Background: Alkaline phosphatase is an important enzyme of helminth parasites that are found to be associated with absorption and/or digestion of food materials. Any interference to this enzyme could lead to paralysis and death of the parasites. In view of its functional significance, the present study was carried out to partially characterise the alkaline phosphatase of a fluke parasite, Fasciolopsis buski and to study the inhibitory effect of the extracts of Alpinia nigra, a medicinal plant of north-east India.
Methods: Edible fresh shoots of Alpinia nigra were collected from Tripura, India and crude extract was extracted in ethanol. Live and mature F. buski was collected from the intestine of freshly slaughtered pig from the local abattoir and brought to the laboratory and processed for study. Various biochemical parameters like effect of pH, temperature, incubation, kinetic parameters and effects of A. nigra extract were studied on the alkaline phosphatase activity. A commercial anthelmintic drug praziquantel was taken as reference drug.
Results: The optimal pH and temperature of the enzyme ranged between 9.0 to 10.0 and 35ÂºC to 45ÂºC, respectively. Alkaline phosphatase activity exhibited linear Arrhenius relationship with corresponding catalytic energy of activation (Ea) of 10.1 Kcal mole-1. The Km and Vmax values were 2.5 mM and 16.67 Î¼M/min, respectively. The plant extract and the drug inhibited the enzyme activity in a dose-dependent manner with IC50 values of 1.10 mg/ml and 25 Î¼M/ml for the plant extract and praziquantel, respectively. The kinetic parameters (Km and Vmax) were found to be altered both in the plant extract and drug treated parasite. Therefore, the alteration of the kinetic parameters by the crude extract of A. nigra and praziquantel treatment indicates a mixed type of alkaline phosphatase enzyme inhibition in F. buski.
Conclusion: The altered enzyme activities, as observed under influence of the plant extract clearly indicate that the active principle of the plant acts as anthelminthic. However, to exploit the plant for commercial purpose, it is prerequisite to isolate and identify the active component responsible for anthelmintic activity.
Keywords: Alkaline phosphatase, Fasciolopsis buski, Alpinia nigra, praziquantel, Michaelisâ€“Menten