Pharmacological basis and new insights of taxifolin: A comprehensive review

The pharmacological characteristics of phytochemicals have prompted a lot of interest in their application in disease management. Due to the high incidence of cancer related mortality and morbidity throughout the world; experiments have concentrated on identifying the anticancer potential of natural substances. Many phytochemicals such as flavonoids and their derivatives produced from food offer a variety of new anti-cancer agents which prevent the cancer progression. Taxifolin, a unique bioactive flavonoid, is a dietary component that has grabbed the interest of dietitians and medicinal chemists due to its wide range of health benefits. It is a powerful antioxidant with a well-documented effect in the prevention of several malignancies in humans. Taxifolin has shown promising inhibitory activity against inflammation, malignancies, microbial infection, oxidative stress, cardiovascular disease, and liver disease. Anti-cancer activity has been shown to be relatively significant than other activities investigated in vitro and in vivo with a little or no side effects to the normal healthy cells. In summary this review offers the synopsis of recent breakthroughs in the use of taxifolin as a cancer treatment, as well as mechanisms of action. However, to develop a medicine for human usage, more study on pharmacokinetic profile, profound molecular mechanisms, and drug safety criteria should be conducted utilizing well-designed randomized clinical trials.

Evaluation of pro-apoptotic potential of taxifolin against liver cancer

Liver cancer is the second most common cause of cancer-induced deaths worldwide. Liver cirrhosis and cancer are a consequence of the abnormal angio-architecture formation of liver and formation of new blood vessels. This angiogenesis is driven by overexpression of hypoxia-inducible factor 1-alpha (Hif1-α) and vascular endothelial growth factor (VEGF). Apart from this, protein kinase B (Akt) is also impaired in liver cancer. Despite the advancement in conventional treatments, liver cancer remains largely incurable. Nowadays, the use of naturally occurring anticancer agents particularly flavonoids is subject to more attention due to their enhanced physicochemical properties. Therefore, this study underlines the use of a natural anticancer agent taxifolin in the treatment of liver cancer using hepatocellular carcinoma cell line HepG2 and Huh7. The aim of our study is to devise a natural and efficient solution for the disease prevalent in Pakistan. The study involved the assessment of binding of ligand taxifolin using molecular docking. The binding of taxifolin with the proteins (Hif1-α, VEGF and Akt) was calculated by docking using Vina and Chimera. Further evaluation was performed by cell viability assay (MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay), colony formation assay, cell migration assay, DNA ladder assay and flow cytometry. To see whether taxifolin directly affected expression levels, analysis of gene expression of Hif1-α, VEGF and Akt was performed using real-time polymerase chain reaction (qPCR) and western blotting. In silico docking experiments revealed that these proteins showed favorable docking scores with taxifolin. Treatment with taxifolin resulted in the inhibition of the liver cancer growth and migration, and induced apoptosis in HepG2 and Huh7 cell lines at an inhibitory concentration (IC50) value of 0.15 µM and 0.22 µM, respectively. The expression of HIF1-α, VEGF and Akt was significantly reduced in a dose- dependent manner. The inhibitory effect of taxifolin on hepatic cells suggested its chemopreventive and therapeutic potential. The studied compound taxifolin exhibited pronounced pro-apoptotic and hepatoprotective potential. Our study has confirmed the pro-apoptotic potential of taxifolin in liver cancer cell lines and will pave a way to the use of taxifolin as a chemotherapeutic agent after its further validation on the animal models and humans based epidemiological studies.

Protective effect of taxifolin against prooxidant and proinflammatory kidney damage associated with acrylamide in rats

The current study investigates the biochemical and histopathological effects of taxifolin on acrylamide-induced kidney damage. A 50 mg/kg dose of taxifolin was administered via oral gavage to the taxifolin + acrylamide (TACR) group (n-6) consisting of male albino Wistar rats. The same volume of distilled water used as solvent was orally administered to the acrylamide (ACR) (n-6) and healthy (HG) (n-6) groups. One hour after the administration of taxifolin and distilled water, a 20 mg/kg dose of acrylamide was orally administered to the TACR and ACR groups. This procedure was repeated once a day for 30 days. In the acrylamide group, malondialdehyde (MDA), tumour necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) levels were found to be high, total glutathione (tGSH) levels were found to be low, and there was severe interstitial haemorrhage; additionally, tubular necrosis, tubular atrophy, leucocyte infiltration, and glomerular structures with expanded Bowman's space were observed. In the taxifolin group, where the increase of MDA, IL-1β, and TNF-α and the decrease of tGSH associated with acrylamide have been prevented, any histopathological finding other than mild necrosis and atrophic tubules was not found. This suggests that Taxifolin would prevent kidney tissue from acrylamide-induced damage would be effective in treating acrylamide-induced nephrotoxicity, inhibiting the increase of MDA, IL-1β and TNF-α, and decreasing tGSH associated with acrylamide.

