Anticancer Properties of Chrysin on Colon Cancer Cells, In vitro and In vivo with Modulation of Caspase-3, -9, Bax and Sall4

BACKGROUND

The SALL4/Sall4 is constitutively expressed in human and mice. SALL4 mRNA could be used as a marker for the diagnosis of different types of cancers. On the other hand, chrysin has diverse biological properties.

OBJECTIVES

In the present study, the effect of the chrysin was investigated on the CT26 colon cancer in vitro and in vivo. Furthermore, the expression levels of the stem cell markers; sall4 and Bax was analyzed, as well.

MATERIALS AND METHODS

The cytotoxic effects and the type of cell death induced by chrysin were evaluated using a number of biological assays. The apoptotic pathway was examined by caspase-3and caspase-9 assay. The in vivo antitumor efficacy of chrysin on transplanted CT26 tumor cells in BALB/c mice was investigated. In addition, mRNA expression of sall4, Bax was analyzed with RT-PCR.

RESULTS

MTT assay and morphological characteristics showed that chrysin exerted a cytotoxic effect on CT26 cells in a dose dependent manner with IC₅₀= 80 μg.mL^-1. The biological assays have indicated that chrysin administrated cytotoxicity on colon cancer cells through recruitment of the apoptosis. Caspase-3 and caspase-9 colorimetric assays, in addition to Bax expression analysis, have indicated the involvement of intrinsic apoptotic pathway in the cytotoxic effect of the chrysin. The in vivo assay revealed a remarkable reduction of the colon tumor volume in treated mice (8, 10 mg.kg ^-1) as compared to the untreated mice. RT-PCR elucidated that chrysin attenuated tumor volume through down regulation of the sall4 and up-regulation of the Bax.

CONCLUSIONS

It was demonstrated that chrysin accomplishes anti-cancer effect on colon cancer cells via induction of the apoptosis and attenuation of the sall4 the expression. These findings introduce chrysin as an efficient apoptosis based therapeutic agent against colon cancer.

Chrysin exerts neuroprotective effects against 3-Nitropropionic acid induced behavioral despair-Mitochondrial dysfunction and striatal apoptosis via upregulating Bcl-2 gene and downregulating Bax-Bad genes in male wistar rats

3-Nitropropionic acid (3-NP) is an irreversible inhibitor of mitochondrial complex-II that causes transcriptional dysregulation, bioenergetics failure, protein aggregation and oxidative damage similar to Huntington's disease (HD) pathogenesis. Chrysin, a bioactive flavonoid reported to have anti-inflammation, antioxidant, vasorelaxant and neuroprotective property. The present study was framed to determine the neuroprotective efficiency of chrysin upon 3-NP induced oxidative stress, mitochondrial dysfunctions and neurodegeneration. 3-NP (10mg/kg b.w. i.p.) administration for 14days exhibited significant (P<0.01) behavioral alterations, mitochondrial dysfunction and oxidative damages to biomolecules, finally causes cell death. Chrysin at 50mg/kg b.w. orally for 14days improved all the behavioral performances and regulated the complex activities in mitochondria. Further, chrysin diminished the oxidative stress markers (lipid peroxidation, nitrite and protein carbonyls) by significantly (P<0.01) improving the antioxidant status (superoxide dismutase, catalase and reduced glutathione) in striatal mitochondria. Indeed, chrysin prevents apoptosis by upregulating the Bcl-2 mRNA expression and downregulating the pro-apoptotic (Bax, Bad) mRNAs in 3-NP induced condition. Furthermore, the survival of striatal neurons against 3-NP toxicity was enhanced upon chrysin treatment which was evidenced by observing histopathological studies. Hence, the present study collectively suggests that the chrysin can serve as a potential therapeutic agent on 3-NP induced mitochondrial deficits and subsequent apoptosis.

Mitigating effect of chrysin loaded solid lipid nanoparticles against Amyloid β25-35 induced oxidative stress in rat hippocampal region: An efficient formulation approach for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent form of dementia. Amyloid-β25-35 (Aβ25-35), a well-established neurotoxicant, is reported to be involved in the etiology of AD. Chrysin (CN) with its wide range of biological activities in terms of reversing the neuronal damage once induced is limited due to its compromised bioavailability. Solid lipid nanoparticles (SLNs) on the other hand due to its improved protein stability, avoids proteolytic degradation, as well as sustained release of the incorporated molecules could be widely applied as a drug delivery vehicle. Hence, in the present investigation, we prepared CN loaded SLNs (CN-SLNs) and investigated its therapeutic role in alleviating Aβ25-35 administered neuronal damage. All the antioxidant enzymes and non-antioxidant enzyme in hippocampus were reduced significantly (P<0.01) in the Aβ25-35 injected group, whereas lipid peroxidation and acetylcholine esterase were increased significantly (P<0.01). These changes were restored significantly (P<0.01) by CN-SLNs (5mg/kg and 10mg/kg) and (P<0.05) by free CN (50mg/kg and 100mg/kg). Aβ25-35 also resulted in poor memory retention in behavioral tasks and histopathological sections of the hippocampal region showed the extent of neuronal loss which was thereby restored back on treatment with CN-SLNs and free CN. Our findings demonstrate that the therapeutic efficacy of CN could be attained at lower dose and also its oral bioavailability could be increased by encapsulating CN in SLNs. Thus the results suggest that CN-SLNs could be used as a potential therapeutic and a brain targeting strategy to combat the global burden of Alzheimer's disease.

