Modulation of platelet aggregation by areca nut and betel leaf ingredients: roles of reactive oxygen species and cyclooxygenase

Betel quid use is associated with anemia among both men and women in Matlab, Bangladesh

Anemia accounts for 8.8% of total disability burden worldwide. Betel quid use among pregnant women has been found to increase anemia risk. Betel quid is prepared by wrapping the betel (or areca) nut, with spices and other additions, in betel or tobacco leaf and it is chewed or placed in the mouth. We explored the association between betel quid use and anemia among men and non-pregnant women. We collected data from a random sample of women and their husbands in Matlab, Bangladesh. Participants reported their current betel quid use and individual characteristics. We assessed hemoglobin (a biomarker of anemia) with a hemoglobinometer and soluble transferrin receptor (a biomarker of iron deficiency) and C-reactive protein (a biomarker of inflammation) in dried blood spots via enzyme immunoassay. We estimated logistic regression models to evaluate the association between betel quid use and anemia and structural equation models (SEM) to evaluate mediating roles of iron deficiency and elevated inflammation. A total of 1133 participants (390 men and 743 non-pregnant women) were included. After controlling for important confounders, any betel quid use was positively associated with anemia among men (OR: 1.80; 95% CI: 1.12, 2.89). Among women, betel quid use was associated with anemia only among the most frequent users (OR: 1.62; 95% CI: 1.03, 2.53). SEM did not reveal indirect paths through inflammation or iron deficiency. Betel quid use may contribute to the burden of anemia among adults in Bangladesh. Our findings suggest the burden of disease attributed to betel quid use has been underestimated.

Natural antioxidants from some fruits, seeds, foods, natural products, and associated health benefits: An update

Antioxidants are compounds that inhibit the oxidation of other molecules and protect the body from the effects of free radicals, produced either by normal cell metabolism or as an effect of pollution and exposure to other external factors and are responsible for premature aging and play a role in cardiovascular disease. degenerative diseases such as cataracts, Alzheimer's disease, and cancer. While many antioxidants are found in nature, others are obtained in synthetic form and reduce oxidative stress in organisms. This review highlights the pharmacological relevance of antioxidants in fruits, plants, and other natural sources and their beneficial effect on human health through the analysis and in-depth discussion of studies that included phytochemistry and their pharmacological effects. The information obtained for this review was collected from several scientific databases (ScienceDirect, TRIP database, PubMed/Medline, Scopus, Web of Science), professional websites, and traditional medicine books. Current pharmacological studies and evidence have shown that the various natural antioxidants present in some fruits, seeds, foods, and natural products have different health-promoting effects. Adopting functional foods with high antioxidant potential will improve the effective and affordable management of free radical diseases while avoiding the toxicities and unwanted side effects caused by conventional medication.

Betelvine (Piper betle L.): A comprehensive insight into its ethnopharmacology, phytochemistry, and pharmacological, biomedical and therapeutic attributes

Piper betle L. (synonym: Piper betel Blanco), or betel vine, an economically and medicinally important cash crop, belongs to the family Piperaceae, often known as the green gold. The plant can be found all over the world and is cultivatedprimarily in South East Asian countries for its beautiful glossy heart-shaped leaves, which are chewed or consumed as betelquidand widely used in Chinese and Indian folk medicine, as carminative, stimulant,astringent, against parasitic worms, conjunctivitis, rheumatism, wound, etc., andis also used for religious purposes. Hydroxychavicol is the most important bioactive compound among the wide range of phytoconstituents found in essential oil and extracts. The pharmacological attributes of P. betle are antiproliferation, anticancer, neuropharmacological, analgesic, antioxidant, antiulcerogenic, hepatoprotective, antifertility, antibacterial, antifungal and many more. Immense attention has been paid to nanoformulations and their applications. The application of P. betle did not show cytotoxicity in preclinical experiments, suggesting that it could serve as a promising therapeutic candidate for different diseases. The present review comprehensively summarizes the botanical description, geographical distribution, economic value and cultivation, ethnobotanical uses, preclinical pharmacological properties with insights of toxicological, clinical efficacy, and safety of P. betle. The findings suggest that P. betle represents an orally active and safe natural agent that exhibits great therapeutic potential for managing various human medical conditions. However, further research is needed to elucidate its underlying molecular mechanisms of action, clinical aspects, structure-activity relationships, bioavailability and synergistic interactions with other drugs.

Hydroxychavicol, a polyphenol from Piper betle leaf extract, induces cell cycle arrest and apoptosis in TP53-resistant HT-29 colon cancer cells

This study aims to elucidate the antiproliferative mechanism of hydroxychavicol (HC). Its effects on cell cycle, apoptosis, and the expression of c-Jun N-terminal kinase (JNK) and P38 mitogen-activated protein kinase (MAPK) in HT-29 colon cancer cells were investigated. HC was isolated from Piper betle leaf (PBL) and verified by high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and gas chromatography-mass spectrometry (GC-MS). The cytotoxic effects of the standard drug 5-fluorouracil (5-FU), PBL water extract, and HC on HT-29 cells were measured after 24, 48, and 72 h of treatment. Cell cycle and apoptosis modulation by 5-FU and HC treatments were investigated up to 30 h. Changes in phosphorylated JNK (pJNK) and P38 (pP38) MAPK expression were observed up to 18 h. The half maximal inhibitory concentration (IC₅₀) values of HC (30 μg/mL) and PBL water extract (380 μg/mL) were achieved at 24 h, whereas the IC₅₀ of 5-FU (50 μmol/L) was obtained at 72 h. Cell cycle arrest at the G₀/G₁ phase in HC-treated cells was observed from 12 h onwards. Higher apoptotic cell death in HC-treated cells compared to 5-FU-treated cells (P<0.05) was observed. High expression of pJNK and pP38 MAPK was observed at 12 h in HC-treated cells, but not in 5-FU-treated HT-29 cells (P<0.05). It is concluded that HC induces cell cycle arrest and apoptosis of HT-29 cells, with these actions possibly mediated by JNK and P38 MAPK.

Antioxidant activity of eugenol in Piper betel leaf extract

Background:

Extracts of Piper betel are used for the treatment of various ailments since ages due to its essential properties like antioxidant, anticancer, anti-allergic etc. In the present study antioxidant activity for Piper betel leaf extract and Eugenol was assessed. Eugenol was taken as marker compound.

Methods:

Nitric oxide, Hydroxyl radical and Reducing power assay methods were carried out for assessment of antioxidant activity of Piper betel.

Results:

The antioxidant activity for Nitric oxide, Hydroxyl radical and Reducing power assay at 1000 to 62.5μg/ml was performed. The antioxidant activity of Piper betel leaf extract exhibited the IC50 value for Nitric oxide and Hydroxyl radical >1000 whereas Eugenol exhibited the IC50 value 114.34± 0.46 and 306.44 ± 5.28 respectively, for reducing power assay (RPA) Piper betel leaf extract and Eugenol revealed the RPA value ranging from 0.44-0.08 and 0.53-0.12.

