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Resveratrol affords protection against reactive oxygen species (ROS)-related diseases via activation of SIRT1, an NAD+-dependent deacetylase. However, the low bioavailability of resveratrol limits its therapeutic applications. Since piceatannol is a hydroxyl analog of resveratrol with higher bioavailability, it could be an alternative to resveratrol. In this study, we compared the cytotoxicity, antioxidative activity, and mechanisms of cytoprotection of piceatannol with those of resveratrol. In C2C12 cells incubated with piceatannol, electrospray ionization mass spectrometry analysis showed that piceatannol was present in the intracellular fraction. A high concentration (50 μM) of piceatannol, but not resveratrol, induced mitochondrial depolarization and apoptosis. However, piceatannol at 10 μM inhibited the increase in mitochondrial ROS level induced by antimycin A, and this ROS reduction was greater than that by resveratrol. The reduction in hydrogen peroxide–induced ROS by piceatannol was also greater than that by resveratrol or vitamin C. Piceatannol reduced antimycin A–induced apoptosis more than did resveratrol. SIRT1 knockdown abolished the antiapoptotic activity of resveratrol, whereas it blocked only half of the antiapoptotic activity of piceatannol. Piceatannol, but not resveratrol, induced heme oxygenase-1 (HO1) expression, which was blocked by knockdown of the transcription factor NRF2, but not by SIRT1 knockdown. HO1 knockdown partially blocked the reduction of ROS by piceatannol. Furthermore, the antiapoptotic action of piceatannol was abolished by HO1 knockdown. Our results suggest that the therapeutic dose of piceatannol protects cells against mitochondrial ROS more than does resveratrol via SIRT1- and NRF2/HO1–dependent mechanisms. The activation of NRF2/HO1 could be an advantage of piceatannol compared with resveratrol for cytoprotection. Significance Statement This study showed that piceatannol and resveratrol were different in cytotoxicity, oxidant-scavenging activities, and mechanisms of cytoprotection. Protection by piceatannol against apoptosis induced by reactive oxygen species was superior to that by resveratrol. In addition to the sirtuin 1–dependent pathway, piceatannol exerted nuclear factor erythroid 2–related factor 2/heme oxygenase-1–mediated antioxidative and antiapoptotic effects, which could be an advantage of piceatannol compared with resveratrol.

Activation of SIRT1, an NAD+-dependent protein deacetylase, ameliorates muscular pathophysiology of δ-sarcoglycan-deficient TO-2 hamsters and dystrophin-deficient mdx mice. We found that SIRT1 was highly expressed beneath the cellular membranes of muscle cells. To elucidate functional roles of SIRT1 on muscles, skeletal muscle-specific SIRT1 knockout mice (SIRT1-MKO) were generated. SIRT1-MKO mice showed muscular pathology similar to mild muscular dystrophies with increased numbers of centrally nucleated small myofibers and decreased numbers of middle-sized (2000-3001 μm2) myofibers compared to those of wild-type (WT) mice. Accordingly, SIRT1-MKO mice showed significantly decreased exercise capacity in treadmill and inverted hanging tests with higher levels of serum creatine kinase activities compared with those in WT mice. Evans blue dye uptake after exercise was greater in the muscles of SIRT1-MKO than those of WT mice, suggesting membrane fragility in SIRT1-MKO mice. Because SIRT1 was dominantly localized beneath the membranes of muscular cells, SIRT1 may have a new role in the membranes. We found that levels of fluorescent FM1-43 dye intake after laser-induced membrane disruption in C2C12 cells were significantly increased by SIRT1 inhibitors or Sirt1-siRNA compared with those of control cells. Inhibition of SIRT1 or SIRT1-knockdown severely disturbed the dynamic aggregation of membrane vesicles under the injured site but did not affect expression levels of membrane repair proteins. These data suggested that SIRT1 had a critical role in the resealing of membrane-ruptured muscle cells, which could affect phenotypes of SIRT1-MKO mice. To our knowledge, this report is the first to demonstrate that SIRT1 affected plasma-membrane repair mechanisms.

The glycosylation of pterostilbene by cultured plant cells of Phytolacca americana gave pterostilbene 4′- O-β-D-glucoside. Both pterostilbene and its 4- O-β-D-glucoside induced type XVII collagen expression in the EpiDermFT EFT-400 human skin cell model. Pterostilbene 4′- O-β-D-glucoside strongly induced type XVII collagen expression rather than pterostilbene.