Inhibition of precancerous lesions development in kidneys by chrysin via regulating hyperproliferation, inflammation and apoptosis at pre clinical stage

Chrysin (CH) is natural, biologically active compound, belongs to flavoniod family and possesses diverse pharmacological activities as anti-inflammatory, anti-oxidant and anti-cancer. It is found in many plants, honey and propolis. In the present study, we investigated the chemopreventive efficacy of CH against N-nitrosodiethylamine (DEN) initiated and Fe-NTA induced precancerous lesions and its role in regulating oxidative injury, hyperproliferation, tumor incidences, histopathological alterations, inflammation, and apoptosis in the kidneys of Wistar rats. Renal cancer was initiated by single intraperitoneal (i.p.) injection of DEN (200 mg/kg bw) and promoted by twice weekly injection of ferric nitrilotriacetate (Fe-NTA) 9 mg Fe/kg bw for 16 weeks. CH attenuated Fe-NTA enhanced renal lipid peroxidation, serum toxicity markers and restored renal anti oxidant armory significantly. CH supplementation suppressed the development of precancerous lesions via down regulation of cell proliferation marker like PCNA; inflammatory mediators like TNF-α, IL-6, NFkB, COX-2, iNOS; tumor incidences. CH up regulated intrinsic apoptotic pathway proteins like bax, caspase-9 and caspase-3 along with down regulation of Bcl-2 triggering apoptosis. Histopathological and ultra structural alterations further confirmed biochemical and immunohistochemical results. These results provide powerful evidence for the chemopreventive efficacy of CH against chemically induced renal carcinogenesis possibly by modulation of multiple molecular pathways.

Antiplatelet activity of chrysin via inhibiting platelet αIIbβ3-mediated signaling pathway

SCOPE

Propolis is thought to help prevent thrombotic and related cardiovascular diseases in humans. Chrysin, a bioflavonoids compound found in high levels in propolis and in honey, has been reported to possess antiplatelet activity. However, the mechanism by which it inhibits platelet function is unclear.

METHODS AND RESULTS

The effects of chrysin on agonist-activated platelet-aggregation, granule-secretion, and integrin αIIbβ3 activation were examined. Its effects on the phosphorylation of Akt, GSK3β, MAPKs, and several proteins of the glycoprotein VI (GPVI) signaling pathway were also studied on collaged-activated platelets. In addition, human platelet spreading on immobilized fibrinogen was also tested. We found that chrysin dose dependently inhibited platelet aggregation and granule secretion induced by collagen, as well as platelet aggregation induced by ADP, thrombin, and U46619. Chrysin also markedly reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen. Biochemical analysis revealed that chrysin inhibited collagen-induced activation of Syk, PLCγ2, PKC, as well as the phosphorylation of Akt and ERK1/2. Additionally, chrysin attenuated phosphorylation of molecules such as FcγRIIa, FAK, Akt, and GSK3β in platelet spreading on immobilized fibrinogen.

CONCLUSIONS

Our findings indicate that chrysin suppresses not only integrin αIIbβ3-mediated "inside-out" signaling, but also the "outside-in" signal transmission. This implies that chrysin may represent a potential candidate for an antiplatelet agent.

Pharmacokinetic Interaction of Chrysin with Caffeine in Rats

Pharmacokinetic interaction of chrysin, a flavone present in honey, propolis and herbs, with caffeine was investigated in male Sprague-Dawley rats. Because chrysin inhibited CYP1A-selective ethoxyresorufin O-deethylase and methoxyresorufin O-demethylase activities in enriched rat liver microsomes, the pharmacokinetics of caffeine, a CYP 1A substrate, was studied following an intragastric administration with 100 mg/kg chrysin. In addition to the oral bioavailability of chrysin, its phase 2 metabolites, chrysin sulfate and chrysin glucuronide, were determined in rat plasma. As results, the pharmacokinetic parameters for caffeine and its three metabolites (i.e., paraxanthine, theobromine and theophylline) were not changed following chrysin treatment in vivo, despite of its inhibitory effect on CYP 1A in vitro. The bioavailability of chrysin was found to be almost zero, because chrysin was rapidly metabolized to its sulfate and glucuronide conjugates in rats. Taken together, it was concluded that the little interaction of chrysin with caffeine might be resulted from the rapid metabolism of chrysin to its phase 2 metabolites which would not have inhibitory effects on CYP enzymes responsible for caffeine metabolism.

