Tewin Tencomnao

Rhinacanthus nasutus Extracts Prevent Glutamate and Amyloid-β Neurotoxicity in HT-22 Mouse Hippocampal Cells: Possible Active Compounds Include Lupeol, Stigmasterol and β-Sitosterol

The Herb Rhinacanthus nasutus (L.) Kurz, which is native to Thailand and Southeast Asia, has become known for its antioxidant properties. Neuronal loss in a number of diseases including Alzheimer’s disease is thought to result, in part, from oxidative stress. Glutamate causes cell death in the mouse hippocampal cell line, HT-22, by unbalancing redox homeostasis, brought about by a reduction in glutathione levels, and amyloid-β has been shown to induce reactive oxygen species (ROS) production. Here in, we show that ethanol extracts of R. nasutus leaf and root are capable of dose dependently attenuating the neuron cell death caused by both glutamate and amyloid-β treatment. We used free radical scavenging assays to measure the extracts antioxidant activities and as well as quantifying phenolic, flavonoid and sterol content. Molecules found in R. nasutus, lupeol, stigmasterol and β-sitosterol are protective against glutamate toxicity.

Association between Toll-like receptor 2 (TLR2) polymorphisms and asymptomatic bancroftian filariasis.

Lymphatic filariasis is mainly caused by the filarial nematodes Wuchereria bancrofti and Brugia malayi. Wolbachia, intracellular symbiotic bacteria in filarial parasite, is known to induce immune response predominantly through Toll-like receptor 2 (TLR2). This study was performed to investigate the association between polymorphisms of the TLR2 gene and susceptibility to asymptomatic bancroftian filariasis. A total of 142 unrelated asymptomatic bancroftian filariasis patients and 151 endemic normal controls in Tak province, Thailand were recruited into this study. The −196 to −173 deletion (del) polymorphism in the 5′ untranslated region was investigated by allele-specific polymerase chain reaction. Two single nucleotide polymorphisms, +597 T>C and +1350 T>C, in exon 3 were identified by polymerase chain reaction–restriction fragment length polymorphism analysis. Furthermore, we analyzed the functional difference between the TLR2 −196 to −173 del and wild-type (wt) alleles using the luciferase reporter assay. All three polymorphisms were associated with a higher risk of asymptomatic bancroftian filariasis and were in strong linkage disequilibrium with each other. The TLR2 haplotype −196 to −173del/+597C/+1350C was strongly associated with an increased risk of asymptomatic bancroftian filariasis. The TLR2 −196 to −173 del allele had a significantly lower transcriptional activity than wt allele. The results of our study indicate that TLR2 −196 to −173 del, +597 T>C and +1350 T>C polymorphisms are associated with asymptomatic bancroftian filariasis in Thailand. Our functional study also supports this finding with respect to differential TLR2 gene expression by −196 to −173 del polymorphism.

Effects of Thai Medicinal Herb Extracts with Anti-Psoriatic Activity on the Expression on NF-κB Signaling Biomarkers in HaCaT Keratinocytes

Psoriasis is a chronic inflammatory skin disorder characterized by rapid proliferation of keratinocytes and incomplete keratinization. Discovery of safer and more effective anti-psoriatic drugs remains an area of active research at the present time. Using a HaCaT keratinocyte cell line as an in vitro model, we had previously found that ethanolic extracts from three Thai medicinal herbs, namely Alpinia galanga, Curcuma longa and Annona squamosa, possessed anti-psoriatic activity. In the current study, we aimed at investigating if these Thai medicinal herb extracts played a molecular role in suppressing psoriasis via regulation of NF-κB signaling biomarkers. Using semi-quantitative RT-PCR and report gene assays, we analyzed the effects of these potential herbal extracts on 10 different genes of the NF-κB signaling network in HaCaT cells. In accordance with our hypothesis, we found that the extract derived from Alpinia galanga significantly increased the expression of TNFAIP3 and significantly reduced the expression of CSF-1 and NF-κB2. Curcuma longa extract significantly decreased the expression of CSF-1, IL-8, NF-κB2, NF-κB1 and RelA, while Annona squamosa extract significantly lowered the expression of CD40 and NF-κB1. Therefore, this in vitro study suggested that these herbal extracts capable of functioning against psoriasis, might exert their activity by controlling the expression of NF-κB signaling biomarkers.

