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PubMed1998

Molecular characterization of CDSP 34, a chloroplastic protein induced by water deficit in Solanum tuberosum L. plants, and regulation of CDSP 34 expression by ABA and high illumination.

We previously described the accumulation of a 34 kDa thylakoid protein, named CDSP 34 for chloroplastic drought-induced stress protein, in Solanum tuberosum plants subjected to water deficit. A full-length CDSP 34 cDNA has been isolated and we report here that mature CDSP 34 is highly similar to two chromoplastic proteins, fibrillin from Capsicum annuum and CHRC (for chromoplast protein C) from Cucumis sativus, components of carotenoid-accumulating structures. Northern and Western analyses showed that both CDSP 34 transcript and protein accumulated from early stages of water deficit. In water-stressed tomato plants, similar increases in the CDSP 34-related transcript amount were noticed in wild-type and ABA-deficient flacca mutant, but protein accumulation was observed only in wild-type, suggesting a posttranscriptional role of ABA in CDSP 34 synthesis regulation. Substantial increases in CDSP 34 transcript and protein abundances were also observed in potato plants subjected to high illumination. The CDSP 34 protein is proposed to play a structural role in stabilizing stromal lamellae thylakoids upon osmotic or oxidative stress.

Abscisic Acid↗
PubMed2002

Polyphenol-enriched extract of oil palm fronds (Elaeis guineensis) promotes vascular relaxation via endothelium-dependent mechanisms.

Plant-based polyphenolic compounds have been reported to possess cardiovascular health benefits. Several dietary sources, including herbs and spices, fruits and vegetables, and tea and wine, contain an array of biologically active compounds that have been shown to be effective in retarding oxidation of low-density lipoproteins (LDL) and promoting vascular relaxation. In the present study four different plant sources, both edible and non-edible, were evaluated for potential activity. Organic extracts enriched in polyphenols were prepared from palm fronds (Elaesis guineensis); lemongrass (Cymbopogon citrates); papaya shoots (Carica papaya) and green chilli (Capsicum frutescenes) and tested for their ability to prevent in vitro oxidation of LDL, and for potential vascular relaxation actions. Rings of rat thoracic aorta and isolated perfused mesenteric vascular beds were mounted in organ baths, contracted using a half-maximal dose of noradrenaline and exposed to cumulative additions of test extracts. Palm frond extract resulted in considerable relaxation (>75%) in both preparations and was found to be endothelium-dependent as removal of endothelium or inhibition of endogenous nitric oxide (NO) led to a total loss in relaxant activity. Lemongrass extract caused a greater relaxation action in the mesenteric preparation compared to aortic rings, and appears to be mediated via NO-independent and non-prostanoid mechanisms. Of the extracts tested, palm fronds also demonstrated the highest antioxidant capacity, as determined by the ferric reducing activity/potential assay, and resulted in a significant delay (P < 0.05) in the oxidation of LDL. Collectively, these preliminary findings lend further support to the potential cardiovascular actions of plant polyphenols and also identify oil palm fronds as containing constituents that promote vascular relaxation via endothelium-dependent mechanisms.

Animals↗
PubMed2002

Morbidity mortality paradox of 1st generation Greek Australians.

