The developed TLC plates were carefully overlaid with nutrient
agar containing an aliquot of an overnight culture. The cultures
were incubated at 37 ° C for 72 h under anaerobic condition
for P. acnes and 24 h for S. epidermidis . The plates were sprayed
with 1% of 2,3,5-triphenyl-tetrazolium chloride solution. The areas
of inhibition were indicated by clear zones on the chromatogram
and were compared with the R f values of the related spots
on the reference TLC plate.