Dibutyl phthalate-induced oxidative stress, inflammation and apoptosis in grass carp hepatocytes and the therapeutic use of taxifolin

The widespread use of plastic products has led to the widespread presence of plasticizers in the environment. As a common environmental pollutant, research on plasticizer toxicity is insufficient in fish cells. In particular, research on the toxicity of dibutyl phthalate (DBP) in grass carp hepatocyte lines is insufficient. To further explore these mechanisms, we treated grass carp hepatocytes with 300 μM DBP, a common plasticizer, for 24 h, and hepatocytes were also treated with 1 μM taxifolin (TAX), an antioxidant, for 24 h to study its antagonistic effect on DBP. After DBP exposure, oxidative stress levels and inflammation in hepatocytes increased, and the mRNA and protein expression of apoptosis-related markers increased significantly, leading to hepatocyte apoptosis. Moreover, AO/EB staining, Hoechst staining and flow cytometry also showed that the level of apoptotic cells increased after DBP exposure. Notably, both TAX pretreatment and TAX simultaneous treatment alleviated oxidative stress, increased inflammatory factor levels and apoptosis induced by DBP. In comparison, the effect of simultaneous TAX treatment was better than that of TAX pretreatment. Our results showed that TAX alleviates DBP-induced apoptosis in grass carp hepatocytes through oxidative stress and inflammation, and TAX pretreatment and simultaneous treatment exhibited specific effects. Specifically, simultaneous treatment had a better effect. Our study assessed the toxicity of DBP in grass carp hepatocytes and provided a theoretical and research basis for the in vivo study of animal models in the future. The innovation of this study involves the exploration of the interaction between DBP and TAX for the first time. This study may enrich knowledge regarding the theoretical mechanism of DBP toxicity in fish hepatocytes and propose methods address DBP toxicity.

Taxifolin ameliorates Benzo[a]pyrene-induced lung injury possibly via stimulating the Nrf2 signalling pathway

Benzo[a]pyrene, an environmental contaminant as well as a mutagen is widely found in cigarette smoke, automobile exhaust particles among other sources. The present study underlines the protective effect of Taxifolin on B[a]P induced lung injury in male Swiss Albino Mice by analyzing the activity/level of various pro and anti-oxidant parameters, Inflammatory markers, Phase II enzyme, as well as lung histology. Taxifolin was administered orally to mice at either dose of 20 or 40 mg/kg body weight for 14 days and then challenged with a single dose of B[a]P (125 mg/kg body weight by oral gavage) on the 14th day. Our results show treatment with B[a]P leads to increased activity/level of CYP450R, EH, pro-inflammatory proteins, as well as lipid peroxidation and reduce level/activity of anti-oxidant molecules while Taxifolin treatment shows ameliorative effect. Administration of B[a]P also leads to decrease in expression of ROS sensitive factor Nrf2 and its downstream target NQO1,HO-1,SOD while Taxifolin treated animals showed a very high level of expression of Nrf2,NQO1,HO-1,SOD. Since Nrf2 plays central role in providing resistance to oxidative stress and also suppresses inflammation by inhibiting NF-κB,we concluded Taxifolin suppresses oxidative stress and inflammation in B[a]P induced lung injury possibly via stimulating the Nrf2 signaling pathway.

Taxifolin and gastro-adhesive microparticles containing taxifolin promotes gastric healing in vivo, inhibits Helicobacter pylori in vitro and proton pump reversibly in silico

Taxifolin (3,5,7,3,4-pentahydroxy flavanone or dihydroquercetin, Tax) was identified as a gastroprotective compound and a gastroadhesive formulation was recently developed to prolong its residence time and release in the stomach. So, the gastric healing effectiveness of Tax and gastro-mucoadhesive microparticles containing Tax (MPTax) against the acetic acid induced-gastric ulcer in rats was investigated in this study. Moreover, the interactions between Tax and H⁺/K⁺-ATPase were investigated in silico, and its anti- H. pylori activity was determined in vitro. The oral treatment with MPTax (81.37 mg/kg, containing 12.29% of Tax) twice a day for seven days reduced the ulcer area by 63%, compared to vehicle-treated group (Veh: 91.9 ± 10.3 mm²). Tax (10 mg/kg, p.o) reduced the ulcer by 40% but with a p = 0.07 versus Veh group. Histological analysis confirmed these effects. Tax and MPTax increased the gastric mucin amount, reduced the myeloperoxidase activity, and increased the glutathione reduced content at ulcer site. However, only MPTax decreased the lipoperoxide accumulation at ulcer site. Besides, Tax and MPTax normalize the catalase and glutathione S-transferase activity. Tax showed reversible interaction with H⁺/K⁺-ATPase in silico and its anti-H. pylori effects was confirmed (MIC = 625 μg/mL). These results suggest that the antiulcer property of Tax involves the strengthening of the gastric protective factors in parallel to its inhibitory interaction with H⁺/K⁺-ATPase and H. pylori. Considering that ulcer healing action displayed by Tax was favored by gastroadhesive microparticles, this approach seems to be promising for its oral delivery to treat acid-peptic diseases.