There is evidence in Australia that 1st generation Greek Australians (GA), despite their high prevalence of cardiovascular disease (CVD) risk factors (e.g. obesity, diabetes, hyperlipidaemia, smoking, hypertension, sedentary lifestyles) continue to display more than 35% lower mortality from CVD and overall mortality compared with the Australian-born after at least 30 years in Australia. This has been called a 'morbidity mortality paradox' or 'Greek-migrant paradox'. Retrospective data from elderly Greek migrants participating in the International Union of Nutrition Sciences Food Habits in Later Life (FHILL) study suggests that diets changed on migration due to the: (i) lack of familiar foods in the new environment; (ii) abundant and cheap animal foods (iii) memories of hunger before migration; and (iv) status ascribed to energy dense foods (animal foods, white bread and sweets) and 'plumpness' as a sign of affluence and plant foods (legumes, vegetable dishes, grainy bread) and 'thinness' as a sign of poverty. This apparently resulted in traditional foods (e.g. olive oil) being replaced with 'new' foods (e.g. butter), 'traditional' plant dishes being made more energy dense, larger serves of animal foods, sweets and fats being consumed, and increased frequency of celebratory feasts. This shift in food pattern contributed to significant weight gain in GA. Despite these potentially adverse changes, data from Greece in the 1960s (seven countries study) and from Australia in the 1990s (FHILL study) has shown that Greek migrants have continued to eat large serves of putatively protective foods (leafy vegetables, onions, garlic, tomatoes, capsicum, lemon juice, herbs, legumes, fish) prepared according to Greek cuisine (e.g. vegetables stewed in oil). Furthermore, GA were found to return to the traditional Greek food pattern with advancing years. We suspect that these factors may explain why GA have recently been found to have over double the circulating concentrations of antioxidant carotenoids, especially lutein, compared with Australians of Anglo-Celtic ancestry. This in turn may have helped to make the CVD risk factors 'benign' and reduce the risk of death. This raises the question whether specific dietary guidelines need to be developed for recent migrants to Australia, encouraging them to retain the best of their traditional cultures and include the best of the mainstream culture.

Acculturation↗
PubMed2001

The efficacy and safety of a homeopathic gel in the treatment of acute low back pain: a multi-centre, randomised, double-blind comparative clinical trial.

Acute low back pain is a very common condition in Western industrialised countries. In most cases analgesics or topical medications are prescribed at first encounter with the general practitioner (GP). The aim of this study was to investigate whether the homeopathic gel Spiroflor SRL gel (SRL) is equally effective and better tolerated than Cremor Capsici Compositus FNA (CCC) in patients with acute low back pain. A multi-centre, randomised, double-blind, controlled clinical trial was conducted in the practices of 19 GPs in the districts of Bristol and Manchester, UK. One hundred and sixty-one subjects suffering from acute low back pain were treated for one week either with SRL or with CCC. Pain was scored on a 100 mm visual analogue scale (VAS). Main efficacy parameter VAS reduction was compared between treatments. Evaluation of safety was primarily based on the number of subjects with adverse events (AEs), withdrawals due to an AE and adverse drug reactions (ADRs). The mean difference between the VAS reduction in the SRL group and the CCC group adjusted for VAS at baseline and age was -0.6mm (90% CI = -6.5-5.3mm). Fewer subjects in the SRL group (11%) experienced an AE than in the CCC group (26%). The same applies to the number of subjects with an ADR (3/81 = 4% vs 18/74 = 24%) and the number of subjects withdrawn due to an ADR (0/81 = 0% vs 8/74 = 11%). In conclusion, SRL and CCC are equally effective in the treatment of acute low back pain, however, SRL has a better safety profile. Spiroflor SRL gel is preferable to Capsicum-based products for the topical treatment of low back pain, because of the lower risk of adverse effects.

Administration, Cutaneous↗
PubMed2000

Biosynthesis of terpenoids: YgbB protein converts 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate to 2C-methyl-D-erythritol 2,4-cyclodiphosphate.

In many microorganisms, the putative orthologs of the Escherichia coli ygbB gene are tightly linked or fused to putative orthologs of ygbP, which has been shown earlier to be involved in terpenoid biosynthesis. The ygbB gene of E. coli was expressed in a recombinant E. coli strain and was shown to direct the synthesis of a soluble, 17-kDa polypeptide. The recombinant protein was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol 2-phosphate into 2C-methyl-D-erythritol 2,4-cyclodiphosphate and CMP. The structure of the reaction product was established by NMR spectroscopy using (13)C-labeled substrate samples. The enzyme-catalyzed reaction requires Mn(2+) or Mg(2+) but no other cofactors. Radioactivity from [2-(14)C]2C-methyl-D-erythritol 2,4-cyclodiphosphate was diverted efficiently to carotenoids by isolated chromoplasts from Capsicum annuum and, thus, was established as an intermediate in the deoxyxylulose phosphate pathway of isoprenoid biosynthesis. YgbB protein also was found to convert 4-diphosphocytidyl-2C-methyl-D-erythritol into 2C-methyl-D-erythritol 3,4-cyclophosphate. This compound does not serve as substrate for the formation of carotenoids by isolated chromoplasts and is assumed to be an in vitro product without metabolic relevance.

