Quantitation of capsiate and dihydrocapsiate and tentative identification of minor capsinoids in pepper fruits (Capsicum spp.) by HPLC-ESI-MS/MS(QTOF)

Analysis of Volatile and Non-Volatile Components of Dried Chili Pepper (Capsicum annuum L.)

As an important crop in the world, dried pepper is widely used in various foods. However, the sensory quality, fruit shape index, edible index, nutrition index, and volatile components of dried pepper have not been comprehensively analyzed. This study elucidated the differences between different varieties of dried pepper and provided the basis for the selection of raw materials for different varieties of dried pepper products. The varieties with high scores in sensory evaluation were Henan new generation, Neihuang new generation, Chengdu Erjingtiao, India S17, and Honglong 12. The varieties with the highest fruit shape index, edible rate, and nutrition index were Chengdu Erjingtiao and Guizhou Erjingtiao. A total of 380 volatile organic compounds were identified by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry with headspace sampling (HS-GC-TOF MS), including 62 alcohols, 50 aldehydes, 68 ketones, 60 hydrocarbons, 99 esters, 18 acids, and 23 other substances such as pyrazoles and ethers.

Characterization of Thirty Germplasms of Millet Pepper (Capsicum frutescens L.) in Terms of Fruit Morphology, Capsaicinoids, and Nutritional Components

BACKGROUND

Millet peppers have rich and diverse germplasm resources. It is of great significance to characterize their phenotypes and physicochemical indicators.

METHODS

30 millet germplasms were selected to measure the fruit length and width, flesh thickness, number of ventricles, fruit stalk length, and single fruit weight, and the texture characteristics of fruit such as hardness, cohesiveness, springiness, gumminess, and chewiness were determined by a texture analyzer. At the same time, high-performance liquid chromatography (HPLC) and gas chromatography (GC) were used to determine the fruit of capsaicin, dihydrocapsaicin, nordihydrocapsaicin, fatty acids, vitamin E (VE), total phenol, total sugar, and total dietary fiber.

RESULTS

M11 showed outstanding parameters in phenotype and texture. The coefficient of variation (CV) for VE was as high as 94.943% and the highest diversity index (H') was total soluble solid, at 1.988%. M5 and M18 contained rich and diverse fatty acids. At the same time, the content of capsaicinoids in M18 also ranks among the top, second only to M27 (with a total capsaicin content of 5623.96 μg/g). PCA analysis using phenotypic data and physicochemical data showed that the classification results were different. Further hierarchical group analysis was carried out using all the index data. The results showed that 30 millet pepper germplasms were divided into three new categories: M5, M9, M18, and M24 formed one group (C1), M10, M14, M16, M19, M20, M22, M25, M26, M28, M29, and M30 formed another cluster (C2), and the remaining germplasms formed a third cluster (C3). Among them, the abundance of fatty acids in the C1 germplasm was higher than that in the other two groups.

CONCLUSIONS

Our study showed that different germplasms had significant differences in morphological traits and nutritional metabolic components and were rich in genetic diversity. This study provides a theoretical basis for the improvement of millet varieties and the development of functional food.

Quality by Design-Steered Chromatographic Separation and Identification of the Geometric Isomers of Capsiate by Reversed-Phase HPLC and LC-MS

An efficient reverse-phase high-performance liquid chromatographic method, based on the design of the experiment approach, was developed for the simultaneous determination of capsiate isomers. Critical method parameters, i.e., flow rate and mobile phase composition, demarcated during preliminary screening were optimized using central composite design. Chromatographic separation was achieved on a Nucleodur C18 column (250 × 4.6 mm, 5 μm), with the mobile phase consisting of water-acetonitrile (40:60), both acidified with 0.1% v/v formic acid, passed at a flow rate of 1 mL/min. E- and Z-capsiates were eluted from the column at the retention times of 18.56 ± 0.09 and 17.30 ± 0.08 min, respectively, with a resolution factor of 1.693 ± 0.046. The method was found to be linear within the concentration range of 1.054-5.270 and 8.623-43.115 μg/mL for Z- and E-isomers, respectively, with an R2 of >0.99. Recovery of the individual values was in range of 96.15-101.92%, with a relative standard deviation of <2%. The developed method was used to quantify capsiate isomers extracted from sweet pepper fruits. Therefore, the proposed method is presented for optimum isomeric resolution of these closely related E- and Z-isomers with convenient sample preparation, acceptable run-time, cost effectiveness and use of conventional instruments.

