Dietary capsaicin and its anti-obesity potency: from mechanism to clinical implications

Accumulating evidence to support the safe and efficacious use of a proprietary blend of capsaicinoids in mediating risk factors for obesity

Obesity is a significant public health concern, and finding safe and effective means for combating this condition is needed. This study investigates the safety and efficacy of supplementation of a blend of capsaicinoids on weight gain, fat mass, and blood chemistry in a high-fat diet (HFD) model of obesity in mice and on adipocyte differentiation and gene expression in 3T3-L1 preadipocytes. High-fat diet (HFD)-fed mice were treated with a proprietary capsaicinoid concentrate (Capsimax®; OmniActive Health Technologies Ltd., India) and compared to orlistat (ORL) and normal chow-fed mice (NC). Mice fed a high-fat diet showed significantly lower weight gain upon Capsimax® (CAP) administration than their HFD counterparts and similar to that observed with ORL animals. In addition, CAP decreased the high-fat diet-induced increases in adipose tissue and epididymal fat pad mass and hypertrophy after 52 days of treatment. Both the CAP and ORL groups had increased plasma concentrations of leptin. CAP extracts decreased triacylglycerol content in 3T3-L1 preadipocytes and decreased markers of adipogenesis including peroxisome proliferator-activated receptor (PPAR-ɣ) and fatty acid-binding protein 4 (FABP4). Expression of genes involved in lipogenesis such as stearoyl-CoA desaturase (SCD) and fatty acid synthase (FSN) was decreased by CAP in a dose-dependent manner. Thermogenic genes and markers of brown adipose tissue including uncoupling protein 1 (UCP1) and PR domain-containing 16 (Prdm16) were induced by CAP in the preadipocyte cells. These in vivo and in vitro data support that this proprietary capsaicinoid concentrate reduces weight gain and adiposity at least in part through decreasing lipogenesis and increasing thermogenesis.

Nutritional Regulation of Human Brown Adipose Tissue

The recent identification of brown adipose tissue in adult humans offers a new strategy to increase energy expenditure to treat obesity and associated metabolic disease. While white adipose tissue (WAT) is primarily for energy storage, brown adipose tissue (BAT) is a thermogenic organ that increases energy expenditure to generate heat. BAT is activated upon cold exposure and improves insulin sensitivity and lipid clearance, highlighting its beneficial role in metabolic health in humans. This review provides an overview of BAT physiology in conditions of overnutrition (obesity and associated metabolic disease), undernutrition and in conditions of altered fat distribution such as lipodystrophy. We review the impact of exercise, dietary macronutrients and bioactive compounds on BAT activity. Finally, we discuss the therapeutic potential of dietary manipulations or supplementation to increase energy expenditure and BAT thermogenesis. We conclude that chronic nutritional interventions may represent a useful nonpharmacological means to enhance BAT mass and activity to aid weight loss and/or improve metabolic health.

Type I diabetes suppresses intracellular calcium ion increase normally evoked by heat stress in rat skeletal muscle

Heat stress, via its effects on muscle intracellular Ca2+ concentrations ([Ca2+]i), has been invoked as a putative therapeutic countermeasure to type 1 diabetes-induced muscle atrophy. Using a circulation- and neurally intact in vivo muscle preparation, we tested the hypothesis that impaired muscle Ca2+ homeostasis in type 1 diabetic rats is due to attenuated heat stress tolerance mediated via transient receptor potential vanilloid 1 (TRPV1). Male Wistar rats were randomly assigned to one of the following four groups: 1) healthy control 30°C (CONT 30°C); 2) CONT 40°C; 3) diabetes 30°C (DIA 30°C); and 4) DIA 40°C. The temperature of 40°C was selected because it exceeds the TRPV1 activation threshold. Spinotrapezius muscles of Wistar rats were exteriorized in vivo and loaded with the fluorescent Ca2+ probe Fura-2 AM. [Ca2+]i was estimated over 20 min using fluorescence microscopy (340/380 nm ratio) in quiescent muscle held at the required temperature, using a calibrated heat source applied to the ventral muscle surface. Western blotting was performed to determine the protein expression levels of TRPV1 in spinotrapezius muscle. After 20 min of heat stress, the CONT 40°C condition induced a 12.3 ± 5% [Ca2+]i (P < 0.05) elevation that was markedly absent in the DIA 40°C or other conditions. Thus, no significant differences were found among DIA 40°C, DIA 30°C, and CONT 30°C. TRPV1 protein expression was decreased by 42.0 ± 9% in DIA compared with CONT (P < 0.05) and, unlike CONT, heat stress did not increase TRPV1 phosphorylation. In conclusion, diabetes suppresses TRPV1 protein expression and function and inhibits the elevated myocyte [Ca2+]i evoked normally by heat stress. These results suggest that capsaicin or other therapeutic strategies to increase Ca2+ accumulation via TRPV1 might be more effective than hyperthermic therapy for type 1 diabetic patients.

