Capsaicinoids differences

The intermediates for the branched chain fatty acid production have been detected in tissues [69], The saturated and desaturated forms of the branched chain acyl-ACP and acyl-CoA are in the same relative amounts as in the final capsaicinoid products, as demonstrated for two different cultivated species, habanero (C. chinense) and jalapeno (C. annuum). From these results the authors indicate that the desaturation step occurs prior to release from the FAS complex. 

Although most consumers appreciate the fieriness of chile, capsaicinoids are not perceived through odor or taste receptors but through the nociceptive pain receptors described earlier. The compounds in chile fruit that create the flavor and aroma are produced in the fruit wall. Buttery et al. [90] generated vacuum steam distilled oil from green bell pepper macerate, with well over 40 peaks on subsequent GC/MS analysis. Of these peaks, the major flavor compound associated with bell pepper aroma was 2-methoxy-3-isobutylpyrazine (Fig. 8.1). They also reported several monoterpenoids in abundance, limonene, trans- 3-ocimene, and linalool as well as other aliphatic aldehydes and ketones. The flavor composition of dried red bell pepper powder (sweet paprika) extracted with ether identified 44 key peaks by GC/MS [91]. In these dried samples the key compounds were P-ionone and several furanones. The post-harvest processing and the different fruit maturities as well as possible varietal differences are all causes for the different aromatic profiles. 

The threshold values obtained by this improved procedure for the different capsaicinoids and some synthetics are given in Table X. These values were used to calculate actual pungency of capsicum extract from the gas chromatographic determination of individual capsaicinoids, and a significant correlation with sen-sorily estimated pungency was found (See later, Figure 3). 

The estimation of individual components and different synthetics was effectively achieved by gas chromatography after simple silylation (10). Figure 2 shows the separation obtained, clearly away from other volatiles in a capsicum extract. The individual capsaicinoids were quantitated in relation to vanillyl octanamide as the internal standard chosen, because it eluted just prior to the capsaicinoids and the response factors of the capsaicinoids with reference to this standard were close to unity. The standardised conditions were as follows Silylation with N,0-bis (trimethylsilyl)-trifluoroacetamide in tetrahydrofuran gave clear rapid reaction at room temperature. The silylated extracts were injected directly on to a stainless steel column of 2 m x 3 mm, filled with 3% SE-30 on Chromosorb-GHP, (100-120 mesh) the column temperature was programmed from 170° to 215°C at 4°/min. and held at 215°C for 10 minutes. The injection port temperature was important for rapid volatilisation of all the components without decomposition, and was fixed at 200°C. The flame ionisation detector temperature was kept at 250°C, and nitrogen flow at 20 ml/min. The percentages of the individual capsaicinoids were calculated from the areas of the peaks, the response factors, and the weight and area of the reference compound. 

Yun et al. (2002) observed the changes in fruit component by temperature treatment after harvest of unripened fruit in hot pepper. The capsaicinoid contents of 100% coloured red fruits were highest at 30°C and lowest at 25°C. The capsaicin and (3-carotene contents of 100% coloured red fruits of hot pepper were highest when stored at 15°C, while there were no significant differences in those contents among the other temperature treatments. In addition, the contents of cryptoflavin and cryptocapsin were highest at 15 and 25°C, respectively. 

The effect of seasonal changes on the pungency level of Padron pepper fruits was studied. The pattern of capsaicinoid accumulation was the same during the different months, but there was a considerable increase in capsaicinoid levels in August and September in all the growth stages studied (Estrada et al., 1999b). 

The capsaicinoid concentrations of the developing (20-100 days after flowering (DAF)) fruits of C. annuum and C. frutescens-chinense complex cultivars were determined by HPLC. Three capsaicinoids were detected (capsaicin, dihydrocapsaicin and nordihydrocapsaicin), and intercultivar and interspecific differences in capsaicinoid concentrations were observed as early as 20 DAF. Capsaicinoid concentrations were highest between 20 and 40 DAF (Rani, 1996 Minami et al., 1998). 

Saga, K. and Sato, G. (2003) Varietal differences in phenolic, flavonoid and capsaicinoid contents in pepper fruits (Capsicum annuum L.). Journal of the Japanese Society for Horticultural Science 72(4), 335-341. 

The formation of acyl conjugates of vanillamine (capsaicinoids, 20) or vanillic alcohol (capsinoids, 21) with various Cg/Ci3 alkenoic and alkanoic acids is a unique chemical trait of plants from the genus Capsicum. Hot peppers are characterized by the presence of vanillyl conjugates of the amide type, absent or replaced by their nonpungent ester isosters (capsinoids) in bell (sweet) peppers [19]. Indeed, the difference between the sensory properties of capsaicin (la) and its naturally occurring ester analog capsiate (22) is a remarkable example of the biological relevance of isosterism. 

