Puerarin attenuates pressure overload-induced cardiac hypertrophy

Evaluation of kudzu root extract-induced hepatotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Kudzu root, the root of Pueraria lobata (Willd.) Ohwi, has been used as food and medicine for centuries, but few studies indicate that kudzu root may cause liver damage.

AIM OF STUDY

We studied the hepatotoxicity of kudzu root extract in mice, HepG2 cells and mice hepatocytes.

MATERIALS AND METHODS

Mice were administrated with kudzu root extract (10mg/day) for 4 weeks, and then the biochemical analysis and histopathological changes were carried out. To explore the potential mechanism by which kudzu root extract-induced hepatotoxicity, HepG2 cells and mice hepatocytes were co-cultured with kudzu root extract or puerarin, which is a kudzu root isoflavone, for 2h.

RESULTS

The increase of serum ALT and AST and histopathological changes in treated mice revealed that kudzu root extract was hepatotoxic. The increase of LDH leakage for HepG2 cells and mice hepatocytes further confirmed hepatotoxicity of kudzu root extract. Kudzu root extract and puerarin significantly up-regulated Mt1 mRNA involved in the acute phase response and Bax which is crucial for apoptosis. Gclc, Nrf2 and Ho-1 mRNA expressions did not change in treatment group.

CONCLUSIONS

Kudzu root extract may be hepatotoxic and caution may be required for its use.

Shensongyangxin protects against pressure overload‑induced cardiac hypertrophy

Shensongyangxin (SSYX) is a medicinal herb, which has long been used in traditional Chinese medicine. Various pharmacological activities of SSYX have been identified. However, the role of SSYX in cardiac hypertrophy remains to be fully elucidated. In present study, aortic banding (AB) was performed to induce cardiac hypertrophy in mice. SSYX (520 mg/kg) was administered by daily gavage between 1 and 8 weeks following surgery. The extent of cardiac hypertrophy was then evaluated by pathological and molecular analyses of heart tissue samples. In addition, in vitro experiments were performed to confirm the in vivo results. The data of the present study demonstrated that SSYX prevented the cardiac hypertrophy and fibrosis induced by AB, as assessed by measurements of heart weight and gross heart size, hematoxylin and eosin staining, cross‑sectional cardiomyocyte area and the mRNA expression levels of hypertrophic markers. SSYX also inhibited collagen deposition and suppressed the expression of transforming growth factor β (TGFβ), connective tissue growth factor, fibronectin, collagen Ⅰα and collagen Ⅲα, which was mediated by the inhibition of the TGFβ/small mothers against decapentaplegic (Smad) signaling pathway. The inhibitory action of SSYX on cardiac hypertrophy was mediated by the inhibition of Akt signaling. In vitro investigations in the rat H9c2 cardiac cells also demonstrated that SSYX attenuated angiotensin II‑induced cardiomyocyte hypertrophy. These findings suggested that SSYX attenuated cardiac hypertrophy and fibrosis in the pressure overloaded mouse heart. Therefore, the cardioprotective effect of SSYX is associated with inhibition of the Akt and TGFβ/Smad signaling pathways.

Puerarin attenuates the inflammatory response and apoptosis in LPS-stimulated cardiomyocytes

Patients with septic shock suffer from high mortality rates, particularly when complicated by severe myocardial depression which is characterized by hypotension and a reduction in cardiac output. Inflammation is an important factor involved in the early stages of sepsis. The aim of the present study was to investigate the effect of the Chinese herbal compound puerarin (1, 5, 10, 20 and 40 µM) on cardiomyocyte inflammatory response in a sepsis model using H9c2 cardiomyocytes stimulated with 1 µg/ml lipopolysaccharide (LPS). The mRNA expression levels of tumor necrosis factor (TNF)-α and interleukin (IL)-β were evaluated using reverse transcription-quantitative polymerase chain reaction. In addition, the protein expression levels of various factors were determined using western blot analysis. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling was used to evaluate the apoptosis rates in the various groups, and immunocytochemical analysis was employed to determine the effect of puerarin on the nuclear translocation of p65 protein. The present study demonstrated that LPS stimulation increased IL-1β and TNF-α mRNA expression levels, as compared with the controls (P<0.05). Following treatment with various concentrations of puerarin, the expression levels of IL-1β and TNF-α were markedly blunted, particularly in the LPS + 40 µM puerarin group (P<0.05 vs. the LPS group). Furthermore, puerarin administration significantly inhibited LPS-induced apoptosis in H9c2 cardiomyocytes, as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining (TUNEL positive cells: LPS + 40 µM puerarin group, 5.5% vs. LPS group, 10.5%; P<0.01). In addition, puerarin significantly decreased LPS-induced phosphorylated nuclear factor (p-NF)-κB p65 and Bax expression levels, and increased the expression levels of Bcl-2, as compared with the LPS group (P<0.05). These data indicated that puerarin may serve as a valuable protective agent against cardiovascular inflammatory diseases.

