Título da Tese: Comparação dos conteúdos de capsainóides, fenólicos e atividade antioxidante e composição de ácidos graxos de pimentas do gênero Capsicum

Orientador: Profa. Dra. Rosane Marina Peralta

Data da Defesa: 20/03/2015



INTRODUCTION AND AIMS – Numerous spices contain chemical compounds exhibiting antioxidant properties. These properties are attributed to a variety of active phytochemicals including vitamins, carotenoids, alkaloids, flavonoids, simple phenols, phenolic acids, etc. Peppers (Capsicum spp.), are grown worldwide, used extensively as a natural food colorant and seasoning agent due to their attractive color, flavor, and taste. Pepper has a high nutritive value and has long been recognized as an excellent source of vitamin C, carotenoids, phenolic compounds and other phytochemicals that are powerful antioxidants that destroy free radicals. The concentrations of these compounds in pepper depend on many factors, including cultivar, maturity, growing conditions, and climate. Numerous studies have examined peppers mainly to evaluate the chemical composition and/or antioxidant activities of the various cultivars and the effects of drying and cooking methods on their physicochemical properties. One of the important commercial attribute of peppers is its pungency. The pungency is due to the presence of six chemically related compounds knowed as capsaicinoids. The two most abundant capsaicinoids in peppers are capsaicin (trans-8-metil-N-vanilil-6-nonenamide) and dihydrocapsaicin (8-metil-Nvanillylnonanamide), both constituting around 90%, with capsaicin accounting for ~71% of the total capsaicinoids in most of the pungent varieties. The capsaicin content of peppers is one of the major parameters that determine their commercial quality. Capsaicin is also the active principle that accounts for the pharmaceutical properties of peppers. It has been used as an analgesic against arthritis pain and inflammation. A beneficial role of capsaicin has been reported in obesity, cardiovascular and gastrointestinal conditions, various cancers, neurogenic bladder, and dermatologic conditions. Lipids and fatty acids represent in general a small portion of the edible portion in peppers. However, they have a great metabolic and structural importance. The content of lipids is an important parameter of quality, considering that several bioactives and molecules responsible for the pericarp (pulp) colour are liposoluble. Additionally, the nutritional quality of lipids is dependent on its fatty acid composition. Evaluation of the fatty acid composition of peppers of the genus Capsicum is still incomplete and is limited to C. annuum. Thus, the objectives of this work were 1) to review the main nutritional, functional and chemical aspects of the most consumed peppers in the world (ARTICLE 1); 2) to compare the capsaicin, dihydrocapsaicin and phenolic contents 8 as well as the antioxidant activities of pulp and seed extracts of six different peppers of the genus Capsicum using multivariate statistical techniques (ARTICLE 2); 3) to evaluate the fatty acid composition of six peppers of the genus Capsicum. Considering that the fatty acids are present in both pericarp and seed, these parts were previously separated for evaluation of distribution of those compounds. The methodology of principal component analysis (PCA) was used to scrutinize the relationships between variables and standards (ARTICLE 3). METHODS – Six peppers of the genus Capsicum were used in this work: C. annuum (cayenne pepper and bell pepper), C. baccatum var. pendulum (known in Brazil as dedo de moça pepper), C. chinense (red habañero pepper and orange habañero pepper) and C. frutescens (malagueta pepper). Three samples of each pepper were purchased at three different supermarkets between April and May 2013. In the article 2, pulps and seeds were manually separated and grounded in a blender. For extracting the phenolics from the pulps, a volume of 20 mL of 40% ethanol in water was added to 10 g of pulp. For extracting the phenolics from the seeds, a volume of 40 mL of 80% ethanol in water was added to 5 g of each seed. The mixtures were maintained in a rotary shaker at 22 rpm for 24 h at room temperature in the dark and thereafter centrifuged at 3.370g for 10 min at 5º C. The supernatants were then filtered using Whatman paper n° 41 and maintained at -20ºC until analysis. Capsainoids were evaluated by liquid chromatography. The total phenolic contents were determined using the Folin–Ciocalteu method. The antioxidant capacities of the pulp and seed extracts were evaluated using three methods and expressed as μmol trolox equivalents per g of pulp or seed (µmol TEg -1 ). The radical scavenging capacity was evaluated using the DPPH assays, ABTS assay and FRAP assay. A chemometric approach, composed of principal component analysis (PCA), multiple linear regression (MLR) and hierarchical cluster analysis (HCA), implemented in Statistica 7.0 software, was used to analyze the data. In the article 3, pulps (pericarp) and seeds were manually separated and grounded in a blender. Lipids were extracted using a mixture of chloroform:methanol:water (45:30:25).To determine the fatty acid composition, the lipids were converted into fatty acid methyl esters (FAME). The FAME were separated and evaluated by gas chromatograph. RESULTS AND DISCUSSION – In the article 2, the contents of phenolics and capsainoids as well as the antioxidant activities were higher in seeds than in pulps. The correlations (ρ <0.01) between the phenolic composition and the capsaicinoids concentrations 9 were high (r = 0.98). Similarly high were also the correlations between the antioxidant activities and the contents of total phenolics and capsaicinoids. Data were analyzed using principal component analysis (PCA), hierarchical cluster analysis (HCA) and multiple linear regression (MLR). PCA explained 97.92% of the total variance of the data, and their separation into 3 groups in a scatter plot was divided. Using HCA, 3 clusters were suggested. Cluster 1, formed by pulps (bell pepper, orange habanero, cayenne, dedo de moça and red habanero), showed the lowest concentrations of the compounds quantified. Most seed samples were grouped in cluster 2 (bell pepper, cayenne, dedo de moça and malagueta) together with malagueta pulp. Cluster 3 was formed by orange and red habanero seeds, which showed the highest concentrations of all compounds analyzed. The MRL revealed that the values of capsaicinoids and total phenols are more adequate to predict the antioxidant activity measured by the FRAP assay. In the article 3, A total of 25 different fatty acids, including some with odd number of carbons, were identified in the samples. The most abundant fatty acids were palmitic (16:0), oleic (18:1n-9) e linoleic (18:2n-6) acids. The unsaturated/saturated (PUFA/SFA) ratios for all peppers were high due to the elevated amounts of polyunsaturated acids, particularly linoleic acid (n-6). In the pulps, the omega-6/omega-3 ratios ranging from1.28 to 4.33, were relatively adequate if one considers that ratios between 0.25 and 1.0 in the human diet are regarded as highly appropriate. In the seeds, the concentrations of n-3 were very low whereas the concentrations of n-6 were high, leading to very inadequate omega6/omega-3 ratios ranging from 74.2 to 279.6. Principal component analysis (PCA) explained 72.46% of the total variance of the data. CONCLUSIONS - From the extracts of seed and pulp examined in the present work, the two with the highest capsainoid and phenolic contents and antioxidant activity were those of the red and orange habanero seeds. Considering the PUFA/SFA ratio and n-6/n-3 ratio, our data suggest that, among the peppers of the genus Capsicum evaluated in this work, the bell pepper and orange habanero pepper present the best nutritional characteristics concerning fatty acid composition. KEY-WORS: Capsicum, phenolics, antioxidant activity, capsaicinoids, fatty acids, MUFA/SFA ratio, n6/n3 ratio, multivariate analysis.


Artigos Publicados Vinculados a Tese:

https://doi.org/10.1007/s13197-015-1935-8 https://doi.org/10.1590/S1413-70542015000400008 https://doi.org/10.46420/9786588319277cap7