Association of angiotensin-converting enzyme gene promoter single nucleotide polymorphisms and haplotype with major depression in a northeastern Thai population

Introduction. Angiotensin-converting enzyme (ACE) is thought to influence the activity of the hypothalamic-pituitary-adrenocortical system, which shows hyperactivity in the majority of patients with major depressive disorder (MDD). This study aimed at determining an association between two single nucleotide polymorphisms (SNPs) (rs4291;−240A/T and rs4292;−93T/C) of the ACE gene promoter and MDD in northeastern Thais. Subjects and methods. In the present case-control study, genotyping of 187 unrelated patients with MDD (44.89±12.92 years) and 207 unrelated healthy controls (41.34±9.76 years) from the northeastern part of Thailand was performed using polymerase chain reaction-restriction fragment length polymorphism technique. Results. Comparing the two groups, no significant difference was observed with regard to either genotype distributions or allele frequencies of the −93T/C SNP of ACE. For the −240A/T SNP, a significant difference in genotype distributions was found (χ2=6.65, df=2, p=0.036).The presence of the −240A allele of ACE was associated with a decreased risk for MDD compared with the −240T allele (χ2=4.24, df=1, p=0.040, odds ratio=0.702 [95% confidence interval=0.508—0.971]). Moreover, haplotype frequency analysis revealed that the −240T/—93T combination was significantly over-represented in patients with MDD in comparison with controls (13.6% and 6.8%, p=0.002 on χ2 test, empirical p=0.004). Conclusions. In the present investigation, an association between the −240A allele and a reduced risk for MDD was observed, but the genotype distributions of controls were only just in marginal agreement with Hardy-Weinberg equilibrium.The T-T haplotype in the ACE gene was significantly associated with an increased risk for MDD.

Rhinacanthus nasutus Protects Cultured Neuronal Cells against Hypoxia Induced Cell Death

Rhinacanthus nasutus (L.) Kurz (Acanthaceae) is an herb native to Thailand and Southeast Asia, known for its antioxidant properties. Hypoxia leads to an increase in reactive oxygen species in cells and is a leading cause of neuronal damage. Cell death caused by hypoxia has been linked with a number of neurodegenerative diseases including some forms of dementia and stroke, as well as the build up of reactive oxygen species which can lead to diseases such as Huntington’s disease, Parkinson’s disease and Alzeheimer’s disease. In this study we used an airtight culture container and the Mitsubishi Gas Company anaeropack along with the MTT assay, LDH assay and the trypan blue exlusion assay to show that 1 and 10 µg mL−1 root extract of R. nasutus is able to significantly prevent the death of HT-22 cells subjected to hypoxic conditions, and 0.1 to 10 µg mL−1 had no toxic effect on HT-22 under normal conditions, whereas 100 µg mL−1 reduced HT-22 cell proliferation. We also used H2DCFDA staining to show R. nasutus can reduce reactive oxygen species production in HT-22 cells.

Turmeric Toxicity in A431 Epidermoid Cancer Cells Associates with Autophagy Degradation of Anti-apoptotic and Anti-autophagic p53 Mutant

The keratinocyte‐derived A431 Squamous Cell Carcinoma cells express the p53R273H mutant, which has been reported to inhibit apoptosis and autophagy. Here, we show that the crude extract of turmeric (Curcuma longa), similarly to its bioactive component Curcumin, could induce both apoptosis and autophagy in A431 cells, and these effects were concomitant with degradation of p53. Turmeric and curcumin also stimulated the activity of mTOR, which notoriously promotes cell growth and acts negatively on basal autophagy. Rapamycin‐mediated inhibition of mTOR synergized with turmeric and curcumin in causing p53 degradation, increased the production of autophagosomes and exacerbated cell toxicity leading to cell necrosis. Small‐interference mediated silencing of the autophagy proteins BECLIN 1 or ATG7 abrogated the induction of autophagy and largely rescued p53 stability in Turmeric‐treated or Curcumin‐treated cells, indicating that macroautophagy was mainly responsible for mutant p53 degradation. These data uncover a novel mechanism of turmeric and curcumin toxicity in chemoresistant cancer cells bearing mutant p53. Copyright

Amyloidosis in Alzheimer’s Disease: The Toxicity of Amyloid Beta (Aβ), Mechanisms of Its Accumulation and Implications of Medicinal Plants for Therapy

