Investigation of the Distribution and Content of Acetylcholine, a Novel Functional Compound in Eggplant

Eggplants are rich in acetylcholine (ACh), which can improve high blood pressure and negative psychological states. However, information on ACh content in individual parts of eggplant and the changes in ACh content during eggplant development is limited. Therefore, we investigated the ACh content in various parts of eggplant, namely, the leaf, root, bud, calyx, ovary, fruit, exocarp, mesocarp, partition, placenta, core, fruit base, fruit center, and fruit top in 26 eggplant varieties. Furthermore, the effect of heat treatment on ACh content was investigated. The ACh content significantly differed among the eggplant varieties. The difference between the varieties with the highest and lowest ACh content was 100-fold (Tosataka: 11 ± 0.61 mg/100 g fresh weight (FW) and Ryoma: 0.11 ± 0.046 mg/100 g FW, respectively). Eggplant fruit presented the highest ACh content (4.8 mg/100 g FW); it was three times higher than that in other parts combined (1.6 mg/100 g FW). The root contained the lowest ACh content among all parts. The ACh content increased with growth after flowering. The ACh content in the fruit 1.5 months after flowering was 400 times that in the ovary. ACh was uniformly distributed in eggplant flesh. Heat treatment did not cause ACh loss in eggplant. Thus, eggplant is an excellent raw material for functional foods.