Vitexin as an active ingredient in passion flower with potential as an agent for nicotine cessation: vitexin antagonism of the expression of nicotine locomotor sensitization in rats

Context: Nicotine, a bioactive component of tobacco, is highly addictive. Numerous therapies have been developed for smoking cessation, and all have met with limited success. Our laboratory has previously shown that an extract of Passiflora incarnata Linn. (Passifloraceae) antagonized the expression of nicotine locomotor sensitization in rats. Objective: This study examined the ability of vitexin, a flavonoid found in P. incarnata, to ameliorate the signs of nicotine sensitization in rats. Materials and methods: Male Wistar rats were administered 0.4 mg/kg nicotine or vehicle (n = 16–18 per group) once a day for four consecutive days. Nicotine administration produces sensitization of locomotor activity. On the fifth day, locomotor activity was monitored as rats from each treatment group were administered either 30 or 60 mg/kg vitexin or its vehicle (n = 4–6 per group) 30 min before a challenge dose of 0.4 mg/kg nicotine. Results: The challenge dose of nicotine resulted in locomotor activity in rats sensitized to nicotine for 4 days that was approximately twice that measured in rats treated with vehicle during the sensitization phase. Rats sensitized to nicotine and then treated with 60 mg/kg vitexin prior to the nicotine challenge exhibited a level of locomotor activity equivalent to the vehicle-treated controls. Discussion: Vitexin antagonized the expression of nicotine locomotor sensitization in rats as the whole extract did in the previous study. Conclusion: Vitexin should be examined in future studies to evaluate its potential for treating nicotine addiction in humans.