Chrysin, a PPAR-γ agonist improves myocardial injury in diabetic rats through inhibiting AGE-RAGE mediated oxidative stress and inflammation

AGE-RAGE interaction mediated oxidative stress and inflammation is the key mechanism involved in the pathogenesis of cardiovascular disease in diabetes. Inhibition of AGE-RAGE axis by several PPAR-γ agonists has shown positive results in ameliorating cardio-metabolic disease conditions. Chrysin, a natural flavonoid has shown to possess PPAR-γ agonist activity along with antioxidant and anti-inflammatory effect. Therefore, the present study was designed to evaluate the effect of chrysin in isoproterenol-induced myocardial injury in diabetic rats. In male albino Wistar rats, diabetes was induced by single injection of streptozotocin (70 mg/kg, i.p.). After confirmation of the diabetes, rats were treated with vehicle (1.5 mL/kg, p.o.), chrysin (60 mg/kg, p.o.) or PPAR-γ antagonist GW9662 (1 mg/kg, i.p.) for 28 days. Simultaneously, on 27th and 28th day myocardial injury was induced by isoproterenol (85 mg/kg, s.c.). Chrysin significantly ameliorated cardiac dysfunction as reflected by improved MAP, ±LVdP/dtmax and LVEDP in diabetic rats. This improvement was associated with increased PPAR-γ expression and reduced RAGE expression in diabetic rats. Chrysin significantly decreased inflammation through inhibiting NF-κBp65/IKK-β expression and TNF-α level. Additionally, chrysin significantly reduced apoptosis as indicated by augmented Bcl-2 expression and decreased Bax and caspase-3 expressions. Furthermore, chrysin inhibited nitro-oxidative stress by normalizing the alteration in 8-OHdG, GSH, TBARS, NO and CAT levels and Nox4, MnSOD, eNOS and NT expressions. Co-administration of GW9662 significantly blunted the chrysin mediated cardioprotective effect as there was increase in oxidative stress, inflammation and apoptosis markers. Chrysin significantly ameliorated isoproterenol-induced myocardial injury in diabetic rats via PPAR-γ activation and inhibition of AGE-RAGE mediated oxidative stress and inflammation.

Chrysin induces brown fat-like phenotype and enhances lipid metabolism in 3T3-L1 adipocytes

OBJECTIVES

Many studies have to do with promising therapeutic phytochemicals such as flavonoids to treat obesity and related complications, and a number of dietary compounds have been proposed as tools for increasing energy expenditure and decreasing fat accumulation in mammals. Here, we show that the flavonoid chrysin induces browning of 3T3-L1 adipocytes via enhanced expression of brown fat-specific genes and proteins as well as enhances lipid metabolism.

METHODS

Chrysin-induced fat browning was investigated by determining expression levels of brown fat-specific genes and proteins by real-time polymerase chain reaction and immunoblot analysis, respectively.

RESULTS

Chrysin enhanced expression of brown fat-specific markers and increased protein levels of peroxisome proliferator-activated receptor (PPAR)α, PPARγ, PPARδ, phosphorylated AMP-activated protein kinase (p-AMPK), phosphorylated acetyl-CoA carboxylase, hormone sensitive lipase, perilipin, carnitine palmitoyltransferase 1, acyl-coenzyme A oxidase 1, peroxisome proliferator-activated receptor-1 alpha (PGC-1α), and uncoupling protein 1 (UCP-1), suggesting its possible role in augmentation of lipolysis, fat oxidation, and thermogenesis as well as reduction of lipogenesis. Increased expression of UCP-1 and other brown fat-specific markers was possibly mediated by chrysin-induced activation of AMPK based on the fact that inhibition of AMPK by dorsomorphin abolished expression of PR domain-containing 16, UCP-1, and PGC-1α while the activator 5-aminoimidazole-4-carboxamide ribonucleotide elevated expression of these brown marker proteins.

CONCLUSION

Our findings suggest that chrysin plays a dual modulatory role in the form of inducing the brown-like phenotype as well as enhancing lipid metabolism and thus may be explored as a potentially promising food additive for prevention of obesity.

Chrysin-piperazine conjugates as antioxidant and anticancer agents

Synthesis of 7-(4-bromobutoxy)-5-hydroxy-2-phenyl-4H-chromen-4-one intermediate treating chrysin with 1,4-dibromobutane facilitated combination of chrysin with a wide range of piperazine moieties which were equipped via reacting the corresponding amines with bis(2-chloroethyl)amine hydrochloride in diethylene glycol monomethyl ether solvent. Free radical scavenging potential of prepared products was analyzed in vitro adopting DPPH and ABTS bioassay in addition to the evaluation of in vitro anticancer efficacies against cervical cancer cell lines (HeLa and CaSki) and an ovarian cancer cell line SK-OV-3 using SRB assay. Bearable toxicity of 7a-w was examined employing Madin-Darby canine kidney (MDCK) cell line. In addition, cytotoxic nature of the presented compounds was inspected utilizing Human bone marrow derived mesenchymal stem cells (hBM-MSCs). Overall, 7a-w indicated remarkable antioxidant power in scavenging DPPH(·) and ABTS(·+), particularly analogs 7f, 7j, 7k, 7l, 7n, 7q, 7v, 7w have shown promising free radical scavenging activity. Analogs 7j and 7o are identified to be highly active candidates against HeLa and CaSki cell lines, whereas 7h and 7l along with 7j proved to be very sensitive towards ovarian cancer cell line SKOV-3. None of the newly prepared scaffolds showed cytotoxic nature toward hBM-MSCs cells. From the structure-activity point of view, nature and position of the electron withdrawing and electron donating functional groups on the piperazine core may contribute to the anticipated antioxidant and anticancer action. Different spectroscopic techniques (FT-IR, (1)H NMR, (13)C NMR, Mass) and elemental analysis (CHN) were utilized to confirm the desired structure of final compounds.