Conclusion:

The benefits of Piper betel have been mentioned in our ancient texts. Keeping in view the emergence of various diseases and the benefits of Piper betei, there is need that every effort should be made to revive this treasure of nature into our daily supplement.

Stimulation of MMP-9 of oral epithelial cells by areca nut extract is related to TGF-β/Smad2-dependent and -independent pathways and prevented by betel leaf extract, hydroxychavicol and melatonin

BACKGROUND

There are 200-600 million betel quid (BQ) chewers in the world. BQ increases oral cancer risk. Matrix metalloproteinase-9 (MMP-9) is responsible for matrix degradation, cancer invasion and metastasis. Whether areca nut extract (ANE), a BQ component, stimulates MMP-9 secretion, and the related signaling pathways awaits investigation.

RESULTS

ANE (but not arecoline) stimulated MMP-9 production of gingival keratinocytes and SAS cancer epithelial cells. ANE stimulated TGF-β1, p-Smad2, and p-TAK1 protein expression. ANE-induced MMP-9 production/expression in SAS cells can be attenuated by SB431542 (ALK5/Smad2 inhibitor), 5Z-7-Oxozeaenol (TAK1 inhibitor), catalase, PD153035 (EGFR tyrosine kinase inhibitor), AG490 (JAK inhibitor), U0126 (MEK/ERK inhibitor), LY294002 (PI3K/Akt inhibitor), betel leaf (PBL) extract, and hydroxychavicol (HC, a PBL component), and melatonin, but not by aspirin.

CONCLUSIONS

AN components contribute to oral carcinogenesis by stimulating MMP-9 secretion, thus enhancing tumor invasion/metastasis. These events are related to reactive oxygen species, TGF-β1, Smad2-dependent and -independent signaling, but not COX. These signaling molecules can be biomarkers of BQ carcinogenesis. PBL, HC and melatonin and other targeting therapy can be used for oral cancer treatment.

METHODS

ANE-induced MMP-9 expression/secretion of oral epithelial cells and related TGF-β1, Smad-dependent and -independent signaling were studied by MTT assay, RT-PCR, western blotting, immunofluorescent staining, and ELISA.

Relationship of Oxidative Stress, Inflammation, and the Risk of Metabolic Syndrome in Patients with Oral Cancer

Oral cancer is the fifth leading cause of cancer death in Taiwan, and the prevalence of metabolic syndrome (MS) has also increased globally. The purpose of this study was to investigate the correlations between the components of MS and oxidative stress and inflammation in patients with oral cancer based on their areca-nut-chewing habits. Two hundred patients diagnosed with oral cancer were recruited, and metabolic parameters, oxidative stress, antioxidant enzyme activities, and inflammatory markers were measured. 63% of the subjects have concomitant MS. Subjects who had an areca-nut-chewing habit had significantly higher levels of fasting glucose (p = 0.04), oxidative stress (p = 0.02), and inflammatory markers (p = 0.02) than those who never chewed. High-density lipoprotein-cholesterol level (p = 0.03) and superoxidase dismutase activity (p = 0.02) were significantly lower in individuals who had chewed or were currently chewers. Areca-nut-chewing habit was associated with the increased risks for MS and hypertriglyceridemia; the components of MS were positively correlated with oxidative stress and inflammation. In conclusion, patients with oral cancer who had an areca-nut-chewing habit exhibited higher levels of oxidative stress and inflammation, which might be related to an increased risk of MS.

An investigation of the antiplatelet effects of succinobucol (AGI-1067)

Succinobucol is a phenolic antioxidant with anti-inflammatory and antiplatelet effects. Given the importance of oxidant stress in modulating platelet-platelet and platelet-vessel wall interactions, the aim of this study was to establish if antioxidant activity was responsible for the antiplatelet activity of succinobucol. Platelet aggregation in response to collagen and adenosine diphosphate (ADP) was studied in rabbit whole blood and platelet-rich plasma using impedance aggregometry. The effect of oxidant stress on aggregation, platelet lipid peroxides, and vascular tone was studied by incubating platelets, washed platelets or preconstricted rabbit iliac artery rings respectively with a combination of xanthine and xanthine oxidase (X/XO). To study the effect of succinobucol in vivo, anaesthetized rats were injected with up to 150 mg/kg succinobucol and aggregation measured in blood removed 15 mins later. Succinobucol (10^-5-10^-4 M) significantly attenuated platelet aggregation to collagen and ADP in whole blood and platelet-rich plasma. X/XO significantly increased aggregation to collagen and platelet lipid peroxides and this was reversed by succinobucol. Addition of X/XO to denuded rabbit iliac arteries caused a dose-dependent relaxation which was significantly inhibited by succinobucol. In vivo administration up to 150 mg/kg had no effect on heart rate or mean arterial blood pressure but significantly inhibited platelet aggregation to collagen ex vivo. In conclusion, succinobucol displays anti-platelet activity in rabbit and rat blood and reverses the increase in platelet aggregation in response to oxidant stress.

Piper betle leaf extract enhances the cytotoxicity effect of 5-fluorouracil in inhibiting the growth of HT29 and HCT116 colon cancer cells

OBJECTIVE

The combination effect of Piper betle (PB) and 5-fluorouracil (5-FU) in enhancing the cytotoxic potential of 5-FU in inhibiting the growth of colon cancer cells was investigated.

METHODS

HT29 and HCT116 cells were subjected to 5-FU or PB treatment. 5-FU and PB were then combined and their effects on both cell lines were observed after 24 h of treatment. PB-5-FU interaction was elucidated by isobologram analysis. Apoptosis features of the treated cells were revealed by annexin V/PI stain. High-performance liquid chromatography (HPLC) was performed to exclude any possible chemical interaction between the compounds.

RESULTS

In the presence of PB extract, the cytotoxicity of 5-FU was observed at a lower dose (IC50 12.5 µmol/L) and a shorter time (24 h) in both cell lines. Both cell lines treated with 5-FU or PB alone induced a greater apoptosis effect compared with the combination treatment. Isobologram analysis indicated that PB and 5-FU interacted synergistically and antagonistically in inhibiting the growth of HT29 and HCT116 cells, respectively.

CONCLUSIONS

In the presence of PB, a lower dosage of 5-FU is required to achieve the maximum drug effect in inhibiting the growth of HT29 cells. However, PB did not significantly reduce 5-FU dosage in HCT116 cells. Our result showed that this interaction may not solely contribute to the apoptosis pathway.

