Zanthoxylum piperitum, an Asian spice, inhibits food intake in rats

We investigated the effects of a total extract from Zanthoxylum piperitum f ruit, of the volatile components of extract, and of a non-volatile fraction containing the major alkylamides of Zanthoxylum (NVA) on food intake in ra ts. In Experiment 1, three groups (A, B, C) of mildly food deprived rats we re given one hour long feeding trials during which they were offered choice s between an oat-bran wafer paired with vegetable oil and a wafer paired wi th a Zanthoxylum preparation in vegetable oil. Trials were divided into thr ee blocks of two tests each. During Blocks 1 and 3, two wafers coated with vegetable oil were offered to establish baseline consumption. During Block 2, Group A was given choices between wafers coated with oil and wafers coat ed with total extract. Group B was offered oil coated wafers and wafers coa ted with the NVA fraction. Group C received two oil coated wafers. One was served on top of a screened dish containing a sample of total extract. In t his manner, the rats were exposed to volatile compounds emanating from the extract but could not contact the extract. The second wafer was served on t op of a screened sample of oil. Results: In Blocks 1 and 3 trials, the rats fed indiscriminately from both wafers. During Block 2, total extract, the NVA fraction and the volatile compounds from extract all significantly redu ced food consumption. In Experiment 2, habituation to the NVA fraction and to the volatile constituents of extract was examined in two additional grou ps (D, E), using the methods described above. Baseline consumption was test ed in Blocks 1 and 3 by offering two oil coated wafers. During Block 2, gro up D was given 10 trials with oil coated and NVA-fraction coated wafers. Gr oup E was given 10 trials with oil coated wafers paired with the volatile c onstituents of total extract and with those of oil. Results: Both groups fa iled to habituate to the Zanthoxylum stimuli. Wafers treated with the NVA f raction and wafers paired with the volatile constituents of extract were av oided throughout the 10 test days.