Anti-obesity Medications in Cancer Therapy: A Comprehensive Insight

The interplay between cancer and obesity is multifactorial and complex with the increased risk of cancer development in obese individuals posing a significant threat. Obesity leads to the upregulation or hyperactivation of several oncogenic pathways in cancer cells, which drives them towards a deleterious phenotype. The cross-talk between cancer and obesity is considered a large contributing factor in the development of chemotherapeutic drug resistance and the resistance to radiotherapy. The link between obesity and the development of cancer is so strong that a medication that demonstrates effectiveness against both conditions would serve as an essential step. In this context, anti-obesity medications provide a worthy list of candidates based on their chemo-preventive potential and chemotherapeutic properties. The current study focuses on exploring the potential of anti-obesity medicines as dual anticancer drugs. These medications target several key signaling pathways (e.g., AMPK, PI3K/Akt/mTOR, MAPK, NF-κB, JNK/ERK), which prove to be crucial for both cancer growth and metastases. Some of these drugs also play an important role in attenuating the signaling and cellular events which incite cancer-obesity cross-talk and demonstrate efficient counteraction of neoplastic transformation. Thus, this review highlights a comprehensive view of the potential use of anti-obesity medicines to treat both cancer and obesity for patients exhibiting both comorbities.

Spicy food consumption and risk of gastrointestinal-tract cancers: findings from the China Kadoorie Biobank

BACKGROUND

Previous case-control studies have reported positive associations of spicy food consumption with risks of certain gastrointestinal-tract (GI) cancers. However, there is no prospective evidence on such associations, particularly from China, where there are high incidence rates of GI cancers and spicy food is widely consumed.

METHODS

The prospective China Kadoorie Biobank study recruited >512 000 adults aged 30-79 years from 10 areas in China during 2004-2008; 2350 oesophageal, 3350 stomach and 3061 colorectal incident cancer cases were recorded by 1 January 2017, after a median of 10.1 years of follow-up. Cox regression yielded adjusted hazard ratios (HRs) for each cancer associated with spicy food intake.

RESULTS

Overall, 30% of participants reported daily spicy food consumption at baseline. Spicy food consumption was inversely associated with oesophageal cancer risk, with adjusted HRs of 1.00, 0.88, 0.76, 0.84 and 0.81 for those who never/rarely consumed (reference) and consumed monthly, 1-2 days/week, 3-5 days/week and 6-7 days/week, respectively (ptrend < 0.002). The association remained similar after excluding the first 3 years of follow-up but appeared stronger in participants who did not smoke or drink alcohol regularly (ptrend < 0.0001). The corresponding HRs for stomach cancer were 1.00, 0.97, 0.95, 0.92 and 0.89 (ptrend = 0.04), with the association disappearing after excluding the first 3 years of follow-up. For colorectal cancer, the HRs were 1.00, 1.00, 0.95, 0.87 and 0.90, respectively (ptrend = 0.04) and the inverse association appeared to be restricted to rectal rather than colon cancer (pheterogeneity = 0.004). The types and strength of spice used showed little additional effects on these associations.

CONCLUSION

In Chinese adults, higher spicy food consumption was associated with lower risks of certain GI cancers, particularly among individuals who never smoked or drank alcohol regularly.

Extraction, purification, bioactivity and pharmacological effects of capsaicin: a review

