Capsaicin synthase

Capsaicin is a bioactive molecule synthesized by enzymatic (putative capsaicin synthase) condensation of vanillylamine, a phenyl propanoid intermediate with 8-methyl-nonenoic acid, a fatty acid derivative from the leucine/valine pathway. Analysis of levels of 8-methyl-nonenoic acid and phenyl propanoid intermediates in high-, medium- and low-pungent Capsicum genotypes revealed that the 8-methyl-nonenoic acid pool plays a crucial role in determining the efficacy of capsaicin levels. Cerulenin-mediated inhibition of 8-methyl-nonenoic... 

Hydroxy-3-methylglutaryl coenzyme A synthase inhibition. Seed oil, administered intragastrically to rats at a dose of 2 mL/kg, was active k Hydrogen peroxide release inhibition. Seed oil, administered to rats at a concentration of 8% of diet, was active on macrophages. Capsaicin or curcumin enhanced the effect° h... 

It has been known for many years that autonomic effector tissues (eg, gut, airways, bladder) contain nerve fibers that do not show the histochemical characteristics of either cholinergic or adrenergic fibers. Both motor and sensory NANC fibers are present. Although peptides are the most common transmitter substances found in these nerve endings, other substances, eg, nitric oxide synthase and purines, are also present in many nerve terminals (Table 6-1). Capsaicin, a neurotoxin derived from chili peppers, can cause the release of transmitter (especially substance P) from such neurons and, if given in high doses, destruction of the neuron. 

Yu et al. (2005) evaluated capsaicin biosynthesis in water-stressed hot pepper fruits. The concentration of capsaicin in the placenta of fruits in the water deficit treatment began to increase rapidly 10 DAF. It reached maximum at 30 DAF and was 3.84-fold higher than in the placenta of control treatment plants. In the pericarp, the concentration of capsaicin reached maximum at 50 DAF and was 4.52-fold higher than in the control treatment. PAL activity was higher in the placenta of fruits in the water deficit treatment than in the fruits of control plants at 50 DAF. At 40 or 50 DAF, cinnamic acid 4-hydroxylase (trans-cinnamate-4-monoox-ygenase) (C4H) activity was higher in plants subjected to the water deficit treatment than in control plants. Capsaicinoid synthase (CS) activity 40 DAF was 1.45- to 1.58-fold higher in fruits in the water deficit treatment than in fruits in the control treatment. 

Fig. 6.5 Biosynthesis of bianched-chain capsaicinoids starting with a branched amino acid, e.g., L-valine — 2-oxovalerate —> isobutyryl CoA —> elongation (-t 3 x malonyl CoA) —> [- 3 x COj] — (activated) 8-methylnonanoicacid+vanillylamine—>dihydiocapsaicin[R=(Cllj) CH(CH3)CHj] CS = capsaicin(oid) synthase...

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