Biological Activities of Red Pepper (Capsicum annuum) and Its Pungent Principle Capsaicin: A Review

Topical capsaicin versus topical ibuprofen in acute musculoskeletal injuries: A randomized, double-blind trial

Background:

Acute musculoskeletal pain is one of the common causes of emergency admissions. Topical analgesics are an easily tolerated option in the treatment of these pains.

Objective:

This study aimed to compare the efficacy of topical capsaicin and topical non-steroidal anti-inflammatory drugs in acute musculoskeletal injuries.

Methods:

In this prospective, randomized, controlled, double-blinded study, patients were allocated to two groups—the topical non-steroidal anti-inflammatory drug (n = 60) and topical capsaicin (n = 59). For both groups, the first dose treatment was applied as a thin layer in the emergency department to a maximum area of 5 × 5 cm. The remaining doses were administered at home by the patients for 72 h. The initial visual analog scale scores were compared with the 60th and 120th minute as well as the 24th and 72nd hour values. Differences between the visual analog scale scores, clinical response to the treatment, and side effects were evaluated.

Results:

The proportional reduction in visual analog scale scores for topical capsaicin was significantly higher, especially at 36 and 72 h. These rates were 0.75 (95% confidence interval: 0.77–1.42; p = 0.029) and 9.08 (95% confidence interval: 1.02–17.14; p = 0.028) at 36 h, respectively. At 72 h, they were 1.27 (95% confidence interval: 0.48–2.05; p = 0.002) and 17.07 (95% confidence interval: 8.39–25.76; p < 0.001), respectively. In the topical capsaicin group, the clinical response to treatment was significantly higher (p = 0.001). Treatment-related systemic side effects were experienced only in the topical non-steroidal anti-inflammatory drug group (1.7%).

Conclusion:

Topical capsaicin can be used safely in patients presenting to the emergency department with acute pain with its high analgesic efficacy and absence of systemic side effects.

Effects of capsaicin on laying performance, follicle development, and ovarian antioxidant capacity in aged laying ducks

The present study was conducted to evaluate the effects of dietary addition of capsaicin (CAP) on egg production performance, follicular development, and ovarian antioxidant capacity in laying ducks. Three hundred seventy eight 58-wk-old laying ducks were randomly divided into 3 treatments, each treatment consisted 6 replicates, with 12 individually caged laying ducks per replicate. Ducks fed a basal diet served as control, the other 2 groups of ducks were fed the same diet containing 150 mg/kg CAP but in the manner of feed restriction (pair-fed) or ad libitum fed. The experiment lasted for 8 wk. The results showed that the dietary supplementation with CAP under conditions of ad libitum feeding increased feed intake (P < 0.001) and tended (P < 0.1) to increase egg production and egg weight in laying ducks but had no effects on daily egg mass and feed conversion ratio. The relative weight of large yellow follicles from the 2 CAP-supplemented groups at 64 wk of age were significantly higher than that of the controls (P = 0.01). The relative weight of the small yellow follicles in the CAP free-fed group was significantly higher than that of the other 2 groups (P < 0.01). Capsaicin supplementation under ad libitum feding conditions tended to increase the number of dominant follicles in laying ducks (P = 0.06). The ovarian mRNA expression of genes related to calcium signaling (TRPV4, ATP2A2, ITPR1, and CaM) in the CAP ad libitum fed groups were significantly higher than those of the other 2 groups (P < 0.05). The ovarian mRNA expression of CDK1 in CAP free-fed ducks was significantly higher than that of the other 2 groups (P = 0.01). Capsaicin supplementation significantly increased the plasma glutathione peroxidase activity (P < 0.01) in comparison with the control group but reduced the malondialdehyde content in the ovaries of laying ducks (P < 0.01). The results of this study indicates that dietary supplementation of CAP increased feed intake and improved egg production performance probably by activating calcium signaling pathway and improving redox status.

Effects of Capsicum annuum supplementation on the components of metabolic syndrome: a systematic review and meta-analysis

Metabolic syndrome (MetS) has increasingly gained importance as the main risk factor for cardiovascular diseases and type II diabetes mellitus. Various natural compounds derived from plants are associated with beneficial effects on the incidence and progression of MetS. This study aimed to evaluate the effects of Capsicum annuum on factors related to MetS by assessing randomized controlled trials (written in English). We searched the online databases of PubMed, Embase, Google scholar, and Cochrane Library up to April 2020. 'Patient/Population, Intervention, Comparison and Outcomes' format was used to determine whether intervention with C. annuum supplementation compared with placebo supplementation had any effect on the components of MetS among participants. We considered standardized mean differences (SMD) with 95% confidence intervals (CI) as effect size measures using random-effects model. Analysis of the included 11 studies (n = 609) showed that C. annuum supplementation had significant effect on low density lipoprotein-cholesterol [SMD = - 0.39; 95% CI - 0.72, - 0.07; P = 0.02; prediction interval, - 1.28 to 0.50] and marginally significant effect on body weight [SMD = - 0.19; 95% CI - 0.40, 0.03; P = 0.09]. However, larger and well-designed clinical trials are needed to investigate the effects of C. annuum on MetS.