Role of chrysin on expression of insulin signaling molecules

Background:

Currently available drugs are unsuccessful for the treatment of tye-2 diabetes due to their adverseside-effects. Hence, a search for novel drugs, especially ofplant origin, continues. Chrysin (5,7-dihydroxyflavone) is a flavonoid, natural component of traditional medicinal herbs, present in honey, propolis and many plant extracts that hasbeen used in traditional medicine around the world to treat numerous ailments.

Objective:

The present study was aimed to identify the protective role of chrysin on the expression of insulin-signaling molecules in the skeletal muscle of high fat and sucrose-induced type-2 diabetic adult male rats.

Materials and Methods:

The oral effective dose of chrysin (100 mg/kg body weight) was given once a day until the end of the study (30 days post-induction of diabetes) to high fat diet-induced diabetic rats. At the end of the experimental period, fasting blood glucose, oral glucose tolerance, serum lipid profile, lipid peroxidation (LPO) and free radical generation, as well as the levels of insulin signaling molecules and tissue glycogen in the gastrocnemius muscle were assessed.

Results:

Diabetic rats showed impaired glucose tolerance and impairment in insulin signaling molecules (IR, IRS-1, p-IRS-1Tyr⁶³², p- Akt^Thr308), glucose transporter subtype 4 [GLUT4] proteins and glycogen concentration. Serum insulin, lipid profile, LPO and free radical generation were found to be increased in diabetic control rats. The treatment with chrysin normalized the altered levels of blood glucose, serum insulin, lipid profile, LPO and insulin signaling molecules as well as GLUT4 proteins.

Conclusion:

Our present findings indicate that chrysin improves glycemic control through activation of insulin signal transduction in the gastrocnemius muscle of high fat and sucrose-induced type-2 diabetic male rats.

Down regulation of miR-18a, miR-21 and miR-221 genes in gastric cancer cell line by chrysin-loaded PLGA-PEG nanoparticles

Chrysin were well-documented as having significant biological roles particularly cancer chemo-preventive activity. However, the poor water solubility of chrysin limited their bioavailability and biomedical applications. In this study, we encapsulate the chrysin into PLGA-PEG nanoparticles for local treatment. In regard to the amount of the drug load, IC50 was significant decreased in nanocapsulated chrysin in comparison with free chrysin. This was confirmed through decrease of miR-18a, miR-21, and miR-221 genes expression by real-time PCR. The results demonstrated that PLGA-PEG-chrysin complexes can be more effective than free chrysin. Therefore, PLGA-PEG can be a better nanocarrier for this kind of hydrophobic flavonoid.

Chrysin rich Scutellaria discolor Colebr. induces cervical cancer cell death via the induction of cell cycle arrest and caspase-dependent apoptosis

AIMS

Scutellaria discolor Colebr. has been extensively used in traditional medicine against several diseases. The purpose of this study was to investigate the anticancer potential of S. discolor and to isolate the bioactive principle responsible for the anticancer activity.

METHODS

Cytotoxicity experiments were performed on cancer and normal cells using MTT assay. The mechanism of cell death was evaluated using real time PCR array, fluorescence microscopy, flow cytometry and Western blotting. MTT assay guided isolation (partition and column chromatography) was performed to identify the antiproliferative principle. Quantification of the active principle was done using HPLC.

KEY FINDINGS

Acetone extract of S. discolor (SDE) inhibited the growth and survival of cancer cells to varying degree, but the inhibition was found to be maximum in cervical cancer cell lines. There was no significant toxicity induced to normal cells. The cell death was mediated through apoptosis. There was increased mitochondrial membrane depolarization, expression of Bax, caspase-9, caspase-3 and cleaved-PARP indicating that SDE-induced caspase dependent apoptosis in HeLa cells. Moreover, SDE caused cell cycle arrest in G2 phase in HeLa cells. Cytotoxicity guided fractionation of SDE led to the isolation of chrysin as the active principle responsible for the antiproliferative activity for cervical cancer cells. Interestingly, chrysin was the major phytochemical constituent present in S. discolor.