Bacterial Proteins↗
PubMed2000

An alternative pathway to beta -carotene formation in plant chromoplasts discovered by map-based cloning of beta and old-gold color mutations in tomato.

Carotenoid pigments in plants fulfill indispensable functions in photosynthesis. Carotenoids that accumulate as secondary metabolites in chromoplasts provide distinct coloration to flowers and fruits. In this work we investigated the genetic mechanisms that regulate accumulation of carotenoids as secondary metabolites during ripening of tomato fruits. We analyzed two mutations that affect fruit pigmentation in tomato (Lycopersicon esculentum): Beta (B), a single dominant gene that increases beta-carotene in the fruit, and old-gold (og), a recessive mutation that abolishes beta-carotene and increases lycopene. Using a map-based cloning approach we cloned the genes B and og. Molecular analysis revealed that B encodes a novel type of lycopene beta-cyclase, an enzyme that converts lycopene to beta-carotene. The amino acid sequence of B is similar to capsanthin-capsorubin synthase, an enzyme that produces red xanthophylls in fruits of pepper (Capsicum annum). Our results prove that beta-carotene is synthesized de novo during tomato fruit development by the B lycopene cyclase. In wild-type tomatoes B is expressed at low levels during the breaker stage of ripening, whereas in the Beta mutant its transcription is dramatically increased. Null mutations in the gene B are responsible for the phenotype in og, indicating that og is an allele of B. These results confirm that developmentally regulated transcription is the major mechanism that governs lycopene accumulation in ripening fruits. The cloned B genes can be used in various genetic manipulations toward altering pigmentation and enhancing nutritional value of plant foods.

Chloroplasts↗
PubMed1988

Carotenoid biosynthesis: Isolation and characterization of a bifunctional enzyme catalyzing the synthesis of phytoene.

Phytoene is the first C(40) intermediate in the biogenesis of carotenoids. It is formed by two enzyme activities, catalyzing (i) the coupling of two molecules of geranylgeranyl diphosphate to yield prephytoene diphosphate and (ii) the conversion of prephytoene diphosphate into phytoene. We show now, with Capsicum chromoplast stroma, that the overall activity resides in a single protein, which has been purified to homogeneity by affinity chromatography. The monomeric structure and the molecular size (M(r) 47,500) were demonstrated by NaDodSO(4)/PAGE and glycerol gradient centrifugation. Further characterization was achieved by using specific antibodies which allowed immunofractionation and immunoprecipitation of the enzymatic activity from chromoplast stroma. The two reactions followed conventional Michaelis-Menten kinetics, with K(m) values of 0.30 muM and 0.27 muM, respectively, for geranylgeranyl diphosphate and prephytoene diphosphate. The activity of the enzyme depends strictly upon the presence of Mn(2+). This selectivity may be one of the factors regulating the competition with potentially rival enzymes converting geranylgeranyl diphosphate into other plastid terpenoids. The two enzymatic reactions were inhibited by inorganic pyrophosphate and by the arginine-specific reagent hydroxyphenylglyoxal. In no instance were the two reactions kinetically uncoupled. These properties strongly suggest that the same enzyme catalyzes the two consecutive reactions, and we propose to name it phytoene synthase.

Journal Article↗
PubMed1999

Cytidine 5'-triphosphate-dependent biosynthesis of isoprenoids: YgbP protein of Escherichia coli catalyzes the formation of 4-diphosphocytidyl-2-C-methylerythritol.

