Ultrasonic-Assisted Extraction of Bioactive Extract from Napier Grass (Pennisetum purpureum), Evaluation of Its Bioactivity, Antimutagenicity and Cytotoxicity

Abstract

The antioxidant characteristics of Napier grass (Pennisetum purpureum) can vary significantly depending on the age of the plant, species, and environmental constraints. In this study, ultrasonic extraction was performed to obtain the bioactive extract from Napier grass. Napier grass at different growth periods (50, 70, and 90 days) was evaluated for phenolic and flavonoid quantity followed by antioxidant activity. The effect of extraction parameters was evaluated using response surface methodology (RSM) with Box-Behnken design. The optimum condition for extraction of bioactive compounds from Napier grass was selected through RSM as 10 mL of ethanol (47.68% v/v) and 50 min of extraction time with ultrasound assisted process (100% amplitude and 20 kHz). The extract from 50 days old grass showed excellent antioxidant properties (68.4 μm Fe (II)/g, 5.1 mg AAE/g, 56.7% of DPPH activity), higher phenolic (8.5 mg GAE/g), flavonoid (3.9 mg QE/g) and protein content (14.9% w/w) which also good antimicrobial and antimutagenic activity. The bioactive extract from 50 days of grass demonstrated strong antimutagenicity (>60%) against sodium azide-induced mutation in S. typhimurium TA 100 strain and did not exhibit a cytotoxic effect on Vero and Caco-2 cells at the concentration of 250 µg/mL and 500 µg/mL, respectively. Keywords: Napier grass, Ultrasonic extraction, Antioxidant, Antimutagenicity, Cytotoxicity