Taxifolin: A Potential Therapeutic Agent for Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is characterized by the accumulation of β-amyloid (Aβ) in the walls of cerebral vessels, leading to complications such as intracerebral hemorrhage, convexity subarachnoid hemorrhage and cerebral microinfarcts. Patients with CAA-related intracerebral hemorrhage are more likely to develop dementia and strokes. Several pathological investigations have demonstrated that more than 90% of Alzheimer's disease patients have concomitant CAA, suggesting common pathogenic mechanisms. Potential causes of CAA include impaired Aβ clearance from the brain through the intramural periarterial drainage (IPAD) system. Conversely, CAA causes restriction of IPAD, limiting clearance. Early intervention in CAA could thus prevent Alzheimer's disease progression. Growing evidence has suggested Taxifolin (dihydroquercetin) could be used as an effective therapy for CAA. Taxifolin is a plant flavonoid, widely available as a health supplement product, which has been demonstrated to exhibit anti-oxidative and anti-inflammatory effects, and provide protection against advanced glycation end products and mitochondrial damage. It has also been shown to facilitate disassembly, prevent oligomer formation and increase clearance of Aβ in a mouse model of CAA. Disturbed cerebrovascular reactivity and spatial reference memory impairment in CAA are completely prevented by Taxifolin treatment. These results highlight the need for clinical trials on the efficacy and safety of Taxifolin in patients with CAA.

The effect of taxifolin on experimental testicular ischaemia reperfusion injury in rats. A biochemical and histopathological analysis

OBJECTIVES

The aim of the study is to investigate the protective effect of taxifolin (3,5,7,3,4-pentahydroxy flavanone), a strong antioxidant, against testicular I/R injury in rats biochemically and histopathologically.

MATERIALS AND METHODS

50mg/kg taxifolin was administered to taxifolin+testicular torsion-detorsion (TTTD, n-10) group of Albino Wistar male rats by oral gavage. Distilled water .5ml as a solvent was administered to testicular torsion-detorsion (TTD, n-10) and Healthy Control (SG, n-10) groups using the same method. An hour after the administration of taxifolin and distilled water, anaesthesia (ketamine 60mg/kg) was administered to all animal groups. TTD and TTTD group animals were subjected to testicular torsion at 720 degrees for four hours during anaesthesia. At the end of this period, testicular detorsion was applied and perfusion was allowed for four hours. Sham operation was applied to SG group.

RESULTS

Our biochemical experiment results showed that the amount of malondialdehyde (MDA) in testicular tissue of TTD group presented a significant increase compared to SG and TTTD groups whereas total glutathione (tGSH) and superoxide dismutase (SOD) levels decreased. In addition, while TTD group presented severe histopathological damage in germinal epithelium cell and seminiferous tubule, mild damage was observed in TTTD group.

CONCLUSIONS

The results of our experiment indicate that taxifolin could be useful in the treatment of testicular I/R damage.

Inhibition of HMGB1 Might Enhance the Protective Effect of Taxifolin in Cardiomyocytes via PI3K/AKT Signaling Pathway

Cardiovascular diseases (CVD) affect millions of people and spend a lot of medical costs around the world each year. Taxifolin is a natural anti-oxidative reagent obtained from multiple plants and exhibits a wide range of pharmacological effects. High mobility group box protein 1 (HMGB1) is expressed in multiple types of cells in the extracellular environment, regulating the pro-inflammatory process. Here, we detected the viability of cells using MTT assay, and the expression of each target protein was detected using western blotting analysis. The expression of each target mRNA was detected using the qPCR method, and the concentration of each cytokine in serum samples was detected using the ELISA method. In this study, we found that taxifolin could decrease the expression of hypoxia-inducible factor-1α (HIF-1α) while increasing the expression of endothelial nitric oxide synthase (eNOS), presented a protective role. Besides, taxifolin could also increase the expression of vascular endothelial growth factor-α (VEGF-α), transforming growth factor-β (TGF-β) and fibroblast growth factor21 (FGF21), resulting in viability rate increasing. And these effects were mediated by phosphatidylinositol 3-hydroxy kinase (PI3K)/AKT/mTOR signaling pathway; a similar trend was also observed in HMGB1 knockdown mice. We also found that inhibition of HMGB1 could enhance the cardioprotective effect of taxifolin and might be a new therapeutic strategy for cardiovascular disease.