Alzheimers disease (AD) is a progressive neurodegenerative disorder that leads to memory deficits and death. While the number of individuals with AD is rising each year due to the longer life expectancy worldwide, current therapy can only somewhat relieve the symptoms of AD. There is no proven medication to cure or prevent the disease, possibly due to a lack of knowledge regarding the molecular mechanisms underlying disease pathogenesis. Most previous studies have accepted the “amyloid hypothesis,” in which the neuropathogenesis of AD is believed to be triggered by the accumulation of the toxic amyloid beta (Aβ) protein in the central nervous system (CNS). Lately, knowledge that may be critical to unraveling the hidden pathogenic pathway of AD has been revealed. This review concentrates on the toxicity of Aβ and the mechanism of accumulation of this toxic protein in the brain of individuals with AD and also summarizes recent advances in the study of these accumulation mechanisms together with the role of herbal medicines that could facilitate the development of more effective therapeutic and preventive strategies.

The PEI-introduced CS shell/PMMA core nanoparticle for silencing the expression of E6/E7 oncogenes in human cervical cells.

In this study, we examined the potential of cationic nanoparticle - polyethyleneimine-introduced chitosan shell/poly (methyl methacrylate) core nanoparticles (CS-PEI) for siRNA delivery. Initially, DNA delivery was performed to validate the capability of CS-PEI for gene delivery in the human cervical cancer cell line, SiHa. siRNA delivery were subsequently carried out to evaluate the silencing effect on targeted E6 and E7 oncogenes. Physicochemical properties including size, zeta potential and morphology of CS-PEI/DNA and CS-PEI/siRNA complexes, were analyzed. The surface charges and sizes of the complexes were observed at different N/P ratios. The hydrodynamic sizes of the CS-PEI/DNA and CS-PEI/siRNA were approximately 300-400 and 400-500nm, respectively. Complexes were positively charged depending on the amount of added CS-PEI. AFM images revealed the mono-dispersed and spherical shapes of the complexes. Gel retardation assay confirmed that CS-PEI nanoparticles completely formed complexes with DNA and siRNA at a N/P ratio of 1.6. For DNA transfection, CS-PEI provided the highest transfection result. Localization of siRNA delivered through CS-PEI was confirmed by differential interference contrast (DIC) confocal imaging. The silencing effect of siRNA specific to HPV 16 E6/E7 oncogene was examined at 18 and 24h post-transfection. The results demonstrated the capacity of CS-PEI to suppress the expression of HVP oncogenes.

Effects of Thai black sticky rice extract on oxidative stress and lipid metabolism gene expression in HepG2 cells.

Anthocyanins, which are found in some food, including Thai black sticky rice, are reported to have health-promoting properties. Oxidative stress plays a major role in the pathogenesis of many degenerative diseases induced by free radicals, such as cardiovascular disease, stroke and cancer. We evaluated the anthocyanin-rich extract (ARE) from Thai black sticky rice for antioxidative and antihyperlipidemic effects on HepG2 cells. Cell viability was investigated with the neutral red assay and the MTT assay, and oxidative stress was determined by the DCFH-DA assay. RT-PCR was used to evaluate the effect of ARE on LDLR, HMG-CoAR, PPAR (α1,γ) and LXRa gene expression. We found that ARE at high doses (≥ 800 mg/L) induces cytotoxicity. However, at 600-1000 mg/L it reduced intracellular oxidative stress (P < 0.05) in a dose-dependent manner, and at 200 mg/L it significantly enhanced the expression of the LDLR gene in HepG2 cells. We concluded that ARE can be beneficial for health promotion by reducing oxidative stress and enhancing LDL clearance, regulating LDLR production on the cell surface membrane, thereby maintaining lipid homeostasis.

No relationship found between -1438A/G polymorphism of the serotonin 2A receptor gene (rs6311) and major depression susceptibility in a northeastern Thai population.

Several lines of evidence suggest a molecular role of -1438A/G single nucleotide polymorphism in the 5-HTR2A gene promoter (rs6311) in regulating the expression of this gene, making rs6311 polymorphism a promising candidate for an association study. We looked for a possible association between rs6311 polymorphism and major depressive disorder (MDD) in a northeastern Thai population. We included 180 patients with MDD and 183 unrelated healthy controls in our study. Genotyping was performed using PCR-RFLP. We found no significant differences between the two groups with regard to both genotype distributions (chi(2) = 1.32, d.f. = 2, P = 0.516) and allele frequencies (chi(2) = 0.01, d.f. = 1, P = 0.913, odds ratio = 0.96, 95% confidence interval = 0.67-1.39). Therefore, this single nucleotide polymorphism appears not to be involved in the etiology of MDD.