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), a well-known vanilloid, which is the main spicy component in chili peppers, showing several biological activities and the potential applications range from food flavorings to therapeutics. Traditional extraction of capsaicin by organic solvents was time-consuming, some new methods such as aqueous two-phase method and ionic liquid extraction method have been developed. During past few decades, an ample variety of biological effects of capsaicin have been evaluated. Capsaicin can be used in biofilms and antifouling coatings due to its antimicrobial activity, allowing it has a promising application in food packaging, food preservation, marine environment and dental therapy. Capsaicin also play a crucial role in metabolic disorders, including weight loss, pressure lowing and insulin reduction effects. In addition, capsaicin was identified effective on preventing human cancers, such as lung cancer, stomach cancer, colon cancer and breast cancer by inducing apoptosis and inhibiting cell proliferation of tumor cells. Previous research also suggest the positive effects of capsaicin on pain relief and cognitive impairment. Capsaicin, the agonist of transient receptor potential vanilloid type 1 (TRPV1), could selectively activate TRPV1, inducing Ca²⁺ influx and related signaling pathways. Recently, gut microbiota was also involved in some diseases therapeutics, but its influence on the effects of capsaicin still need to be deeply studied. In this review, different extraction and purification methods of capsaicin, its biological activities and pharmacological effects were systematically summarized, as well as the possible mechanisms were also deeply discussed. This article will give an updated and better understanding of capsaicin-related biological effects and provide theoretical basis for its further research and applications in human health and manufacture development.

A Systematic Review of the European Rapid Alert System for Food and Feed: Tendencies in Illegal Food Supplements for Weight Loss

Background: Slimming products represent a dynamically growing group of food supplements worldwide. The efficacy of safely usable natural ingredients is usually below consumers' expectations. Certain manufacturers add unauthorized or prohibited ingredients to weight loss supplements in order to increase their efficacy. Hence, many of these products are adulterated and may pose a risk to the consumers' health. Aims: The aim of our work was to give an overview on natural ingredients used in slimming products, to summarize the frequently used synthetic adulterants and also to assess the trends of adulterated and illegal food supplements in the European Union based on the warnings of the Rapid Alert System for Food and Feed (RASFF) in the time period of 1988-2019. Methods: Reports between 1988-2019 were extracted from the RASFF portal on January 1, 2020. Each entry was individually reviewed. Results: 2,559 records of food supplements with quality problems were identified in the RASFF, several of which [319 (12,5%)] were marketed to facilitate weight loss. 202 (63,3%) contained unapproved, synthetic drug ingredients. The major adulterant (113 of 319, 35.4%) was DNP (2,4-dinitrophenol), whereas sibutramine was the second most frequent adulterant agent (69 products, 21,6%) between 1988 and 2019. Conclusion: The number of approved medicines for the indication of weight loss is relatively low and their efficacy (and also that of the natural ingredients) is limited. Therefore, a significant number of weight loss supplements is adulterated to satisfy patients' expectations. Hence, these products may cause serious adverse effects in sensitive patients.

Capsaicin and Gut Microbiota in Health and Disease

Capsaicin is a widespread spice known for its analgesic qualities. Although a comprehensive body of evidence suggests pleiotropic benefits of capsaicin, including anti-inflammatory, antioxidant, anti-proliferative, metabolic, or cardioprotective effects, it is frequently avoided due to reported digestive side-effects. As the gut bacterial profile is strongly linked to diet and capsaicin displays modulatory effects on gut microbiota, a new hypothesis has recently emerged about its possible applicability against widespread pathologies, such as metabolic and inflammatory diseases. The present review explores the capsaicin–microbiota crosstalk and capsaicin effect on dysbiosis, and illustrates the intimate mechanisms that underlie its action in preventing the onset or development of pathologies like obesity, diabetes, or inflammatory bowel diseases. A possible antimicrobial property of capsaicin, mediated by the beneficial alteration of microbiota, is also discussed. However, as data are coming mostly from experimental models, caution is needed in translating these findings to humans.

Role of TRPV1 in colonic mucin production and gut microbiota profile

This study focuses on exploring the role of sensory cation channel Transient Receptor Potential channel subfamily Vanilloid 1 (TRPV1) in gut health, specifically mucus production and microflora profile in gut. We employed resiniferatoxin (ultrapotent TRPV1 agonist) induced chemo-denervation model in rats and studied the effects of TRPV1 ablation on colonic mucus secretion patterns. Histological and transcriptional analysis showed substantial decrease in mucus production as well as in expression of genes involved in goblet cell differentiation, mucin production and glycosylation. 16S metagenome analysis revealed changes in abundance of various gut bacteria, including decrease in beneficial bacteria like Lactobacillus spp and Clostridia spp. Also, TRPV1 ablation significantly decreased the levels of short chain fatty acids, i.e. acetate and butyrate. The present study provides first evidence that systemic TRPV1 ablation leads to impairment in mucus production and causes dysbiosis in gut. Further, it suggests to address mucin production and gut microbiota related adverse effects during the development of TRPV1 antagonism/ablation-based therapeutic and preventive strategies.

