Our study represents the first step to understand the effects of
D. malabarica seed extract on CNS using mice model. We found that
D. malabarica extract possesses significant anxiolytic, antidepressant, and explorative behavioral activities. In OFT and HCT, the extract treated groups significantly (*
p < 0.05) decrease the movement of animals when compared with vehicle treated group. Highest decrease was seen after 120 min of administrating the dosages; and this reduction was gradual and somehow follow dose dependent manner. According to the Mechan et al., OFT is a reliable method to assess the anxiety-like behavior characterized through the detestation of mice to bright lit open area. Anxiolytic agents can reduce such fearful attitude of mice in OFT [
19,
20]. Similarly reduction of the hole cross number was seen in HCT, where
D. malabarica extract (both doses) decreased the spontaneous motor activities. As a result, it can be said that our tested extract possess significant anxiolytic-like effect. On the other hand, in EPZ experiment, the natural antipathy of mice to the open arm of EPZ apparatus indicates the anxiolytic-like effect of the compounds. We found that higher dose (400 mg/kg b.w, oral.) of
D. malabarica extract significantly increased the spending time in open arm of EPZ, which support the anxiolytic-like effect of the extract. Phytochemical investigation claimed that
D. malabarica extract possesses flavonoids, alkaloids, phenolic acids, essential oil, saponins, tannins etc. Presence of these phytoconstituent may responsible for CNS effects [
21]. The effect may be due to hyperpolarization of CNS through interacting with gamma-amino-butyric acid (GABA
A) receptor or benzodiazepine (BZD) receptor. GABA is the major inhibitory neurotransmitter of CNS, and most of the neurological drugs exert their anxiolytic effect by acting on GABA
A receptor [
22]. Therefore our hypothesis stand that anxiolytic activity of
D. malabarica extract may be due to binding of any phytoconstituent with GABA
A [
21,
22].
The anxiolytic-like effect of
D. malabarica extract was also assessed using LDT box. We found that the mice treated with this extract spent more time in lightened side rather than darker one, which clearly indicates the possibility of having anxiolytic efficacy (transition parameter being highly dependent on locomotor activity) of the plants extract [
23]. The effect may be due to agonistic effect of extract on GABA/BZD receptor complex, or antagonize 5-HT1B receptor, or agonize 5-HT1A receptor [
20,
24]. In HBT, we found similar decreasing in exploratory behavior pattern of mice.
According to the Riaz et al., shortening of immobility period indicates antidepressant, and prolongation of this period symbolizes the CNS depression-like effect in FST and TST [
25]. In both experiments,
D. malabarica extract significantly decreased the immobility time which indicates the possession of antidepressant active constituents in extract. Approx. 20.71%, and 31.59% of the reductions of immobility time were found for 200 mg/kg and 400 mg/kg doses (crude extract), which were comparable to the reduction of imipramine (40%).
In-vitro antibacterial assay of
D. malabarica extract has been studied. We found that ethyl acetate extract of this plant seeds possess slight antibacterial efficacy against Gram negative strains; however the effect is not significant. We didn’t find any effect of extract on Gram positive strain. The differences of bacterial cell wall compositions may responsible for the variation of antibacterial effect. Perhaps, the antimicrobial effect was found due to the attachment of phytoconstituents (present in the extract) with cell proteins of bacteria, which was followed by the disruption of microbial protein synthesis [
18,
22]. Our results partially support the finding of Taranath et al., although the observed antibacterial effect is not significant to declare according to our experimental result [
26].