2.7. Parasite lactate dehydrogenase assay for antimalarial
activity
In vitro antimalarial activity was performed by Parasite Lactate
Dehydrogenase Assay (pfLDH) [21] by using P. falciparum
3D7 strain. Pure compounds and standard drugs were serially
diluted (two fold) with complete culture medium in 96-well plates.
Infected RBCs solution with 2% parasitemia and 1% hematocrit was
added, making the total volume 200 L in each well. Plates were
incubated in candle jar with 5% CO2, 5% O2 and 90% N2 at 37 ◦C for
72 h. For malstat reaction, in 100 L of malstat solution, 20 L solution
from each well of Plate 1 to respective well of malstat plate was
added. Plates were placed in shaking water bath at 37 ◦C for 30 min.
25 L solution (1:1 solution of nitro blue tetrazolium, 2 mg/mL and
phenazine ethano sulphate, 0.1 mg/mL) was added in each well and
the plates were keptin dark for complete reaction. Plates were read
at 650 nm, and the OD was recorded. IC50 value was calculated with
the help of EZfit (Software for enzyme inhibition kinetic study by
Perrella Scientific, USA) computer program.
3.