Capsaicin alleviates acetaminophen-induced acute liver injury in mice

Overdose of N-acetyl-para-aminophenol (APAP) can induce acute liver injury (ALI). We evaluated the potential protective effect of 8-methyl-N-geranyl-6-nonamide (capsaicin (CAP)) in APAP-induced ALI in mice. ALI was induced by APAP (150 mg/kg, i.p.) administration; CAP pretreatment (1 mg/kg) was undertaken before APAP injection for 3 consecutive days. We found that CAP pretreatment attenuated ALI significantly; improve the oxidative stress-associated indicators (hepatic expression of malondialdehyde (MDA) superoxide dismutase (SOD) and glutathione (GSH)); downregulate expression of proinflammatory cytokines (interleukin (IL)-6, IL-1β, tumor necrosis factor-α) through the high-mobility group box 1/toll-like receptor-4/nuclear factor-kappa B (HMGB1/TLR4/NF-κB) signaling pathway; alleviate hepatocyte apoptosis by inhibiting expression of B-cell lymphoma-2-associated X, caspase-3 and cleaved caspase-3. CAP pretreatment reduced expression of B-cell lymphoma-2, which served as a hepatotoxic factor rather than an anti-apoptotic protein in our mouse model. We propose that CAP can alleviate APAP-induced ALI by inhibiting the inflammatory response, attenuating oxidative stress, and reducing hepatocyte apoptosis.

Influence of a Novel Food-Grade Formulation of Red Chili Extract (Capsicum annum) on Overweight Subjects: Randomized, Double-Blinded, Placebo-Controlled Study

Capsaicinoids from pungent red chilies (Capsicum annum and Capsicum frutescens) have received significant attention as a natural supplement for the management of obesity. However, the consumption of chili extract at physiologically relevant dosage of capsaicinoids is a challenge owing to its pungency and gastrointestinal discomforts. The present study reports the systemic absorption, safety and influence of a novel, food-grade, and sustained-release formulation of capsaicinoids-rich red chili extract using fenugreek dietary fiber (Capsifen^®). Twenty-four healthy overweight subjects were randomized into placebo (n = 12) and Capsifen (n = 12) groups and supplemented with 200 mg × 1/day of Capsifen (4 mg capsaicinoids/day) for 28 days. Influence of Capsifen on eating behavior and appetite was followed by Three-Factor Eating Questionnaire (TFEQ) and Council of Nutrition Appetite Questionnaire (CNAQ), respectively. Consumption of Capsifen did not reveal any adverse events or deviations in hematology and biochemical parameters related to safety. However, a significant decrease in body weight (2.1%), w/h ratio (4%) and body mass index (BMI) (2.2%) were observed among Capsifen group when compared to placebo. The TFEQ and appetite analysis revealed a significant improvement in uncontrolled eating and reduction in appetite among Capsifen subjects. The UPLC-ESI-MS/MS analysis confirmed the absorption of capsaicinoids from CAP supplementation. The study further demonstrated the safety and tolerability of Capsifen at the investigational dosage. Thus, the significant reduction in anthropometric parameters such as body weight, w/h ratio, and BMI along with the improvement in eating behaviour as well as appetite, indicated the potential body weight management effect of Capsifen.

A Critical Review on the Role of Food and Nutrition in the Energy Balance

The mass media has increasingly frequently suggested to the general population that specific foods or nutritional schemes are able to affect both human metabolism and energy expenditure, thus facilitating weight loss. This critical review is aimed at assessing available evidence on the roles of nutrients, food and dietary regimens in energy intake and energy expenditure. We queried the National Library of Medicine, the Cochrane Library, Excerpta Medica dataBASEand the Cumulative Index to Nursing and Allied Health Literature database, and a search strategy was performed by using database-specific subject headings and keywords. We found that available scientific evidence on these topics is scarce, and that the limited number of available studies often have poor methodological quality. Only a few foods show beneficial effects on metabolism and energy expenditure, as the human energy balance is complex and multifactorial. Finally, microbiota may interfere with the intake, use and expenditure of energy in the human body. Conclusive evidence is still lacking, and, at present, it is not possible to identify a food or a diet with a significant impact on human energy expenditure.

