The RRn extract used in this study was standardized by the HPLC method to contain total rhinacantins not less than 70% w/w. The content of rhinacanthin-C, -D and -N in the RRn extract were 71.09, 8.85 and 2.65% w/w, respectively. The total rhinacanthin content of the RRn extract was 82.59% w/w.