• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.6403-6407
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• 2012

Detoxifying enzymes are present in most epithelial cells of the human gastrointestinal tract where they protect against xenobiotics which may cause cancer. Induction of examples such as glutathione S-transferase (GST) and its thiol conjugate, glutathione (GSH) as well as NAD(P)H: quinoneoxidoreductase (NQO1) facilitate the excretion of carcinogens and thus preventing colon carcinogenesis. Pterostilbene, an analogue of resveratrol, has demonstrated numerous pharmacological activities linked with chemoprevention. This study was conducted to investigate the potential of pterostilbene as a chemopreventive agent using the HT-29 colon cancer cell line to study the modulation of GST and NQO1 activities as well as the GSH level. Initially, our group, established the optimum dose of 24 hours pterostilbene treatment using MTT assays. Then, effects of pterostilbene ($0-50{\mu}M$) on GST and NQO1 activity and GSH levels were determined using GST, NQO1 and Ellman assays, respectively. MTT assay of pterostilbene ($0-100{\mu}M$) showed no cytotoxicity toward the HT-29 cell line. Treatment increased GST activity in the cell line significantly (p<0.05) at 12.5 and $25.0{\mu}M$. In addition, treatment at $50{\mu}M$ increased the GSH level significantly (p<0.05). Pterostilbene also enhanced NQO1 activity significantly (p<0.05) at $12.5{\mu}M$ and $50{\mu}M$. Hence, pterostilbene is a potential chemopreventive agent capable of modulation of detoxifiying enzyme levels in HT-29 cells.

• Preventive Nutrition and Food Science
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• v.21 no.2
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• pp.155-159
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• 2016

Previous research showed that resveratrol (trans-3,4',5-trihydroxystilbene) and pinostilbene (trans-3-methoxy-4',5-dihydroxystilbene) were able to inhibit tyrosinase directly; however, anti-melanogenic effects of pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene) and resveratrol trimethyl ether (RTE) have not been compared. To investigate the hypopigmentation effects of pterostilbene and RTE, melanin contents and intracellular tyrosinase activity were determined by western blot analysis. Firstly, pterostilbene showed the inhibitory effects on ${\alpha}$-melanocyte stimulating hormone (MSH)-induced melanin synthesis stronger than RTE, resveratrol, and arbutin. Pterostilbene inhibited melanin biosynthesis in a dose-dependent manner in ${\alpha}$-MSH-stimulated B16/F10 murine melanoma cells. Specifically, melanin content and intracellular tyrosinase activity were inhibited by 63% and 58%, respectively, in response to treatment with $10{\mu}m$ of pterostilbene. The results of western blot analysis indicated that pterostilbene induced downregulation of tyrosinase protein expression and suppression of ${\alpha}$-MSH-stimulated melan-A protein expression stronger than RTE or resveratrol. Based on these results, our study suggests that pterostilbene can induce hypopigmentation effects more effectively than resveratrol and RTE, and it functions via downregulation of protein expression associated with hyperpigmentation in ${\alpha}$-MSH-triggered B16/F10 murine melanoma cells.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1163-1169
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• 2014

Astragalus, a commonly used traditional Chinese medicine, has exhibited antitumor actions in patients. In this study, in vitro and in vivo antitumor effects of astragalus and synergistic antitumor efficacy in combination with pterostilbene were investigated. Melanoma cells were treated with pterostilbene (Pt), graduated doses of astragalus injection (AI), or these in combination. Cell viability was measured using a MTT assay. Released nucleosomes and caspase activity were measured using enzyme-linked immunosorbent assay. Growth inhibition in vitro and in vivo was also assessed. Analysis of variance and t tests were used for statistical analysis. Significant reduction (p<0.05) in cellular proliferation were observed with AI and AI-Pt in a time- and concentration-dependent manner. Apoptosis and caspase-3/7 activity were significantly increased by AI and AI-Pt treatment (p<0.05). In vivo, AI inhibited melanoma tumor growth, with inhibition rates ranging from 36.5 to 62.3%, by inducing apoptosis via up-regulation Bax expression and the Bax/Bcl-2 ratio and down-regulating Bcl-2 expression. AI significantly inhibits the growth of melanoma in vitro and in vivo by inducing apoptosis. These data suggest that combined treatment of astragalus with pterostilbene enhances antitumor efficacy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.124-128
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• 2008

This study was aimed to analyze the composition and to quantify the contents of stilbenoids in the leaves and fruits of Morus alba L. using high performance liquid chromatography with phodtodiode array detector and UV detector. Optimal wavelength for the detection of various stilbenoids such as resveratrol, piceatannol, rhapontigenin, astringin, pterostilbene, piceid, rhaponticin and vitisin A was screened by DAD detector and set to 308 nm. Seven kinds of stilbenoids except vitisin A were identified in fruits, while 5 kinds of stilbenoids in leaves. Total stilbenoids contents were $609.15{\pm}7.24$ mg/100 g d.w. in fruits and $188.57{\pm}1.70$ mg/100 g d.w in leaves. Stilbenoids contents in fruits were 3 times higher than those in leaves. Rhaponticin was the most profound stilbene, analyzed to $389.26{\pm}5.22$ mg/100 g d.w. (63.8% of total stilbenoids) in fruits and $99.17{\pm}2.79$ mg/100 g d.w. (52.5% of total stilbenoids) in leaves. Astringin and piceatannol were only detected in fruits and vitisin A was not detected. Contents of piceid and rhaponticin were higher than those of aglycone forms, rhapontigenin and resveratrol.