Nitrogen Source Affects the Composition of Metabolites in Pepper (Capsicum annuum L.) and Regulates the Synthesis of Capsaicinoids through the GOGAT-GS Pathway

Phytochemical analyses of pepper fruit metabolites have been reported; however, much less is known about the influence of different forms of nitrogen (N), which is critical for plant growth and fruit quality formation. The "Longjiao No. 5" variety (Capsicum annuum L.) grown in Northwestern China was profiled using liquid chromatography-mass spectrometry (LC-MS) coupled with multivariate data analysis to explore the composition of different metabolites in pericarp and placenta, and to investigate the effect of three ammonium (NH4+)-to-nitrate (NO3-) ratios (0:100, 25:75, and 50:50). A total of 215 metabolites were obtained by qualitative analysis, where 31 metabolites were the major differential metabolite components of pepper fruits between placenta and pericarp, and 25 among N treatments. The addition of ammonium up-regulated carbohydrates, such as α-lactose and sucrose, as well as phenylalanine lyase (PAL) of placenta tissue. The supply of 25% NH4+-N and 75% NO3--N exhibited a relatively higher levels of ascorbic acid in pericarp and amino acids, capsaicin, and dihydrocapsaicin in placenta, and led to higher fruit weight among the ammonium-to-nitrate ratios. The expression and activities of glutamic acid synthetase (GOGAT) and glutamine synthetase (GS) that are involved in ammonium assimilation were affected by adjusting the ammonium-N proportion, and they were significantly positively correlated with capsaicin, dihydrocapsaicin contents, capsaicinoid synthetase (CS), as well as the relative expression levels of genes related to capsaicinoid biosynthesis, such as acyltransferase 3 (AT3) and acyl-ACP thioesterase (FatA).

Fruits

Fruits come in a wide variety of colors, shapes, and flavors. This chapter will cover selected fruits that are known to be healthy and highly nutritious. These fruits were chosen due to their common usage and availability. Since it is not possible to cover all health benefits or essential nutrients and important phytochemicals of the fruit composition, this chapter will focus on the key valuable constituents and their potential health effects.

Capsaicin—the major bioactive ingredient of chili peppers: bio-efficacy and delivery systems

The mechanisms of bio-efficacy of capsaicin and delivery systems with enhanced bioavailability were reviewed.

Mediterranean products as promising source of multi-target agents in the treatment of metabolic syndrome

Alteration of nutritional habits play an essential role on the risk of developing Metabolic Syndrome (MetS). Several epidemiological studies have shown that assuming diets rich of foods included in the Mediterranean diet (MetDiet) pattern like, such as olive oil, nuts, fruit, fiber, vegetables, wine and grain cereals has protective effects on the different risk factors characterizing the MetS. The beneficial effects of the MetDiet in the MetS are mainly due to the antioxidant and anti-inflammatory properties of the most abundant phytochemical components of such foods as polyphenols like resveratrol and oleuropein, allyl sulfides, ellagic acid, mono- and poly-unsaturated fatty acids (MUFA and PUFA), tocopherols and flavonoids like quercetin, which have shown positive results in the prevention of cardiovascular diseases (CVDs), with related risk factors, like hypertension, hypercholesterolemia and obesity. In this review, we highlighted the multi-target activities of the bioactive components contained in some foods typical of the Mediterranean area like olive oil, onion, liquorice, rosemary, oregano, hazelnut, pistachio, "Melannurca" apple, red wine, hot pepper, Citrus sp. fruits, saffron and garlic, with particular focus on their impact on health outcomes in relation to MetS main key factors, such as insulin resistance (IR) and type 2 diabetes mellitus (T2DM), endothelial dysfunctions, inflammatory response, oxidative stress and dyslipidaemic and hypercholesterolemic effects.

Virus-induced gene silencing in chili pepper by apple latent spherical virus vector

Apple latent spherical virus (ALSV) can infect a variety of crops, usually without inducing symptoms. Partial gene sequences can be introduced into ALSV vectors for the induction of virus-induced gene silencing (VIGS). These features are beneficial for the estimation of gene functions in plants, with relatively concise experimental manipulations. Given that the infectability of chili peppers (Capsicum spp.) by ALSV was unknown, an ALSV infectivity test was performed on the highly pungent Capsicum chinense cultivar 'Habanero'. The chili pepper plants were not infected after rub-inoculation with a crude homogenate of ALSV-infected Chenopodium quinoa leaves, whereas inoculating them with a concentrated ALSV virus preparation caused an infection. Inoculation with an ALSV RNA preparation by gold particle bombardment resulted in high infection rates (about 90%). The infection was systemic and the infected plants were symptomless. For the induction of VIGS, 201-nucleotide fragments of the putative aminotransferase (pAMT) gene were introduced into the ALSV vector. These ALSV vectors infected 80-90% of RNA-inoculated chili pepper seedlings. Expression of pAMT-mRNA was repressed in the placenta of immature fruit of infected plants. The silencing of pAMT in the infected plants caused a substantial decrease in capsaicin content and a concomitant moderate accumulation of the non-pungent bioactive metabolite capsiate in these plants. These results showed that ALSV could be used to study gene functions by VIGS and to enhance capsiate accumulation in chili pepper through genetic modification.

