Comparison of microwave, ultrasound, and ultrasound-microwave assisted extraction on bioactive compounds, antioxidant activities and antimicrobial properties of hemp seed (Cannabis sativa L.) and wheat bran extracts

Agricultural by-products such as wheat bran and hemp seeds (Cannabis sativa L.) are rich in bioactive compounds but remain underutilized. Their recovery and valorization promote sustainability and expand their applications in the food, nutraceutical, and pharmaceutical industries. This study aimed to identify the most effective green extraction method for maximizing the yield of bioactive compounds from these matrices while minimizing the use of harmful solvents. Four extraction techniques-maceration, ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and ultrasound-microwave-assisted extraction (UMAE)-were compared using water and 50 % ethanol as solvents. The impact of these methods on polyphenol and flavonoid content and in vitro antioxidant activities was evaluated. Moreover, the antimicrobial activity of optimized extracts from wheat bran and hemp seeds was assayed on Staphylococcus epidermidis, Bacillus subtilis, and Pseudomonas stutzeri. Results showed that ethanol (50 %) consistently enhanced extraction efficiency. Regarding wheat bran, poly-phenol and flavonoid levels remained similar across techniques, but MAE, UAE, and UMAE improved antioxidant activity compared to maceration. In contrast, hemp seed extracts obtained via MAE and UMAE exhibited the highest polyphenol and flavonoid content, alongside superior antioxidant activities. Moreover, wheat bran extracts, particularly those obtained through MAE, exhibited strong antibacterial activity at 6 mg/mL. Additionally, optimizing the solid-to-liquid ratio was crucial for improving extraction efficiency while reducing solvent consumption. These findings highlight the potential of innovative green extraction technologies for the sustainable recovery of bioactive compounds, fostering their application in functional foods, natural antimicrobial agents, and bioactive edible coatings.