Pharmacological Investigation of Dichloromethane Fraction of Geodorum densiflorum (Lam.) Schltr

Abstract

Geodorum densiflorum (Family: Orchidacea), locally known as ‘Shankhamul’ in Bangladesh, is an endangered terrestrial orchid, which has long been used traditionally for various medicinal purposes in the Indian subcontinent. In this consequences, the present study was designed to investigate the analgesic and CNS activity properties of two different fraction (n-hexane and Dicloromethane soluble fraction, coded as HF and DCM respectively) of the root parts of Geodorum densiflorum. Analgesic potential of the different fractions of the root parts of G. densiflorum was evaluated using acetic acid induced writhing method. The dichloromethane fraction of the methanolic extract of root part of G. densiflorum showed significant activity with 21.36 % (p<0.05) and 71.84 % (P<0.05) writhing inhibition in mice at a dose of 200 mg/kg body weight and 400 mg/kg body weight.The inhibitory response decreased in the order Diclofenac(85.44%) > n-hexane-400(75.73%) > n-hexane-200(25.25%) > DCM-400(21.36%). On the other hand the analgesic activity graph showed that the activity was dose dependent as in all test sample activity were high at 200 mg of dose than 400 mg of dose. In addition, sedative and anxiolytic properties of the two different fractions of G. densiflorum were investigated using rodent behavioural models, such as Hole Cross, Open Field for sedative property and Elevated Plus-Maze (EPM) test and Hole Board for anxiolytic potential, respectively. DCM fractions, at the doses of 200 mg/kg and 400 mg/kg, displayed a dose dependent exploratory behaviour (in Hole Cross). In Open Field Test, DCM fraction at the dose of 200mg/kg showed statistically significant (p<0.001) exploratory behavior. In the Hole Board Test in mice, DCM fraction at doses of 200mg/kg BW and 400mg/kg BW showed anxiolytic activity which is statistically highly significant (p<0.001). In EPM test, DCM fraction with 200mg/kg BWand 400mg/kg BW doses significantly (p < 0.05) showed increased exploration and time spent by the DCM fraction treated mice in EPM open arms in a way greater than that of the reference anxiolytic drug Diazepam. The results of the present study suggest that the root parts of G. densiflorum in general; DCM soluble fractions in particular, possess strong potential. Therefore, these findings may justify the use of this plant in folk medicine for the treatment of the aforementioned disease conditions. However, further studies are warranted to clearly understand the underlying mechanism of the observed activities in animal models.