Sample Conc. (%) Dry weight Equivalent (mg/ml) % radical inhibition at 517 nm (mean ± S.E.M)
A 2.5 2.2 41.0
B 2.5 2.1 44.4
C 2.5 3.5 47.7
D 2.5 3.8 28.7
Quercetin 2.5 - 55.0
Methanol 2.5 - 0.1
Table 3: Free radical inhibition of extracts A, B, C and D, quercetin and methanol. Using DPPH assay Calendula extracts and quercetin (stock 1.61 mg/ml in methanol) were tested. Calendula extracts added neat to 2 ml DPPH solution. Each value represent the mean ± S.E.M; n = 3.