2-C-methylerythritol 4-phosphate has been established recently as an intermediate of the deoxyxylulose phosphate pathway used for biosynthesis of terpenoids in plants and in many microorganisms. We show that an enzyme isolated from cell extract of Escherichia coli converts 2-C-methylerythritol 4-phosphate into 4-diphosphocytidyl-2-C-methylerythritol by reaction with CTP. The enzyme is specified by the hitherto unannotated ORF ygbP of E. coli. The cognate protein was obtained in pure form from a recombinant hyperexpression strain of E. coli harboring a plasmid with the ygbP gene under the control of a T5 promoter and lac operator. By using the recombinant enzyme, 4-diphosphocytidyl-[2-(14)C]2-C-methylerythritol was prepared from [2-(14)C]2-C-methylerythritol 4-phosphate. The radiolabeled 4-diphosphocytidyl-2-C-methylerythritol was shown to be efficiently incorporated into carotenoids by isolated chromoplasts of Capsicum annuum. The E. coli ygbP gene appears to be part of a small operon also comprising the unannotated ygbB gene. Genes with similarity to ygbP and ygbB are present in the genomes of many microorganisms, and their occurrence appears to be correlated with that of the deoxyxylulose pathway of terpenoid biosynthesis. Moreover, several microorganisms have genes specifying putative fusion proteins with ygbP and ygbB domains, suggesting that both the YgbP protein and the YgbB protein are involved in the deoxyxylulose pathway. A gene from Arabidopsis thaliana with similarity to ygbP carries a putative plastid import sequence, which is well in line with the assumed localization of the deoxyxylulose pathway in the plastid compartment of plants.

Amino Acid Sequence↗
PubMed1991

Effects of capsaicin on rat liver S9-mediated metabolism and DNA binding of aflatoxin.

At concentrations of 25, 50, and 100 microM, capsaicin, which is the major component in various aspects of Capsicum hot peppers, decreased the binding of aflatoxin (AFB1) to calf thymus DNA by 19%, 44%, and 71%, respectively, in incubations with rat liver S9. At concentrations of 50 and 100 microM, capsaicin decreased the formation of AFB-DNA adducts (AFB1-N7-Gua) by 53% and 75% as determined by high-pressure liquid chromatography (HPLC). HPLC analysis of organo-soluble fractions showed that these effects correlated with a concentration-dependent decrease in S9-mediated metabolism of AFB1 by capsaicin. Capsaicin also altered the formation of water-soluble conjugates of AFB1. This was indicated by a decrease in radioactivity in water-soluble fractions and in glutathione conjugates of AFB1 analyzed by HPLC. These results suggest that capsaicin inhibited the biotransformation of AFB1 by modifying Phase I hepatic enzyme activity.

Aflatoxin B1↗
PubMed2004

Determination of cadmium and lead in vegetables by stripping chronopotentiometry.

A method for the determination of cadmium and lead in vegetables by stripping chronopotentiometric analysis, after digestion of the sample with concentrated sulphuric acid and dry-ashing, is described. Metal ions were concentrated as their amalgams on a glassy carbon-working electrode previously coated with a thin mercury film and then stripped by a suitable oxidant. Potential and time data were digitally derived and E was plotted versus dt/dE(-1), thus increasing both the sensitivity of the method and the resolution of the analysis. Quantitative analysis was carried out by the method of standard addition; good linearity was obtained in the range of examined concentrations, as was shown by the determination coefficients, which were 0.998 (n = 4) for cadmium and 0.993 (n = 4) for lead. Recoveries of 85-100% for cadmium and of 84-97% for lead were obtained from a sample spiked at different levels. Accuracy was demonstrated by analysis of a matching reference sample of cabbage. The detection limits were 1.8 ng g(-1) of wet mass for cadmium and 5.1 ng g(-1) of wet mass for lead. The relative standard deviations (mean of nine determinations), evaluated on a real sample, were 6.7 and 6.2%, respectively. Results obtained on 10 different commercial samples of pepper (Capsicum annuum), and egg plant (Solanum melongena) were not significantly different from those obtained by graphite furnace atomic absorption spectrophotometry technique. The average content was in the range 3.1-18.6 ng g(-1) for cadmium and 38.2-64.3 ng g(-1) for lead.

Cadmium↗
PubMed2001

Microbiological quality of fresh leafy vegetables, salad components and ready-to-eat salads: an evidence of inhibition of Listeria monocytogenes in tomatoes.

