Optimisation of the extraction of crude polysaccharides from Clinacanthus nutans leaves for antioxidant applications: Content analysis, chemometrics and metabolomics analysis

This study aimed to evaluate the optimal method for extracting crude polysaccharides from Clinacanthus nutans leaves (CNP) as natural antioxidants. Five different extraction methods, including hot water (HW_CNP), ultrasound-assisted (UL_CNP), freeze-thaw (FT_CNP), alkaline (ALK_CNP), and acid (ACD_CNP). The extraction yield, chemical composition, antioxidant properties, and chemometrics and metabolomics analysis were investigated and compared. The results showed that the ALK_CNP and UL_CNP methods were the most effective for extracting CNP, with the highest extraction yield and antioxidant properties. The total phenolic content (TPC) was found to be directly related to antioxidant activity, with the highest TPC exhibited by the FT_CNP. The metabolomics analysis confirmed that the extraction method played a significant role in determining the antioxidant properties of CNP extracts. The findings of this study have implications for the food industry, as natural antioxidants are in high demand for food preservation and enhancement.