Antianxiety-Like Effects of Chimpi (Dried Citrus Peels) in the Elevated Open-Platform Test

Dried citrus peels (Chimpi) is one of the most common natural medicines with qi (energy flow) rectifying and shi (dampness) drying actions, which originates from Citrus unshiu, and/or C. reticulata according to the definition of the pharmacopoeiae of Japan and China. In this study, the pharmacological effects of their extracts and major chemical constituents hesperidin and its aglycone hesperetin on anxiety were examined with an anxiety model of elevated open-platform test using ICR male mice (6-week-old) and total duration of freezing was decreased in fluoxetine-treated mice, which is a simple and highly sensitive to the effects of serotonergic anxiolytics. Moreover, yokukansankachimpihange (YKH), a combination of yokukansan with Chimpi and Hange (Pinellia) was also examined because Chimpi is considered to play a crucial part in this formula against anxious symptoms in dementia patients. The results showed that Chimpi and YKH possess a significant anxiolytic-like effect similar to that of fluoxetine, suggesting that they might be similar to fluoxetine in their pharmacological actions through the serotonergic neurotransmission pathway. Moreover, it also suggested that the major chemical constituent, hesperidin could be an active principle attributed to the antianxiety-like effects with a direct and indirect role via its aglycone hesperetin.