A total of 116 samples of 11 different fresh vegetables from a local market generally consumed in raw form as well as 12 samples of ready-to-eat green salads procured from three grade 1 and 2 restaurants in Mumbai, India were examined for overall microbial quality in terms of bacterial, mold and coliform levels and incidence of pathogens such as Listeria and Yersinia. Standard procedures and media were used for isolation and identification studies. Thoroughly washed samples of 26 leafy vegetables, 12 roots, 62 tomatoes and four samples each of cabbage, capsicum and cucumber showed total bacterial and yeast-mold count in 10(6)-10(7) cfu/gm and 10(2)-10(5) cfu/gm range respectively. On the other hand, higher range of bacterial (10(6)-10(8) cfu/gm) and mold (10(4)-10(7) cfu/gm) count were noticed in ready-to-eat salads from restaurants. The MPN index/gm for coliforms for vegetables from a local market ranged from < 3 to > 1100 whereas for ready-to-eat salads it was 11 to 460. Evidence of higher number of coliforms was observed mostly in green leafy vegetables. All (100%) local vegetables exhibited the incidence of Listeria and Yersinia. On the other hand, ready-to-eat salads showed 20 and 73% presence of Yersinia and Listeria respectively. Higher occurrence of fecal coliforms was (65.6%) found in raw vegetables while they were absent in ready-to-eat salad samples. Non-pathogenic species like Y. intermedia and L. innocua were predominating species in most of the samples. Nevertheless, presence of L. monocytogenes was observed in 7 out of 62 tomatoes, 5 out of 10 coriander leaves, 2 out of 4 spinach samples and one from 4 cabbage samples. Studies conducted to understand the ability of L. monocytogenes 036 and 35152 to grow in tomato in the presence of naturally occurring bacteria suggested that artificially inoculated (10(3) cfu/ml) cells are killed after 3 days, 12 days and 14 days of incubation at 37 degrees C, 8-10 degrees C and 2-4 degrees C respectively.

Colony Count, Microbial↗
PubMed2004

Involvement of NADPH oxidase-mediated generation of reactive oxygen species in the apototic cell death by capsaicin in HepG2 human hepatoma cells.

Although capsaicin (8-methyl-N-vanillyl-6-nonenamide), a pungent ingredient in a variety of red peppers of the genus Capsicum, has been shown to induce apoptotic cell death in many cancer cells, the exact mechanism of this action of capsaicin is not completely understood. In this study, we investigated the possible mediation of the NADPH oxidase-modulated production of reactive oxygen species (ROS) in the apoptotic mechanism of capsaicin in HepG2 human hepatoblastoma cells. Capsaicin induced apoptotic cell death in a time- and dose-dependent manner. Capsaicin at the concentration of inducing apoptosis also markedly increased the level of ROS. The capsaicin-induced generation of ROS and apoptosis was significantly suppressed by treatment with antioxidants, DPPD and tocopherol. In addition, inhibitors of NADPH oxidase, diphenylene iodonium, apocynin and neopterine, profoundly blocked the capsaicin-induced ROS generation and apoptosis. The expression of Rac1N17, a dominant negative mutant of Rac1, also significantly inhibited the capsaicin-induced apoptosis. Activation of nuclear factor-kappaB, a transcription factor essentially involved in ROS-induced apoptosis, was also observed by treatment with capsaicin. Collectively, these results suggest that the NADPH oxidase-mediated generation of ROS may be essentially involved in the mechanism of capsaicin-induced apoptosis in HepG2 cells. These results further suggest that capsaicin may be a valuable agent for the therapeutic intervention of human hepatomas.

Antioxidants↗
PubMedDate not supplied

Determination of capsaicin and dihydrocapsaicin in air in a pickle and pepper processing plant.

A sampling and analytical method has been developed for measurement of capsaicin and dihydrocapsaicin in air. This method is applicable to measurement of the capsaicinoids in air in pepper processing plants and involves air sampling with a 13-mm glass fiber filter, recovery of the sample with 2 mL of acetonitrile, filtration of the solution, and analysis by high performance liquid chromatography with fluorescence detection. Excitation and emission wavelengths of the detector were 281 and 312 nm, respectively. Average recoveries were 98 to 104% after fortification of glass fiber filters with 0.13- to 2.9-microg quantities of capsaicin. Average recoveries of dihydrocapsaicin were 93 to 99% after fortification of glass fiber filters with 0.11- to 3.0-microg quantities. Detection limits of capsaicin and dihydrocapsaicin were 0.015 and 0.02 microg per sample, respectively. This method was used successfully for determining air concentrations of capsaicin and dihydrocapsaicin in a health hazard evaluation at a large pickle and pepper processing plant. An interesting phenomenon was the fact that the ratio of capsaicin to dihydrocapsaicin in each of the largest air samples was in the range of 0.3:1 to 0.5:1. Generally, capsaicin is the capsaicinoid that occurs in Capsicum fruit in the greatest relative abundance.

