Chilean Azorella monantha: A Green approach for the extraction of secondary metabolites by using microwave-assisted green solvents extraction

According to the fundamental principles of green chemistry, it is recommended the use unconventional extraction techniques and green solvents to reduce the environmental impact associated with traditional extraction methods. In this context, the Chilean Azorella monantha served as the study model. The objective of this research was to compare microwave-assisted green solvent extraction with conventional solvent extraction processes, including UHPLC/ESI/MS/MS analysis and the assessment of the antioxidant capacity of all extracts. Based on the yield obtained, our results showed that MAE with limonene (23.9 %) and ethyl lactate (14.8 %) was more effective than maceration-assisted methanol extraction (12.3 %). In the case of the UHPLC/ESI/MS/MS profile, the results indicated that the number of compounds detected through by microwave-assisted ethyl lactate extraction (forty compounds) was higher than that observed in the methanolic extract prepared by maceration (thirty-two compounds). Furthermore, MAE with limonene was selective for the extraction of diterpenoids and some less polar isoflavonoids such as prenylalpinumisoflavone, alpinumisoflavone, acetylalpinumisoflavone, and licoisoflavone B. Quantitative analysis indicated that the concentration of the diterpenoid mulin-11,13-diene-20-oic acid was consistent across all green extracts obtained by MAE (135–136.3 mg/g of extract). The EL/MAE extract exhibited antioxidant properties by scavenging DPPH (201.2 ± 0.01 mg TE/g), ABTS (98.0 ± 0.03 µg/mL) radicals, and FRAP (9.82 ± 0.02 μmol Trolox/g dry weight). The ORAC assay indicated that the ethyl lactate MAE extract (141.6 ± 4.9 mg TE/g extract) exhibited greater antioxidant activity than the methanol extract (94.7 ± 1.7 mg TE/g extract). This is the first study realized on A. monantha using green strategies, demonstrating that the unconventional techniques related to green solvents can effectively replace toxic solvents for the extraction of secondary metabolites.