Abstract
Pereskia bleo (Kunth) DC. (Cactaceae) is a plant commonly used in popular medicine in Malaysia. In this work, we evaluate the antinociceptive effect of P. bleo leaf extracts and isolated compounds in central antinociceptive model. Ethanol extract (E), hexane (H), ethyl acetate (EA), or butanol (B) fractions (30, 50, or 100 mg/kg, p.o.), sitosterol (from hexane) and vitexin (from ethyl acetate), were administered to mice. Antinociceptive effect was evaluated in the hot plate and capsaicin- or glutamate-induced licking models. Morphine (1 mg/kg, p.o.) was used as reference drug. Naloxone (1 mg/kg, i.p.), atropine (1 mg/kg, i.p.), and L-nitro arginine methyl ester (L-NAME, 3 mg/kg, i.p.) were administered 30 min earlier (100 mg/kg, p.o.) in order to evaluate the mechanism of the antinociceptive action. Higher dose of B developed an effect significantly superior to morphine-treated group. Naloxone prevented the antinociceptive effect of all fractions. L-NAME demonstrated effect against E, EA, and B. In all fractions, sitosterol and vitexin reduced the licking time after capsaicin injection. Glutamate-induced licking response was blocked by H, EA, and B. Our results indicate that Pereskia bleo fractions, sitosterol and vitexin, possessed a central antinociceptive effect. Part of this effect is mediated by opioid receptors and nitrergic pathway.
Highlights
Pain is a major cause of distress, both physical and psychological, and is associated with increased inpatient hospital stay, poor wound healing, and prolonged rehabilitation
A previous work from our group showed the isolation of few substances in fractions obtained from leaves of P. bleo as well as the anti-inflammatory and peripheral antinociceptive effects of the crude ethanol extract and its hexane, ethyl acetate, and butanol fractions [8]
The pretreatment of mice with increasing doses of E, H, ethyl acetate (EA), and B fractions led to a correspondent increase in the time that the animal took to jump after being placed in the hot plate
Summary
Pain is a major cause of distress, both physical and psychological, and is associated with increased inpatient hospital stay, poor wound healing, and prolonged rehabilitation. Opioids and nonopioids are the major classes of analgesic drugs used for the relief of pain While these agents are effective, they are associated with considerable adverse effects, including ulcers, nausea, vomiting, pruritus, tolerance, confusion/hallucinations, respiratory depression, and constipation. Our group isolated for the first time vitexin and β-sitosterol glucoside from the fraction obtained from leaves of P. bleo. We decided to go further and evaluate the antinociceptive effect of P. bleo leaves’ ethanol extract and its fractions as well as sitosterol and vitexin, isolated from hexane and ethyl acetate fractions, respectively, using the central antinociceptive model, hot plate, followed by the investigation of the possible mechanism of action using some antagonists as well as their response on capsaicin- and glutamate-induced licking
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