SIGNIFICANCE

S. discolor is an important anticancer plant and a new source of chrysin.

Aryl hydrocarbon receptor-dependent apoptotic cell death induced by the flavonoid chrysin in human colorectal cancer cells

The polyphenolic flavone chrysin has been evaluated as a natural chemopreventive agent due to its anti-cancer effects in a variety of cancer cell lines. However, the mechanism of the chemopreventive effect has been not well established, especially in human colorectal cancer cells. We evaluated the chemopreventive effect of chrysin in three different human colorectal cancer cell lines. We found that chrysin treatment consequently reduced cell viability via induction of apoptosis. We identified that the involvement of up-regulation of pro-apoptotic cytokines tumor necrosis factor (Tnf) α and β genes and consequent activation of the TNF-mediated transcriptional pathway in chrysin-induced apoptosis. Using our generated AHR siRNA expressing colorectal cancer cells, we demonstrated that the chrysin-induced up-regulation of Tnfα and β gene expression was dependent on the aryl hydrocarbon receptor (AHR), which is a ligand-receptor for chrysin. Subsequently, we found that the AHR siRNA expressing colorectal cancer cells were resistant to chrysin-induced apoptosis. Therefore, we concluded that AHR is required for the chrysin-induced apoptosis and the up-regulation of Tnfα and β gene expression in human colorectal cancer cells.

Chrysin-benzothiazole conjugates as antioxidant and anticancer agents

7-(4-Bromobutoxy)-5-hydroxy-2-phenyl-4H-chromen-4-one, obtained from chrysin with 1,4-dibromobutane, was combined with a wide range of 6-substituted 2-aminobenzthiazoles, which had been prepared from the corresponding anilines with potassium thiocyanate. Free radical scavenging efficacies of newer analogues were measured using DPPH and ABTS assays, in addition to the assessment of their anticancer activity against cervical cancer cell lines (HeLa and CaSki) and ovarian cancer cell line (SK-OV-3) implementing the SRB assay. Cytotoxicity of titled compounds was checked using Madin-Darby canine kidney (MDCK) non-cancer cell line. Overall, 6a-r indicated remarkable antioxidant power as DPPH and ABTS(+) scavengers; particularly the presence of halogen(s) (6g, 6h, 6j-6l) was favourable with IC50 values comparable to the control ascorbic acid. Unsubstituted benzothiazole ring favored the activity of resultant compounds (6a and 6r) against HeLa cell line, whereas presence of chlorine (6g) or a di-fluoro group (6k) was a key to exert strong action against CaSki. Moreover, a mono-fluoro (6j) and a ketonic functionality (6o) were beneficial to display anticipated anticancer effects against ovarian cancer cell line SK-OV-3. The structural assignments of the new products were done on the basis of IR, (1)H NMR, (13)C NMR spectroscopy and elemental analysis.

Neuroprotective effects of chrysin: From chemistry to medicine

The World Health Organization estimated that the proportion of older people (over 60 years) will increase from 11% to 22% during next 40 years throughout the world. With respect to this, the morbidity and mortality rates of age-related diseases will increase. Mental diseases are the most common and important health problems among elderly people. Therefore, much attention has been paid to the discovery of neuroprotective drugs with high efficacy and negligible adverse effects. A growing body of scientific evidence has shown that phytochemicals possess neuroprotective effects and also mitigate neurodegeneration under both in vivo and in vitro conditions. Polyphenolic compounds, especially flavonoids, are known as most common chemical class of phytochemicals which possess a multiple range of health promoting effects. Chrysin, belonging to the flavone class, is one of the most important bioactive constituents of different fruits, vegetables and even mushrooms. Chrysin possesses potent neuroprotective effects and suppress neuroinflammation. In addition, chrysin improves cognitive decline and possesses a potent anti-amyloidogenic and neurotrophic effects. Furthermore, beneficial effects of chrysin on both depression and epilepsy have been reported. The present paper aimed to critically review the available literature data regarding the neuroprotective effects of chrysin as well as its chemistry, sources and bioavailability.

Chrysin suppresses human CD14(+) monocyte-derived dendritic cells and ameliorates experimental autoimmune encephalomyelitis

Chrysin, a naturally flavonoid of plant, has various biological activities. However, the effects of chrysin on dendritic cells (DCs) and multiple sclerosis (MS) remain unknown. In this study, we demonstrate that chrysin inhibited human DC differentiation, maturation, function and the expression of the Th1 cells polarizing cytokines IFN-γ and IL-12p35 form DCs. In addition, chrysin ameliorated experimental autoimmune encephalomyelitis (EAE), an animal model of MS, by reducing CNS inflammation and demyelination. Furthermore, chrysin suppressed DCs and Th1 cells in the EAE mice. Taken together, chrysin exerts anti-inflammatory and immune suppressive effects, and suggests a possible therapeutic application of chrysin in MS.

