Identification of vanilloid compounds in grains of paradise and their effects on sympathetic nerve activity.

Background: Grains of paradise (GP) is the seed of Aframomum melegueta, which is widely distributed throughout West Africa and has been used as a spice and a folk remedy for a long time. Anti-obesity effect of GP intake was demonstrated in a previous report. Aim of the present study was to isolate some compounds in GP and clarify the anti-obesity mechanism.

Results: Ten vanilloid compounds were isolated. Among them, 1-(4'-hydroxy-3'-methoxyphenyl)-decan-3-ol and 1-(4'-hydroxy-3'-methoxyphenyl)-3-octen-5-one were determined as novel compounds and 6-gingerol, 6-paradol and 6-shogaol were identified as the major constituents in GP extract. Moreover, the extract and 6-gingerol, which is one of the principal components of GP extract, were orally administered to rats to investigate the effect on sympathetic nerve activity (SNA) in brown adipose tissue (BAT). The injection of GP extract and 6-gingerol decreased BAT-SNA, whereas capsaicin, which is a major component of chili pepper, activates the sympathetic nervous system.

Conclusion: This study suggested that GP extract and 6-gingerol were largely unrelated to the anti-obesity effect by the activation of interscapular BAT-SNA and had a different anti-obesity mechanism to capsaicin. © 2018 Society of Chemical Industry.