Investigation of scavenging activities and distribution of paramagnetic species in Zanthoxylum limonella seeds

Abstract

We investigated the scavenging activities of methanol-extracted oil and the distribution of paramagnetic species in Zanthoxylum limonella (ZL) seeds using noninvasive 9 GHz electron paramagnetic resonance (EPR) imaging and continuous wave EPR. EPR detected three different stable paramagnetic species that were assigned to stable organic radicals, Mn²⁺, and other paramagnetic metal complexes. Two-dimensional EPR imaging showed that the stable paramagnetic species were located in the pigmented seed region with a strong intensity. Gas chromatography–mass spectrophotometric (GC–MS) analyses were then performed to identify the compound possibly related to the scavenging activity. The DPPH scavenging activities of ZL were slightly higher than those of Piper nigrum and Coriandrum sativum. Based on the results of EPR, GC–MS, and other methods, limonene in ZL is one of the major compounds that can be related to the scavenging activities.

Keywords:

• EPR
• EPR imaging
• free radical
• antioxidant
• total phenolic contents
• plant seed

Disclosure statement

There are no conflicts of interest to declare.

Additional information

Funding

Part of this research was supported by a Grant-in-Aid for Challenging Exploratory Research (JP15K12499) and for Scientific Research (B) (25282124) from the Japan Society for the Promotion of Science (JSPS) (K.N.).