Puerarin Inhibits oxLDL-Induced Macrophage Activation and Foam Cell Formation in Human THP1 Macrophage

Puerarin, an isoflavone derived from Kudzu roots, has been widely used for treatment of cardiovascular and cerebral vascular diseases in China and other Asian countries. However, the underlying mechanisms are largely unknown. The present study investigated whether puerarin inhibited atherogenic lipid oxLDL-mediated macrophage activation and foam cell formation in human THP1 macrophage. Treatment with oxLDL significantly increased the mRNA expression of proinflammatory cytokines tumor necrosis factor α (TNFα, 160%) and interleukin (IL) 1β (13 fold) accompanied by upregulation of toll-like receptor 4 (TLR4, 165%) and the ratio of phospho-IκBα/IκBα in THP1 macrophage. Puerarin dose-dependently prevented an increase in oxLDL-induced proinflammatory gene expression with downregulation of TLR4 and the ratio of phospho-IκBα/IκBα. Furthermore, puerarin prevented oxLDL-mediated lipid deposition and foam cell formation associated with downregulation of scavenger receptor CD36. Flow cytometry analysis showed that puerarin reduced the number of early apoptotic cells of macrophages induced by oxLDL. Our results show that puerarin has anti-inflammatory and antiatherogenic effects in vitro; the underlying mechanisms may involve the inhibition of TLR4/NFκB pathway and downregulation of CD36 expression. The results from the present study provide scientific evidence and may expand our armamentarium to use puerarin for prevention and treatment of cardiovascular and atherosclerotic diseases.

Naringenin attenuates pressure overload-induced cardiac hypertrophy

Cardiac hypertrophy is characterized by abnormal enlargement of cardiomyocytes and disproportionate accumulation of extracellular interstitial fibrosis, which are major predictors of the development of coronary artery disease and heart failure. Naringenin is a bitter principle component of grapefruit that has numerous pharmacological effects, including anti-inflammatory, hypolipidemic, antithrombotic and antiatherogenic properties. In order to investigate whether naringenin is able to exert a protective effect against cardiac hypertrophy induced by pressure overload, aortic banding (AB) was performed to induce cardiac hypertrophy in mice, and naringenin was administered for 7 weeks. A total of 60 mice were allocated into four groups: Sham + vehicle, AB + vehicle, sham + naringenin and AB + naringenin. Naringenin treatment attenuated cardiac dysfunction, as indicated by the results of echocardiography and catheter-based measurements at 8 weeks post-surgery. The extent of cardiac hypertrophy was assessed by the heart weight/body weight, heart weight/tibial length and lung weight/body weight ratios, in addition to the cardiomyocyte cross-sectional area and the mRNA expression levels of hypertrophic maker, all of which were mitigated by naringenin administration. Naringenin also inhibited the expression of transforming growth factor-β1, connective tissue growth factor, collagen Iα and collagen IIIα, and attenuated interstitial fibrosis. In addition, naringenin downregulated the activation of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathways. In conclusion, naringenin attenuated cardiac hypertrophy and interstitial fibrosis, in addition to improving left ventricular function in pressure-overloaded mice. The cardioprotective effect exerted by naringenin may be associated with the inhibition of PI3K/Akt, ERK and JNK signaling pathways.

Puerarin prevents cardiac hypertrophy induced by pressure overload through activation of autophagy

This study aimed to explore the effects of puerarin on autophagy in cardiac hypertrophy. Decreased 5'-adenosine monophosphate kinase (AMPK) activity alone with inhibited autophagy could be detected in rats within 3 weeks after aortic banding (AB). Puerarin treatment for 3 weeks in AB rats significantly restored autophagy. Administration of puerarin for 6 weeks effectively restricted cardiomyocyte hypertrophy and apoptosis. In an in vitro study, similar anti-hypertrophy and anti-apoptosis effects of puerarin on isoprenaline-induced H9c2 cells were also observed. After inhibition of autophagy by pretreatment with 3-methyladenine, the protective effects of puerarin were blocked. Further in vivo study demonstrated that puerarin significantly enabled phosphorylation of 5'-AMPK to be activated, subsequently inhibiting expression of the mammalian target of rapamycin (mTOR) target proteins S6 ribosomal protein and 4E-binding protein 1. All these data indicate that puerarin exerts protective effects against cardiomyocyte hypertrophy and apoptosis, partly by restoration of autophagy through AMPK/mTOR-mediated signaling.

Synergistic antitumor effect of puerarin combined with 5-fluorouracil on gastric carcinoma

Combination chemotherapy is a crucial method in the treatment of gastric cancer. The aim of the present study was to investigate the inhibitory effects of puerarin and 5‑fluorouracil (5‑FU) on BGC‑823 gastric cancer cells in vitro and in vivo. The in vitro growth inhibition of puerarin or 5‑FU alone or combined on BGC‑823 cells was determined using a cell counting kit 8 (CCK‑8) on living cells. Apoptotic morphological features and proteins expression levels were detected by Hoechst 33258 staining, an Annexin V/propidium iodide apoptosis kit and western blot analysis, respectively. Tumor xenografts were established in nude mice and the inhibitory effects and side effects were detected. Results of the CCK‑8, Hoechst 33258 staining and flow cytometry revealed that the combined treatment was more effective than the separate treatments. The tumor volume was 90.65% of that of the controls and the mean tumor weight was only 0.125 g at the end of the experiment in the combination group compared with the control group (0.822 g). In addition, it was determined that liver and renal toxicity did not increase in combined treatment. These findings showed that puerarin and 5‑FU produced a significant synergic effect on gastric cancer cells, while there was no increase in side effects.