Cassia S. Mizuno

Differential effects of resveratrol and its naturally occurring methylether analogs on cell cycle and apoptosis in human androgen-responsive LNCaP cancer cells.

Stilbenes are phytoalexins that become activated when plants are stressed. These compounds exist in foods and are widely consumed. Resveratrol is a grape-derived stilbene, which possesses a wide range of health-promoting activities, including anticancer properties. Several other stilbenes structurally similar to resveratrol are also available in food, but their biological activities remain largely unknown. In this study, we compared the effects of resveratrol and its natural derivatives pterostilbene, trans-resveratrol trimethylether, trans-pinostilbene and trans-desoxyrhapontigenin on androgen-responsive human prostate cancer LNCaP cells. We found that these compounds exert differential effects on LNCaP cell growth, cell cycle and apoptosis. Trans-resveratrol trimethylether appeared to be the most potent compound among the stilbenes tested. Treatment of LNCaP cells with trans-resveratrol trimethylether resulted in G2/M blockage while other compounds, including resveratrol, induced G1/S arrest. Moreover, different from other compounds, trans-resveratrol trimethylether induced apoptosis. At the molecular level, the effects of these compounds on cell cycle correlated with induction of the cyclin-dependent kinase inhibitor 1A and B mRNA levels. Additionally, these compounds also inhibited both androgen- as well as estrogen-mediated pathways. These results provide mechanistic information on how resveratrol and its methylether analogs may act to contribute to potential antiprostate cancer activity.

Type 2 diabetes and oral antihyperglycemic drugs.

Type II diabetes is a heterogeneous disease where environment and genetics are important factors for the expression of the disease. The high cost for treating complications of diabetes is a burden for public health systems and governments worldwide. Type II diabetes has been causing debilitation worldwide for many decades, and a single drug that safely treats the disease has yet to be discovered. Sulfonylureas, biguanides, alpha-glucosidase, meglitinides, DPP-4 inhibitors and thiazolidinediones are among the classes of oral hypoglycemic drugs available to treat Type II diabetes, but concerns exist regarding safety and efficacy of these drugs. In this article we present the pros and cons of the six classes and discuss some of the latest advances towards the development of new drugs for the treatment of Type II diabetes.

Pterostilbene Acts through Metastasis-Associated Protein 1 to Inhibit Tumor Growth, Progression and Metastasis in Prostate Cancer

The development of natural product agents with targeted strategies holds promise for enhanced anticancer therapy with reduced drug-associated side effects. Resveratrol found in red wine, has anticancer activity in various tumor types. We reported earlier on a new molecular target of resveratrol, the metastasis-associated protein 1 (MTA1), which is a part of nucleosome remodeling and deacetylation (NuRD) co-repressor complex that mediates gene silencing. We identified resveratrol as a regulator of MTA1/NuRD complex and re-activator of p53 acetylation in prostate cancer (PCa). In the current study, we addressed whether resveratrol analogues also possess the ability to inhibit MTA1 and to reverse p53 deacetylation. We demonstrated that pterostilbene (PTER), found in blueberries, had greater increase in MTA1-mediated p53 acetylation, confirming superior potency over resveratrol as dietary epigenetic agent. In orthotopic PCa xenografts, resveratrol and PTER significantly inhibited tumor growth, progression, local invasion and spontaneous metastasis. Furthermore, MTA1-knockdown sensitized cells to these agents resulting in additional reduction of tumor progression and metastasis. The reduction was dependent on MTA1 signaling showing increased p53 acetylation, higher apoptotic index and less angiogenesis in vivo in all xenografts treated with the compounds, and particularly with PTER. Altogether, our results indicate MTA1 as a major contributor in prostate tumor malignant progression, and support the use of strategies targeting MTA1. Our strong pre-clinical data indicate PTER as a potent, selective and pharmacologically safe natural product that may be tested in advanced PCa.

Trimethoxy-Resveratrol and Piceatannol Administered Orally Suppress and Inhibit Tumor Formation and Growth in Prostate Cancer Xenografts

Resveratrol (Res) is recognized as a promising cancer chemoprevention dietary polyphenol with antioxidative, anti‐inflammatory, and anticancer properties. However, the role of its analogues in prostate cancer (PCa) chemoprevention is unknown.

In vitro and in vivo studies on stilbene analogs as potential treatment agents for colon cancer

Based on the potential of resveratrol as a colon cancer chemopreventive agent, a set of 26 stilbenes were synthesized and tested against the colon cancer cell lines HT-29 and Caco-2. (Z)-4-(3,5-Dimethoxystyryl)aniline (4), (Z)-methyl-4-(3,5-dimethoxystyryl)benzoate (6), and (Z)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (10) showed strong inhibitory activity in vitro. In vivo studies using HT-29 xenografts in immunodeficient mice were conducted with 4, 6 and 10, together with their corresponding trans isomers (3, 5, and 9, respectively), at the dose of 10 mg/kg body weight. Tumor volume was significantly lowered in 3-, 4-, and 9-treated groups. The cis- and trans-amino analogs (4 and 3, respectively) had similar effect on tumor growth, a 40% decrease compared to the control. Analysis of the serum revealed that 4 isomerized to 3, which may explain their similar effects in SCID mice. Stilbenes 5, 6, 9, and 10 retained their configurations in the serum. Stilbenes 6 and 10 lacked tumor-suppressive effect in SCID mice; the serum levels of these analogs were low (18.8 and 15.5 ng/mL, respectively). Stilbene 9, while weakly active in vitro demonstrated good activity in vivo, was found at higher levels in the serum (69.9 ng/mL) compared to 10. The anti-tumorigenic activity of these stilbene analogs may be partly linked to their effects on proteins involved in cell proliferation, as observed by lowered expression of proliferating cell nuclear antigen and upregulation of the cyclin-dependent kinase inhibitor, p27, in the tumor tissues. Overall, identification of the anti-tumorigenic potential of these compounds provides opportunities for their use against colorectal cancer.