In vitro anti-inflammatory and anti-lipid accumulation properties of taxifolin-rich extract from the Japanese larch, Larix kaempferi

The Japanese larch, (Larix kaempferi) is known to contain abundant taxifolin (dihydroquercetin) in its xylem. In this study, to assess the bioactivities of taxifolin rich methanol extract of L. kaempferi (LK-ME), anti-inflammatory effect, and the anti-lipid accumulation effect of LK-ME were investigated. The results showed that nitric oxide (NO) and reactive oxygen species (ROS) were reduced after treatment with LK-ME, and that lipid accumulation in adipocyte differentiated 3T3-L1 cells was inhibited after the cells were grown in medium containing LK-ME. Taxifolin, the major compound contained in LK-ME, and its related compounds, quercetin and luteolin also exhibited similar effects with LK-ME. The LK-ME exhibits relatively strong anti-inflammatory and anti-lipid accumulation activities compared with that of similar amounts of taxifolin contained in LK-ME, suggesting that other minor compounds contained in LK-ME is involved in the effects. These results indicate the potential of taxifolin-rich L. kaempferi extract for use as a supplement to prevent excess inflammation and obesity.

Effect of taxifolin on cisplatin-associated oxidative optic nerve damage in rats

AIM

To investigate the effect of taxifolin on cisplatin-induced oxidative and proinflammatory optic nerve damage in rats.

METHODS

A total of 18 albino Wistar male rats were assigned into 3 groups, as follows; Group 1: Control group, Group 2: Only cisplatin administered group for 14 days (Cisplatin group), and Group 3: Taxifolin + cisplatin administered group for 14 days (CIS + TAX group). Serum malondialdehyde (MDA), total Glutathione (tGSH), Nuclear Factor-Kappa B (NF-ƘB), Total Oxidative Status (TOS) and Total Antioxidant Status (TAS) levels were collected from the left eyes of rats. Rats' right eyes were enucleated for histopathological evaluations of optic nerves.

RESULTS

NF-ƘB, MDA and TOS levels were statistically significantly higher (p < 0.001) in cisplatin group when compared to other 2 groups, the tGSH and TAS levels of which were statistically significantly lower (p < 0.001). Regarding these parameters, in cisplatin group NF-ƘB, MDA and TOS levels were statistically significantly increased with cisplatin administration and giving taxifolin concomitantly with cisplatin prevented this elevation. On the other hand, tGSH and TAS levels were statistically significantly decreased with cisplatin administration and routine simultaneous application of taxifolin with cisplatin prevented this decrease. In histopathological findings, haemorrhage was observed in the perineum of the injured optic nerves in the cisplatin treated group. And also edoema and degeneration in nerve fascicles in damaged optic nerves were seen in the cisplatin group. In the taxifolin treated group histopathological examinations were close to normal appearance, except mild edoema in nerve fascicles.

CONCLUSION

Cisplatin causes oxidative stress on the rat optic nerves, and these changes lead to significant histopathological damage. Taxifolin, which we used to prevent oxidative damage to the optic nerves caused by cisplatin, has been emphasized as a powerful antioxidant agent in many previous scientific investigations. Concomitant administration of taxifolin may prevent these adverse effects of cisplatin, as well as histopathological damage. Further studies are needed to fully determine the effects of cisplatin and taxifolin on the eye.

Taxifolin improves disorders of glucose metabolism and water-salt metabolism in kidney via PI3K/AKT signaling pathway in metabolic syndrome rats

AIMS

Our study was designed to explore the function and mechanism of taxifolin on glucose metabolism and water-salt metabolism in kidney with metabolic syndrome (MS) rats.

MAIN METHODS

Spontaneous hypertensive rats were induced by fructose to establish MS model. Systolic blood pressure (SBP) and homeostasis model assessment of insulin resistance (HOMA-IR) were measured after 7 weeks of continuous administration with taxifolin. Kidney injury indices and histopathological evaluation were done. The apoptosis rate of primary kidney cells was detected by flow cytometry. Insulin signaling pathway related proteins and renal glucose transport-related proteins were detected by western blotting. We assessed the effects of taxifolin on sodium water retention and renin-angiotensin-aldosterone system (RAAS) in MS rats. We examined not only changes in urine volume, osmotic pressure, urinary sodium and urinary chloride excretion, but also the effects on NA⁺/K⁺-ATPase and RAAS indicators. We also detected changes in inflammatory factors by immunohistochemical staining and immunofluorescence. In vitro experiment, high glucose and salt stimulated NRK-52E cells. By adding the PI3K inhibitor (wortmannin) to inhibit the PI3K, the effects of inhibiting the PI3K/AKT signaling pathway on glucose metabolism, water-sodium retention and inflammatory response were discussed.

