In order to obtain bioactive compounds from the natural plants and PCTOC raw material, the existing techniques are: (1) soxhlet extraction, (2) maceration and (3) hydro-distillation. Non-conventional techniques involve: (1) ultrasound-assisted extraction, (2) pulsed-electric field extraction, (3) enzyme-assisted extraction, (4) microwave assisted extraction, (5) pressurised liquid extraction and (6) supercritical fluid extraction and detailed procedures can be found elsewhere.