Linear capsiacinoids with a C9/C12 chain are only trace constituents of capsicum oleoresin, which mainly contains branched capsaicinoids. The acyl moiety of these compounds is produced by the branched chain fatty acids pathway (Scheme 4.1) [30[. Depending on the nature of the amino acid that acts as the acyl starter precursor, different capsaicinoids are formed. Thus, capsaicinoids of the iso series such as CPS and homocapsaicin I are derived from valine and leucine via isobutyrylCoA and isovalerylCoA, respectively, while those from the anteiso series such as homocapsaicin II originate from isoleucine via 2-methylbutyrylCoA (Scheme 4.1) [31[. The polymethylene moiety of norcapsaicin has one less carbon than capsaicin. The... 

Since hot pepper is important for the food and the pharmaceutical industries, a range of different methods have been developed for the analysis of capsaicinoids in plant material and finished products. The separation of CPS (la) and nonivamide (11) is especially challenging, since these compounds have similar behavior in many chromatographic conditions. Since synthetic nonivamide is the most common adulterant of capsicum oleoresin, various strategies have been suggested to overcome this problem. Capillary GC does not require previous derivatization of capsaicinoids, but its separatory power seems lower than that of HPLC, currently the most popular technique for the quantization of capsaicinoids. GC is, however, the method of choice for the analysis of the acyl moieties of capsaicinoids as methyl esters. These can be directly produced from capsaicinoids by oxidative N-dealkylation with DDQ (2,3-dichloro-5,6-dicyanobenzoquinone), followed by alcoholysis of the resulting amides with methanol in the presence of an acidic resin (Scheme 4.4) [41]. 

In 1989, a different approach was published by Orito [60], in which elaidinization ((Z) —> ( ) double bond isomerization) is used to obtain ( )-MNA from a (Z, )-mixture ofdiastereomers (Scheme 4.6). Gannet had observed that the iodine-induced photoisomerization of the methyl ester of MNA (48) gave only a 7 3 ( /Z) mixture [59], but Orito obtained a better diastereomeric ratio (8 1) using nitrous acid. Remarkably, no double-bond migration to form the more stable trisubstituted olefin was observed. This discovery paved the way to a very simple and general synthesis of the acidic component of capsaicinoids. Thus, a Wittig reaction of the phosphonium salt of a 6-bromohexanoic acid (49) with isobutyraldehyde (SO) afforded a 1 11... 

Various studies have evidenced strict structure-activity relationships within capsaicinoids, and the existence of these relationships provided a hint for the existence of a specific receptor [72]. On the other hand, different end-points have been used in the literature, and it is difficult to draw a consistent picture. In vivo assays such as pungency and ocular irritancy, functional assays such as the measurement of calcium currents in dorsal root ganglion neurons, and receptor assays such as the displacement of labeled RTX have been used. The relationship between the results of these assays is, at best, approximate [75]. 

Capsaicin was prepared and being evaluated by the military as early as the 1920s in the United States. Interest in its development waned when CS was synthesized, and research efforts were redirected to the development of CS as an RCA. Unlike the other RCAs such as CS, CR and CN, which have definite chemical compositions, OC is a mixture of compounds containing capsaicinoids, various acids and esters, alcohols, aldehydes, ketones, and carotenoid pigments. Capsaicin as the major component is considered to be the active ingredient without consideration as to the activity or interactions of the other capsaicinoids or components. Although the activity of the other capsaicinoids is similar, they differ in potency. 

In the past few decades, the various activities such as antioxidant, cell inflammation, antimutagenic, and toxicity of capsaicinoid compounds have been investigated and reported by many researchers and scientists. Materska and Perucka reported the determination of the antioxidant activity of the capsaicinoid compounds isolated from hot and semi-hot pepper fruits at two different maturity stages during their cultivation [26], Reilly et al. have found that capsaicinoids are able to activate the vanilloid receptors, which are responsible for inflanunation and epithelial cell death in animal and human bodies [27,28]. The characteristic pharmacological responses of capsaicinoids include severe irritation, inflanunation, erythema, and transient hyper- and hypoalgesia at exposed sites such as, eyes, skin, nose, tongue, and respiratory tract. The vanilloid receptors are the calcium channel when activated by capsaicinoids they produce the characteristic sensations and causes toxicity in many mammalian cell types [27-29],... 

The capsaicinoids are extracted using different solvents and more recently ultrasound-assisted extraction [61], extraction by means of supercritical fluids [65], extraction by pressurized liquids [58] and enzymatic extraction [59], and analyzed by HPLC [64,93-95], GC [72-76], hyphenated systems as HPLC-MS [96-100], and GC-MS [77]. Normally the GC methods require derivatization of the compounds to make them sufficiently volatile for determination. There are many other reported papers have been found in the literature for the analytical separation, quantitation, and identification of naturally occurring capsaicinoids in different matrices. Select matrices are discussed here. 

Laskaridou-Monnerville developed micellar electrokinetic capillary chromatography, which is a modified capillary chromatography technique and was applied to determine capsaicin and dihydrocapsaicin in different varieties of C. frutescens [19]. Using their method, they had separated the samples by differential partition between micelles (pseudo stationary stage) and the mobile phase (aqueous buffer at pH 9). Both of the capsaicinoid compounds, capsaicin and dihydrocapsaicin, were detected within 11 min with an excellent resolution [19]. 

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