Publication: Optimization of ultrasound-assisted extraction of polyphenols from moringa oleifera leaves
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Date
2024-06
Authors
Paveanthan a/l Mehganathan
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Abstract
The healing properties of the flavonols found in abundance in the Moringa oleifera plant's leaves include anti-inflammatory and anticancer actions. M. oleifera leaves can be used to extract these flavonols using both traditional and modern extraction techniques. The flavonoids quercetin and kaempferol were extracted from the leaves of M. oleifera utilising an ultrasound-assisted direct probe extraction method in this study ultrasound-assisted extraction (UAE). However, to optimize this extraction process and enhance its efficiency, it is essential to identify and understand the key factors influencing the yield of these flavonoids. The most crucial elements influencing the extraction of quercetin and kaempferol were determined by applying the One-Factor-At-A-Time (OFAT) technique to five operational parameters: solvent concentration, extraction temperature, extraction time, amplitude, duty of cycle, and solid-to-solvent ratio. By adjusting the extraction temperature 30-50 °C, duration 5-15 minutes, ethanol concentration 60-80%, and liquid-to-solid ratio 40-60 mL/g, an optimization utilising Box Behnken Design (BBD) was employed; the results included quercetin yield, kaempferol yield, total phenolic content, and antioxidant assay (IC50). The highest yields of quercetin and kaempferol were obtained under ideal circumstances, which included a 60% ethanol concentration, a 14-minute extraction time, a 48 °C extraction temperature, and a 45:1 ml/g liquid-to-solid ratio (L/S). The respective yields were 0.0503 mg/g and 0.1255 mg/g. Furthermore, it was found that a 60% ethanol extraction yielded the highest amount of total phenolic content (TPC), reaching 5.2737 mg GAE/g D.W. Additionally, the ethanol extract exhibited effective DPPH scavenging activity. Patricelli's model fit the extraction data of quercetin and kaempferol well for kinetic investigations; the highest R2 values were reported for quercetin (0.98415) and kaempferol (0.99212). The results reveal the outstanding behaviour of Patricelli's model in fitting the extracts, and the high R2 values reflect a robust and accurate fit to the data by indicating a strong positive link between the model's independent variables and dependent variable and a mean relative percentage deviation value of <10%. Scanning electron microscopy (SEM) surface characterization demonstrates that UAE can modify the leaf's structural surface to improve chemical extraction into the solvent. Overall, UAE technique successfully extracted quercetin and kaempferol from M. oleifera leaves faster than maceration, therefore provide insight on possibility for scaling up and wider application of UAE for bioactive extraction.