Antiviral Activity of Chrysin Derivatives against Coxsackievirus B3 in vitro and in vivo

Chrysin is a 5,7-dihydroxyflavone and was recently shown to potently inhibit enterovirus 71 (EV71) by suppressing viral 3C protease (3C^pro) activity. In the current study, we investigated whether chrysin also shows antiviral activity against coxsackievirus B3 (CVB3), which belongs to the same genus (Enterovirus) as EV71, and assessed its ability to prevent the resulting acute pancreatitis and myocarditis. We found that chrysin showed antiviral activity against CVB3 at 10 μM, but exhibited mild cellular cytotoxicity at 50 μM, prompting us to synthesize derivatives of chrysin to increase the antiviral activity and reduce its cytotoxicity. Among four 4-substituted benzyl derivatives derived from C(5) benzyl-protected derivatives 7, 9–11 had significant antiviral activity and showed the most potent activity against CVB3 with low cytotoxicity in Vero cells. Intraperitoneal injection of CVB3 in BALB/c mice with 1×10⁶ TCID₅₀ (50% tissue culture infective dose) of CVB3 induced acute pancreatitis with ablation of acinar cells and increased serum CXCL1 levels, whereas the daily administration of 9 for 5 days significantly alleviated the pancreatic inflammation and reduced the elevation in serum CXCL1 levels. Collectively, we assessed the anti-CVB3 activities of chrysin and its derivatives, and found that among 4-substituted benzyl derivatives, 9 exhibited the highest activity against CVB3 in vivo, and protected mice from CVB3-induced pancreatic damage, simultaneously lowering serum CXCL1 levels.

Mexican propolis flavonoids affect photosynthesis and seedling growth

As a continuous effort to find new natural products with potential herbicide activity, flavonoids acacetin (1), chrysin (2) and 4',7-dimethylnarangenin (3) were isolated from a propolis sample collected in the rural area of Mexico City and their effects on the photosynthesis light reactions and on the growth of Lolium perenne, Echinochloa crus-galli and Physalis ixocarpa seedlings were investigated. Acacetin (1) acted as an uncoupler by enhancing the electron transport under basal and phosphorylating conditions and the Mg(2+)-ATPase. Chrysin (2) at low concentrations behaved as an uncoupler and at concentrations up to 100 μM its behavior was as a Hill reaction inhibitor. Finally, 4',7-dimethylnarangenin (3) in a concentration-dependent manner behaved as a Hill reaction inhibitor. Flavonoids 2 and 3 inhibited the uncoupled photosystem II reaction measured from water to 2,5-dichloro-1,4-benzoquinone (DCBQ), and they did not inhibit the uncoupled partial reactions measured from water to sodium silicomolybdate (SiMo) and from diphenylcarbazide (DPC) to diclorophenol indophenol (DCPIP). These results indicated that chrysin and 4',7-dimethylnarangenin inhibited the acceptor side of PS II. The results were corroborated with fluorescence of chlorophyll a measurements. Flavonoids also showed activity on the growth of seedlings of Lolium perenne and Echinochloa crus-galli.

Terminal modification of polymeric micelles with π-conjugated moieties for efficient anticancer drug delivery

High drug loading content is the critical factor to polymeric micelles for efficient chemotherapy. Small molecules of cinnamic acid, 7-carboxymethoxy coumarin and chrysin with different π-conjugated moieties were immobilized on the terminal hydroxyl groups of PCL segments in mPEG-PCL micelles to improve drug loading content via the evocation of π-π stacking interaction between doxorubicin (DOX) and polymeric micelles. The modification of π-conjugated moieties enhanced the capability of crystallization of mPEG-PCL block copolymers. The drug loading content increased dramatically from 12.9% to 25.5% after modification. All the three modified mPEG-PCL micelles were nontoxic to cells. Chrysin modified polymeric micelles exhibited the most efficient anticancer activity. The in vivo anticancer activity of 10 mg/kg DOX dose of chrysin modified micelle formulation for twice injections was comparable to that of 5 mg/kg dose of free DOX·HCl for four injections under the circumstance of same total DOX amount. The systemic toxicity of DOX loaded chrysin modified micelles was significantly reduced. This research provided a facile strategy to achieve polymeric micelles with high drug loading content and efficient anticancer activity both in vitro and in vivo.

Chrysin-organogermanium (IV) complex induced Colo205 cell apoptosis-associated mitochondrial function and anti-angiogenesis

Colorectal cancer, a kind of malignant cancer, has more than 1 million new patients and results in 0.5 million deaths every year globally based on the estimation of Globocan in 2008. One of the most important issues against colon cancer is tumor metastasis. Anti-angiogenesis, a form of targeted therapy uses drugs or other substances to prevent the new blood vessel formation, which is critical for tumor metastasis. In our previous studies, we have demonstrated a simple method to synthesize Chry-Ge complex through the reaction between chrysin and triphenylgermanium bromide. In this work, we investigated the mechanism of Chry-Ge induced Colo205 cell apoptosis. We found that Chry-Ge could induce apoptosis in Colo205 cells in mitochondrial-dependent pathway, cause the reorganization of cytoskeleton and induce the damage of nucleus in Colo205 cells. Besides, Chry-Ge was also found to induce membrane ultrastructural changes in Colo205 cells by AFM. Further, we found that Chry-Ge can inhibit tube formation of human umbilical vascular endothelial cell in vitro. Chry-Ge was also tested in vivo in the chicken chorioallantoic membrane (CAM) assay and found to inhibit bFGF-treated CAMs development. These results suggested that Chry-Ge could induce Colo205 cell apoptosis by mitochondrial pathway and anti-angiogenesis, highlighting the use of organic germanium agents for the treatment of colorectal cancer.