HIGHLIGHTS

Sweet pepper and its principle constituent capsiate: functional properties and health benefits

Capsiate is a non-pungent analogue of capsaicin. It belongs to the family of capsinoids which are esters of vanillyl alcohol with fatty acids while capsaicin belongs to the family of capsaicinoids that are amides of vanillylamine with a variety of branched-chain fatty acids. While capsaicin is extensively reported for plethora of pharmacological actions, capsiate remains much less explored. Extracted from various species of Capsicum plant, the molecule has also been chemically synthesized via a number of synthetic and enzymatic routes. Based on its action on transient receptor potential vanilloid subfamily member 1 receptors, recent research has focused on its potential roles in treatment of obesity, metabolic disorders, cancer, cardiovascular disorders and gastro-intestinal disorders. Its toxicity profile has been reported to be much safe. The molecule, however, faces the challenge of low aqueous solubility and stability. It has been commercialized for its use as a weight loss supplement. However, the therapeutic potential of the compound which is much beyond boosting metabolism remains unexplored hitherto. This comprehensive review summarizes the studies demonstrating the therapeutic potential of capsiate in various pathological conditions. Discussed also are potential future directions for formulation strategies to develop efficient, safe and cost-effective dosage forms of capsiate to explore its role in various disease conditions. The databases investigated include Cochrane library, Medline, Embase, Pubmed and in-house databases. The search terms were "capsiate," "capsinoids," "thermogenesis," and their combinations. The articles were screened for relevance by going through their abstract. All the articles pertaining to physicochemical, physiological, pharmacological and therapeutic effects of capsiate have been included in the manuscript.

Simultaneous determination by UHPLC-PDA of major capsaicinoids and capsinoids contents in peppers

Capsaicinoids and capsinoids compounds have been a focus of special attention for their health benefits. An effective and rapid Ultra-High-Performance Liquid Chromatography (UHPLC-PDA) method has been developed and validated for the simultaneous separation and quantitative determination of the major capsaicinoids and capsinoids present in peppers. The separation of all the compounds of interest was achieved in less than 2 min by means of an ACQUITY UPLC BEH rp-C18 column (100 mm × 2.1 mm i.d., 1.7 µm particle size). The variables that have been optimized are the mobile phase (water as solvent A and acetonitrile as solvent B, both acidified by adding 0.1% acetic acid), separation gradient, column temperature (35-70 °C), flow rate (0.6-0.95 mL min^-1), and injection volume (2.5-3.5 µL). The evaluation of the chromatographic performance revealed excellent resolution, retention factor, and selectivity. The method was satisfactorily validated in terms of linearity, detection and quantification limits, precision, and robustness.

The Beneficial Effects of Red Sun-Dried Capsicum annuum L. Cv Senise Extract with Antioxidant Properties in Experimental Obesity are Associated with Modulation of the Intestinal Microbiota

SCOPE

Capsicum annuum L. cv Senise is a sweet pepper containing health promoting compounds that can be modified by ripening and drying. This study focuses on finding the peppers with the best antioxidant properties, which are evaluated on an experimental model of obesity.

METHODS AND RESULTS

Phytochemical profile and antioxidant activity are evaluated on several peppers obtained from the same cultivar at different ripening stages. Red sweet peppers show the highest content in polyphenols, β-carotene, lycopene, and capsinoids, and demonstrate the best antioxidant activity in vitro. Mice fed a high fat diet are orally treated with an extract from these peppers (Capsicum annuum extract [CAE]) (1, 10, and 25 mg/kg/day). It promotes weight loss and improves plasma markers related to glucose and lipid metabolisms. CAE also ameliorates obesity-associated systemic inflammation reducing the expression of pro-inflammatory cytokines in adipose and hepatic tissues and improving the expression of different markers involved in the gut epithelial barrier function. These effects are associated with a modulation of the intestinal microbiome, which appears altered.

CONCLUSIONS

The extract can be considered a new potential approach for the treatment of obesity, complementary to dietary restrictions.