Distinguishing between long-term-stored and fresh chili pepper powder through fingerprinting of volatiles by headspace capillary-gas chromatography-ion mobility spectrometry

Long-term storage of chili pepper powder results in physicochemical and microbiological changes that decrease its commercial value; these changes occur owing to fungal growth and production of off-flavor compounds. Herein, long-term-stored chili pepper powder (LSCPP) and fresh chili pepper powder (FCPP) were analyzed using internal transcribed spacer sequencing and volatile organic compound fingerprinting by headspace capillary-gas chromatography-ion mobility spectrometry. Fungal analysis detected only Xeromyces bisporus with high accuracy in all the analyzed LSCPP samples. However, the proliferation of X. bisporus on nonspecific spots complicated the distinguishing process between the two groups based solely on fungal analysis. Therefore, nine compounds (three ketones, one alcohol, two aldehydes, one ester, one furan, and one sulfur compound) obtained by autoxidation and fungal metabolism were selected as potential markers for distinguishing LSCPP and FCPP. These above-mentioned substances, which were confirmed as off-flavor species owing to "stale" odor, emitted lipid fragrance and were used to successfully distinguish LSCPP from FCPP using principal component analysis and linear discriminant analysis. PRACTICAL APPLICATION: According to the research results, it was possible to discriminate between long-term stored and fresh chili pepper powders using nine VOC markers for quality control in industry. In addition, the fungus generated from long-term storage of chili pepper powder was Xeromyces bisporus, which was confirmed to be safe for intake because it does not form secondary toxic metabolites.

Antioxidant and Anti-Inflammatory Activities in Relation to the Flavonoids Composition of Pepper (Capsicum annuum L.)

The chili pepper (Capsicum annuum L.) is a food source that is rich in flavonoids such as luteolin and apigenin. Flavonoids are known to have anti-inflammatory and antioxidant activities; however, studies on the flavonoids composition identified and the anti-inflammatory and antioxidant effects in pepper leaves (PL) and fruits (PF) are insufficient. In the present study, we investigated the antioxidant and anti-inflammatory effects in vitro, and the flavonoids contents of the PL and PF. Pepper extracts showed radical scavenging activities and ameliorated the lipopolysaccharide (LPS)-stimulated inflammatory response by decreasing nitric oxide production and interluekin-6 and tumor necrosis factor alpha levels in RAW 264.7 cells, with more effective activities noted for PL than for PF. Furthermore, PL extracts markedly inhibited the LPS-induced production of reactive oxygen species accumulation. The flavonoid profile and content of pepper were dependent on the part, with PL showing higher total flavonoids than PF. In particular, the content of luteolin glycosides in PL was twice that in PF. Thus, PL may be useful to prevent oxidative stress and inflammation-related diseases.

Extracts from Six Native Plants of the Yucatán Peninsula Hinder Mycelial Growth of Fusarium equiseti and F. oxysporum, Pathogens of Capsicum chinense

Fusarium equiseti strain FCHE and Fusarium oxysporum strain FCHJ were isolated from the roots of wilting habanero pepper (Capsicum chinense Jacq.) seedlings with root rot. Toward developing a biorational control of these serious phytopathogenic strains, ethanolic (EE) and aqueous (AE) extracts of different vegetative parts of 40 tropical native plants of the Yucatán Peninsula were screened for antifungal activity. Extracts of six out of 40 assayed plants were effective, and the most inhibitory extracts were studied further. EEs from Mosannona depressa (bark from stems and roots), Parathesis cubana (roots), and Piper neesianum (leaves) inhibited mycelial growth of both strains. Each active EE was then partitioned between hexane and acetonitrile. The acetonitrile fraction from M. depressa stem bark (MDT-b) had the lowest minimum inhibitory concentration of 1000 µg/mL against both pathogens and moderate inhibitory concentration (IC₅₀) of 462 against F. equiseti and 472 µg/mL against F. oxysporum. After 96 h treatment with EE from M. depressa stem bark, both strains had distorted hyphae and conidia and collapsed conidia in scanning electron micrographs. Liquid chromatography–ultraviolet–high resolution mass spectrometry analysis revealed that the major component of the fraction was α-asarone. Its antifungal effect was verified using a commercial standard, which had an IC₅₀ of 236 µg/mL against F. equiseti and >500 µg/mL against F. oxysporum. Furthermore, the P. cubana hexane fraction and P. neesianum acetonitrile fraction had antifungal activity against both Fusarium pathogens. These compounds provide new options for biorational products to control phytopathogenic fungi.

Capsaicin Is a Negative Allosteric Modulator of the 5-HT3 Receptor

In this study, effects of capsaicin, an active ingredient of the capsicum plant, were investigated on human 5-hydroxytryptamine type 3 (5-HT₃) receptors. Capsaicin reversibly inhibited serotonin (5-HT)-induced currents recorded by two-electrode voltage clamp method in Xenopus oocytes. The inhibition was time- and concentration-dependent with an IC₅₀ = 62 μM. The effect of capsaicin was not altered in the presence of capsazepine, and by intracellular BAPTA injections or trans-membrane potential changes. In radio-ligand binding studies, capsaicin did not change the specific binding of the 5-HT₃ antagonist [³H]GR65630, indicating that it is a noncompetitive inhibitor of 5-HT₃ receptor. In HEK-293 cells, capsaicin inhibited 5-HT₃ receptor induced aequorin luminescence with an IC₅₀ of 54 µM and inhibition was not reversed by increasing concentrations of 5-HT. In conclusion, the results indicate that capsaicin acts as a negative allosteric modulator of human 5-HT₃ receptors.