Synthesis and antiplatelet activity of antithrombotic thiourea compounds: biological and structure-activity relationship studies

The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p) displayed IC₅₀ values ranging from 29 to 84 µM with direct influence over in vitro PGE₂ and TXA₂ formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE₂ and TXB₂ production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

Antiplatelet effect of catechol is related to inhibition of cyclooxygenase, reactive oxygen species, ERK/p38 signaling and thromboxane A2 production

Catechol (benzenediol) is present in plant-derived products, such as vegetables, fruits, coffee, tea, wine, areca nut and cigarette smoke. Because platelet dysfunction is a risk factor of cardiovascular diseases, including stroke, atherosclerosis and myocardial infarction, the purpose of this study was to evaluate the anti-platelet and anti-inflammatory effect of catechol and its mechanisms. The effects of catechol on cyclooxygenase (COX) activity, arachidonic acid (AA)-induced aggregation, thromboxane B2 (TXB2) production, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production and extracellular signal-regulated kinase (ERK)/p38 phosphorylation were determined in rabbit platelets. In addition, its effect on IL-1β-induced prostaglandin E2 (PGE2) production by fibroblasts was determined. The ex vivo effect of catechol on platelet aggregation was also measured. Catechol (5-25 µM) suppressed AA-induced platelet aggregation and inhibited TXB2 production at concentrations of 0.5-5 µM; however, it showed little cytotoxicity and did not alter U46619-induced platelet aggregation. Catechol (10-50 µM) suppressed COX-1 activity by 29-44% and COX-2 activity by 29-50%. It also inhibited IL-1β-induced PGE2 production, but not COX-2 expression of fibroblasts. Moreover, catechol (1-10 µM) attenuated AA-induced ROS production in platelets and phorbol myristate acetate (PMA)-induced ROS production in human polymorphonuclear leukocytes. Exposure of platelets to catechol decreased AA-induced ERK and p38 phosphorylation. Finally, intravenous administration of catechol (2.5-5 µmole/mouse) attenuated ex vivo AA-induced platelet aggregation. These results suggest that catechol exhibited anti-platelet and anti-inflammatory effects, which were mediated by inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation. The anti-platelet effect of catechol was confirmed by ex vivo analysis. Exposure to catechol may affect platelet function and thus cardiovascular health.

Areca nut components affect COX-2, cyclin B1/cdc25C and keratin expression, PGE2 production in keratinocyte is related to reactive oxygen species, CYP1A1, Src, EGFR and Ras signaling

AIMS

Chewing of betel quid (BQ) increases the risk of oral cancer and oral submucous fibrosis (OSF), possibly by BQ-induced toxicity and induction of inflammatory response in oral mucosa.

METHODS

Primary gingival keratinocytes (GK cells) were exposed to areca nut (AN) components with/without inhibitors. Cytotoxicity was measured by 3-(4,5-dimethyl- thiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. mRNA and protein expression was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. PGE2/PGF2α production was measured by enzyme-linked immunosorbent assays.

RESULTS

Areca nut extract (ANE) stimulated PGE2/PGF2α production, and upregulated the expression of cyclooxygenase-2 (COX-2), cytochrome P450 1A1 (CYP1A1) and hemeoxygenase-1 (HO-1), but inhibited expression of keratin 5/14, cyclinB1 and cdc25C in GK cells. ANE also activated epidermal growth factor receptor (EGFR), Src and Ras signaling pathways. ANE-induced COX-2, keratin 5, keratin 14 and cdc25C expression as well as PGE2 production were differentially regulated by α-naphthoflavone (a CYP 1A1/1A2 inhibitor), PD153035 (EGFR inhibitor), pp2 (Src inhibitor), and manumycin A (a Ras inhibitor). ANE-induced PGE2 production was suppressed by piper betle leaf (PBL) extract and hydroxychavicol (two major BQ components), dicoumarol (a

NAD(P)H

Quinone Oxidoreductase--NQO1 inhibitor) and curcumin. ANE-induced cytotoxicity was inhibited by catalase and enhanced by dicoumarol, suggesting that AN components may contribute to the pathogenesis of OSF and oral cancer via induction of aberrant differentiation, cytotoxicity, COX-2 expression, and PGE2/PGF2α production.

CONCLUSIONS

CYP4501A1, reactive oxygen species (ROS), EGFR, Src and Ras signaling pathways could all play a role in ANE-induced pathogenesis of oral cancer. Addition of PBL into BQ and curcumin consumption could inhibit the ANE-induced inflammatory response.

A review of the systemic adverse effects of areca nut or betel nut

Areca nut is widely consumed by all ages groups in many parts of the world, especially south-east Asia. The objective of this review is to systematically review and collate all the published data that are related to the systemic effects of areca nut. The literature search was performed by an electronic search of the Pubmed and Cochrane databases using keywords and included articles published till October 2012. We selected studies that covered the effect of areca nut on metabolism, and a total of 62 studies met the criteria. There is substantial evidence for carcinogenicity of areca nut in cancers of the mouth and esophagus. Areca nut affects almost all organs of the human body, including the brain, heart, lungs, gastrointestinal tract and reproductive organs. It causes or aggravates pre-existing conditions such as neuronal injury, myocardial infarction, cardiac arrhythmias, hepatotoxicity, asthma, central obesity, type II diabetes, hyperlipidemia, metabolic syndrome, etc. Areca nut affects the endocrine system, leading to hypothyroidism, prostate hyperplasia and infertility. It affects the immune system leading to suppression of T-cell activity and decreased release of cytokines. It has harmful effects on the fetus when used during pregnancy. Thus, areca nut is not a harmless substance as often perceived and proclaimed by the manufacturers of areca nut products such as Pan Masala, Supari Mix, Betel quid, etc. There is an urgent need to recognize areca nut as a harmful food substance by the policy makers and prohibit its glamorization as a mouth freshener. Strict laws are necessary to regulate the production of commercial preparations of areca nut.

Tobacco exposure may enhance inflammation in prostate carcinoma patients: an explorative study in north Indian population

Prostate cancer is responsible for major deaths globally after lung cancer. However, etiology of prostate cancer is still unknown. Individual risk and incidence of prostate cancer may result from the interaction of genetic susceptibility with exposure to environmental factors such as infectious agents, tobacco, occupational exposure, dietary carcinogens, and/or hormonal imbalances leading to injury of the prostate and to the development of chronic inflammation. About 30% of all human cancers are caused by tobacco smoking and inhaled pollutants. Inflammation is now regarded as an important hallmark of cancer. The present study has been aimed to explore the pro-inflammatory levels in prostate carcinoma patients by examining the serum levels of novel cytokine interleukin-18 (IL-18) expression in tobacco exposed population. A total of 578 (n = 284 biopsy proven prostate cancer patients, n = 294 controls with and without tobacco exposed population) were recruited. Serum IL-18 (Interleukin-18) level was done by ELISA. The IL-18 levels between cancer patients and controls within same mode tobacco exposure as tobacco smoking (overall) showed significant difference (P < 0.0001) and further we compared within stratified group, it significantly differ (P < 0.0001) in bidi and cigarette smoking than control non users. Furthermore, IL-18 levels in tobacco chewers (overall) with gutkha and khaini chewers showed significant difference (P < 0.01) than controls non users. Moreover, the IL-18 levels between cancer patients and controls with in of combined mode chewers smokers and alcohol (CSA), smokers with alcohol showed significant difference (P < 0.01) than controls. The IL-18 levels also differed significantly (P < 0.05) with smokers and chewers in higher stages of III and IV, and showed non significant with in lower stages. Tobacco exposure enhance the inflammation in prostate carcinoma patients in stratified group as it have been represented as a risk factors in various cancers, but this study provide further its role that seems to influence inflammation especially in prostate carcinoma.