TRPV1 Antagonists as Novel Anti-Diabetic Agents: Regulation of Oral Glucose Tolerance and Insulin Secretion Through Reduction of Low-Grade Inflammation?

With a global prevalence among adults over 18 years of age approaching 9%, Type 2 diabetes mellitus (T2DM) has reached pandemic proportions and represents a major unmet medical need. To date, no disease modifying treatment is available for T2DM patients. Accumulating evidence suggest that the sensory nervous system is involved in the progression of T2DM by maintaining low-grade inflammation via the vanilloid (capsaicin) receptor, Transient Receptor Potential Vanilloid-1 (TRPV1). In this study, we tested the hypothesis that TRPV1 is directly involved in glucose homeostasis in rodents. TRPV1 receptor knockout mice (Trpv1^−/−) and their wild-type littermates were kept on high-fat diet for 15 weeks. Moreover, Zucker obese rats were given the small molecule TRPV1 antagonist, N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyrazine-1(2H)-carbox-amide (BCTC), per os twice-a-day or vehicle for eight days. Oral glucose tolerance and glucose-stimulated insulin secretion was improved by both genetic inactivation (Trpv1^−/− mice) and pharmacological blockade (BCTC) of TRPV1. In the obese rat, the improved glucose tolerance was accompanied by a reduction in inflammatory markers in the mesenteric fat, suggesting that blockade of low-grade inflammation contributes to the positive effect of TRPV1 antagonism on glucose metabolism. We propose that TRPV1 could be a promising therapeutic target in T2DM by improving glucose intolerance and correcting dysfunctional insulin secretion.

Assessment of Pharmacology, Safety, and Metabolic activity of Capsaicin Feeding in Mice

Capsaicin (CAP) activates transient receptor potential vanilloid subfamily 1 (TRPV1) to counter high-fat diet (HFD)-induced obesity. Several studies suggest that CAP induces the browning of white adipocytes in vitro or inguinal white adipose tissue (iWAT) in vivo. However, there is a lack of data on the dose-response for CAP to inhibit HFD-induced obesity. Therefore, we first performed experiments to correlate the effect of various doses of CAP to prevent HFD-induced weight gain in wild-type (WT) mice. Next, we performed a subchronic safety study in WT mice fed a normal chow diet (NCD ± CAP, 0.01% in NCD) or HFD ± CAP (0.01% in HFD) for eight months. We analyzed the expression of adipogenic and thermogenic genes and proteins in the iWAT from these mice, conducted histological studies of vital organs, measured the inflammatory cytokines in plasma and iWAT, and evaluated liver and kidney functions. The dose-response study showed that CAP, at doses above 0.001% in HFD, countered HFD-induced obesity in mice. However, no difference in the anti-obesity effect of CAP was observed at doses above 0.003% in HFD. Also, CAP, above 0.001%, enhanced the expression of sirtuin-1 and thermogenic uncoupling protein 1 (UCP-1) in the iWAT. Safety analyses suggest that CAP did not cause inflammation. However, HFD elevated plasma alanine aminotransferase and creatinine, caused iWAT hypertrophy and hepatic steatosis, and CAP reversed these. Our data suggest that CAP antagonizes HFD-induced metabolic stress and inflammation, while it does not cause any systemic toxicities and is well tolerated by mice.

Multifunctional TRPV1 Ion Channels in Physiology and Pathology with Focus on the Brain, Vasculature, and Some Visceral Systems

TRPV1 has been originally cloned as the heat and capsaicin receptor implicated in acute pain signalling, while further research has shifted the focus to its importance in chronic pain caused by inflammation and associated with this TRPV1 sensitization. However, accumulating evidence suggests that, apart from pain signalling, TRPV1 subserves many other unrelated to nociception functions in the nervous system. In the brain, TRPV1 can modulate synaptic transmission via both pre- and postsynaptic mechanisms and there is a functional crosstalk between GABA receptors and TRPV1. Other fundamental processes include TRPV1 role in plasticity, microglia-to-neuron communication, and brain development. Moreover, TRPV1 is widely expressed in the peripheral tissues, including the vasculature, gastrointestinal tract, urinary bladder, epithelial cells, and the cells of the immune system. TRPV1 can be activated by a large array of physical (heat, mechanical stimuli) and chemical factors (e.g., protons, capsaicin, resiniferatoxin, and endogenous ligands, such as endovanilloids). This causes two general cell effects, membrane depolarization and calcium influx, thus triggering depending on the cell-type diverse functional responses ranging from neuronal excitation to secretion and smooth muscle contraction. Here, we review recent research on the diverse TRPV1 functions with focus on the brain, vasculature, and some visceral systems as the basis of our better understanding of TRPV1 role in different human disorders.