KEY FINDINGS

Taxifolin effectively reversed SBP, HOMA-IR, the kidney indices and abnormal histopathological changes induced by MS. Besides, taxifolin called back the protein associated with the downstream glucose metabolism pathway of PI3K/AKT. It also inhibited overactivation of RAAS and inflammatory response. In vitro experiments have demonstrated that the PI3K/AKT signaling pathway plays an important role in this process.

SIGNIFICANCE

Taxifolin can improve homeostasis of glucose, inhibit overactivation of RAAS and reduce inflammatory response by PI3K/AKT signaling pathway.

Taxifolin ameliorates iron overload-induced hepatocellular injury: Modulating PI3K/AKT and p38 MAPK signaling, inflammatory response, and hepatocellular regeneration

Although physiological levels of iron are essential for numerous biological processes, excess iron causes critical tissue injury. Under iron overload conditions, non-chelated iron generates reactive oxygen species that mediate iron-induced tissue injury with subsequent induction of apoptosis, necrosis, and inflammatory responses. Because liver is a central player in iron metabolism and storage, it is vulnerable to iron-induced tissue injury. Taxifolin is naturally occurring compound that has shown potent antioxidant and potential iron chelation competency. The aim of the current study was to investigate the potential protective effects of taxifolin against iron-induced hepatocellular injury and to elucidate the underlining mechanisms using rats as a mammalian model. The results of the current work indicated that taxifolin inhibited iron-induced apoptosis and enhanced hepatocellular survival as demonstrated by decreased activity of caspase-3 and activation of the pro-survival signaling PI3K/AKT, respectively. Western blotting analysis revealed that taxifolin enhanced liver regeneration as indicated by increased PCNA protein abundance. Taxifolin mitigated the iron-induced histopathological aberration and reduced serum activity of liver enzymes (ALT and AST), highlighting enhanced liver cell integrity. Mechanistically, taxifolin modulated the redox-sensitive MAPK signaling (p38/c-Fos) and improved redox status of the liver tissues as indicated by decreased lipid peroxidation and protein oxidation along with enhanced total antioxidant capacity. Interestingly, it decreased liver iron content and down-regulated the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. Collectively, these data highlight, for the first time, the ameliorating effects of taxifolin against iron overload-induced hepatocellular injury that is potentially mediated through anti-inflammatory, antioxidant, and potential iron chelation activities.

The effects of taxifolin on alveolar bone in experimental periodontitis in rats

OBJECTIVE

This study aimed to evaluate the effect of taxifolin, a powerful antioxidant, on the progression of periodontitis by immunohistochemical and cone-beam computed tomography (CBCT) examination.

DESIGN

This study was performed with 32 rats in four experimental groups: a non-ligated group (Control, n = 8), periodontitis group (Perio, n = 8), periodontitis with 1 mg/kg/day taxifolin group (Taxi-1, n = 8), and periodontitis with 10 mg/kg/day taxifolin group (Taxi-10, n = 8). A ligature-induced experimental periodontitis design was used. All rats were sacrificed at 30 days. Alveolar bone loss was determined by CBCT. Hematoxylin-eosin stained slides were examined. The expression levels of bone morphogenetic protein 2 (BMP-2), osteocalcin (OCN), alkaline phosphatase (ALP), collagen type I (Col 1), Bcl-2, Bax, and receptor activator of NF-κB ligand (RANKL) were determined immunohistochemically.

RESULTS

Both doses of taxifolin showed a decrease in alveolar bone loss. The inflammatory reaction was higher in the Perio group and lower in the taxifolin groups. BMP-2, OCN, ALP, and Col 1 expression were dose-dependently elevated in the taxifolin groups. RANKL immunoexpression decreased with both doses of taxifolin. Bcl-2 expression increased and Bax expression decreased in the taxifolin groups.

CONCLUSION

Taxifolin successfully reduced apoptosis and improved bone formation in alveolar bone in this experimental periodontitis model.

Taxifolin attenuates the developmental testicular toxicity induced by di-n-butyl phthalate in fetal male rats

Di-n-butyl phthalate (DBP) is widely used in consumer products as a plasticizer. Here, we report a natural product taxifolin that can attenuate developmental and reproductive toxicity of DBP. Pregnant rats were daily gavaged with 500 mg/kg DBP alone or together with taxifolin (10 and 20 mg/kg) from gestational day (GD) 12-21. At GD21, sera and testes of male fetus were collected. DBP significantly lowered serum testosterone level at 500 mg/kg and taxifolin can completely reverse its action. DBP caused abnormal aggregation of fetal Leydig cells and taxifolin can reverse it. DBP down-regulated the expression of the genes of cholesterol side-chain cleavage enzyme (Cyp11a1), 17β-hydroxysteroid dehydrogenase 3 (Hsd17b3), and insulin-like 3 (Insl3) and taxifolin can reverse its action. DBP increased malondialdehyde levels and decreased superoxide dismutase and glutathione peroxidase expression and taxifolin can reverse it. DBP increased incidence of multinucleated gonocytes and taxifolin can prevent it. Moreover, DBP lowered sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) and phosphorylated AMP-activated protein kinase (pAMPK) signalling and taxifolin antagonized DBP. In conclusion, in utero exposure to DBP caused developmental/reproductive toxicity of male offspring via increasing reactive oxygen species and taxifolin is an effective food component that completely reverses DBP-mediated action.