Combination of chrysin and cisplatin promotes the apoptosis of Hep G2 cells by up-regulating p53

Cisplatin is a chemotherapy drug commonly used for the treatment of human cancers, however, drug resistance poses a major challenge to clinical application of cisplatin in cancer therapy. Recent studies have shown that chrysin, a natural flavonoid widely found in various plants and foods, demonstrated effective anti-cancer activity. In the present study, we found that the combination chrysin and cisplatin significantly enhanced the apoptosis of Hep G2 cancer cells. Combination of chrysin and cisplatin increased the phosphorylation and accumulation of p53 through activating ERK1/2 in Hep G2 cells, which led to the overexpression of the pro-apoptotic proteins Bax and DR5 and the inhibition of the anti-apoptotic protein Bcl-2. In addition, combination of chrysin and cisplatin promoted both extrinsic apoptosis by activating caspase-8 and intrinsic apoptosis by increasing the release of cytochrome c and activating caspase-9 in Hep G2 cells. Our results suggest that combination of chrysin and cisplatin is a promising strategy for chemotherapy of human cancers that are resistant to cisplatin.

Inhibition of TGF-β by a novel PPAR-γ agonist, chrysin, salvages β-receptor stimulated myocardial injury in rats through MAPKs-dependent mechanism

Background

Pharmacological stimulation of peroxisome proliferator-activated receptor-gamma (PPAR-γ) has been recognized as a molecular switch in alleviating myocardial injury through modulating oxidative, inflammatory and apoptotic signaling pathways. This study was designed to elucidate the effect of chrysin, a novel PPAR-γ agonist and its functional interaction with TGF-β/MAPKs in isoproterenol-challenged myocardial injury in rats.

Methods

Male Wistar Albino rats were either subjected to vehicle (1.5 mL/kg, p.o.) or chrysin (15–60 mg/kg, p.o.) for 28 days. Isoproterenol (85 mg/kg, s.c.) was administered to rats on 27^th and 28^th day to induce myocardial injury.

Results

Chrysin dose dependently improved ventricular (±LVdP/dtmax and LVEDP) and hemodynamic (SAP, MAP and DAP) dysfunction in isoproterenol-insulted rats. This beneficial effect of chrysin was well supported with increased expression of PPAR-γ and decreased expression of TGF-β as evidenced by western blotting and immunohistochemistry analysis. Moreover, downstream signaling pathway of TGF-β viz. P-ERK½/ERK½ activation and P-JNK/JNK, P-p38/p38 and MMP-2 inhibition were also observed. Chrysin also attenuated NF-κBp65 and IKK-β expressions, TNF-α level and TUNEL positivity thereby validating its anti-inflammatory and anti-apoptotic properties. Additionally, chrysin in a dose dependent fashion improved NO level, redox status of the myocardium (GSH and MDA levels and SOD, GSHPx and CAT activities), cardiac injury markers (CK-MB and LDH levels) and oxidative DNA damage marker (8-OHdG level) and displayed preservation of subcellular and ultrastructural components.

Conclusion

We established that activation of PPAR-γ and inhibition of TGF-β via MAPKs dependent mechanism is critical for cardioprotective effect of chrysin.

Effects of chrysin (5,7-dihydroxyflavone) on vascular remodeling in hypoxia-induced pulmonary hypertension in rats

BACKGROUND

Chrysin (5,7-dihydroxyflavone) inhibits platelet-derived growth factor-induced vascular smooth muscle cell proliferation and arterial intima hyperplasia. This study aims to investigate the effects of chrysin on rat pulmonary vascular remodeling in hypoxia-induced pulmonary hypertension (PH).

METHODS

Sprague-Dawley rats were continuously exposed to 10% O2 for 4 weeks to induce PH. The effect of chrysin (50 or 100 mg/kg/d, subcutaneous) on vascular remodeling was investigated in hypoxia-induced PH model. At the end of the experiments, the indexes for pulmonary vascular remodeling and right ventricle hypertrophy were measured by vascular medial wall thickness and the ratio of right ventricle to (left ventricle plus septum). The expressions of NOX4, collagen I, and collagen III were analyzed by immunohistochemistry, real-time PCR, or western blotting. The proliferation of cultured pulmonary artery smooth muscle cells (PASMCs) was determined by BrdU incorporation and flow cytometry. The levels of malondialdehyde (MDA) and reactive oxygen species (ROS) were also determined by thiobarbituric acid reactive substances assay and 2'7'-dichlorofluorescein diacetate method.

