a furan ring, are unique secondary metabolites widely distributed in the families of Rutaceae, particularly in Citrus species and Meliaceae. Studies on health benefits have demonstrated that limonoids have a range of biological activities. Dietary intake of citrus limonoids may provide a protective effect against the onset of various cancers and other xenobiotic related diseases. However, few studies about the metabolic profiles of limonoids have been carried out.

METHODS

The objectives of this study were to investigate the metabolic profiles of four limonoids (limonin, obacunone, nominin and gedunin) in human liver microsomes (HLMs) using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC/HRMS) and to identify the cytochrome P450 (CYP) enzymes involved in the formation of their metabolites by recombinant human CYP enzymes.

RESULTS

Based on the accurate HR-MS/MS spectra and the proposed MS/MS fragmentation pathways, four metabolites of limonin (M1-1, M1-2, M1-3 and M1-4), eight metabolites ofobacunone (M2-1, M2-2, M2-3, M2-4, M2-5, M2-6, M2-7 and M2-8), six metabolites of nominin (M3-1, M3-2, M3-3, M3-4, M3-5 and M3-6) and three metabolites of gedunin (M4-1, M4-2 and M4-3) in HLMs were tentatively identified and the involved CYPs were investigated.

CONCLUSIONS

The results demonstrated that reduction at C-7 and C-16, hydroxylation and reaction of glycine with reduction limonoids were the major metabolic pathways of limonoids in HLMs. Among them, glycination with reduction was the unique metabolic process of limonoids observed for the first time. CYP2D6 and CYP3A4 played an important role in the isomerization and glycination of limonoids in HLMs, whereas other CYP isoforms were considerably less active. The results might help to understand the metabolic process of limonoids in vitro such as the unidentified metabolites of limonin glucoside observed in the medium of microbes and the biotransformation of limonin in juices. Moreover, it would be beneficial for us to further study the pharmacokinetic behavior of limonoids in vivo systematically.

Hesperidin from Citrus seed induces human hepatocellular carcinoma HepG2 cell apoptosis via both mitochondrial and death receptor pathways

Citrus seeds are full of phenolic compounds, such as flavonoids. The aims of this study were to identify the types of flavonoids in Citrus seed extracts, the cytotoxic effect, mode of cell death, and signaling pathway in human hepatic cancer HepG2 cells. The flavonoids contain anticancer, free radical scavenging, and antioxidant activities. Neohesperidin, hesperidin, and naringin, active flavanone glycosides, were identified in Citrus seed extract. The cytotoxic effect of three compounds was in a dose-dependent manner, and IC50 levels were determined. The sensitivity of human HepG2 cells was as follows: hesperidin > naringin > neohesperidin > naringenin. Hesperidin induced HepG2 cells to undergo apoptosis in a dose-dependent manner as evidenced by the externalization of phosphatidylserine and determined by annexin V-fluorescein isothiocyanate and propidium iodide staining using flow cytometry. Hesperidin did not induce the generation of reactive oxygen species, which was determined by using 2',7'-dichlorohydrofluorescein diacetate and flow cytometry method. The number of hesperidin-treated HepG2 cells with the loss of mitochondrial transmembrane potential increased concentration dependently, using 3,3'-dihexyloxacarbocyanine iodide employing flow cytometry. Caspase-9, -8, and -3 activities were activated and increased in hesperidin-treated HepG2 cells. Bcl-xL protein was downregulated whereas Bax, Bak, and tBid protein levels were upregulated after treatment with hesperidin in a dose-dependent manner. In conclusion, the bioflavanone from Citrus seeds, hesperidin, induced human HepG2 cell apoptosis via mitochondrial pathway and death receptor pathway. Citrus seed flavonoids are beneficial and can be developed as anticancer drug or food supplement, which still needs further in vivo investigation in animals and human beings.