Detection of Electron Beam Irradiated Crude Drugs by Electron Spin Resonance (ESR)

Abstract

Perillae Herba, Sennae Folium, Cinnamomi Cortex, Phellodendri Cortex, Ginseng Radix, Glycyrrhizae Radix, Paeoniae Radix, and Zingiberis Rhizoma were irradiated with electron beam (5 MeV) and organic radicals were detected by ESR measurement, before and after irradiation (10 kGy). A single line spectrum was detected at around g=2.005 in non-irradiated crude drugs, and radical concentrations were high in the leaf varieties of crude drugs. After irradiation, the signal intensity around g=2.005 increased, and a new subsignal was detected as a 3 mT shoulder of this signal. Broad, asymmetrically divided signals were also detected in irradiated root varieties of crude drugs. The free radical localized on the organic components of irradiated crude drugs tended to decrease with the water content. After irradiation, signal intensity reduced and reached a steady state after about 1 to 2 months. However, specificity of the ESR signal shape appearing after irradiation continued to be detectable for 6 months in leaf varieties and for a year in bark and root varieties of crude drugs. Consequently, it was concluded that ESR could be applied as an initial screening procedure to detect irradiated crude drugs.

Analysis of electron spin resonance spectra of irradiated gingers: Organic radical components derived from carbohydrates

“…2.4 mT) are persistently present in the observed spectra. In contrast, the widths of singlet spectra near g = 2.005 observed in un-irradiated plant materials are around 1 mT (Yamaoki et al, 2007). Therefore, in plant materials that consist mainly of carbohydrates and contain more than 1% mono-or disaccharides (w/w dry), the emergence of major spectral components with a line width of ca.…”

“…This observation is a characteristic of spectra observed in non-irradiated lightly pigmented root or rhizome drugs because the spectra near g =2.005 are considered to involve phenoxy radical signals derived from plant pigment such as polyphenol. We have found that the radical concentrations of non-irradiated peony root and ginseng root were lower than that of herb drugs containing anthocyanin, such as red pellila (Yamaoki et al, 2007). After EB irradiation, complex asymmetric spectra were observed in gingers.…”

“…When spices and herbal drugs using different plant parts (herbs, fruits, barks, roots and rhizomes) were irradiated to the level of disinfection or sterilization, sugar-like radical signals, including those of cellulose radicals (at ca. 6 mT apart), were detected for extended periods after irradiation (Yamaoki et al, 2005(Yamaoki et al, , 2007. However, the radical components in irradiated dry plant materials have not been fully identified, because the ESR spectra of irradiated plants are composite spectra, overlapping with those of a number of radical species of various stabilities.…”

Free radical kinetics on irradiated fennel

“…On the other hand, the two signals observed approximately 73 mT of the signal at g ¼ 2.005 were regarded to be derived from cellulose radicals, and assigned as part of the triplet spectrum (Raffi and Agnel, 1989). These signals have been previously determined in the irradiation of fruits, spices and medicinal herbs, and were observed in irradiated samples for a long time period (Korkmaz and Polat, 2001;Raffi and Agnel, 1989;Yamaoki et al, 2005Yamaoki et al, , 2007.…”

Evaluation of absorbed dose in irradiated sugar-containing plant material (peony roots) by an ESR method

“…ESR spectral characteristics similar to those of irradiated food containing crystalline sugars have been observed in irradiated samples (Yamaoki et al, 2007). In this study, the major ESR components of irradiated peony root were identified by spectral analysis, and the relationship between the ESR signal intensity and the sugar content was investigated.…”