Metabolism capsaicinoids

The effect of water stress on phenyl pro-panoid metabolism was studied in Padron pepper plants growing in a greenhouse. The soluble phenolic and lignin contents of fruits from control plants were higher than those of water-stressed plants. The amount of capsaicinoids (capsaicin and dihydrocapsaicin) in the fruits of water-stressed plants was higher than that in control plants (Estrada et al., 1999a). 

From a biogenetic standpoint, capsaicin is an acylated degraded phenylpropanoid. Both its aromatic and its acyl moiety are the result of unique metabolic processes that, though simple in principle, are still poorly characterized in terms of enzymology and regulation. Since vanillamine (23) is abundant in placental tissues of Capsicum, the only site of biosynthesis of capsaicinoids, the limiting factor for the synthesis of... 

Capsaicin and capsaicinoids undergo Phase I metabolic bioconversion to catechol metabolites via hydroxylation of the vanillyl ring moiety (Lee and Kumar, 1980 Miller et al, 1983). Metabohsm involves oxidative, in addition to non-oxidative, mechanisms. An example of oxidative conversion involves the liver mixed-function oxidase system to convert capsaicin to an electrophilic epoxide, a reactive metabolite (Olajos, 2004). Surh and Lee (1995) have also demonstrated the formation of a phenoxy radical and quinine product the quinine pathway leads to formation of a highly reactive methyl radical (Reilly et al, 2003). The alkyl side chain of capsaicin also undergoes rapid oxidative deamination (Wehmeyer et al, 1990) or hydroxylation (Surh et al, 1995 Reilly et al, 2003) to hydroxycapsaicin as a detoxification pathway. An example of nonoxidative metabolism of capsaicin is hydrolysis of the acid-amide bond to yield vanillylamide and fatty acyl groups (Kawada et al, 1984 Oi et al, 1992). 

Miller, M.S., Brendel, K., Burks, T.F., Sipes, LG. (1983). Interaction of capsaicinoids with drug metabolizing systems relationship to toxicity. Biochem. Pharmacol. 32 547-51. 

Surh YJ, Ahn SH, Kim KC et al. (1995). Metabolism of capsaicinoids evidence for aliphatic hydroxylation and its pharmacological implications. Life Sci, 56, PL305-PL311. 

Capsaicin and capsaicinoids may be involved in complex interactions in vivo related to carcinogenesis, cocarcinogenesis and anticarcinogenesis, which are a reflection, in part, of metabolism and metabolite activity. Capsaicin... 

Metabolism of Capsaicinoids. Turnover and degradation during fruit development is possible. The role of peroxidases in capsaicinoid oxidation has been reviewed in detail recently (Diaz et al. 2004 and references therein). 5,5 -Dicapsaicin and 4 -0-5-dicapsaicin ether were obtained from the oxidation of capsaicin by pepper Bg peroxidase/H O (radical-radical coupling reactions). Indeed, a first capsaicinoid dimer, 6",7"-dihydro-5, 5 "-dicapsaicin, has been discovered as a constituent of C. annuum fruits (Ochi et al. 2003). 

Capsaicin and capsaicinoids xmdergo phase I metabolic bioconversion to catechol metabolites via hydroxy-lation of the vanillyl ring moiety (Miller et al., 1983). Metabolism involves oxidative, in addition to nonoxida-tive, mechanisms. An example of oxidative conversion... 

The biosynthetic pathway for capsaicinoids has been established and several genes involved in important steps of transformation of key precursors have been identified. In such manner, it is known that the genes Pal, Ca4h, and Comt are involved in the phenylpropanoid pathway Kas, Ad, and Fat encoding for the enzymes involved in fatty acid metabolism and the spicy... 

An exhaustive analysis of the structural implications of capsaicinoids on their metabolism by P450 enzymes and how they contribute to both detoxification and bioactivation processes in humans has been proposed. CycUzation, dehydrogenation to afford the terminal diene and imides, oxidatiOTi at the end of the carbon chain to render primary and tertiary alcohols, and demethylation and aromatic hydroxylation, are typical reactions in these processes, yielding metabolites with limited pharmacological and toxicological effects via reduction in their affinity for TRPVl [148]. 

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