Piper betle shows antioxidant activities, inhibits MCF-7 cell proliferation and increases activities of catalase and superoxide dismutase

BACKGROUND

Breast cancer is the most common form of cancer and the focus on finding chemotherapeutic agents have recently shifted to natural products. Piper betle is a medicinal plant with various biological activities. However, not much data is available on the anti-cancer effects of P. betle on breast cancer. Due to the current interest in the potential effects of antioxidants from natural products in breast cancer treatment, we investigated the antioxidant activities of the leaves of P. betle and its inhibitory effect on the proliferation of the breast cancer cell line, MCF-7.

METHODS

The leaves of P. betle were extracted with solvents of varying polarities (water, methanol, ethyl acetate and hexane) and their phenolic and flavonoid content were determined using colorimetric assays. Phenolic composition was characterized using HPLC. Antioxidant activities were measured using FRAP, DPPH, superoxide anion, nitric oxide and hyroxyl radical scavenging assays. Biological activities of the extracts were analysed using MTT assay and antioxidant enzyme (catalase, superoxide dismutase, glutathione peroxidase) assays in MCF-7 cells.

RESULTS

Overall, the ethyl acetate extract showed the highest ferric reducing activity and radical scavenging activities against DPPH, superoxide anion and nitric oxide radicals. This extract also contained the highest phenolic content implying the potential contribution of phenolics towards the antioxidant activities. HPLC analyses revealed the presence of catechin, morin and quercetin in the leaves. The ethyl acetate extract also showed the highest inhibitory effect against the proliferation of MCF-7 cells (IC50=65 μg/ml). Treatment of MCF-7 cells with the plant extract increased activities of catalase and superoxide dismutase.

CONCLUSIONS

Ethyl acetate is the optimal solvent for the extraction of compounds with antioxidant and anti-proliferative activities. The increased activities of catalase and superoxide dismutase in the treated cells could alter the antioxidant defense system, potentially contributing towards the anti-proliferative effect. There is great potential for the ethyl acetate extract of P. betle leaf as a source of natural antioxidants and to be developed as therapeutics in cancer treatment.

Antiplatelet effect of phloroglucinol is related to inhibition of cyclooxygenase, reactive oxygen species, ERK/p38 signaling and thromboxane A2 production

Platelet dysfunction is a major risk factor of cardiovascular diseases such as atherosclerosis, stroke and myocardial infarction. Many antiplatelet agents are used for prevention and treatment of these diseases. In this study, phloroglucinol (2.5-25 μM) suppressed AA-induced platelet aggregation and thromboxane B(2) (TXB(2)) production, but not U46619-induced platelet aggregation. Phloroglucinol (100-250 μM) showed little cytotoxicity to platelets. Phloroglucinol inhibited the COX-1 and COX-2 activities by 45-74% and 49-72% respectively at concentrations of 10-50 μM. At concentrations of 1 and 5 μM, phloroglucinol attenuated the AA-induced ROS production in platelets by 30% and 53%, with an IC(50) of 13.8 μM. Phloroglucinol also inhibited the PMA-stimulated ROS production in PMN. Preincubation of platelets by phloroglucinol (10-25 μM) markedly attenuated the AA-induced ERK and p38 phosphorylation. Intravenous administration of phloroglucinol (2.5 and 5 μmol/mouse) suppressed the ex vivo AA-induced platelet aggregation by 57-71%. Phloroglucinol administration also elevated the mice tail bleeding time. Moreover, phloroglucinol inhibited the IL-1β-induced PGE(2) production in pulp fibroblasts. These results indicate that antiplatelet and anti-inflammatory effects of phloroglucinol are related to inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation in platelets. Phloroglucinol further suppress PMA-induced ROS production in PMN. The antiplatelet effect of phloroglucinol was confirmed by ex vivo study. Clinically, the consumption of phloroglucinol-containing food/natural products as nutritional supplement may be helpful to cardiovascular health. Phloroglucinol has potential pharmacological use.

Atherogenic effect of Arecoline: A computational study

There are over 600 million people worldwide covering Asian and Oceanic countries including India have the habit of chewing areca nut as masticator in different forms. Arecoline (C(8)H(13)NO(2)) has been reported as one of the abundant constituents of areca nut. A good number of scientific publications have made Arecoline responsible for oral cancer. Based on observation from clinical situation in North East India, one of the most betel quid chewing region of the country, we suspected a link between consumption of areca nut and Cerebro Vascular Disease like stroke. Therefore, we considered Low Density Lipoprotein (LDL) receptor as target and Arecoline as ligand and studied ligand -target interaction using computational tools. Also we considered High Density Lipoprotein (HDL) receptor as another target to see if Arecoline has any binding potential with it over and above LDL receptor. Docking result indicated that Arecoline and Cholesterol both, have affinity towards extracellular domain of Human LDL receptor but affinity of Arecoline is much higher (-12.3560.) than that of Cholesterol(-0.1810). Docking of Arecoline and 1, 2-Hexyl-1- cyclopentanone thiosemicarbazone (thiosemicarbazone) with Bovine HDL receptor showed that Arecoline also has the potential (Score, -6.2690Kcal/Mol) to block HDL receptor though its potential is less than that (score, -10.0509 Kcal/Mol) of control (thiosemicarbazone). We, therefore, suggest that by inhibiting endocytosis of LDL cholesterol because of blocking LDL receptor function and also by preventing LDL cholesterol uptake by liver from blood because of interference with HDL receptor, Arecoline may contribute to atherosclerosis. The study therefore, indicates a positive correlation between chewing of betel quid and Cerebro Vascular Disease.

Identification of antiplatelet and acetylcholinesterase inhibitory constituents in betel nut

OBJECTIVE

To investigate the possible mechanism and the compound(s) responsible for the antiplatelet and acetylcholinesterase (AChE) inhibitory effects of Areca catechu crude extract (Ac.Cr).

METHODS

Aqueous-methanol (70%) was used for extraction of plant material (betel nut). Antiplatelet activity was measured in human platelet-rich plasma by using a Lumi-aggregometer while anti-AChE activity was measured spectrophotometrically in vitro. In an attempt to find the responsible compound(s) in betel nut for antiplatelet and anti-AChE activities, different commercially available betel nut compounds were tested.