RESULTS

Chrysin treatment for 4 weeks significantly attenuated pulmonary vascular remodeling and improved collagen accumulation and down-regulated collagen I and collagen III expressions, accompanied by downregulation of NOX4 expression in the pulmonary artery (P = 0.012 for 50 mg/kg/d, P < 0.001 for 100 mg/kg/d) and lung tissue (P = 0.026, P < 0.001). In vitro, chrysin (1, 10, and 100 μM) remarkably attenuated PASMC proliferation (P = 0.021 for 1 μM, P < 0.001 for 10 μM, and P < 0.001 for 100 μM), collagen I expression (P = 0.035, P < 0.001, and P < 0.001), and collagen III expression (P = 0.027, P < 0.001, and P < 0.001) induced by hypoxia, and these inhibitory effects of chrysin were accompanied by inhibition of NOX4 expression (P = 0.019, P < 0.001, and P < 0.001), ROS production (P = 0.038, P < 0.001, and P < 0.001), and MDA generation (P = 0.024, P < 0.001, and P < 0.001).

CONCLUSIONS

This study demonstrated that chrysin treatment in hypoxia-induced PH in rats reversed the hypoxia-induced (1) elevations of NOX4 expression, (2) productions of ROS and MDA, (3) proliferation of PASMC, and (4) accumulation of collagen.

Effect of chrysin on nociception in formalin test and serum levels of noradrenalin and corticosterone in rats

OBJECTIVE

The levels of corticosterone and noradrenalin as the two nociception modulators modify after stress condition. The propose of current study was to investigate the effect of chrysin on formalin-induced nociceptive behaviors and serum levels of corticosterone and noradrenalin in rats.

MATERIALS AND METHODS

Pain was induced by applying 20 μL of 5% formalin in distilled water in the subplantar of the right hind paw. Chrysin (50, 100 and 150 mg/kg, intraperitoneally (i.p.) was administered 60 min before formalin injection. Morphine (10 mg/kg, i.p.) was administered 30 min before formalin injection. The control group received the same volume of saline by i.p. injection 30 min before formalin injection.

RESULTS

Chrysin treatment can significantly decrease formalin-induced pain in rat in a dose-dependent manner. Chrysin (150 mg/kg) significantly inhibit the first phase (P < 0.01), whereas, the all concentration of chrysin were affected on the later phase of formalin-induced pain (P < 0.05). Chrysin could significantly attenuate the content of corticosterone and noradrenalin in the serum versus to the control rats (P < 0.01).

CONCLUSION

The current study confirms that the chrysin decreased the nociceptive behaviors in the formalin test and indicate a correlation with decrease in serum corticosterone and noradrenalin levels.

Screening of Vietnamese medicinal plants for NF-κB signaling inhibitors: assessing the activity of flavonoids from the stem bark of Oroxylum indicum

ETHNOPHARMACOLOGICAL RELEVANCE

Seventeen plants used in Vietnamese traditional medicine for the treatment of inflammatory disorders were screened for NF-κB inhibitory activity. Oroxylum indicum, which exhibited activity, was investigated in detail.

MATERIALS AND METHODS

Forty plant extracts from 17 species were prepared by maceration using dichloromethane and methanol and were tested (10µg/mL) to evaluate their ability to inhibit NF-κB activation using TNF-α-stimulated HEK-293 cells stably transfected with a NF-κB-driven luciferase reporter. The active extract of Oroxylum indicum was subsequently fractionated by different chromatographic techniques. After isolation, all single compounds were identified by spectroscopic methods and assessed for NF-κB inhibitory effects.

RESULTS

The dichloromethane extracts obtained from Chromolaena odorata leaves and the stem bark of Oroxylum indicum showed distinct inhibitory effects on NF-κB activation at a concentration of 10µg/mL. The active extract of Oroxylum indicum was subjected to further phytochemical studies resulting in identification of four flavonoid aglyca and six flavonoid glycosides. Pharmacological evaluation of the obtained compounds identified oroxylin A as the most active substance (IC50=3.9 µM, 95% CI: 3.5-4.4 µM), while chrysin and hispidulin showed lower activity with IC50=7.2µM (95% CI: 6.0-8.8 µM) and 9.0 µM (95% CI: 7.9-10.2 µM), respectively. Interestingly, in this study the activity of baicalein (IC50=28.1 µM, 95% CI: 24.6-32.0 µM) was weak. The isolated glycosides showed no inhibitory activity when tested at a concentration of 30 µM. Quantification of the four active flavonoids in extracts and plant materials suggested that oroxylin A contributes to the NF-κB inhibitory activity of the stem barks of Oroxylum indicum to a greater extent than baicalein which was thought to be responsible for the anti-inflammatory activity of this plant.

CONCLUSIONS

The screening presented in this study identified the dichloromethane extracts of Chromolaena odorata and Oroxylum indicum as promising sources for NF-κB inhibitors. Hispidulin, baicalein, chrysin and oroxylin A, isolated from Oroxylum indicum, were identified as inhibitors of NF- κB activation.