The anti-tumor effect of taxifolin on lung cancer via suppressing stemness and epithelial-mesenchymal transition in vitro and oncogenesis in nude mice

Background

Taxifolin is a natural flavonoid with anti-oxidant and anti-proliferative properties. In this study, we investigated the stemness-related inhibitory effects of taxifolin in two lung cancer cell lines, A549 and H1975, as well as in A549 xenografts.

Methods

A549 and H1975 cells, as well as A549 xenograft BALB/c mice were treated with taxifolin. Cell viability, stemness, mobility and protein expression were tested with Cell counting kit-8 (CCK-8), Colony formation assay, Flow cytometry, Transwell, Western blot and Immunohistochemistry, respectively.

Results

CCK-8 exhibited an obvious toxicity of taxifolin to both cell lines at higher dose. Then taxifolin of 0, 25, 50, and 100 µM/L were subsequently used. Taxifolin exhibited inhibitory effects on stemness and sphere formation, reduced protein expression of SOX2 and OCT4, and reduced CD133-positive cells. Furthermore, taxifolin decreased invasive cells, reduced N-cadherin and vimentin while increased E-cadherin expression, indicating that epithelial-mesenchymal transition (EMT) was inhibited. All of the effects observed were exhibited in a dose-dependent manner, and A549 cells proved to be more sensitive to taxifolin than H1975 cells. Taxifolin inactivated PI3K and TCF4 protein phosphorylation; however, taxifolin was not observed to have an effect on NF-κB P65 or STAT3. Taxifolin also suppressed tumor growth in A549 xenograft BALB/c mice, with decreased SOX2 and OCT4 expression and inhibited PI3K and TCF4.

Conclusions

In summary, taxifolin inhibited stemness and EMT in lung cancer cells possibly via the inactivation of PI3K and OCT4. Taxifolin could be a potential prodrug or serve as an adjuvant in lung cancer treatment.

Di-(2-ethyl hexyl) phthalate induces necroptosis in chicken cardiomyocytes by triggering calcium overload

Di-(2-ethyl hexyl)phthalate (DEHP) is a kind of plasticizer that can cause cardiovascular disorders in animals, but its specific mechanism of action has not been determined. We aimed to investigate whether taxifolin (TAX) can antagonize the cytotoxicity of DEHP on cardiomyocytes. Chicken cardiomyocytes were treated with DEHP (500 μM) and/or TAX (0.5 μM) for 24 h. Ca²⁺ staining showed that the concentration of Ca²⁺ in the cytoplasm of cardiomyocytes was significantly increased under DEHP stimulation. However, in the DEHP + TAX group, the Ca²⁺ concentration was largely restored. In addition, the results of necroptosis--fluorescent and flow cytometry analysis showed that the DEHP group had severe necroptosis compared with the control group. The necrotic rate in the DEHP + TAX group was significantly lower than that in the DEHP group. At the mRNA and protein levels, the expression of the necrotic-calcium pathway genes RIPK1, RIPK3, MLKL, FAS, Caspase-8, CAMKII, and SERCA in the DEHP group increased to varying degrees relative to the control group. However, TAX improved this injury. Compared with the DEHP group, the expression of these genes was significantly decreased in the DEHP + TAX group. The present study indicate that DEHP could trigger cardiomyocyte necroptosis through Ca²⁺ overload, which could be alleviated by TAX.

Green production of silybin and isosilybin by merging metabolic engineering approaches and enzymatic catalysis

Silymarin extracted from milk thistle seeds, is used for treating hepatic diseases. Silybin and isosilybin are its main components, and synthesized from coupling of taxifolin and coniferyl alcohol. Here, the biosynthetic pathways of taxifolin and coniferyl alcohol were reconstructed in Saccharomyces cerevisiae for the first time. To alleviate substantial burden caused by a great deal of genetic manipulation, expression of the enzymes (e.g. ZWF1, TYR1 and ARO8) playing multiple roles in the relevant biosynthetic pathways was selectively optimized. The strain YT1035 overexpressing seven heterologous enzymes and five native enzymes and the strain YC1053 overexpressing seven heterologous enzymes and four native enzymes, respectively produce 336.8 mg/L taxifolin and 201.1 mg/L coniferyl alcohol. Silybin and isosilybin are synthesized from taxifolin and coniferyl alcohol under catalysis of APX1t (the truncated milk thistle peroxidase), with a yield of 62.5%. This study demonstrates an approach for producing silybin and isosilybin from glucose for the first time.

