Effect of E-Beam Irradiation on Microbial Load, Stability of Active Components, and Anti-Inflammatory Activity of Cnidii Rhizoma and Alismatis Rhizoma

To reduce microbial loads in medicinal herbs, Cnidii Rhizoma and Alismatis Rhizoma were subjected to electron-beam (e-beam) irradiation at doses (≤10 kGy) as permitted by the Korean Food Code. The effects of e-beam irradiation on the microbial load, stability of the active components, and anti-inflammatory activity of medicinal herbs were determined. We observed that the total aerobic bacteria (TAB; 4.0-7.0 log CFU/g), yeasts and molds (Y&M; 3.3-6.8 log CFU/g), and coliform counts (CC; 3.2-3.8 log CFU/g) in both herb samples were effectively reduced in a dose-dependent manner, resulting in acceptable levels of <3.0 log CFU/g in TAB and Y&M and negative in CC at 10 kGy irradiation. The concentration of the active components (0.87-4.22 mg/g) of Cnidii Rhizoma, including z-ligustilide, chlorogenic acid, senkyunolide A, and ferulic acid, in order of prevalence and those (0.86-2.76 mg/g) of Alismatis Rhizoma, including Alisol B acetate and Alisol B, were not changed at irradiation doses of ≤10 kGy. The extracts of e-beam irradiated Cnidii Rhizoma and Alismatis Rhizoma showed a reduced production of inflammation-related factors, such as nitric oxide, prostaglandin E₂, interleukin (IL)-1β, and IL-6, in a concentration-dependent manner, which was induced by lipopolysaccharide in RAW 264.7 cell. However, there was no significant difference observed at e-beam irradiation doses of 0, 1, 5, and 10 kGy. Thus, we confirm that e-beam irradiation up to 10 kGy was effective for the control of microbial load in Cnidii Rhizoma and Alismatis Rhizoma without causing considerable changes in their major active components and anti-inflammatory activity. The results show the potential of e-beam application for sanitization of medicinal herbs.