Spilanthol from Traditionally Used Spilanthes acmella Enhances AMPK and Ameliorates Obesity in Mice Fed High-Fat Diet

Spilanthol (SP) is a bioactive compound found in Spilanthes acmella, giving the flowers and leaves a spicy taste. Studies found that phyto-ingredients stored in spice plants act against obesity-related diseases. SP has antimicrobial, anti-inflammatory, and analgesic properties, but the effects on obesity are not yet known. We investigated the effects of SP in differentiated adipocytes (3T3-L1 cells) and mice fed a high-fat diet (HFD). SP significantly inhibited intracellular lipid accumulation and significantly reduced the expression of lipogenesis-related proteins, including acetyl-CoA carboxylase (ACC) and fatty-acid synthase (FAS). In contrast, SP increased the expression of carnitine palmitoyltransferase (CPT)1 and AMP-activated protein kinase (AMPK) in adipocytes. However, SP suppressed the levels of cyclooxygenase-2 (COX-2), phospho-p38 (pp38), and phospho-JNK (c-Jun N-terminal kinase) (pJNK) in LPS (lipopolysaccharide)-stimulated murine pre-adipocytes. SP administered to HFD-induced obese mice via intraperitoneal injections twice a week for 10 weeks decreased body weight gain, visceral adipose tissue weight, and adipocyte size. SP inhibited lipogenic proteins FAS and ACC, and suppressed adipogenic transcription factors, enhancing lipolysis and AMPK protein expression in the liver. SP has anti-obesity effects, upregulating AMPK to attenuate lipogenic and adipogenic transcription factors.

Nutritionist and obesity: brief overview on efficacy, safety, and drug interactions of the main weight-loss dietary supplements

Over the past 20 years the use of dietary supplements as adjuvant therapy for weight loss gained growing favor among consumers and dietician-nutritionists, with the subsequent astounding increase in health costs. Despite the reassuring label of natural remedy for losing weight, dietary supplements contain a wide variety of ingredients on which available information is rather scanty and scientifically incomplete. Currently, there is little evidence that weight-loss supplements offer effective aids to reduce weight and meet criteria for recommended use. Robust, randomized, placebo-controlled studies to provide clear-cut scientific evidence of their efficacy and potential side effects in clinical practice are still lacking. Understanding the evidence for the efficacy, safety, and quality of these supplements among nutritionists and physicians is critical to counsel patients appropriately, especially considering the risk of serious adverse effects and interference with concomitant therapies. Detailed information on the efficacy and safety of the most commonly used weight-loss dietary supplements has been recently published by the National Institutes of Health (NIH). However, in this report the thorny issue that may result from drug interactions with weight-loss dietary supplements has been not sufficiently addressed. The aim of this review was to provide a synthetic, evidence-based report on efficacy and safety of the most commonly used ingredients in dietary supplements marketed for weight loss, particularly focusing on their possible drug interactions.

Combination of the natural product capsaicin and docetaxel synergistically kills human prostate cancer cells through the metabolic regulator AMP-activated kinase

Background

Current chemotherapy for castration-resistant prostate cancer is established on taxane-based compounds like docetaxel. However, eventually, the development of toxic side effects and resistance limits the therapeutic benefit being the major concern in the treatment of prostate cancer. Combination therapies in many cases, enhance drug efficacy and delay the appearance of undesired effects, representing an important option for the treatment of castration-resistant prostate cancer. In this study, we tested the efficacy of the combination of docetaxel and capsaicin, the pungent ingredient of hot chili peppers, on prostate cancer cells proliferation.

Methods

Prostate cancer LNCaP and PC3 cell lines were used in this study. Levels of total and phosphorylated forms of Akt, mTOR, S6, LKB1, AMPK and ACC were determined by Western blot. AMPK, LKB1 and Akt knock down was performed by siRNA. PTEN was overexpressed by transient transfection with plasmids. Xenograft prostate tumors were induced in nude mice and treatments (docetaxel and capsaicin) were administered intraperitoneally. Statistical analyses were performed with GraphPad software. Combination index was calculated with Compusyn software.

