Publications

• Vanillin reduction in the biosynthetic pathway of capsiate, a non-pungent component of Capsicum fruits, is catalyzed by cinnamyl alcohol dehydrogenase.

  Sano K., Uzawa Y., Kaneshima I., Nakasato S., Hashimoto M., Tanaka Y., Nakatani S., Kobata K.

  Capsicum fruits synthesize capsaicin from vanillylamine, which is produced from vanillin in a reaction catalyzed by a putative aminotransferase (pAMT). Capsiate, a non-pungent compound that is structurally similar to capsaicin, is synthesized from vanillyl alcohol rather than vanillylamine. Vanill ... >> More

  Capsicum fruits synthesize capsaicin from vanillylamine, which is produced from vanillin in a reaction catalyzed by a putative aminotransferase (pAMT). Capsiate, a non-pungent compound that is structurally similar to capsaicin, is synthesized from vanillyl alcohol rather than vanillylamine. Vanillyl alcohol is possibly generated by the enzymatic reduction of vanillin, but the enzyme responsible for this reaction is unknown. In the present study, we revealed that the vanillin reductase in the capsiate biosynthetic pathway is cinnamyl alcohol dehydrogenase (CAD), which is an enzyme involved in lignin synthesis. The reduction of vanillin to vanillyl alcohol was greater in the mature red fruit placental extract than in the immature green fruit placental extract. This reduction was suppressed by both N-(O-hydroxyphenyl) sulfinamoyltertiobutyl acetate, a specific inhibitor of CAD, and ethylenediaminetetraacetic acid, a metalloenzyme inhibitor. The CaCAD1 transcript levels in the placenta were higher in the red fruits than in the green fruits. A recombinant CaCAD1 protein obtained using an Escherichia coli expression system reduced vanillin to vanillyl alcohol. This reaction was suppressed by the CAD inhibitors. These results strongly suggest that CAD is the enzyme that catalyzes the reduction of vanillin to vanillyl alcohol during capsiate biosynthesis. Syntenic analyses indicated that genes encoding CAD and capsaicin synthase (Pun1) involved in capsiate biosynthesis were acquired before the pAMT gene during the evolution of the family Solanaceae. This raises the possibility that in the genus Capsicum, the capsiate biosynthetic pathway emerged before the pAMT-encoding gene was acquired as the final trigger for capsaicin biosynthesis. << Less

  Sci. Rep. 12:12384-12384(2022) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Potent production of capsaicinoids and capsinoids by Capsicum peppers.

  Kobata K., Sugawara M., Mimura M., Yazawa S., Watanabe T.

  The fundamental structure of capsinoids is a fatty acid ester with vanillyl alcohol, whereas in capsaicinoids, a fatty acid amide is linked to vanillylamine. To clarify the relationship between their biosynthesis in Capsicum plants, we carried out an in vivo tracer experiment using stable isotopic ... >> More

  The fundamental structure of capsinoids is a fatty acid ester with vanillyl alcohol, whereas in capsaicinoids, a fatty acid amide is linked to vanillylamine. To clarify the relationship between their biosynthesis in Capsicum plants, we carried out an in vivo tracer experiment using stable isotopically labeled putative precursors. Liquid chromatography-tandem mass spectrometry was used to measure the uptake of isotopes into metabolites after injection of the labeled precursors into intact fruits of a pungent cultivar, Peru, and a non-pungent cultivar, CH-19 Sweet. Labeled vanillylamine was incorporated into capsaicinoids in both cultivars. While labeled vanillyl alcohol was incorporated into capsinoids in both cultivars, the accumulation of intact capsaicinoids in Peru was suppressed by over 60% after administration of vanillyl alcohol. In Peru, labeled vanillin was converted to both vanillylamine and, in 5-fold excess, vanillyl alcohol. Moreover, labeled vanillin was converted exclusively to vanillyl alcohol in CH-19 Sweet. These data are consistent with the incorporation of labeled vanillin into capsaicinoids and capsinoids in both cultivars. We conclude that pungent cultivars are highly potent producers of vanillyl alcohol that is incorporated into capsinoids and that biosynthesis of capsinoids is catalyzed by capsaicin synthase. << Less

  J Agric Food Chem 61:11127-11132(2013) [PubMed] [EuropePMC]