A comprehensive review of natural products to fight liver fibrosis: Alkaloids, terpenoids, glycosides, coumarins and other compounds

The discovery of drugs to treat liver fibrosis has long been a challenge over the past decades due to its complicated pathogenesis. As a primary approach for drug development, natural products account for 30% of clinical drugs used for disease treatment. Therefore, natural products are increasingly important for their medicinal value in liver fibrosis therapy. In this part of the review, special focus is placed on the effect and mechanism of natural compounds, including alkaloids, terpenoids, glycosides, coumarins and others. A total of 36 kinds of natural compounds demonstrate significant antifibrotic effects in various liver fibrosis models in vivo and in hepatic stellate cells (HSCs) in vitro. Revealing the mechanism will provide further basis for clinical conversion, as well as accelerate drug discovery. The mechanism was further summarized with the finding of network regulation by several natural products, such as oxymatrine, paeoniflorin, ginsenoside Rg1 and taurine. Moreover, there are still improvements needed in investigating clinical efficacy, determining mechanisms, and combining applications, as well as semisynthesis and modification. Therefore, natural products area promising resource for agents that protect against liver fibrosis.

Sustainable Protected Cropping: A Case Study of Seasonal Impacts on Greenhouse Energy Consumption during Capsicum Production

Sustainable food production in protected cropping is increasing rapidly in response to global climate change and population growth. However, there are significant knowledge gaps regarding energy consumption while achieving optimum environmental conditions for greenhouse crop production. A capsicum crop cultivated in a high-tech greenhouse facility in Australia was analysed in terms of relationships between key environmental variables and the comparative analysis of energy consumption during different seasons. We showed that daily energy consumption varied due to the seasonal nature of the external environment and maintenance of optimal growing temperatures. Total power consumption reported throughout the entire crop cycle for heating (gas hot water system) and cooling (pad and fan) was 12,503 and 5183 kWh, respectively; hence, heating consumed ca. 70% of the total energy requirement over the 8-month growing period (early spring to late autumn) in the greenhouse facility. Regressions of daily energy consumption within each season, designated either predominantly for heating or cooling, indicated that energy consumption was 14.62 kWh per 1 °C heating and 2.23 kWh per 1 °C cooling. Therefore, changing the planting date to late spring is likely to significantly reduce heating energy costs for greenhouse capsicum growers in Australia. The findings will provide useful guidelines to maximise the greenhouse production of capsicum with better economic return by taking into consideration the potential optimal energy saving strategy during different external environment conditions and seasons.

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.

Biological Properties, Bioactive Constituents, and Pharmacokinetics of Some Capsicum spp. and Capsaicinoids

Pepper originated from the Capsicum genus, which is recognized as one of the most predominant and globally distributed genera of the Solanaceae family. It is a diverse genus, consisting of more than 31 different species including five domesticated species, Capsicum baccatum, C. annuum, C. pubescen, C. frutescens, and C. chinense. Pepper is the most widely used spice in the world and is highly valued due to its pungency and unique flavor. Pepper is a good source of provitamin A; vitamins E and C; carotenoids; and phenolic compounds such as capsaicinoids, luteolin, and quercetin. All of these compounds are associated with their antioxidant as well as other biological activities. Interestingly, Capsicum fruits have been used as food additives in the treatment of toothache, parasitic infections, coughs, wound healing, sore throat, and rheumatism. Moreover, it possesses antimicrobial, antiseptic, anticancer, counterirritant, appetite stimulator, antioxidant, and immunomodulator activities. Capsaicin and Capsicum creams are accessible in numerous ways and have been utilized in HIV-linked neuropathy and intractable pain.

Therapeutic potential of targeting MKK3-p38 axis with Capsaicin for Nasopharyngeal Carcinoma

Background: Capsaicin is an active compound found in plants of the Capsicum genus; it has a range of therapeutic benefits, including anti-tumor effects. Here we aimed to delineate the inhibitory effects of capsaicin on nasopharyngeal carcinoma (NPC). Methods: The anti-cancer effects of capsaicin were confirmed in NPC cell lines and xenograft mouse models, using CCK-8, clonogenic, wound-healing, transwell migration and invasion assays. Co-immunoprecipitation, western blotting and pull-down assays were used to determine the effects of capsaicin on the MKK3-p38 axis. Cell proliferation and EMT marker expression were monitored in MKK3 knockdown (KD) or over-expression NPC cell lines treated with or without capsaicin. Finally, immunohistochemistry was performed on NPC specimens from NPC patients (n = 132) and the clinical relevance was analyzed. Results: Capsaicin inhibited cell proliferation, mobility and promoted apoptosis in NPC cells. Then we found that capsaicin directly targets p38 for dephosphorylation. As such, MKK3-induced p38 activation was inhibited by capsaicin. Furthermore, we found that capsaicin-induced inhibition of cell motility was mediated by fucokinase. Xenograft models demonstrated the inhibitory effects of capsaicin treatment on NPC tumor growth in vivo, and analysis of clinical NPC samples confirmed that MKK3 phosphorylation was associated with NPC tumor growth and lymphoid node metastasis. Conclusions: The MKK3-p38 axis represents a potential therapeutic target for capsaicin. MKK3 phosphorylation might serve as a biomarker to identify NPC patients most likely to benefit from adjunctive capsaicin treatment.

Clinical Efficacy of Ultrasound-Mediated Transdermal Lidocaine and Capsaicin Delivery for the Treatment of Allodynia Caused by Herpes Zoster

OBJECTIVE

To investigate the efficacy of ultrasound-mediated drug delivery for allodynia caused by herpes zoster.

DESIGN

Unblinded randomized controlled study with two treatment groups and an additional control group.

SUBJECTS

Patients hospitalized with allodynia caused by herpes zoster were enrolled.

METHODS

Patients were randomly assigned to three groups: ultrasound-mediated transdermal drug delivery (group U), lidocaine intradermal injection (group I), or control group (group C). The primary outcome was pain intensity associated with allodynia, assessed with the visual analog scale (VAS) while brushing the skin with clothing after treatment stimulated allodynia. The secondary outcomes included an emotional functioning score (ES), average gabapentin consumption, and incidence of adverse events of each group.