Results

Docetaxel and capsaicin synergistically inhibited the growth of LNCaP and PC3 cells, with a combination index lower than 1 for most of the combinations tested. Co-treatment with docetaxel and capsaicin notably decreased Akt and its downstream targets mTOR and S6 phosphorylation. Overexpression of PTEN phosphatase abrogated the synergistic antiproliferative effect of docetaxel and capsaicin. The combined treatment also increased the phosphorylation of AMP-activated kinase (AMPK) and the phosphorylation of its substrate ACC. In addition, pharmacological inhibition of AMPK with dorsomorphin (compound C) as well as knock down by siRNA of AMPK or its upstream kinase LKB1, abolished the synergy of docetaxel and capsaicin. Mechanistically, we showed that the synergistic anti-proliferative effect may be attributed to two independent effects: Inhibition of the PI3K/Akt/mTOR signaling pathway by one side, and AMPK activation by the other. In vivo experiments confirmed the synergistic effects of docetaxel and capsaicin in reducing the tumor growth of PC3 cells.

Conclusion

Combination of docetaxel and capsaicin represents a therapeutically relevant approach for the treatment of Prostate Cancer.

Topical treatments for diabetic neuropathic pain

Diabetic neuropathic pain (DNP) has a huge impact on quality of life and can be difficult to treat. Oral treatment is the most frequently used method for DNP, but its use is often limited by systemic side effects. Topical use of drugs as an alternative option for DNP treatment is currently gaining interest. In the present review, a summary is provided of the available agents for topical use in patients with DNP, including lidocaine plasters or patches, capsaicin cream, gel or patches, amitriptyline cream, clonidine gel, ketamine cream, extracts from medicinal plants including nutmeg extracts and Citrullus colocynthis extract oil, and certain compounded topical analgesics. Furthermore, the potential efficacy of these treatments is addressed according to the available clinical research literature. It has been indicated that these topical drugs have the potential to be valuable additional options for the management of DNP, with adequate safety and continuous long-term treatment efficacy. Compounded topical agents are also effective and safe for patients with DNP and could be another area worthy of further investigation based on the strategy of using low-dose, complementary therapies for DNP. The findings indicate that developing topical drugs acting on different targets in the process of DNP is a valuable area of future research.

Properties of capsaicin and its utility in veterinary and human medicine

The main aim of this paper was to show the variety of capsaicin's properties. Capsaicin is an active component of plants of the Capsicum genus, and is known for its pungency. Capsaicin is used in the food, pharmaceutical and cosmetic industries. Additional properties of capsaicin have been demonstrated, including pain relief, weight loss, body thermoregulation, and antioxidant, antimicrobial and anticancer activities. Studies of capsaicin's effects on the human and animal organism need to be continued, with special emphasis on new applications.

Hesperidin and capsaicin, but not the combination, prevent hepatic steatosis and other metabolic syndrome-related alterations in western diet-fed rats

We aimed to assess the potential effects of hesperidin and capsaicin, independently and in combination, to prevent the development of obesity and its related metabolic alterations in rats fed an obesogenic diet. Three-month-old male Wistar rats were divided into 5 groups: Control (animals fed a standard diet), WD (animals fed a high fat/sucrose (western) diet), HESP (animals fed a western diet + hesperidin (100 mg/kg/day)), CAP (animals fed a western diet + capsaicin (4 mg/kg/day)), and HESP + CAP (animals fed a western diet + hesperidin (100 mg/kg/day) + capsaicin (4 mg/kg/day)). Hesperidin and capsaicin were administered by gavage. Capsaicin decreased body fat gain and prevented insulin resistance, whereas hesperidin showed little effect on body fat gain and no apparent effects on insulin resistance. No additive effects were observed with the combination. Capsaicin and hesperidin, separately, improved blood lipid profile, diminished hepatic lipid accumulation, and prevented non-alcoholic steatohepatitis in western diet-fed rats, but the combination showed lower effects. Hesperidin alone, and to a lesser extent capsaicin or the combination, displayed hypotensive effects in western diet-fed rats. In conclusion, capsaicin and hesperidin, separately, exhibit health beneficial effects on metabolic syndrome-related alterations in western diet-fed rats, but the effects are mitigated with the combination.