Autophagy activation improves the phenotype in mdx mice, a Duchenne muscular dystrophy (DMD) model, although the underlying mechanisms are obscure. We previously found that resveratrol, a strong inducer of autophagy, ameliorates the cardiac pathology of mdx mice. Autophagy could eliminate damaged mitochondria, a major source of intracellular reactive oxygen species (ROS), although there is no evidence for mitochondriopathy in dystrophic cardiomyopathy. To elucidate resveratrol’s function, we investigated the deletion of mitochondrial DNA (mtDNA), autophagy of damaged mitochondria (mitophagy), and ROS accumulation in the mdx mouse heart. Low levels of normal mtDNA and abnormal accumulations of mitochondria-containing autophagosomes were found in the mdx mouse heart. Administering resveratrol to mdx mice for 56 weeks ameliorated the cardiomyopathy, with significant reductions in the amount of mtDNA deletion, the number of mitochondria-containing autophagosomes, and the ROS levels. Resveratrol induced nuclear FoxO3a accumulation and the expression of autophagy-related genes, which are targets of FoxOs. The most effective dose in mdx mice was 0.4 g resveratrol/kg food. In conclusion, resveratrol improved cardiomyopathy by promoting mitophagy in the mdx mouse heart. We propose that acquired mitochondriopathy worsens the pathology of DMD and is a potential therapeutic target for the cardiomyopathy in DMD patients.

Cardiomyopathy is the main cause of death in Duchenne muscular dystrophy. Here, we show that oral administration of resveratrol, which leads to activation of an NAD+-dependent protein deacetylase SIRT1, suppresses cardiac hypertrophy and fibrosis and restores cardiac diastolic function in dystrophin-deficient mdx mice. The pro-hypertrophic co-activator p300 protein but not p300 mRNA was up-regulated in the mdx heart, and resveratrol administration down-regulated the p300 protein level. In cultured cardiomyocytes, cardiomyocyte hypertrophy induced by the α1-agonist phenylephrine was inhibited by the overexpression of SIRT1 as well as resveratrol, both of which down-regulated p300 protein levels but not p300 mRNA levels. In addition, activation of atrial natriuretic peptide promoter by p300 was inhibited by SIRT1. We found that SIRT1 induced p300 down-regulation via the ubiquitin-proteasome pathway by deacetylation of lysine residues for ubiquitination. These findings indicate the pathological significance of p300 up-regulation in the dystrophic heart and indicate that SIRT1 activation has therapeutic potential for dystrophic cardiomyopathy. Background: Dystrophin deficiency leads to life-threatening cardiomyopathy, whereas cardiac p300 promotes cardiac hypertrophy/failure. Results: The SIRT1 activator resveratrol inhibited p300 protein up-regulation and attenuated cardiomyopathy in dystrophin-deficient mice, and SIRT1-induced p300 down-regulation was mediated via its deacetylation and ubiquitination. Conclusion: SIRT1 activation ameliorates dystrophic cardiomyopathy by targeting p300. Significance: Negative regulation of p300 is a novel cardioprotective mechanism of SIRT1.

Excessive reactive oxygen species (ROS) induce apoptosis and are associated with various diseases and with aging. SIRT1 (sirtuin-1), an NAD+-dependent protein deacetylase, decreases ROS levels and participates in cell survival under oxidative stress conditions. SIRT1 modulates the transcription factors p53, a tumor suppressor and inducer of apoptosis, and the forkhead O (FOXO) family, both of which play roles for cell survival and cell death. In this study, we aimed to know which is working greatly among p53 and FOXOs transcription factors in SIRT1’s cell protective functions under oxidative stress conditions. The antimycin A-induced increase in ROS levels and apoptosis was enhanced by SIRT1 inhibitors nicotinamide and splitomicin, whereas it was suppressed by a SIRT1 activator, resveratrol, and a SIRT1 cofactor, NAD+. SIRT1-siRNA abolished the effects of splitomicin and resveratrol. p53-knockdown experiment in C2C12 cells and experiment using p53-deficient HCT116 cells showed that splitomicin and resveratrol modulated apoptosis by p53-dependent and p53-independent pathways. In p53-independent cell protective pathway, we found that FOXO1, FOXO3a, and FOXO4 were involved in SOD2’s upregulation by resveratrol. The knockdown of these three FOXOs by siRNAs completely abolished the SOD2 induction, ROS reduction, and anti-apoptotic function of resveratrol. Our results indicate that FOXO1, FOXO3a and FOXO4, are indispensable for SIRT1-dependent cell survival against oxidative stress, although deacetylation of p53 has also some role for cell protective function of SIRT1.