Air Pollutants, Occupational↗
PubMed2004

Ca2+/calmodulin modulates TRPV1 activation by capsaicin.

TRPV1 ion channels mediate the response to painful heat, extracellular acidosis, and capsaicin, the pungent extract from plants in the Capsicum family (hot chili peppers) (Szallasi, A., and P.M. Blumberg. 1999. Pharmacol. Rev. 51:159-212; Caterina, M.J., and D. Julius. 2001. Annu. Rev. Neurosci. 24:487-517). The convergence of these stimuli on TRPV1 channels expressed in peripheral sensory nerves underlies the common perceptual experience of pain due to hot temperatures, tissue damage and exposure to capsaicin. TRPV1 channels are nonselective cation channels (Caterina, M.J., M.A. Schumacher, M. Tominaga, T.A. Rosen, J.D. Levine, and D. Julius. 1997. Nature. 389:816-824). When activated, they produce depolarization through the influx of Na+, but their high Ca2+ permeability is also important for mediating the response to pain. In particular, Ca2+ influx is thought to be required for the desensitization to painful sensations over time (Cholewinski, A., G.M. Burgess, and S. Bevan. 1993. Neuroscience. 55:1015-1023; Koplas, P.A., R.L. Rosenberg, and G.S. Oxford. 1997. J. Neurosci. 17:3525-3537). Here we show that in inside-out excised patches from TRPV1 expressed in Xenopus oocytes and HEK 293 cells, Ca2+/calmodulin decreased the capsaicin-activated current. This inhibition was not mimicked by Mg2+, reflected a decrease in open probability, and was slowly reversible. Furthermore, increasing the calmodulin concentration in our patches by coexpression of wild-type calmodulin with TRPV1 produced inhibition by Ca2+ alone. In contrast, patches excised from cells coexpressing TRPV1 with a mutant calmodulin did not respond to Ca2+. Using an in vitro calmodulin-binding assay, we found that TRPV1 in oocyte lysates bound calmodulin, although in a Ca2+-independent manner. Experiments with GST-fusion proteins corresponding to regions of the channel NH2-terminal domain demonstrated that a stretch of approximately 30 amino acids adjacent to the first ankyrin repeat bound calmodulin in a Ca2+-dependent manner. The physiological response to pain involves an influx of Ca2+ through TRPV1. Our results indicate that this Ca2+ influx may feed back on the channels, inhibiting their gating. This type of feedback inhibition could play a role in the desensitization produced by capsaicin.

Animals↗
PubMed2000

Intravesical neuromodulatory drugs: capsaicin and resiniferatoxin to treat the overactive bladder.

Current pharmacologic treatment of the overactive bladder relies on anticholinergic drugs. However, these drugs often have troublesome side effects and frequently are given in doses insufficient to restore continence in patients with detrusor instability. We present the background and basic and clinical research dealing with intravesical instillation of capsaicin and resinfferatoxin as treatments for the overactive bladder. Capsaicin is the main pungent ingredient in "hot" peppers of the genus Capsicum. It is a specific neurotoxin that desensitizes C-fiber afferent neurons, which may be responsible for the signals that trigger detrusor overactivity. Studies with capsaicin over the past 8 years have demonstrated clinical efficacy with minimal long-term complications. Most of these studies have also shown that the acute pain and irritation associated with capsaicin are a major deterrent to widespread use. Resiniferatoxin (RTX), an ultrapotent analog of capsaicin that appears to have similar efficacy but with much less acute side effects may be more useful. Intravesical instillation of capsaicin or resiniferatoxin is a promising treatment for the overactive bladder.

Administration, Intravesical↗
PubMed2006

Catechin-vanilloid synergies with potential clinical applications in cancer.