RESULTS

Sixty patients were enrolled in the study, but two of them failed to complete the treatment process. Therefore, 58 patients were included in the final analysis. All groups had lower VAS and ES scores after treatment compared with baseline. The VAS scores in groups U and I decreased significantly more than in group C (P < 0.05). Mean VAS scores in group U on days 1, 2, and 3 were lower than in group C (P < 0.01). ES was significantly lower in group U compared with groups I and C after treatment (P < 0.001). Average gabapentin consumption and incidence of adverse events in group C were higher than in the other two groups.

CONCLUSIONS

In this study of treatment of allodynia caused by herpetic zoster, ultrasound-mediated lidocaine and capsaicin delivery provided better pain relief and improved emotional functioning compared with intradermal blockade with local anesthetics.

Structural studies of two capsaicinoids: dihydrocapsaicin and nonivamide. 13C and 15N MAS NMR supported by genetic algorithm and GIAO DFT calculations

Capsaicinoids are alkaloid type capsaicin analogs with prospective pharmacological activity. However their solid state conformations have not been studied yet. As part of the study, cross polarization (CP) magic angle spinning (MAS) solid state ¹³C and ¹⁵N NMR spectra of dihydrocapsaicin (DHCAP) and nonivamide (NVA) were recorded. Solid state chemical shifts differ from their solution counterparts; remarkable differences occur for carbons C2′, C6′ and C7′ linked to C1′ in DHCAP and with methylene carbons C4–C8 in NVA. The doubling of some resonances in the spectra of solid NVA indicates that there are two molecules in the crystallographic asymmetric unit. DFT GIAO calculations of shielding constants were performed for several geometric isomers, including molecules with different orientations of aliphatic chain with respect to aromatic ring. Low-energy conformers were found by genetic algorithm methodology. Comparison of experimental ¹³C chemical shifts with theoretical (GIAO DFT) shielding parameters was helpful in predicting the most reliable geometry in the solid state. Cross polarization time constants T_CP and relaxation times in the rotating frame T^H_1ρ were obtained from variable-contact cross-polarization experiments. T^H_1ρ are longer in the order: NVA < CAP < DHCAP.

The conformations of dihydrocapsaicin and nonivamide were studied by ssNMR spectroscopy supported by theoretical DFT/GIAO and genetic algorithm calculations.

Topical capsaicin cream with moderate exercise protects against hepatic steatosis, dyslipidemia and increased blood pressure in hypoestrogenic obese rats

BACKGROUND

The aim of this study was to evaluate the effects of capsaicin (Cap), moderate exercise (Ex), and their combination on arterial blood pressure (BP) and metabolic complications in hypoestrogenic (HE) obese (HEOb) rats. Female Wistar rats were ovariectomized and given 300 g L^-1 sucrose solution (HEOb), or purified water (HE) ad libitum, for 28 weeks. After shaving the abdominal skin, cold cream vehicle was applied to sedentary (Sed) and exercise (Ex) groups, and 0.75 g kg^-1 Cap cream was applied to Ex groups. Ex groups ran on a treadmill every day for 20 min at speeds from 0.15 to 0.3 m s^-1 . For combination groups (Cap + Ex), topical Cap was applied 90 min before Ex. The treatments were performed for 6 weeks, and BP was recorded before and at the end of the experimental protocol. The animals were killed by decapitation, and blood and tissues were obtained to perform oxidative profile, as well as to undertake biochemical and histologic studies.

RESULTS

Compared with individual treatments, the combined therapy (Cap + Ex) in HEOb rats caused a higher reduction in the caloric intake, body weight, abdominal fat percentage, oxidative stress, and hepatic steatosis. In HEOb groups, Cap was the only treatment that reduced BP and prevented dyslipidemia and oxidative stress.

CONCLUSION

The present data show that Cap improves the metabolic alterations induced by obesity and hypoestrogenism, suggesting that Cap can be considered as an excellent candidate for therapy of these clinical conditions. © 2020 Society of Chemical Industry.

Capsaicinoid nonivamide improves nonalcoholic fatty liver disease in rats fed a high-fat diet

Nonalcoholic fatty liver disease (NAFLD) is a chronic disease that causes morbidity associated with metabolic syndrome. NAFLD is a worldwide problem and represents a major cause of liver injury, which can lead to liver cell death. We investigated the effects of nonivamide (pelargonic acid vanillylamide, PAVA; 1 mg/kg) and rosuvastatin (RSV; 10 mg/kg) on hepatic steatosis induced by a high-fat diet (HFD). Male Sprague-Dawley rats were fed a HFD for 16 weeks then received PAVA or RSV for 4 additional weeks. We examined the metabolic parameters, function, fat content, histological alterations, reactive oxygen species production, and apoptotic cell death of the liver, in addition to the expression of the following important molecules: transient receptor potential cation channel subfamily V member 1 (TRPV1) phosphorylation of sterol regulatory element binding protein (pSREBP-1c/SREBP-1c), total and membrane glucose transporter 2 (GLUT2), 4-hydroxynonenal (4-HNE), and cleaved caspase-3. HFD-induced hepatic steatosis was associated with significantly increased morphological disorganization, injury markers, oxidative stress, lipid peroxidation, and apoptosis. However, metabolic dysfunction and hepatic injury were reduced by RSV and PAVA treatment. PAVA regulated lipid deposition, improved insulin resistance, and decreased oxidative stress and apoptotic cell death. Therefore, PAVA represents a promising therapeutic approach for treating metabolic disorders in patients with NAFLD.