Resveratrol ( trans -3,5,4′-trihydroxystilbene; RSV), a natural polyphenol, exerts a beneficial effect on health and diseases. RSV targets and activates the NAD + -dependent protein deacetylase SIRT1; in turn, SIRT1 induces an intracellular antioxidative mechanism by inducing mitochondrial superoxide dismutase (SOD2). Most RSV found in plants is glycosylated, and the effect of these glycosylated forms on SIRT1 has not been studied. In this study, we compared the effects of RSV and two glycosyl RSVs, resveratrol-3- O - β -d-glucoside (3G-RSV; polydatin/piceid) and resveratrol-4′- O - β -d-glucoside (4′G-RSV), at the cellular level. In oxygen radical absorbance capacity and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays, the antioxidant activity of 3G-RSV was comparable to that of RSV, whereas the radical-scavenging efficiency of 4′G-RSV was less than 50% of that of RSV. However, 4′G-RSV, but not 3G-RSV, induced SIRT1-dependent histone H3 deacetylation and SOD2 expression in mouse C2C12 skeletal myoblasts; as with RSV, SIRT1 knockdown blunted these effects. RSV and 4′G-RSV, but not 3G-RSV, mitigated oxidative stress–induced cell death in C2C12 cells and primary neonatal rat cardiomyocytes. RSV and 4′G-RSV inhibited C2C12 cell proliferation, but 3G-RSV did not. RSV was found in both the intracellular and extracellular fractions of C2C12 cells that had been incubated with 4′G-RSV, indicating that 4′G-RSV was extracellularly deglycosylated to RSV, which was then taken up by the cells. C2C12 cells did not deglycosylate 3G-RSV. Our results point to 4′G-RSV as a useful RSV prodrug with high water solubility. These data also show that the in vitro antioxidative activity of these molecules did not correlate with their ability to protect cells from oxidative stress–induced apoptosis.

Muscular dystrophies are inherited myogenic disorders accompanied by progressive skeletal muscle weakness and degeneration. We previously showed that resveratrol (3,5,4'-trihydroxy-trans-stilbene), an antioxidant and activator of the NAD(+)-dependent protein deacetylase SIRT1, delays the progression of heart failure and prolongs the lifespan of δ-sarcoglycan-deficient hamsters. Because a defect of dystroglycan complex causes muscular dystrophies, and δ-sarcoglycan is a component of this complex, we hypothesized that resveratrol might be a new therapeutic tool for muscular dystrophies. Here, we examined resveratrol's effect in mdx mice, an animal model of Duchenne muscular dystrophy. mdx mice that received resveratrol in the diet for 32 weeks (4 g/kg diet) showed significantly less muscle mass loss and nonmuscle interstitial tissue in the biceps femoris compared with mdx mice fed a control diet. In the muscles of these mice, resveratrol significantly decreased oxidative damage shown by the immunostaining of nitrotyrosine and 8-hydroxy-2'-deoxyguanosine and suppressed the up-regulation of NADPH oxidase subunits Nox4, Duox1, and p47(phox). Resveratrol also reduced the number of α-smooth muscle actin (α-SMA)(+) myofibroblast cells and endomysial fibrosis in the biceps femoris, although the infiltration of CD45(+) inflammatory cells and increase in transforming growth factor-β1 (TGF-β1) were still observed. In C2C12 myoblast cells, resveratrol pretreatment suppressed the TGF-β1-induced increase in reactive oxygen species, fibronectin production, and expression of α-SMA, and SIRT1 knockdown blocked these inhibitory effects. SIRT1 small interfering RNA also increased the expression of Nox4, p47(phox), and α-SMA in C2C12 cells. Taken together, these findings indicate that SIRT1 activation may be a useful strategy for treating muscular dystrophies.

Cultured plant cells of Eucalyptus perriniana catalyzed reduction regioselective hydroxylation and regioselective glycosylation of flavanones. (2 S)-Flavanone was converted into (2 S)-flavan-4-ol (2 S)-flavan-4,7-diol (2 S)-flavan-7-ol (2 S)-flavan-7-yl glucoside and (2 S)-flavan-7-yl gentiobioside. The cells glucosylated (2 S)-flavan-6-ol to (2 S)-flavan-6-yl glucoside. (2 S)-Flavan-2′-ol was transformed to (2 S)-flavan-2′,4-diol (2 S)-flavan-2′,7-diol (2 S)-flavan-2′-yl glucoside. In addition (2 S)-flavan-4′-ol was transformed to (2 S)-flavan-4,4′-diol (2 S)-flavan-4′,7-diol (2 S)-flavan-4′-yl glucoside.