Effect of Extracts and Isolated Pure Compounds of Spondias Mombin (l. Anacardiaceae) Leaves on Gross Exploratory Behaviors in Mice.
Previous studies have reported several neuro-physiological effects of crude extracts of Spondias mombin leaves, which is widely used by traditional medical practitioners in Nigeria for the treatment of neuro-psychiatric disorders. However the neuro-physiological effects of fractionated extracts and pure isolates, with the pharmacological mechanisms responsible for these effects have remained largely unexplored. This study elucidated the neurotransmitter systems and receptors involved in the effects of extracts, and isolated compounds of Spondias mombin leaves in mice (n = 5 - 6) after intraperitoneal (i.p.) route of administration on gross explorative behaviors in mice. The crude ethanolic extract of Spondias mombin leaves was fractionated using the partitioning method to obtain the ethylacetate, butanolic and aqueous fractions. Open column chromatographic fractionation of the ethylacetate fraction yielded seven sub-fractions, out of which the pure coumaroyl, quercetin and gallic acid derivatives were obtained after purification on Sephadex LH-20. The ethanolic extract, butanolic, ethylacetate fractions, ethylacetate subfractions and pure isolates of the Spondias mombin leaves were tested on open field locomotion and head dipping behaviors in mice using standard pharmacological tools. The results showed that the ethanolic and butanolic extracts decreased open field locomotion, while ethylacetate fraction increased open field locomotion at lower doses, but decreased it at higher doses. Subfractions S1 - S7 decreased open field locomotion except S2 ,which had no effect on open field locomotion. The three pure isolates decreased open field locomotion. Pre-treatment with yohimbine, atropine and propranolol had no effect on the coumaroyl derivatibe-induced effect on open field behavior, naloxone reversed this effect while haloperidol potentiated the inhibitory effects of the three pure isolates on open field locomotion. Ethanolic and butanolic decreased head dipping behavior in a dose dependent manner, while ethylacetate fraction increased head dips at lower doses, but decreased it at higher doses. Subfractions S1 - S7 decreased the number of head dips except S2, which had no effect. Coumaroyl derivative had no effect, but gallic acid and quercetin derivatives decreased the number of head dips. Yohimbine, atropine, propranolol and haloperidol potentiated the inhibitory effect of gallic acid and quercetin derivatives on head dips, whereas naloxone reversed the effect of coumaroyl and quercetin derivatives on head dips. It can be inferred that blockade of opioid receptors consistently reversed the effect of coumaroyl derivative on open field locomotion and head dipping behaviors, while blockade of dopaminergic receptors consistently facilitated the effects of the three pure isolates on open field locomotion and head dipping behaviors. It is suggested that the opioid and dopaminergic neurotransmitter systems are strongly involved in the behavioral effects of pure isolates of Spondias mombin leaves in mice.
Keywords : Receptors; Neurotransmitters; Explorative Behaviors; Coumaroyl, Gallic Acid; Quercertine; Spondias mombin;