Antioxidant and antibacterial activity of nutgrass tuber on extraction with different solvent polarity and particle sizes

Nutgrass tuber is a wild weed often used as traditional medicine locally, having potential as an antioxidant and antibacterial. This study aimed to determine the effect of the type of solvent with different polarity and particle size on the antioxidant and antibacterial activity of nutgrass tuber (C. rotundus L.) extract and to determine the best type of solvent and particle size to produce nutgrass tuber extract with the highest antioxidant activity and antibacterial activity. The experiment design was a factorial randomized block design (RBD). A total of three different solvent treatments (ethanol, ethyl acetate and n-hexane) was the first factor while the particle size with three treatment levels of 40-, 60-, and 80-mesh sieves was the second factor. Data were then analyzed by analysis of variance (ANOVA) followed by Tukey's test. The results showed that the type of solvent, particle size, and their interactions were highly significant on the antioxidant activity and the antibacterial activity against Staphylococcus aureus, while the antibacterial activity against Escherichia coli had a significant effect by the interaction. For the antioxidant activity test, the best treatment was ethanol with particle size produced using the 80-mesh sieve resulting in an IC50 value of 192.18±0.43 ppm. The best antibacterial activity was the extract using ethyl acetate and the particle size produced using the 80-mesh sieve. Meanwhile, the antibacterial activity against E. coli and S. aureus was 3.53±0.19 mm2/mL and 10.67±0.14 mm2/mL (AU), respectively. This suggested nutgrass tuber extract with suitable solvent has the potency as an antioxidant and antibacterial.