• Molecules and Cells
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• v.38 no.4
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• pp.318-326
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• 2015

We previously reported that the SbROMT3syn recombinant protein catalyzes the production of the methylated resveratrol derivatives pinostilbene and pterostilbene by methylating substrate resveratrol in recombinant E. coli. To further study the production of stilbene compounds in E. coli by the expression of enzymes involved in stilbene biosynthesis, we isolated three stilbene synthase (STS) genes from rhubarb, peanut, and grape as well as two resveratrol O-methyltransferase (ROMT) genes from grape and sorghum. The ability of RpSTS to produce resveratrol in recombinant E. coli was compared with other AhSTS and VrSTS genes. Out of three STS, only AhSTS was able to produce resveratrol from p-coumaric acid. Thus, to improve the solubility of RpSTS, VrROMT, and SbROMT3 in E. coli, we synthesized the RpSTS, VrROMT and SbROMT3 genes following codon-optimization and expressed one or both genes together with the cinnamate/4-coumarate:coenzyme A ligase (CCL) gene from Streptomyces coelicolor. Our HPLC and LC-MS analyses showed that recombinant E. coli expressing both ScCCL and RpSTSsyn led to the production of resveratrol when p-coumaric acid was used as the precursor. In addition, incorporation of SbROMT3syn in recombinant E. coli cells produced resveratrol and its mono-methylated derivative, pinostilbene, as the major products from p-coumaric acid. However, very small amounts of pterostilbene were only detectable in the recombinant E. coli cells expressing the ScCCL, RpSTSsyn and SbROMT3syn genes. These results suggest that RpSTSsyn exhibits an enhanced enzyme activity to produce resveratrol and SbROMT3syn catalyzes the methylation of resveratrol to produce pinostilbene in E. coli cells.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1105-1111
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• 2018

The flavin-dependent monooxygenase Sam5 was previously reported to be a bifunctional hydroxylase with coumarate 3-hydroxylase and resveratrol 3'-hydroxylase activities. In this article, we showed the Sam5 enzyme has 3'-hydroxylation activities for methylated resveratrols (pinostilbene and pterostilbene), hydroxylated resveratrol (oxyresveratrol), and glycosylated resveratrol (piceid) as substrates. However, piceid, a glycone-type stilbene used as a substrate for bioconversion experiments with the Sam5 enzyme expressed in Escherichia coli, did not convert to the hydroxylated compound astringin, but it was converted by in vitro enzyme reactions. Finally, we report a novel catalytic activity of Sam5 monooxygenase for the synthesis of piceatannol derivatives, 3'-hydroxylated stilbene compounds. Development of this bioproduction method for the hydroxylation of stilbenes is challenging because of the difficulty in expressing P450-type hydroxylase in E. coli and regiospecific chemical synthesis.

• Genomics & Informatics
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• v.12 no.4
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• pp.283-288
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• 2014

Among all serious diseases globally, diabetes (type 1 and type 2) still poses a major challenge to the world population. Several target proteins have been identified, and the etiology causing diabetes has been reasonably well studied. But, there is still a gap in deciding on the choice of a drug, especially when the target is mutated. Mutations in the KCNJ11 gene, encoding the kir6.2 channel, are reported to be associated with congenital hyperinsulinism, having a major impact in causing type 1 diabetes, and due to the lack of its 3D structure, an attempt has been made to predict the structure of kir6.2, applying fold recognition methods. The current work is intended to investigate the affinity of four phytochemicals namely, curcumin (Curcuma longa), genistein (Genista tinctoria), piperine (Piper nigrum), and pterostilbene (Vitis vinifera) in a normal as well as in a mutant kir6.2 model by adopting a molecular docking methodology. The phytochemicals were docked in both wild and mutated kir6.2 models in two rounds: blind docking followed by ATP-binding pocket-specific docking. From the binding pockets, the common interacting amino acid residues participating strongly within the binding pocket were identified and compared. From the study, we conclude that these phytochemicals have strong affinity in both the normal and mutant kir6.2 model. This work would be helpful for further study of the phytochemicals above for the treatment of type 1 diabetes by targeting the kir6.2 channel.