Taxifolin Inhibits Neurosteroidogenic Rat Steroid 5α-Reductase 1 and 3α-Hydroxysteroid Dehydrogenase

AIMS

Taxifolin, a flavonoid, has several pharmacological activities. Taxifolin inhibits some steroid biosynthetic enzymes, suggesting that it might inhibit neurosteroid synthesis. Here, we investigated effects of taxifolin on rat neurosteroidogenic enzymes, steroid 5α-reductase 1 -(SRD5A1), 3α-hydroxysteroid dehydrogenase (AKR1C9), and retinol dehydrogenase 2 (RDH2).

METHODS

SRD5A1, AKR1C9, and RDH2 were expressed in COS-1 cells and the direct effects of taxifolin on these enzymes and the mode of action were determined using steroid substrates and thin chromatography separation-coupled radiometric scanning.

RESULTS

The half maximal inhibitory concentration values of taxifolin on SRD5A1 and AKR1C9 were 100 and 1.01 mol/L. Taxifolin did not inhibit RDH2 even at as high as 100 mol/L. Taxifolin competitively inhibited rat AKR1C9 against steroid dihydrotestosterone (DHT), and docking analysis revealed that taxifolin bound to the steroid binding site of rat AKR1C9 with similar free energy with the substrate DHT.

CONCLUSION

Taxifolin is a potent inhibitor of rat AKR1C9 and moderate inhibitor of rat SRD5A1, thereby controlling the rate of neurosteroid biosynthesis.

Molybdenum sulfide-based electrochemical platform for high sensitive detection of taxifolin in Chinese medicine

MoS₂ and nitrogen doped active carbon composite (MoS₂/ANC) is fabricated to detect taxifolin and exhibits superior redox current response and decreased redox potential difference. Further investigation reveals that the kinetic process of the redox reaction of taxifolin on MoS₂/ANC electrode is controlled by both adsorption and diffusion process. Under the optimum conditions, the redox peak currents linearly relate with the concentration of taxifolin in the range of 1 × 10^-9-1 × 10^-6 mol L^-1, accompanied by the low detection limit (3 × 10^-10 mol L^-1). Meanwhile, outstanding selectivity, stability and repeatability are also obtained at MoS₂/ANC electrode. At last, the proposed method is applied to quantitatively detect taxifolin in fructus polygoni orientalis and satisfactory results have been achieved.

Taxifolin alleviates apoptotic injury induced by DEHP exposure through cytochrome P450 homeostasis in chicken cardiomyocytes

Di-2-ethylhexyl phthalate (DEHP), widely used as a plasticizer, is a ubiquitous artificial pollutant. DEHP can induce biological toxicity in various organs, with an especially high potential for toxicity to the cardiovascular system. Taxifolin (TAX) is used in the treatment of cardiovascular diseases due to its antioxidative capacities. However, it is not clear whether TAX can alleviate apoptosis induced by DEHP exposure through the cytochrome P450 (CYP) pathway in cardiomyocytes. To understand the role of TAX in attenuating cardiomyocyte toxicity induced by DEHP, primary cardiomyocytes were divided into 4 groups (control group, DEHP group, TAX group and DEHP + TAX group). The results showed that in the cardiomyocytes, DEHP initiated apoptosis by increasing the expression of caspase-3, caspase-9, cyt c, and Bax at both the mRNA and protein levels and by decreasing the Bcl-2 levels compared with that of the control group. In addition, the activities of catalase (CAT), superoxide dismutase (SOD), and total antioxidative capacity (T-AOC) were clearly decreased (P < 0.05), while in the DEHP group, the malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels were observably increased (P < 0.05), compared with those in control group. Furthermore, compared with the control group, the DEHP group demonstrated a clear partial decrease in the expression of the mRNA levels of CYP1B1 and CYP2C18 (P < 0.05), and DEHP/TAX cotreatment partially prevented apoptosis and oxidative stress damage (P < 0.05). These results showed that exposure to DEHP induced apoptosis in chicken cardiomyocytes, while TAX could antagonize the toxicity of DEHP on cardiomyocytes by attenuating oxidative stress responses and modulating CYPs.

Chemotaxonomic profiling of Penicillium setosum using high-resolution mass spectrometry (LC-Q-ToF-MS)

In the present study, secondary metabolites produced by an endophytic fungus Penicillium setosum were extracted using colony agar plug and culture broth extraction methods. High resolution LC-MS was used to explore the chemical nature of the secondary metabolites, as well, compare the reliability of the methods. P. setosum was chemotaxonomically distinguished from other members of section Lanata-divaricata, by its ability to produce mycotoxin, patulin and also by the presence of certain phenol-derived compounds, like quercetin, dihydroflavonols (dihydroquercetin and dihydromyricetin), kaempferol, luteolin, while some Penicillium specific compounds such as, citromycetin and andrastin D reveal its similarity towards section Lanata-Divaricata members. For the first time, the presence of dihydroquercetin is remarkably and spectrometrically confirmed from a microbial source. In addition, a few polyketides, anthroquinone compounds, hydrocarbons, and fatty acids were also detected in the culture extract. Being the first report on the production of polyphenolic compounds by an endophytic fungus of Penicillium species, the current research is crucial, and moreover the starin itself is a novel species.