Recovery of Capsaicinoids and Other Phytochemicals Involved With TRPV-1 Receptor to Re-valorize Chili Pepper Waste and Produce Nutraceuticals

The hot chili pepper industry represents one of the most important staple foods in Mexico and many Asian countries. Nowadays, large amounts of waste materials are produced from the pepper supply chain that could be used as a source to obtain nutraceuticals. Among the most common and important bioactive compounds contained in pepper residues are the capsaicinoids, which are the responsible of the pungency of the pepper. Capsaicinoids, mainly capsaicin, may ameliorate obesity, gastric disorder, diabetes, cardiovascular diseases, cancer, rhinitis, asthma, immune system diseases, and important viral diseases as the recent COVID-19. The aim of this review is to review the industrial process for the extraction of capsaicinoids ingredients from pepper residues and to examine the relation of the capsaicin and other chili pepper phytochemicals to prevent and treat chronic diseases explained through the key role of the TRPV1 receptor. The extraction and incorporation of these compounds into nutraceutical formulations depend mainly on the development of new methods to improve not only the yield of a particular compound but the validation of the bioactivity and phytochemical characterization.

Identification and detection of bioactive compounds in turmeric (Curcuma longa L.) using a gas sensor array based on molecularly imprinted polymer quartz crystal microbalance

Four bioactive compounds in turmeric (Curcuma longa L.) have been identified using a gas sensor array based on a molecularly imprinted polymer-quartz crystal microbalance (MIP-QCM).

The gut microbiota metabolite capsiate promotes Gpx4 expression by activating TRPV1 to inhibit intestinal ischemia reperfusion-induced ferroptosis

Ferroptosis, a new type of cell death has been found to aggravate intestinal ischemia/reperfusion (I/R) injury. However, little is known about the changes of gut microbiota and metabolites in intestinal I/R and the role of gut microbiota metabolites on ferroptosis-induced intestinal I/R injury. This study aimed to establish a mouse intestinal I/R model and ileum organoid hypoxia/reoxygenation (H/R) model to explore the changes of the gut microbiota and metabolites during intestinal I/R and protective ability of capsiate (CAT) against ferroptosis-dependent intestinal I/R injury. Intestinal I/R induced disturbance of gut microbiota and significant changes in metabolites. We found that CAT is a metabolite of the gut microbiota and that CAT levels in the preoperative stool of patients undergoing cardiopulmonary bypass were negatively correlated with intestinal I/R injury. Furthermore, CAT reduced ferroptosis-dependent intestinal I/R injury in vivo and in vitro. However, the protective effects of CAT against ferroptosis-dependent intestinal I/R injury were abolished by RSL3, an inhibitor of glutathione peroxidase 4 (Gpx4), which is a negative regulator of ferroptosis. We also found that the ability of CAT to promote Gpx4 expression and inhibit ferroptosis-dependent intestinal I/R injury was abrogated by JNJ-17203212, an antagonist of transient receptor potential cation channel subfamily V member 1 (TRPV1). This study suggests that the gut microbiota metabolite CAT enhances Gpx4 expression and inhibits ferroptosis by activating TRPV1 in intestinal I/R injury, providing a potential avenue for the management of intestinal I/R injury.

Rapid and comprehensive profiling of α-glucosidase inhibitors in Buddleja Flos by ultrafiltration HPLC-QTOF-MS/MS with diagnostic ions filtering strategy

Buddleja Flos is used as yellow rice colorant and a well-known traditional Chinese medicine. But its biochemical profiling is still lack due to complex matrix. Here, ultrafiltration high-performance liquid chromatograph-quadrupole time-of-flight tandem mass spectrometry (HPLC-QTOF-MS/MS) with diagnostic ions filtering strategy was proposed for rapid and comprehensive investigation of its α-glucosidase inhibitors. As a result, 33 bioactive compounds (13 phenylethanoid glycosides and 20 flavonoids) were successfully screened and identified. In addition, α-glucosidase inhibitory activities of twenty-two references were verified. Six flavonoid aglycones (4, 28, and 30-33) showed excellent α-glucosidase inhibitory activities (IC₅₀, from 5.11 ± 0.85 to 32.49 ± 9.76 μg/mL), much higher than that of acarbose (IC₅₀, 195.49 ± 10.05 μg/mL). Five flavonoid-monoglycosides (7, 12, 13, 20, and 22) presented moderate inhibitory activities with IC₅₀ from 160.98 ± 23.19 to 249.37 ± 35.83 μg/mL. Results showcased the high efficiency of proposed strategy in profiling of bioactive compounds from natural products.