RESULTS

Ac.Cr inhibited platelet aggregation induced by arachidonic acid (AA), adenosine diphosphate (ADP), platelet-activating factor (PAF), epinephrine and Ca(2+)-ionophore. Ac.Cr was the most potent in inhibiting ADP- and Ca(2+)-ionophore-induced aggregation. In the AChE assay, Ac.Cr showed significant AChE inhibitory activity with almost complete inhibition of the enzyme. Out of the tested compounds, none of the compounds in betel nut showed any antiplatelet effect except for catechin that was the most potent against epinephrine-induced aggregation. Catechin was significantly less potent than Ac.Cr, indicating a presence of additional compound(s) with antiplatelet activity. For the AChE inhibitory effect, only tannic acid, gallic acid, diosgenin and isoguvacine were found to be active, whereby tannic acid was more potent than Ac.Cr.

CONCLUSION

This study shows the possible antiplatelet and AChE inhibitory potential of betel nut while further studies are needed to confirm and identify more compounds in betel nut for these actions.

Chewing areca nut increases the risk of coronary artery disease in Taiwanese men: a case-control study

Background

Areca nut chewing has been reported to be associated with obesity, metabolic syndrome, hypertension, and cardiovascular mortality in previous studies. The aim of this study was to examine whether chewing areca nut increases the risk of coronary artery disease (CAD) in Taiwanese men.

Methods

This study is a hospital-based case-control study. The case patients were male patients diagnosed in Taiwan between 1996 and 2009 as having a positive Treadmill exercise test or a positive finding on the Thallium-201 single-photon emission computed tomography myocardial perfusion imaging. The case patients were further evaluated by coronary angiography to confirm their CAD. Obstructive CAD was defined as a ≥ 50% decrease in the luminal diameter of one major coronary artery. The patients who did not fulfill the above criteria of obstructive CAD were excluded.

The potential controls were males who visited the same hospital for health check-ups and had a normal electrocardiogram but no history of ischemic heart disease or CAD during the time period that the case patients were diagnosed. The eligible controls were randomly selected and frequency-matched with the case patients based on age. Multiple logistic regression analyses were used to estimate the odds ratio of areca nut chewing and the risk of obstructive CAD.

Results

A total of 293 obstructive CAD patients and 720 healthy controls, all men, were analyzed. Subjects who chewed areca nut had a 3.5-fold increased risk (95% CI = 2.0-6.2) of having obstructive CAD than those without, after adjusting for other significant covariates. The dose-response relationship of chewing areca nut and the risk of obstructive CAD was also noted. After adjusting for other covariates, the 2-way additive interactions for obstructive CAD risk were also significant between areca nut use and cigarette smoking, hypertension and dyslipidemia.

Conclusions

Long-term areca nut chewing was an independent risk factor of obstructive CAD in Taiwanese men. Interactive effects between chewing areca nut and cigarette smoking, hypertension, and dyslipidemia were also observed for CAD risk. Further exploration of their underlying mechanisms is necessary.

Arecoline induced cell cycle arrest, apoptosis, and cytotoxicity to human endothelial cells

Betel quid (BQ) chewing is a common oral habit in South Asia and Taiwan. BQ consumption may increase the risk of oral squamous cell carcinoma (OSCC), oral submucous fibrosis (OSF), and periodontitis as well as systemic diseases (atherosclerosis, hypertension, etc.). However, little is known about the toxic effect of BQ components on endothelial cells that play important roles for angiogenesis, carcinogenesis, tissue fibrosis, and cardiovascular diseases. EAhy 926 (EAHY) endothelial cells were exposed to arecoline, a major BQ alkaloid, for various time periods. Cytotoxicity was estimated by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay. The cell cycle distribution of EAHY cells residing in sub-G0/G1, G0/G1, S-, and G2/M phases was analyzed by propidium iodide staining of cellular DNA content and flow cytometry. Some EAHY cells retracted, became round-shaped in appearance, and even detached from the culture plate after exposure to higher concentrations of arecoline (> 0.4 mM). At concentrations of 0.4 and 0.8 mM, arecoline induced significant cytotoxicity to EAHY cells. At similar concentrations, arecoline induced G2/M cell cycle arrest and increased sub-G0/G1 population, a hallmark of apoptosis. Interestingly, prolonged exposure to arecoline (0.1 mM) for 12 and 21 days significantly suppressed the proliferation of EAHY cells, whereas EAHY cells showed adaptation and survived when exposed to 0.05 mM arecoline. These results suggest that BQ components may contribute to the pathogenesis of OSF and BQ chewing-related cardiovascular diseases via toxicity to oral or systemic endothelial cells, leading to impairment of vascular function. During BQ chewing, endothelial damage may be induced by areca nut components and associate with the pathogenesis of OSF, periodontitis, and cardiovascular diseases.

Studies on anti-inflammatory and analgesic activities of betel nut in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Areca catechu, commonly known as betel nut, is very famous for its medicinal use in multiple disorders. It is also popular as a remedy against inflammatory disorders in the Unani (Greco-Arab) system of medicine.

OBJECTIVE OF THE STUDY

This study was aimed at investigating the anti-inflammatory and analgesic activities of the crude extract of Areca catechu and its respective fractions.

MATERIALS AND METHODS

Paw edema, formalin-induced nociception and acetic acid-induced writhing assays were carried out in vivo. Free radical scavenging activity of the plant extract was performed in vitro.

RESULTS

Preliminary experiments using a single dose (100 mg/kg) of Areca catechu and its respective fractions demonstrated an anti-inflammatory effect on carrageenan-induced edema in mice and rats, the aqueous fraction being distinctly more effective. When studied on prostaglandin E₂ (PGE₂), arachidonic acid, histamine, or serotonin (5HT)-induced edema in rats, Areca catechu and its aqueous fraction markedly repressed only the PGE₂ and arachidonic acid-induced inflammation. When studied for analgesic activity, the crude extract and its aqueous fraction produced a dose-dependent (10-100 mg/kg) inhibitory effect on formalin-induced nociception in mice and acetic acid-induced writhing in rats, similar to aspirin. In DPPH assay, Areca catechu and its aqueous fraction exhibited free radical scavenging activity with respective IC(50) values of 5.34 μg/ml (4.93-5.78, CI; 95%, n=5) and 7.28 μg/ml (6.04-7.95, n=4), like that of rutin with IC(50) value of 4.75 μg/ml (3.89-5.42, n=4).

CONCLUSION

These results indicate the anti-inflammatory and analgesic effects of Areca catechu and provide a rationale for its medicinal use in inflammatory disorders.