In planta production of the highly potent resveratrol analogue pterostilbene via stilbene synthase and O-methyltransferase co-expression

Resveratrol and related stilbenes are thought to play important roles in defence responses in several plant species and have also generated considerable interest as nutraceuticals owing to their diverse health-promoting properties. Pterostilbene, a 3,5-dimethylether derivative of resveratrol, possesses properties similar to its parent compound and, additionally, exhibits significantly higher fungicidal activity in vitro and superior pharmacokinetic properties in vivo. Recombinant enzyme studies carried out using a previously characterized O-methyltransferase sequence from Sorghum bicolor (SbOMT3) demonstrated its ability to catalyse the A ring-specific 3,5-bis-O-methylation of resveratrol, yielding pterostilbene. A binary vector was constructed for the constitutive co-expression of SbOMT3 with a stilbene synthase sequence from peanut (AhSTS3) and used for the generation of stably transformed tobacco and Arabidopsis plants, resulting in the accumulation of pterostilbene in both species. A reduced floral pigmentation phenotype observed in multiple tobacco transformants was further investigated by reversed-phase HPLC analysis, revealing substantial decreases in both dihydroquercetin-derived flavonoids and phenylpropanoid-conjugated polyamines in pterostilbene-producing SbOMT3/AhSTS3 events. These results demonstrate the potential utility of this strategy for the generation of pterostilbene-producing crops and also underscore the need for the development of additional approaches for minimizing concomitant reductions in key phenylpropanoid-derived metabolites.

Algicidal Activity of Stilbene Analogues

Continuing our search for natural product and natural product-based compounds for the control of off-flavor in catfish, 29 stilbene analogues were synthesized and evaluated for algicidal activity against the 2-methylisoborneol (MIB)-producing cyanobacterium Oscillatoria perornata. The cis and trans isomers of 4-(3,5-dimethoxystyryl)aniline showed moderate and selective algicidal activity toward O. perornata with the lowest observed inhibitory concentration and lowest complete inhibition concentrations of 10 muM. This is the first report on selective stilbene algicidal activity toward a MIB-producing cyanobacteria species.

Synthesis and biological evaluation of retinoid-chalcones as inhibitors of colon cancer cell growth

Based on the observed anticancer activity of chalcones and retinoids, a novel class of retinoid-chalcone hybrids was designed and synthesized. As part of our ongoing studies to discover natural product based anticancer compounds, the retinoid-chalcone hybrids were tested against the colon cancer cell line HT-29. Retinoid like moiety was introduced through Friedel-Crafts alkylation of toluene. Among the synthesized compounds, the cyano derivative (E)-3-(3-oxo-3-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)prop-1-enyl)benzonitrile 8 showed submicromolar inhibitory activity with an IC(50) of 0.66 μM.

Design, Synthesis, and Docking Studies of Novel Benzimidazoles for the Treatment of Metabolic Syndrome

In addition to lowering blood pressure, telmisartan, an angiotensin (AT(1)) receptor blocker, has recently been shown to exert pleiotropic effects as a partial agonist of nuclear peroxisome proliferator-activated receptor gamma (PPAR gamma). On the basis of these findings and docking pose similarity between telmisartan and rosiglitazone in PPAR gamma active site, two classes of benzimidazole derivatives were designed and synthesized as dual PPAR gamma agonist/angiotensin II antagonists for the possible treatment of metabolic syndrome. Compound 4, a bisbenzimidazole derivative showed the best affinity for the AT(1) receptor with a K(i) = 13.4 nM, but it was devoid of PPAR gamma activity. On the other hand 9, a monobenzimidazole derivative, showed the highest activity in PPAR gamma transactivation assay (69% activation) with no affinity for the AT(1) receptor. Docking studies lead to the designing of a molecule with dual activity, 10, with moderate PPARgamma activity (29%) and affinity for the AT(1) receptor (K(i) = 2.5 microM).

Activity of Lycorine Analogues against the Fish Bacterial Pathogen Flavobacterium columnare

In a continuing effort to discover natural products and natural product-based compounds for the control of columnaris disease in channel catfish (Ictalurus punctatus), 17 lycorine analogues were synthesized, including new benzoyl analogues 6-16, and evaluated for antibacterial activity against two isolates (ALM-00-173 and BioMed) of Flavobacterium columnare using a rapid bioassay. Two of the lycorine analogues had greater antibacterial activity than 1-O-acetyllycorine, an analogue of lycorine evaluated previously that is highly active against both isolates. Carbamate analogue 18 (1S,2S,3a(1)S,12bS)-2,3a(1),4,5,7,12b-hexahydro-1H-[1,3]dioxolo[4,5-j]pyrrolo[3,2,1-de]phenanthridin-1,2-diylbis(o-tolylcarbamate) had the strongest antibacterial activity toward both F. columnare isolates ALM-00-173 and BioMed, with 24-h IC(50) values of 3.0 ± 1.3 and 3.9 ± 2.2 mg/L, respectively, and a MIC of 5.5 ± 0 mg/L for both isolates. Compound 18 appears to be the most promising lycorine analogue for future efficacy studies to determine its potential for use as an alternative to the currently used compounds to control columnaris disease in channel catfish.