Capsicum cultivated under adverse conditions in Southern Japan produces higher concentrations of antioxidants and pungent components

Abstract

Growing crops in sabulous soils is often challenging due to their limited oligotrophy and weak water retention. However, some plants adapt to these adverse growth conditions, and in some cases, favorable properties are imparted to the fruit. This study investigated the influence of the cultivation environment on Capsicum by assessing the levels and functions of both pungent components and antioxidants when cultivated in sandy soils in Southern Japan; these parameters were then compared to those in traditional tropical-origin Capsicum. In seven varieties of Capsicum, the distribution of capsaicin and dihydrocapsaicin differed between the pericarp and seeds within the placenta. The leaves and fruits of Habanero orange and Tabasco, which are the most suitable for cultivation in sandy soil, were collected during the cultivation period and analyzed in terms of their size, color, and pungent component composition. Pungent components were detected in fruits only, and not in leaf or flower samples. In particular, we found that pungent components were generally present within the seeds and placenta. Antioxidant activity and nitric oxide production within human vascular endothelial cells were also evaluated to compare the differences in their functionality. Satsuma-Habanero orange cultivated under adverse conditions possessed the highest antioxidant activity. Furthermore, Satsuma-Capsicum cultivated under adverse conditions exhibited higher levels of antioxidants than traditional tropical-origin peppers, and induced similar levels of nitric oxide production in the vascular endothelial cells. We concluded that Capsicum cultivated in harsh environments produced beneficial effects such as higher levels of antioxidants and capsaicinoids in seeds and placenta. Moreover, the fruits from these plants could be harvested for a significantly longer period and took longer to spoil than traditional Capsicum; thus, they show merit as a viable commercial crop in Japan.