A Green and Sustainable Approach of Phenolic Compounds Extraction from Orthosiphon stamineus (Misai Kucing) using Deep Eutectic Solvent Incorporated with Non-Conventional Assistive Extraction Techniques Yoke Shan Wong (1), Angky Wahyu Putranto (1,2), Ngoh Gek Cheng (1)*, Rozita Yusoff (1)
1 Department of Chemical Engineering, Sustainable Process Engineering Centre (SPEC),Faculty of Engineering, Universiti Malaya, 50603 Kuala Lumpur.
2 Department of Biosystems Engineering, Faculty of Agricultural Technology, Universitas Brawijaya, Malang, East Java, 65145, Indonesia.
*Corresponding email: ngoh[at]um.edu.my
Abstract
The rising consumer awareness about health and wellness, coupled with a preference for natural and sustainable products, has led to an increased use of plant extracts in industries such as cosmetics, pharmaceuticals, and food and beverages. Orthosiphon stamineus (Misai Kucing), a herb native to Southeast Asia, is renowned for its potential health benefits and extensive use in traditional medicine, largely attributed to its phenolic compounds (PCs). With the growing emphasis on green chemistry, there is a shift towards using environmentally friendly solvents, such as deep eutectic solvents (DES), for the extraction of these valuable compounds. This study aims to develop a green and sustainable extraction strategy for PCs from Orthosiphon stamineus using non-conventional extraction techniques, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and pulse electric field extraction (PEF). Two DESs, choline chloride-ethylene glycol (acidic) and choline chloride-urea (alkaline), were employed alongside water (neutral) as a control. The study investigates the impact of solvent pH and viscosity on extraction efficiency, compares sequential extraction methods to single extraction approaches, and evaluates the toxicity and antioxidant activity of the DES-extracted PCs. The study reveals significant variations in extraction performance among the different techniques and solvents. DESs demonstrated improved extraction efficiency compared to water, with choline chloride-ethylene glycol showing superior performance in combination with MAE. Sequential extraction methods generally yielded higher quantities of PCs and exhibited enhanced antioxidant activities. Additionally, DES-extracted PCs displayed lower toxicity profiles compared to those extracted with conventional solvents such as ethanol. This research highlights the effectiveness of utilizing DESs in conjunction with advanced extraction techniques for obtaining phenolic compounds from Orthosiphon stamineus. The optimized combination of extraction techniques and DESs identified in this study offers a more sustainable and efficient approach, aligning with green chemistry principles and providing valuable insights for the application of natural extracts in various industries.
Keywords: deep eutectic solvent- green extraction- microwave-assisted extraction- phenolic compounds- pulse electric field- ultrasound-assisted extraction