Low-cost microphysiological systems: feasibility study of a tape-based barrier-on-chip for small intestine modeling

We see affordability as a key challenge in making organs-on-chips accessible to a wider range of users, particularly outside the highest-resource environments. Here, we present an approach to barrier-on-a-chip fabrication based on double-sided pressure-sensitive adhesive tape and off-the-shelf polycarbonate. Besides a low materials cost, common also to PDMS or thermoplastics, it requires minimal (€100) investment in laboratory equipment, yet at the same time is suitable for upscaling to industrial roll-to-roll manufacture. We evaluate our microphysiological system with an epithelial (Caco-2/BBe1) barrier model of the small intestine, studying the biological effects of permeable support pore size, as well as stimulation with a common food compound (chili pepper-derived capsaicinoids). The cells form tight and continuous barrier layers inside our systems, with comparable permeability but superior epithelial polarization compared to Transwell culture, in line with other perfused microphysiological models. Permeable support pore size is shown to weakly impact barrier layer integrity as well as the metabolic cell profile. Capsaicinoid response proves distinct between culture systems, but we show that impacted metabolic pathways are partly conserved, and that cytoskeletal changes align with previous studies. Overall, our tape-based microphysiological system proves to be a robust and reproducible approach to studying physiological barriers, in spite of its low cost.

Synthesis and fouling resistance of capsaicin derivatives containing amide groups

Capsaicin, which inhibits the attachment and growth of fouling organisms, is a bioactive substance that is generally recognized as a highly active environmental algaecide agent. Its derivatives are simple in structure and have been proven to have low toxicity and be environmentally friendly. Six capsaicin derivatives were synthesized via Friedel-Crafts alkylation and characterized using melting point (MP) analysis, infrared (IR) spectroscopy, nuclear magnetic resonance (¹H NMR) spectroscopy and high-resolution mass spectrometry (HRMS). The inhibition effect and toxicity of these compounds towards Phaeodactylum tricornutum (P. tricornutum), Skeletonema costatum (S. costatum) and Chaetoceros curvisetus (C. curvisetus) were tested. The capsaicin derivatives all showed inhibitory effects. In particular, compound E with over 95% (3 mg·L^-1) inhibition and intermediate toxicity was superior to the other compounds, reflecting an environmentally friendly effect. This finding indicates that capsaicin derivatives possess the potential to become environmentally friendly algaecide agents. The fouling resistance of capsaicin derivatives incorporated into the coatings as antifouling agents was measured in the marine environment. The results showed that capsaicin derivatives possess excellent fouling resistance, with only a small amount of algae and muck attached to the tested panel at 90 days. The above results provide a scientific basis for the application of capsaicin derivatives as environmentally friendly antifouling agents.

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.

Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin

Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.

Biological Effects of Red Chili Pepper (<i>Capsicum annuum</i>) Consumption on High Fat Diet Female Albino Rats

BACKGROUND AND OBJECTIVE

The evidence for safe consumption of chili pepper to gain health benefits is insufficient as high doses reported to cause gastric erosion. The objective of this study was to investigate the contribution of red chili pepper ethanol extract (RCEE) to weight loss in high fat dieted female albino Wistar rats while monitoring adverse effects of high dose consumption.

MATERIALS AND METHODS

Body weight gain, lipid profile, oxidative stress parameters, liver, kidney and thyroid biochemical functions were determined in addition to histopathological examination of liver and kidney to determine biological effects of 2 ingested concentrations of red chili pepper extract (5 and 10 mg).

RESULTS

Red chili pepper ethanol extract (RCEE) showed anti-obesity potentials and hypolipidemic effects through decreased levels of total cholesterol (T.Ch), low density lipoprotein (LDL), triglycerides (TG) and very low density lipoprotein (VLDL) reached 25, 55, 45 and 45%, respectively, in parallel with increased high density lipoprotein (HDL) levels by 22.6%. The antioxidative potentials of RCEE were pronounced through significant increases in glutathione peroxidase (GPx) and catalase (CAT) activities (346.43 mU mL-1 and 15.33 U L-1 in group 2, respectively). Histological examination of liver and kidney showed adverse results but that did not significantly reflect on their functional biochemical parameters.

CONCLUSION

Results introduced scientific evidence that red chili pepper possesses functional pharmacological properties but the excessive consumption induces liver and kidney damage.

Menopause-Associated Lipid Metabolic Disorders and Foods Beneficial for Postmenopausal Women

Menopause is clinically diagnosed as a condition when a woman has not menstruated for one year. During the menopausal transition period, there is an emergence of various lipid metabolic disorders due to hormonal changes, such as decreased levels of estrogens and increased levels of circulating androgens; these may lead to the development of metabolic syndromes including cardiovascular diseases and type 2 diabetes. Dysregulation of lipid metabolism affects the body fat mass, fat-free mass, fatty acid metabolism, and various aspects of energy metabolism, such as basal metabolic ratio, adiposity, and obesity. Moreover, menopause is also associated with alterations in the levels of various lipids circulating in the blood, such as lipoproteins, apolipoproteins, low-density lipoproteins (LDLs), high-density lipoproteins (HDL) and triacylglycerol (TG). Alterations in lipid metabolism and excessive adipose tissue play a key role in the synthesis of excess fatty acids, adipocytokines, proinflammatory cytokines, and reactive oxygen species, which cause lipid peroxidation and result in the development of insulin resistance, abdominal adiposity, and dyslipidemia. This review discusses dietary recommendations and beneficial compounds, such as vitamin D, omega-3 fatty acids, antioxidants, phytochemicals—and their food sources—to aid the management of abnormal lipid metabolism in postmenopausal women.

