Publications by authors named "Wantha Jenkhetkan"

3 Publications

  • Page 1 of 1

Molecular Characterization and Potential Synthetic Applications of GH1 β-Glucosidase from Higher Termite Microcerotermes annandalei.

Appl Biochem Biotechnol 2018 Dec 19;186(4):877-894. Epub 2018 May 19.

Department of Biochemistry, Faculty of Science, and Center for Advanced Studies in Tropical Natural Resources, NRU-KU, Kasetsart University, 50 Paholyotin Road, Chatuchak, Bangkok, 10900, Thailand.

A novel β-glucosidase from higher termite Microcerotermes annandalei (MaBG) was obtained via a screening method targeting β-glucosidases with increased activities in the presence of glucose. The purified natural MaBG showed a subunit molecular weight of 55 kDa and existed in a native form as a dimer without any glycosylation. Gene-specific primers designed from its partial amino acid sequences were used to amplify the corresponding 1,419-bp coding sequence of MaBG which encodes a 472-amino acid glycoside hydrolase family 1 (GH1) β-glucosidase. When expressed in Komagataella pastoris, the recombinant MaBG appeared as a ~ 55-kDa protein without glycosylation modifications. Kinetic parameters as well as the lack of secretion signal suggested that MaBG is an intracellular enzyme and not involved in cellulolysis. The hydrolytic activities of MaBG were enhanced in the presence of up to 3.5-4.5 M glucose, partly due to its strong transglucosylation activity, which suggests its applicability in biosynthetic processes. The potential synthetic activities of the recombinant MaBG were demonstrated in the synthesis of para-nitrophenyl-β-D-gentiobioside via transglucosylation and octyl glucoside via reverse hydrolysis. The information obtained from this study has broadened our insight into the functional characteristics of this variant of termite GH1 β-glucosidase and its applications in bioconversion and biotechnology.
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December 2018

Molecular and cytogenetic effects of Thai royal jelly: modulation through c-MYC, h-TERT, NRF2, HO-1, BCL2, BAX and cyclins in human lymphocytes in vitro.

Mutagenesis 2017 10;32(5):525-531

Division of Biochemistry, Department of Preclinical Sciences, Faculty of Medicine, Thammasat University, 95 Paholyothin Road, A. Klongluang, Pathumthani 12121, Thailand.

Royal jelly (RJ) is widely used as a food supplement for anti-aging and beauty. However, its use has been linked to asthma and hemorrhagic colitis. Since its mechanisms of toxicity have not been fully identified, we conducted an investigation to elucidate its molecular and cytogenetic effects. Using human lymphocytes in vitro, treatments with RJ (0.0005-5 mg/ml) for 3 h did not induce sister chromatid exchanges until 5 mg/ml was used. Treatments for 24 h showed a dose-dependent reduction in BCL2/BAX, c-MYC/BAX and HO-1/BAX ratios. The exception was the NRF2/BAX ratio, showing a dose-dependent reduction at low doses, but a marked increase at the highest dose. The hTERT/BAX ratio was maintained at approximately a 1.2-fold increase but decreased to nearly normal at the highest dose. Our findings indicated that the lowest dose of RJ treatment provided maximum benefits, mainly through hTERT activation relating to prolonged lifespan. The highest dose of RJ inhibited cell survival, cell proliferation and an antioxidative enzyme; nevertheless, it still activated an antioxidative response through NRF2 and maintained telomeres during cell crisis. RJ treatment at 0.05 mg/ml increased cyclin E, BCL2 and BAX to maximum levels indicating that throughout the active cell cycle, both cell survival and cell apoptosis increased. Using the gene expression ratios over BAX, similar to BCL2/BAX, provided more informative data than using individual protein levels alone. With these informative ratios, our results confirm the potential benefits of RJ in enhancing lifespan and activation antioxidative power. Further, in vivo mechanistic studies will be useful in validating these results.
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October 2017

Synergistic Genotoxic Effects and Modulation of Cell Cycle by Ginger Ethanolic Extracts in Adjunct to Doxorubicin in Human Lymphocytes In Vitro.

J Med Assoc Thai 2015 Apr;98 Suppl 3:S101-9

Background: Several natural phytochemicals are increasingly used, as an adjunct to chemotherapy, to reduce drug adverse effects. Zingiber officinale rhizome (ginger) product has been reported to be effective against nausea and vomiting in patients receiving emetogenic chemotherapy such as cisplatin/doxorubicin (DXR). In addition, its ethanolic extract of Zingiber officinale rhizome (EEZOR) has been reported to possess anticarcinogenic properties. However, the mechanism for anticancer activity of ginger especially when used in combination with chemotherapy has not well elucidated, one of its possible mechanisms might involve its genotoxicity.

Objective: To investigate genotoxic and cytotoxic potentials of EEZOR alone and EEZOR pretreatments followed by 0.1 mcg/ ml DXR, a genotoxic chemotherapeutic agent in human lymphocytes by sister chromatid exchange (SCE) assay in vitro. The effect on cell cycle kinetics was also explored.

Material And Method: Human lymphocytes were treated with EEZOR alone at 25-500 mcg/ml and EEZOR pretreated at 12.5-200 mcg/ml followed by 0.1 mcg/ml DXR. SCE levels and cell cycle kinetics were evaluated.

Results: EEZOR significantly induced biphasic SCE at 50 and 400 mcg/ml (p < 0.05). However, cytotoxicity manifested at 500 mcg/ml. All EEZOR pretreatments at 12.5, 25, 50, and 100 mcg/ml, except at 200 mcg/ml, prior to DXR, moderately enhanced DXR-induced genotoxicity by 1.3 times (p < 0.05). Both EEZOR alone and EEZOR prior to DXR at certain concentrations delayed cell cycle.

Conclusion: At specific doses, EEZOR could induce genotoxicity and in pretreatments could moderately enhance DXR-induced genotoxicity and delay cell cycle. This finding suggests that dosage use of EEZOR needs to be adjusted for long-term safety. In addition, EEZOR in adjunct to DXM might have potential benefits not only as an emetic agent but also in chemotherapy. Further in vivo animal and human studies to support this evidence is essentially needed.
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April 2015