An ethanol extract of Piper betle Linn. mediates its anti-inflammatory activity via down-regulation of nitric oxide

The leaves of Piper betle (locally known as Paan) have long been in use in the Indian indigenous system of medicine for the relief of pain; however, the underlying molecular mechanisms of this effect have not been elucidated. The anti-inflammatory and immunomodulatory effects of an ethanolic extract of the leaves of P. betle (100 mg kg−1; PB) were demonstrated in a complete Freund's adjuvant-induced model of arthritis in rats with dexamethasone (0.1 mg kg−1) as the positive control. At non-toxic concentrations of PB (5–25 μg mL−1), a dose-dependent decrease in extracellular production of nitric oxide in murine peritoneal macrophages was measured by the Griess assay and corroborated by flow cytometry using the nitric oxide specific probe, 4,5-diaminofluorescein-2 diacetate. This decreased generation of reactive nitrogen species was mediated by PB progressively down-regulating transcription of inducible nitric oxide synthase in macrophages, and concomitantly causing a dose-dependent decrease in the expression of interleukin-12 p40, indicating the ability of PB to down-regulate T-helper 1 pro-inflammatory responses. Taken together, the anti-inflammatory and anti-arthrotic activity of PB is attributable to its ability to down-regulate the generation of reactive nitrogen species, thus meriting further pharmacological investigation.

Antiplatelet effects of piplartine, an alkamide isolated from Piper tuberculatum: possible involvement of cyclooxygenase blockade and antioxidant activity

Objectives

Piplartine (piperlongumine; 5,6-dihydro-1-[1-oxo-3-(3,4,5-trimethoxyphenyl]-2(1H) pyridinone) is an alkaloid amide isolated from Piper species (Piperaceae). It has been reported to show multiple pharmacological activities in vitro and in vivo.

Methods

We evaluated the in-vitro antiplatelet effect of piplartine isolated from the roots of P. tuberculatum, on human platelet aggregation induced in platelet-rich plasma by the agonists collagen, adenosine 5′-diphosphate (ADP), arachidonic acid (AA) and thrombin.

Key findings

Piplartine (100μg/ml) caused a 30% inhibition in platelet aggregation when collagen was the agonist. At 200 μg/ml, piplartine significantly inhibited the aggregation induced by arachidonic acid (100%), collagen (59%) or ADP (52%) but not that induced by thrombin. The highest concentration of piplartine (300 μg/ml) inhibited thrombin- (37%), ADP- (71%) and collagen- (98%) induced aggregation. The inhibitory effect of piplartine on ADP-induced platelet aggregation was not modified by pretreatment with pentoxifylline (a phosphodiesterase inhibitor), l-arginine (a substrate for nitric oxide synthase) or ticlopidine (a P2Y12 purinoceptor antagonist). However, aspirin, a well-known inhibitor of cyclooxygenase, greatly increased the inhibitory effect of piplartine on arachidonic-acid-induced platelet aggregation.

Conclusions

The mechanism underlying the piplartine antiplatelet action is not totally clarified. It could be related to the inhibition of cyclooxgenase activity and a decrease in thromboxane A2 formation, similar to that occurring with aspirin. This and other possible mechanisms require further study.

The n-hexane and chloroform fractions of Piper betle L. trigger different arms of immune responses in BALB/c mice and exhibit antifilarial activity against human lymphatic filarid Brugia malayi

Modulation of immune functions by using herbal plants and their products has become fundamental regime of therapeutic approach. Piper betle Linn. (Piperaceae) is a widely distributed plant in the tropical and subtropical regions of the world and has been attributed as traditional herbal remedy for many diseases. We have recently reported the antifilarial and antileishmanial efficacy in the leaf extract of Bangla Mahoba landrace of P. betle which is a female plant. The present report describes the in vivo immunomodulatory efficacy of the crude methanolic extract and its n-hexane, chloroform, n-butanol fractions of the female plant at various dose levels ranging between 0.3 and 500 mg/kg in BALB/c. Attempts were also made to observe antifilarial activity of the active extracts and correlate it with the antigen specific immune responses in another rodent Mastomys coucha infected with human lymphatic filarial parasite Brugia malayi. The crude methanol extract and n-hexane fraction were found to potentiate significant (p<0.001) enhancement of both humoral (plaque forming cells, hemagglutination titre) as well as cell-mediated (lymphoproliferation, macrophage activation, delayed type hypersensitivity) immune responses in mice. The flow cytometric analysis of splenocytes of treated mice indicated enhanced population of T-cells (CD4(+), CD8(+)) and B-cells (CD19(+)). The n-hexane fraction (3 mg/kg) was found to induce biased type 2 cytokine response as revealed by increased IL-4(+) and decreased IFN-gamma(+) T-cell population while the chloroform fraction (10 mg/kg) produced a predominant type 1 cytokines. Crude methanolic extract (100 mg/kg) demonstrated a mixed type 1 and type 2 cytokine responses thus suggesting a remarkable immunomodulatory property in this plant. The induction of differential T-helper cell immune response appears ideal to overcome immunosuppression as observed in case of lymphatic, filarial Brugia malayi infection which may also be extended to other infections as well.

Antioxidant and pro-oxidant properties of chlorhexidine and its interaction with calcium hydroxide solutions

AIM

To evaluate the antioxidant and pro-oxidant properties of chlorhexidine (CHX).

METHODOLOGY

The scavenging and generation of reactive oxygen species (ROS) by CHX in the presence or absence of saturated Ca(OH)(2) solutions was evaluated. The reaction emitted chemiluminescence in the presence of lucigenin thus was determined by a luminometer to evaluate the levels of ROS production. Changes in DNA conformation were analysed by agarose gel electrophoresis. Paired Student's t-test was used to compare the difference between groups.

RESULTS

Chlorhexidine (0.00002-0.02%) effectively scavenged 56-88% of the superoxide radicals generated by the xanthine/xanthine oxidase reaction. Through analysis of PUC18 DNA conformation changes, CHX was shown to be a mild scavenger of hydroxyl radicals generated by H(2)O(2) plus FeCl(2). However, CHX (>0.083%) decreased the mobility of PUC18 plasmid DNA with potential production of DNA-DNA cross-link and severe DNA breaks (presence of DNA smear) at further higher concentrations. Furthermore, CHX induced ROS production including H(2)O(2) and superoxide radicals in 0.1N NaOH (pH = 12.76) or Ca(OH)(2) (pH = 12.5) solutions.

CONCLUSION

Chlorhexidine exhibited both antioxidant and pro-oxidant properties under different conditions. These events are possibly involved in the killing of root canal and periodontal microorganisms when CHX and Ca(OH)(2) were used in combination or separately. Potential genotoxicity and tissue damage when extruded into the periradicular tissue and at higher concentrations should be considered during periodontal and endodontic practice.

Hydroxychavicol, a novel betel leaf component, inhibits platelet aggregation by suppression of cyclooxygenase, thromboxane production and calcium mobilization

BACKGROUND AND PURPOSE

Platelet hyperactivity is important in the pathogenesis of cardiovascular diseases. Betel leaf (PBL) is consumed by 200-600 million betel quid chewers in the world. Hydroxychavicol (HC), a betel leaf component, was tested for its antiplatelet effect.