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.

Capsaicin and gingerol analogues inhibit the growth of efflux-multidrug resistant bacteria and R-plasmids conjugal transfer

ETHNOPHARMACOLOGICAL IMPORTANCE

Capsicum and ginger are used widely in human diets and in folklore medicines. Chemically, gingerol is a relative of capsaicin and both classes of compounds are notable for their spiciness and characteristic pungent aroma. Previous studies have demonstrated that these compounds contain antimicrobial compounds with robust pharmacological importance.

AIM

The present study evaluated the in vitro antibacterial activities of capsaicinoids and gingerols against a panel of clinical MRSA strains and their inhibitory effect on the conjugal transfer of R-plasmids harboured in E. coli.

MATERIALS AND METHODS

Crude methanol extract of C. annum was fractionated using solid phase extraction (SPE) and screened for R-plasmid transfer inhibition: TP114, PUB 307, PKM 101, R6K and R7K. The bio-guided assay led to the isolation of bioactive compounds with strong R-plasmid transfer inhibition. The compounds were identified using Nuclear Magnetic resonance (NMR) and Mass spectroscopy (MS). Capsaicin analogues nonivamide, 6-gingerol, 6-shogaol, capsaicin and dihydrocapsaicin were screened for antimicrobial activity against a panel of methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria strains using microdilution method while the plasmid transfer inhibition assay of the compounds was determined by broth mating method.

RESULTS

The bioactive fraction Ca-11 showed good inhibition rates (8.57-25.52%) against three R-plasmids PUB307, PKM 101, TP114 followed by the crude extract of C. annum (8.59%) respectively leading to the bioassay-guided isolation of capsaicin and dihydrocapsaicin as the bioactive principles. The antiplasmid effect of pure capsaicin and dihydrocapsaicin were broad and within active ranges (5.03-31.76%) against the various antibiotic resistance-conferring plasmids including R6K, R7K. Capsaicin, 6-gingerol and 6-shogaol had good broad antibacterial activity with MIC values ranging from 8 to 256 mg/L against effluxing MRSA strains SA1199B (NorA), XU212 (TetK) and RN4220 (MsrA). While they exhibited moderate antibacterial activity (128-512 mg/L) against the Gram-negative bacteria. The effect of 6-gingerol, 6-shogaol and nonivamide on the plasmids were very active on PKM 101 (6.24-22.16%), PUB 307 (1.22-45.63%) and TP114 (0.1-7.19%) comparative to the positive control plumbagin (5.70-31.76%).

CONCLUSION

These results are suggestive that the R-plasmids could possess substrate for capsaicinoids-like compounds and for their ability to inhibit the plasmid conjugation processes. Plant natural products possess the potential value of antibacterial and mechanistic antiplasmid activity as demonstrated by the compounds and should be evaluated in developing antimicrobial leads to novel mechanism against multidrug-resistant bacteria.

Capsaicinoids: Multiple effects on angiogenesis, invasion and metastasis in human cancers

Cancer progression is a complex multistep process comprising of angiogenesis of the primary tumor, its invasion into the surrounding stroma and its migration to distant organs to produce metastases. Nutritional compounds of the "capsaicinoid" family regulate angiogenesis, invasion and metastasis of tumors. Capsaicinoids display robust anti-angiogenic activity in both cell culture and mice models. However, conflicting reports exist about the effect of capsaicinoids on invasion of metastasis of cancers. While some published reports have described an anti-invasive and anti-metastatic role for capsaicinoids, others have argued that capsaicinoids stimulate invasion and metastasis of cancers. The present review article summarizes these findings involving the bioactivity of capsaicin in angiogenesis, invasion and metastasis of cancer. A survey of literature indicate that they are several articles summarizing the growth-inhibitory activity of capsaicinoids but few describe its effects on angiogenesis, invasion and metastasis in detail. Our review article fills this gap of knowledge. The discovery of a second generation of natural and synthetic capsaicin analogs (with anti-tumor activity) will pave the way to improved strategies for the treatment of several human cancers.

Biochemistry and molecular biology of capsaicinoid biosynthesis: recent advances and perspectives

The most widely known characteristic of chili pepper fruits is their capacity to produce capsaicinoids, which are responsible for the pungent sensation. The capsaicinoids have several uses in different areas, such as the pharmaceutical, cosmetic and agronomic industries, among others. They are synthesized by the condensation of vanillylamine (derived from phenylalanine) with a branched-chain fatty acid (from valine or leucine precursors), and they generally accumulate in the placental tissue of the chili pepper fruits. The pungency grade depends on the genotype of the plant but is also affected by external stimuli. In recent years, new structural and regulatory genes have been hypothesized to participate in the capsaicinoid biosynthetic pathway. Moreover, the role of some of these genes has been investigated. Substantial progress has been made in discerning the molecular biology of this pathway; however, many questions remain unsolved. We previously reviewed some aspects of the biochemistry and molecular biology of capsaicinoid biosynthesis (Aza-González et al. Plant Cell Rep 30:695-706. Aza-González et al., Plant Cell Rep 30:695-706, 2011), and in this review, we describe advances made by different researchers since our previous review, including the contribution of omics to the knowledge of this pathway.

