Green solvent extraction and eco-friendly novel techniques of bioactive compounds from plant waste: Applications, future perspective and circular economy

• Procedure to preparation natural solvents for sustainable extraction of bioactives • Increase the yield of bioactives using Novel extraction techniques and Natural solvents • Use of natural solvent-based bioactives in the formation of functional food and pharmaceutical products • Prospects of green extraction path toward sustainable circular economy and eco-friendly environment Agro-industrial plant waste is rich in bioactive compounds (BCs) which has prompted the search for sustainable extraction technologies aligned with green technologies and circular economy principles. This review evaluates advanced eco-friendly extraction methods and green solvents for isolating valuable bioactives including polyphenols (flavonoids and tannins), alkaloids, terpenes, and from plant waste such as peels, leaves, seeds, and agricultural residues. Conventional extraction techniques, though effective, are environmentally detrimental and energy-intensive, prompting the need for alternatives like ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and supercritical fluid extraction (SCF). These modern methods enhance yield, reduce solvent use, and preserve thermo-labile constituents. Green solvents such as ionic liquids, deep eutectic solvents (DESs), supercritical CO₂, bioethanol, and switchable water offer promising, low-toxicity alternatives to petroleum-based solvents, though challenges such as viscosity, mass transfer limitations, and solvent selectivity persist. The paper highlights the pharmaceutical, nutraceutical, and food applications of BCs. Ultimately, green extraction technologies offer a path toward sustainable resource recovery, aligning economic, environmental, and health-related goals in a bio-circular-green economy paradigm.