Evaluating the Efficiency of Soxhlet Versus Power Ultrasonic Assisted Soxhlet Extraction in Extracting Phenolic Compounds from Mexican Mint leaves (Coleus amboinicus)

Abstract

Coleus amboinicus or commonly known as Mexican mint is a perennial herb which belongs to the mint family. It is well known for its essential oils that are rich in bioactive phenolic compounds, particularly in carvacrol and thymol. Conventional techniques like Soxhlet extraction require long time extraction and high energy consumption, which can lead to the thermal degradation of heat-sensitive phenols. While ultrasound-assisted extraction is an emerging ‘green’ technology, there is limited research on optimizing the hybrid Power Ultrasound-Assisted Soxhlet Extraction (PUASE) specifically for maximizing the recovery of phenolic compounds from Mexican mint leaves. This study was conducted to extract phenolic compound from Mexican mint leaves using various ethanol concentrations and to compare the effectiveness of phenolic compound recovery under different parameters, specifically varying ultrasound amplitude and exposure time in PUASE. The research used PUASE with 100%, 50%, and 25% of ethanol, ultrasound amplitudes of 20 %, 30% and 60 %, together with exposure durations  of 15, 30 and 45 minutes. The extracts that have been obtained were evaluated for percentage of yield, Total Phenolic Content (TPC), Total Flavonoid Content (TFC) and antioxidant activity. The results demonstrated that pure ethanol at 20% amplitude for 15 minutes was the most efficient condition in achieving the highest yield of 15.79% , a TPC of 379.57 mg GAE/g, and a TFC of 7.69 mg QE/g, with an IC₅₀ of 0.347 mg/mL, compared to Soxhlet which only demonstrated percentage of yield of 7.92%, 238.6 mg GAE/g of TPC, 6.63 QE/mg of TFC and IC₅₀ of 0.494mg/mL. These findings indicate that moderate ultrasonication effectively disrupts cell walls and improves penetration while reducing thermal degradation. This study concludes that PUASE significantly enhances the quality and quantity of bioactive recovered compared to traditional methods.