Butyrlycholine esterase inhibitory activity and effects of extracts (fruit, bark and leaf) from Zanthoxylum armatum DC in gut, airways and vascular smooth muscles.

Fruit, bark and leaves of Zanthoxylum armatum DC are popular remedies for gastrointestinal, cardiovascular and respiratory disorders in the subcontinent traditional practices. The aim of the study was to individually probe the profile of methanol extracts from three different parts of Zanthoxylum armatum.The ex-vivo muscle relaxant effects of extracts were assessed in the isolated intestine, trachea and thoracic aortic rings and were compared with the positive controls and CRC were constructed. The anti-diarrheal effect of extracts was evaluated in mice by inducing diarrhea with castor oil. The extracts were also studied for acute toxicity and butyrylcholine esterase inhibition.

The extracts from fruit, bark and leaves of Z. armatum showed inhibitory effect against the butyrylcholine esterase enzyme with percent inhibition of 50.75 ± 1.23, 82.57 ± 1.33, and 37.52 ± 1.11respectively, compared to standard serine (IC₅₀: 0.04 ± 0.001 μmol/L). The fruit and bark extracts provided 75, and 52% diarrheal protection, compared to verapamil (96%). In isolated rabbit jejunum strips, increasing addition of the extracts inhibited the spontaneous and high K⁺ precontractions with EC₅₀ values of 0.71 and 3 mg/mL for fruit, EC₅₀ values of 0.61 and 0.5 mg/mL for bark, EC₅₀ 0.81 and 3.1 mg/mL for leaves, like verapamil. The extracts induced a concentration-dependent relaxation of the carbachol (1 μM) and high K⁺ (80 mM) precontractions with EC₅₀ values of 2.4 and 0.9 mg/mL for fruit, EC₅₀ values of 1.2 and 3 for leaves. The bark extract was equipotent against both contractions with EC₅₀ 3.1 and 0.7 mg/mL, respectively. In the aortic rings, the fruit extract completely relaxed the phenylephrine (1 μM)-induced contractions with (EC₅₀ value = 0.8 mg/ml) and a partial inhibition of high K⁺ induced contractions. The leaves extract completely relaxed the aortic contractions with (EC₅₀ values = 1.0 and 8.5 mg/ml). The extracts caused no acute toxicity up to 3 g/kg dose.

The experiments revealed that the extracts of aerial parts of Z. armatum have antidiarrheal properties in vivo and showed spasmolytic effect in intestinal and tracheal preparations with possible mechanism involving the blockage of Ca⁺⁺ channels. These experiments provide enough justification for use of this plant in ethnomedicine in diarrhea, gut and bronchial spasms.