Comparison of different methods for evaluating the antioxidant activity of instant Torbangun (Coleus amboinicus L.) drinks

Torbangun (Coleus amboinicus L.) is a natural breast milk stimulant with antioxidant activity. This study aimed to compare the antioxidant activity of instant Torbangun drinks (ITD) ethanolic extract using DPPH (2,2-diphenyl-1-picrylhydrazil), ABTS (2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), and FRAP (Ferric Reducing Antioxidant Power) methods. Ethanolic extract of commercial Torbangun tea (CTT) and lactation booster milk (CLM) was also included in all analyses as a product reference. At the same time, vitamin C was used as an antioxidant standard. The antioxidant activity was expressed as EC₅₀ value. Among breastmilk booster drinks, the sample with the highest antioxidant activity obtained from ABTS and FRAP methods was ITD (EC₅₀ 18.26 mg/mL) and CLM (EC₅₀ 0.187 mg/mL), respectively. Assessing with the DPPH method, the activity of ITD and CLM was not significantly different (EC₅₀ 35.200 mg/mL and 33.035 mg/mL, respectively), and those were higher than that of CTT (EC₅₀ 52.22 mg/mL). However, the antioxidant activity of all products was significantly lower than vitamin C in all analysis methods (EC₅₀ < 0.05 mg/mL). This finding was proposed due to different antioxidant compounds and antioxidant mechanisms among breast milk booster products. This study also revealed that ABTS and FRAP were the most suitable methods for determining antioxidant properties in all samples.