Capsaicin: Physicochemical properties, cutaneous reactions and potential applications in painful and inflammatory conditions

Capsaicin is a natural protoalkaloid recognized as the main pungent component in hot peppers (Capsicum annuum L.). The capsaicin receptor is highly expressed in the unmyelinated type C nerve fibers originating from small diameter sensory neurons in dorsal root ganglia and cranial nerve ganglia correspondents. Capsaicin and related vanilloids have a variety of effects on primary sensory neurons function, from sensory neuron excitation characterized by local burning sensation and neurogenic inflammation, followed by conduction blockage accompanied by reversible ultrastructural changes of peripheral nociceptive endings (desensitization), going as far as irreversible degenerative changes (neurotoxicity). The main role in capsaicin-induced neurogenic inflammation relies on the capsaicin sensitive, small diameter primary sensory neurons, therefore its evaluation could be used as a diagnostic instrument in functional alterations of cutaneous sensory nerve fibers. Moreover, capsaicin-induced desensitization and neurotoxicity explain the analgesic/anti-nociceptive and anti-inflammatory effects of topical capsaicin and its potential use in the management of painful and inflammatory conditions. In this study, we describe the effects of capsaicin on neurogenic inflammation and nociception, as well as its potential diagnostic value and therapeutic impact in various conditions involving impairment of sensory nerve fibers.

Generation of BSA-capsaicin Nanoparticles and Their Hormesis Effect on the Rhodotorula mucilaginosa Yeast

Capsaicin is a chemical compound found in pungent chili peppers (Capsicum spp.). In biotechnology, capsaicin has been proposed as a pathogen control; however, its low solubility in water and high instability limits its uses. The aim of this work was to study the effect of high concentrations of capsaicin on the synthesis of nanoparticles and to evaluate their inhibitory effect on the growth of Rhodotorula mucilaginosa yeast. Bovine serum albumin (BSA)-capsaicin nanoparticles were formulated at 0, 16.2, 32.5, 48.7 and 65.0 µg of capsaicin per mg of BSA. Nanoparticle properties were evaluated and they were added to cultures of R. mucilaginosa to quantify their effect on cell viability. We found that increased capsaicin levels caused several changes to the physicochemical parameters, probably due to changes in the hydrophobicity sites of the albumin during the nanostructuration. The administration of nanoparticles to cultures of R. mucilaginosa produced a maximal viability with nanoparticles at 16.2 µg/mg; on the contrary, nanoparticles at 65.0 µg/mg caused maximal cell death. R. mucilaginosa cells displayed a hormesis effect in response to the nanoparticle dose concentration. The nanoparticles showed different responses during the uptake process, probably as a consequence of the nanostructural properties of capsaicin in the BSA molecules.

Capsaicinoids enhance chemosensitivity to chemotherapeutic drugs

Cytotoxic chemotherapy is the mainstay of cancer treatment. Conventional chemotherapeutic agents do not distinguish between normal and neoplastic cells. This leads to severe toxic side effects, which may necessitate the discontinuation of treatment in some patients. Recent research has identified key molecular events in the initiation and progression of cancer, promoting the design of targeted therapies to selectively kill tumor cells while sparing normal cells. Although, the side effects of such drugs are typically milder than conventional chemotherapies, some off-target effects still occur. Another serious challenge with all chemotherapies is the acquisition of chemoresistance upon prolonged exposure to the drug. Therefore, identifying supplementary agents that sensitize tumor cells to chemotherapy-induced apoptosis and help minimize drug resistance would be valuable for improving patient tolerance and response to chemotherapy. The use of effective supplementary agents provides a twofold advantage in combination with standard chemotherapy. First, by augmenting the activity of the chemotherapeutic drug it can lower the dose needed to kill tumor cells and decrease the incidence and severity of treatment-limiting side effects. Second, adjuvant therapies that lower the effective dose of chemotherapy may delay/prevent the development of chemoresistance in tumors. Capsaicinoids, a major class of phytochemical compounds isolated from chili peppers, have been shown to improve the efficacy of several anti-cancer drugs in cell culture and animal models. The present chapter summarizes the current knowledge about the chemosensitizing activity of capsaicinoids with conventional and targeted chemotherapeutic drugs, highlighting the potential use of capsaicinoids in novel combination therapies to improve the therapeutic indices of conventional and targeted chemotherapeutic drugs in human cancers.

Non-Pungent n-3 Polyunsaturated Fatty Acid (PUFA)-Derived Capsaicin Analogues as Potential Functional Ingredients with Antioxidant and Carbohydrate-Hydrolysing Enzyme Inhibitory Activities

N-Eicosapentaenoyl vanillylamine (EPVA) and N-docosahexaenoyl vanillylamine (DHVA), derived from n-3 polyunsaturated eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), respectively, were studied for their potential antioxidant and carbohydrate-hydrolysing enzyme inhibitory activities together with capsaicin and the corresponding n-3 polyunsaturated fatty acids (PUFAs). The antioxidant potential was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay, β-carotene bleaching test, and ferric reducing ability power (FRAP). In the ABTS assay the following trend of potency could be observed EPVA > DHVA ≥ capsaicin. In addition, except for the FRAP test, all samples showed a greater activity than the positive controls used as reference compounds in the antioxidant assays. Both EPVA and DHVA showed half maximal inhibitory concentration (IC₅₀) values much lower than acarbose, which was used as the reference drug in the carbohydrate-hydrolysing enzyme inhibitory activity assays. It is interesting to note that structural changes in capsaicin derivatives had higher impacts on α-glucosidase than on α-amylase inhibition. Taken together, our data suggest that both EPVA and DHVA, which are not limited in compliance-related considerations with respect to capsaicin, due to absence of pungency, could be proposed as functional ingredients for the development of products for the management of type II diabetes and border-line hyperglycaemic patients.