A cancer-specific cell surface protein, tNOX, has been identified as a target for low-dose cell killing (apoptosis) of cancer cells by green tea catechins and Capsicum vanilloid combinations. This protein is uniquely associated with all forms of cancer and is absent from normal cells and tissues. Its activity is correlated with cancer growth. When blocked, cancer cells fail to enlarge after division and eventually die. Among the most potent and effective inhibitors of tNOX are naturally occurring polyphenols exemplified by the principal green tea catechin (-)-epigallocatechin gallate (EGCg) and the vanilloid capsaicin. Catechin-vanilloid combinations are 10 to 100 times more effective than either catechins or vanilloids alone. Vector-forced overexpression of tNOX cDNA and antisense has demonstrated that the tNOX target is both necessary and sufficient to explain the anticancer properties of green tea catechins alone and in vanilloid-containing combinations. The necessity and sufficiency of tNOX was validated as the catechin target with transgenic mice overexpressing the processed form of tNOX. Transgenic mice grew faster and the increased growth caused by tNOX overexpression was blocked by EGCg in the drinking water. A catechin-vanilloid mixture where one 350-mg capsule is equivalent to 16 cups of green tea in its ability to inhibit tNOX and growth of cancer cells in culture is undergoing clinical evaluation as a therapeutic aid for cancer patients.

Animals↗
PubMed1975

TLC screening techniques for the qualitative determination of natural and synthetic capsaicinoids.

Three TLC methods of qualitative screening of capsicum products are described. A procedure using a two-dimensional reversed phase system and bromination of the sample gave the greatest flexibility but required the longest time. A one-dimensional reversed phase system using silver ion to complex with the unsaturated components is also described. Polyamide plates using silver ion in the developing solvent gave the greatest speed of the three methods compared.

Bromine↗
PubMed1992

Differential inhibition of potassium currents in rat ventricular myocytes by capsaicin.

OBJECTIVE: Capsaicin is a pungent irritant present in peppers of the Capsicum family. Its major target of action is believed to be sensory neurones. Capsaicin has also been shown to prolong cardiac action potential in atrial muscle, perhaps by local release of calcitonin gene related peptide which in turn enhances inward calcium currents. However, capsaicin has been shown to inhibit K+ current in neurones. Since such an action could contribute to action potential prolonging activity of capsaicin in heart, the aim of the study was to examine the effects of capsaicin on cardiac K+ currents. METHODS: Ionic currents and action potentials were examined in isolated adult rat ventricular myocytes using the whole cell variant of the patch clamp technique at 25 degrees C. RESULTS: Capsaicin (10 microM) increased the action potential duration (APD50) from 45 ms to 166 ms. This effect was associated with an inhibition of three distinct K+ currents. The decreasing rank order of potency was: transient outward K+ current (ITO, IC50 = 6.4 microM), a voltage dependent non-inactivating outward current (IK, IC = 11.5 microM), and the inward rectifier K+ current (IK1, IC50 = 46.9 microM). Capsaicin induced block of ITO was characterised by a decrease in the peak current amplitude and an increase in the rate of inactivation. The inactivation of ITO in the absence of capsaicin was well described by a single exponential [tau = 77 (SEM 2) ms at +40 mV, n = 10]. However, in the presence of 10 microM capsaicin inactivation was best described by the sum of two exponentials [tau FAST = 4.4(0.5) ms; tau SLOW = 92.4(3.0) ms, n = 10] with the fast component contributing 46(2)% of the total decay. A small but consistent hyperpolarising shift (approximately 3 mV) in the steady state voltage dependence of inactivation of ITO was induced by 10 microM capsaicin. Capsaicin had no effect on the rate of ITO recovery from inactivation (tau = 49 ms and 48 ms for control and drug respectively). The capsaicin analogue, resiniferatoxin, which as an irritant is up to 10(4)-fold more potent than capsaicin, had no effect on any of the K+ currents when present at concentrations of up to 10 microM. In contrast another capsaicin analogue, zingerone (30 microM) blocked ITO by 52(12)% and IK by 35%. CONCLUSIONS: Capsaicin produces a prolongation of the rat ventricular action potential, an effect which is associated with inhibition of potassium currents.

Action Potentials↗