EXPERIMENTAL APPROACH

We tested the effect of HC on platelet aggregation, thromboxane B(2) (TXB(2)) and reactive oxygen species (ROS) production, cyclooxygenase (COX) activity, ex vivo platelet aggregation and mouse bleeding time and platelet plug formation in vivo. The pharmacokinetics of HC in rats was also assessed.

KEY RESULTS

HC inhibited arachidonic acid (AA) and collagen-induced platelet aggregation and TXB(2) production. HC inhibited the thrombin-induced TXB(2) production, but not platelet aggregation. SQ29548, suppressed collagen- and thrombin-induced TXB(2) production, but not thrombin-induced platelet aggregation. HC also suppressed COX-1/COX-2 enzyme activity and the AA-induced ROS production and Ca(2+) mobilization. HC further inhibited the ex vivo platelet aggregation of platelet-rich plasma (>100 nmole/mouse) and prolonged platelet plug formation (>300 nmole/mouse) in mesenteric microvessels, but showed little effect on bleeding time in mouse tail. Moreover, pharmacokinetics analysis found that more than 99% of HC was metabolized within 3 min of administration in Sprague-Dawley rats in vivo.

CONCLUSIONS AND IMPLICATIONS

HC is a potent COX-1/COX-2 inhibitor, ROS scavenger and inhibits platelet calcium signaling, TXB(2) production and aggregation. HC could be a potential therapeutic agent for prevention and treatment of atherosclerosis and other cardiovascular diseases through its anti-inflammatory and antiplatelet effects, without effects on haemostatic functions.

Antiplatelet effect of sanguinarine is correlated to calcium mobilization, thromboxane and cAMP production

Sanguinarine is a plant alkaloid present in the root of Sanguinaria canadensis and Poppy fumaria species. Sanguinarine has been used as an antiseptic mouth rinse and a toothpaste additive to reduce dental plaque and gingival inflammation. In this study, we investigated the antiplatelet effects of sanguinarine, aiming to extend its potential pharmacological applications. Sanguinarine inhibited platelet aggregation induced by arachidonic acid (AA), collagen, U46619 and sub-threshold concentration of thrombin (0.05 U/ml) with IC(50) concentrations of 8.3, 7.7, 8.6 and 4.4 microM, respectively. Sanguinarine (5-10 microM) inhibited 10-31% of platelet TXB(2) production, but not platelet aggregation induced by higher concentration of thrombin (0.1 U/ml). SQ29548, a thromboxane receptor antagonist, inhibited the AA-induced platelet aggregation but not TXB(2) production. Sanguinarine suppressed cyclooxygenase-1 (COX-1) activity (IC(50)=28 microM), whereas its effect on COX-2 activity was minimal. Sanguinarine (8, 10 microM) further inhibited the AA-induced Ca(2+) mobilization by 27-62%. In addition, SQ22536, an adenylate cyclase inhibitor, attenuated the inhibitory effect of sanguinarine toward AA-induced platelet Ca(2+) mobilization and aggregation. These results suggest that sanguinarine is a potent antiplatelet agent, which activates adenylate cyclase, inhibits platelet Ca(2+) mobilization, TXB(2) production as well as suppresses COX-1 enzyme activity. Sanguinarine may have therapeutic potential for treatment of cardiovascular diseases related to platelet aggregation.

Inhibition of cyclooxygenase activity, platelet aggregation and thromboxane B2 production by two environmental toxicants: m- and o-cresol

Cresol is a well-known environmental pollutant, toluene metabolite, uremic toxicant and accidental poisoning product. Formocresol, a preparation of formalin and cresol, is also used as a root canal medicament and for pulpotomy of primary teeth. However, little is known about its effect on cardiovascular system. In this study, m-cresol inhibited the AA-induced platelet aggregation by 43-97% at concentrations ranging from 0.25 to 1 mM. Collagen-induced platelet aggregation was also inhibited by 0.25-1 mM of m-cresol by 47-98%. Accordingly, o-cresol (0.1-0.5 mM) also inhibited the AA-induced platelet aggregation by 46-96% and the collagen-induced platelet aggregation by 35-88% at concentrations of 0.1-1 mM. AA- and collagen-induced platelet thromboxane B(2) (TXB(2)) production was inhibited by even 0.1 mM of m-cresol with 88 and 54% of inhibition, respectively. The o-cresol (0.1 mM) also inhibited the AA- and collagen-induced platelet TXB(2) production with 91 and 97% respectively. Although m- and o-cresol (<1 mM) showed little effect on thrombin-induced platelet aggregation, they effectively inhibited the thrombin-induced platelet TXB(2) production. The m-cresol (2 and 5 mM) inhibited the COX-1 activity by 55-99%, but showed little effect on COX-2 enzyme activity. Moreover, o-cresol (0.5 and 1 mM) inhibited the COX-1 activity by 40-95%. COX-2 enzyme activity was inhibited by 68% at a concentration of 5 mM o-cresol. These results indicate that acute cresol-poisoning, direct root canal medication with formocresol or long-term occupational exposure to cresol and toluene may potentially suppress blood clot formation and lead to tissue hemorrhage via inhibition of platelet aggregation, TXB(2) production and COX enzyme activity.

Hydrogen peroxide scavenging activity by non-steroidal anti-inflammatory drugs

Hydrogen peroxide (H2O2) has been shown to be formed during inflammatory processes and is implicated in its pathophysiology. Thus, a putative scavenging activity against this reactive oxygen species (ROS) by anti-inflammatory drugs may be of great therapeutical value. The present study was undertaken to evaluate the scavenging activity for H2O2 by several non-steroidal anti-inflammatory drugs (NSAIDs), namely indomethacin, acemetacin, etodolac, tolmetin, ketorolac, oxaprozin, sulindac and its metabolites sulindac sulfide and sulindac sulfone. The H2O2 scavenging assay was performed by measuring H2O2-elicited lucigenin chemiluminescence using a microplate reader. The specificity of the method was confirmed by the use of catalase, which completely prevented the H2O2-induced lucigenin chemiluminescence. The endogenous antioxidants melatonin and reduced glutathione (GSH) were used as positive controls. The obtained results demonstrated that all the studied NSAIDs display H2O2 scavenging activity, although in different extents. The ranking order of potency found was sulindac sulfone > sulindac sulfide > GSH > sulindac > indomethacin > acemetacin > etodolac > oxaprozin > ketorolac approximately melatonin > tolmetin.