Capsaicin inhibits the function of α7-nicotinic acetylcholine receptors expressed in Xenopus oocytes and rat hippocampal neurons

Capsaicin is a naturally occurring alkaloid derived from Chili peppers fruits. Using the two-electrode voltage-clamp technique in Xenopus oocyte expression system, actions of capsaicin on the functional properties of α₇ subunit of the human nicotinic acetylcholine (α₇ nACh) receptor were investigated. Ion currents activated by ACh (100 μM) were reversibly inhibited with an IC₅₀ value of 8.6 μM. Inhibitory actions of capsaicin was independent of membrane potential. Furthermore, Ca²⁺-dependent Cl^- channels expressed endogenously in oocytes were not involved in inhibitory actions of capsaicin. In addition, increasing the ACh concentrations could not reverse the inhibitory effects of capsaicin. Importantly, specific binding of [¹²⁵I] α-bungarotoxin remained unaltered by capsaicin suggesting that its effect is noncompetitive. Whole cell patch-clamp technique was performed in CA1 stratum radiatum interneurons of rat hippocampal slices. Ion currents induced by choline, a selective-agonist of α₇-receptor, were reversibly inhibited by 10 min bath application of capsaicin (10 μM). Collectively, results of our investigation indicate that the function of the α7-nACh receptor expressed in Xenopus oocytes and in hippocampal interneurons are inhibited by capsaicin.

Extensive review of popular functional foods and nutraceuticals against obesity and its related complications with a special focus on randomized clinical trials

Obesity is a multifactorial chronic disease or syndrome mainly caused by an imbalance in energy expenditure and intake. Obesity and its associated complications make it the fifth leading cause of global mortality. The benefits of the current anti-obesity treatment regimen have been marked by high cost and numerous adverse effects. Therefore, many researchers focus on plant-derived/natural products or altered dietary patterns for the management of obesity and its related complications (co-morbidities). Several epidemiological studies have confirmed that the consumption of functional foods/nutraceuticals could considerably lower the risk of various chronic diseases, like obesity, diabetic mellitus, and cancer, but the underpinning mechanism is still unclear. This comprehensive review briefs on the prevalence of obesity, the complications related to obesity, the current treatment regimen and the importance of functional foods and nutraceuticals (molecular mechanism) for the management of body weight and alleviation of its co-morbid conditions. This is the first comprehensive review revealing the in-depth anti-obesity mechanisms of various popular functional foods and nutraceuticals with a special reference to randomized clinical trials (RCTs). Overall, this contribution highlights the importance and beneficial role of functional foods/nutraceuticals on weight management (anti-obesity) and their contributions to the current treatment status, especially related to clinical trials, which could help in the development of novel functional foods/nutraceuticals for combatting obesity and its co-morbidities.

Capsaicin induces apoptosis and autophagy in human melanoma cells

Melanoma is the most lethal type of skin cancer; rapid metastasis and resistance to conventional radio- and chemotherapy make melanoma the most aggressive type of skin cancer. In addition, there is a high recurrence rate within 1 year among patients with melanoma following traditional treatment by chemotherapy or immunotherapy, and these treatment options are only useful in advanced stages. As the efficiency of treatment options for melanoma is not ideal, the present study aimed to confirm that capsaicin has inhibitory effects on the human melanoma A375 and C8161 cell lines in vitro. Capsaicin, the active component of peppers, has been reported to possess substantial anticarcinogenic and antimutagenic activities. Additionally, capsaicin exhibits an inhibitory effect on tumor growth in numerous malignant cell lines. In the present study, flow cytometry, fluorescent puncta detection and western blotting were performed. The experimental results indicated that capsaicin activated apoptosis, and that apoptosis induction was associated with poly(ADP-ribose) polymerase (PARP) cleavage and activation of caspase-3. Additionally, the formation of autophagosomes and accumulation of microtubule-associated proteins 1A/1B light chain 3B-II and beclin 1 suggested that capsaicin induced autophagy in human melanoma cells. Furthermore, inhibiting capsaicin-induced autophagy promoted the activation of cleaved caspase-3 and PARP proteins, which are associated with apoptosis. In addition, inhibition of autophagy using 3-MA enhanced capsaicin-induced cell death, indicating that capsaicin-induced autophagy is a pro-survival process in cells. In conclusion, the results of the present study revealed that capsaicin induced cell apoptosis and autophagy in human melanoma cells and capsaicin may be considered as a novel candidate drug for melanoma treatment.

Capsaicin Targets Lipogenesis in HepG2 Cells Through AMPK Activation, AKT Inhibition and PPARs Regulation

Obesity, a major risk factor for chronic diseases such as type 2 diabetes (T2D), represents a serious primary health problem worldwide. Dietary habits are of special interest to prevent and counteract the obesity and its associated metabolic disorders, including lipid steatosis. Capsaicin, a pungent compound of chili peppers, has been found to ameliorate diet-induced obesity in rodents and humans. The purpose of this study was to examine the effect of capsaicin on hepatic lipogenesis and to delineate the underlying signaling pathways involved, using HepG2 cells as an experimental model. Cellular neutral lipids, stained with BODIPY493/503, were quantified by flow cytometry, and the protein expression and activity were determined by immunoblotting. Capsaicin reduced basal neutral lipid content in HepG2 cells, as well that induced by troglitazone or by oleic acid. This effect of capsaicin was prevented by dorsomorphin and GW9662, pharmacological inhibitors of AMPK and PPARγ, respectively. In addition, capsaicin activated AMPK and inhibited the AKT/mTOR pathway, major regulators of hepatic lipogenesis. Furthermore, capsaicin blocked autophagy and increased PGC-1α protein. These results suggest that capsaicin behaves as an anti-lipogenic compound in HepG2 cells.