5,7,3',4'-flavan-on-ol (taxifolin) protects against acetaminophen-induced liver injury by regulating the glutathione pathway

Taxifolin (TAX) reportedly exerts protective and therapeutic effects in liver. Herein, the effects of TAX against acetaminophen (APAP)-induced hepatotoxicity were investigated. Pharmacodynamics, pharmacology and metabolomics analyses of TAX were assessed on C57 mice and L-02 cells. TAX was administered for 7 days, and APAP was given on the last day to establish an acute liver injury model. ALT and AST levels were determined, and liver ROS, MDA, GST, GSH and GPX1 were analysed. The expression and protein abundance of GPX1, GPS-Pi, GCLC and GCLM were assessed by PCR and western blotting, and metabolic changes in cells and serum were investigated by UPLC-Q-Orbitrap-MS. Serum ALT and AST, and liver ROS, MDA, GST, GSH and GPX1 levels confirmed the protective effects of TAX. Besides, we found Only treating with TAX decreased the expression of CYP2E1 in mice liver tissue. TAX reversed the APAP-induced decrease in cell viability in L-02 cells, and reduced cellular ROS levels. Furthermore, TAX reversed the APAP-induced decrease in antioxidant enzymes at both mRNA and protein levels. Metabolomics analysis identified metabolites mainly related to glutathione metabolism (36 in vivo and 23 in vitro). The concentration of glutathione, oxidized glutathione, carnitine, succinic acid, pyroglutamic acid, citrulline, taurine, palmitoleic acid, phytoshingosine-1-P and sphingosine-1-P were close to normal levels after treating with TAX. These results indicate that TAX prevents APAP-induced liver injury by inhibiting APAP metabolic activation mediated by CYP450 enzymes, modulating glutathione metabolism, and expression of related antioxidative signals. These properties could be harnessed to prevent or treat hepatotoxicity.

An insight into the health-promoting effects of taxifolin (dihydroquercetin)

Taxifolin (3,5,7,3,4-pentahydroxy flavanone or dihydroquercetin) is a flavonoid commonly found in onion, milk thistle, French maritime pine bark and Douglas fir bark. It is also used in various commercial preparations like Legalon™, Pycnogenol^®, and Venoruton^®. This review focuses on taxifolin's biological activities and related molecular mechanisms. Published literatures were gathered from the scientific databases like PubMed, SciFinder, ScienceDirect, Wiley Online Library, Google Scholar, and Web of Science up to January 2019. Taxifolin showed promising pharmacological activities in the management of inflammation, tumors, microbial infections, oxidative stress, cardiovascular, and liver disorders. The anti-cancer activity was more prominent than other activities evaluated using different in vitro and in vivo models. Further research on the pharmacokinetics, in-depth molecular mechanisms, and safety profile using well-designed randomized clinical studies are suggested to develop a drug for human use.

Cell cytotoxity and anti-glycation activity of taxifolin-rich extract from Japanese larch, Larix kaempferi

The larches, the Larix genus of plants are known as a natural source of taxifolin (dihydroquercetin), and extracts of its taxifolin rich xylem are used in dietary supplements to maintain health. In the present study, to assess biological activities of a methanol extract of the Japanese larch, Larix kaempferi (LK-ME), the effects of LK-ME on cell viability, inflammatory cytokine expression, and glycation were investigated. The effects of taxifolin which is known to be a main compound of LK-ME, and its related flavonoids, quercetin and luteolin were also examined. The results show that taxifolin exhibits lower growth inhibition activity and lesser induction activity of inflammatory cytokines in a human monocyte derived cell line, THP-1 cells, while in vitro anti-glycation activities of taxifolin were inhibiting at comparable levels to those of quercetin and luteolin. The growth inhibition and the cytokine induction activities, and the anti-glycation effects of LK-ME are assumed to have properties similar to taxifolin. The results of high performance liquid chromatography (HPLC) analysis indicated that taxifolin was detected as the main peak of LK-ME at the absorbance of 280 nm, and the concentration of taxifolin was measured as 3.12 mg/ml. The actual concentration of taxifolin in LK-ME is lower than the concentration estimated from the IC₅₀ values calculated by the results of glycation assays, suggesting that other compounds contained in LK-ME are involved in the anti-glycation activity.