Hamsters chewing betel quid or areca nut directly show a decrease in body weight and survival rates with concomitant epithelial hyperplasia of cheek pouch

Betel quid (BQ) chewing is strongly associated with the occurrence of oral leukoplakia, oral submucous fibrosis, and oral cancer. There are about 200-600 million BQ chewers in the world. Previous animal studies support the potential carcinogenicity of BQ in different test systems. However, little animal experiment has let hamsters or rats to chew BQ directly, similar to that in humans. In the present study, we established a hamster model of chewing BQ or areca nut (AN). A total of 81 2-week-old hamsters were randomly divided into three groups: 25 for control group, 28 for BQ-chewing group, and 28 for AN-chewing group. These animals were fed with powdered diet with/without BQ or AN for 18 months. Although the consumption of BQ or AN showed some variations, hamsters fed with powdered diet could chew and grind AN or BQ into small pieces of coarse fibers during the entire experimental period. The survival rate of AN-chewing hamsters decreased significantly after 6 months of exposure. The mean survival time was 15.6 +/- 0.9 months for control animals, 13.6 +/- 0.98 months for AN-chewing animals, and 15.7 +/- 0.55 months for BQ-chewing animals. The body weight of BQ- or AN-chewing animals also decreased after 4-13 months. Hamsters fed with AN for 18 months showed hyperkeratosis in 80% and acanthosis in 50% of cheek pouches. Animals fed with BQ for 18 months also showed hyperkeratosis in 93% and acanthosis in 14% of cheek pouches. These results indicate that AN and BQ components may induce alterations in proliferation and differentiation of oral epithelial cells. Animal model of chewing BQ or AN can be useful for future tumor initiation, promotion and chemoprevention experiments simulating the condition of BQ chewing in humans.

The induction of prostaglandin E2 production, interleukin-6 production, cell cycle arrest, and cytotoxicity in primary oral keratinocytes and KB cancer cells by areca nut ingredients is differentially regulated by MEK/ERK activation

There are about 200-600 million betel quid (BQ) chewers in the world. BQ chewing is one of the major risk factor of hepatocarcinoma, oropharyngeal, and esophagus cancers in Taiwan, India, and Southeast Asian countries. Thus, the precise molecular mechanisms deserve investigation. We used cultured primary keratinocytes and KB cells, RT-PCR, flow cytometry, Western blotting, and ELISA to evaluate whether alterations in early gene expression is crucial in the carcinogenic processes of BQ. We observed the induction of c-Fos mRNA expression in human gingival keratinocyte (GK) and KB carcinoma cells by areca nut (AN) extract and arecoline. A maximal increment in c-fos gene expression was shown at about 30 min after challenge. AN extract (100-800 microg/ml) and arecoline (0.1-0.8 mM) also stimulated ERK1/ERK2 phosphorylation with a maximal stimulation at 5-10 min of exposure. Pretreatment by U0126 (30 microM), a MEK inhibitor, markedly inhibited the c-Fos, cyclooxygenase-2 (COX-2), and IL-6 mRNA expression of the KB epithelial cells. In addition, U0126 and PD98059 (50 microM) also decreased AN extract- and arecoline-associated PGE2 and IL-6 production in GK and KB cells. However, U0126 by itself arrested the cells in G0/G1 phase, but was not able to prevent AN- and arecoline-induced cell death or apoptosis. In contrast, U0126 enhanced the AN-induced apoptosis of KB cells. AN ingredients thus play a significant role in the pathogenesis of oropharyngeal cancer by activation of MEK1/ERK/c-Fos pathway, which promotes keratinocyte inflammation, cell survival, and affects cell cycle progression.

Roles of keratinocyte inflammation in oral cancer: regulating the prostaglandin E2, interleukin-6 and TNF-alpha production of oral epithelial cells by areca nut extract and arecoline

Betel quid (BQ) chewing is an etiologic factor of oral cancer and submucus fibrosis (OSF). Keratinocyte inflammation is crucial for the pathogenesis of cancer and tissue fibrosis. We found that areca nut (AN) extract (100-400 micro g/ml) induced PGE2 production by KB cells by 2.34- to 23.1-fold and also TNF-alpha production by gingival keratinocytes (GK). Arecoline (0.2-1.2 mM) elevated PGE2 production by KB cells by 2.5- to 6.1-fold. AN extract (200-400 micro g/ml) also induced IL-6 production by GK (7.5- to 8.4-fold) and KB cells. In contrast, arecoline (0.1-1.2 mM) suppressed IL-6 production by GK and KB cells, with 42-81 and 41-63% inhibition, respectively. A 48 h exposure of GK to 800-1200 micro g/ml AN extract led to 37-69% cell death. Arecoline cytotoxicity to GK was noted at concentrations of 0.8-1.2 mM, which led to 28-38% cell death. AN extract (400-800 micro g/ml) induced Cox-2 and IL-6 mRNA expression and also COX-2 protein production by KB cells. IL-6 (5-100 ng/ml) suppressed GK growth by 20-33%, but enhanced oral fibroblast (OMF) and KB cell growth. PGE2 (0.05-5 micro g/ml) and anti-IL-6 antibody (ab) (50-1000 ng/ml) showed little effect on GK and KB cell growth. Incubation of GK and KB cells with aspirin, anti-IL-6 ab and anti-TNF-alpha ab showed little effect on arecoline- and AN-induced cytotoxicity, cell cycle arrest and apoptosis. Exposure to anti-TNF-alpha ab slightly affected arecoline- and AN-modulated PGE2 and IL-6 production by GK and KB cells. Arecoline- and AN-conditioned medium decreased phytohemagglutinin-mediated CD4+ and CD8+ T cell activation. These results indicate that BQ chewing contributes to the pathogenesis of cancer and OSF by impairing T cell activation and by induction of PGE2, TNF-alpha and IL-6 production, which affect oral mucosal inflammation and growth of OMF and oral epithelial cells.

Scavenging property of three cresol isomers against H2O2, hypochlorite, superoxide and hydroxyl radicals

Formocresol has long been used for pulpotomy of primary teeth and as an intracanal medicament. Little is known, however, about the pharmacological effect of tricresols. This study showed that three cresol isomers, o-cresol, m-cresol and p-cresol, are H2O2 scavengers with a 50% inhibitory concentration (IC50) of 502, 6.7 and 10.16 microM, respectively. o-, m- and p-cresol were also shown to be effective scavengers of superoxide radicals generated by xanthine/xanthine oxidase with an IC50 of 282, 153 and > 4000 microM, respectively, as analyzed by luminometer. o-, m- and p-cresol showed protective effects on the DNA breaks generated by H2O2/FeCl2 and FeCl3/ascorbate/H2O2 systems at concentrations ranging from 70 microM to 1.43 mM, o-, m- and p-cresol also showed differential protective effects against DNA breaks induced by 0.17% NaOCl with 100% inhibitory concentration (IC100) of about 10, 1 and 10 mM, respectively. In addition, reaction with 3% H2O2 and 0.17% NaOCl completely prevented NaOCl-induced DNA breaks. The results indicate that the three cresol isomers are effective ROS scavengers and may prevent ROS induced damage when used as pulpotomy agents or as intracanal medicaments. Owing to the difference in the position of the functional hydroxyl group in the three cresol isomers, m-cresol is the most effective ROS scavenger. Concomitant use of H2O2 for root canal irrigation may diminish both the tissue dissolving capacity of NaOCl and NaOCl-induced DNA damage.