Assessment of Capsaicinoid and Capsinoid Accumulation Patterns during Fruit Development in Three Chili Pepper Genotypes (Capsicum spp.) Carrying Pun1 and pAMT Alleles Related to Pungency

Quantification, using an accurate analytical approach, of capsinoids and capsaicinoids was performed on three chili pepper (Capsicum spp.) genotypes: "Chiltepı́n", "Tampiqueño 74", and "Bhut Jolokia" at various stages of fruit development. The accumulation of capsinoids, in all these peppers started between 10 to 20 days post-anthesis (dpa), increased and reached the highest capsinoid amount at 40 dpa, and then decreased until 60 dpa. Conversely, capsaicinoids could already be determined at 10 dpa in "Bhut Jolokia" and their accumulation pattern was different from that of the capsinoids in this genotype. The capsiate/dihydrocapsiate ratio presented a higher variation between genotypes and developmental stages than the capsaicin/dihydrocapsaicin ratio. Capsinoid ratios (4-24%) and Pun1/pAMT genotyping were determined. These results provide information on the progress of the accumulation of capsinoids in the aforementioned pungent and superhot cultivars and could support future breeding studies toward the understanding of the factors affecting their accumulation.

Optimizing and Comparing Ultrasound- and Microwave-Assisted Extraction Methods Applied to the Extraction of Antioxidant Capsinoids in Peppers

Capsinoids are very similar antioxidant compounds to capsaicinoids, but less irritating, non-pungent and more palatable, and can thus be used in greater concentrations for food applications. To date, three capsinoids (capsiate, dihydrocapsiate, and nordihydrocapsiate) have been isolated from the pepper fruits. Due to its substantial commercial importance, it would be convenient to determine which pepper varieties have a richer content. Ultrasound- (UAE) and microwave- (MAE) assisted extraction have been implemented and analyzed using multivariate statistical methods. Firstly, different solvents were tested individually. The three best solvents were used in a set mixture design, where 42% methanol and 58% ethyl acetate were determined as the optimum combination for UAE, and 100% methanol for MAE. Subsequently, a Box–Behnken experimental design with four variables for both UAE and MAE (time, temperature, pH and sample mass:solvent volume “ratio”) was performed. The sample mass:solvent volume was the most influential variable in UAE; while for MAE no variable was any more influential than the others. Finally, both optimized extraction methods were successfully applied to different varieties of peppers. Besides, to demonstrate the efficiency of both extraction methods, a recovery study was performed. The results prove the potential of both techniques as highly adequate methods for the extraction of capsinoids from peppers.

Placenta, Pericarp, and Seeds of Tabasco Chili Pepper Fruits Show a Contrasting Diversity of Bioactive Metabolites

Chili pepper (Capsicum spp.) is one of the most important horticultural crops worldwide, and its unique organoleptic properties and health benefits have been established for centuries. However, there is little knowledge about how metabolites are distributed throughout fruit parts. This work focuses on the use of liquid chromatography coupled with high resolution mass spectrometry (UHPLC-ESI-HRMS) to estimate the global metabolite profiles of the pericarp, placenta, and seeds of Tabasco pepper fruits (Capsicum frutescens L.) at the red mature stage of ripening. Our main results putatively identified 60 differential compounds between these tissues and seeds. Firstly, we found that pericarp has a higher content of glycosides, showing on average a fold change of 5 and a fold change of 14 for terpenoids when compared with other parts of the fruit. While placenta was the richest tissue in capsaicinoid-related compounds, alkaloids, and tocopherols, with a 35, 3, and 7 fold change, respectively. However, the seeds were richer in fatty acids and saponins with fold changes of 86 and 224, respectively. Therefore, our study demonstrates that a non-targeted metabolomic approach may help to improve our understanding of unexplored areas of plant metabolism and also may be the starting point for a detailed analysis in complex plant parts, such as fruits.