Extraction of bioactive compounds from Pot Marigold (Calendula officinalis) flowers cultivated with grape pomace digestate

The extraction of bioactive compounds from Pot Marigold (Calendula officinalis) presents an innovative approach to enhancing the value of this edible flower. By cultivating marigold with grape pomace digestate, a nutrient-rich byproduct of anaerobic digestion, it is possible to optimize the extraction of bioactive compounds while promoting sustainable agricultural practices within a circular economy framework. The aim of this work was to evaluate the bioactive compound profile of Pot Marigold flowers (PMF) cultivated with grape pomace digestate. To quantify the bioactive compounds, present in the flowers at a ratio of 1:50 (w/v), PMF extracts were prepared using a hydroethanolic solution as the extracting solvent (40:60, ethanol (v/v)). Total phenolic compounds (TPC), total flavonoid content (TFC), total carotenoid content (TCC), and β-carotene (BCC) content were quantified by spectrophotometry. The antioxidant activity was determined by scavenging the DPPH radical (1,1-diphenyl-2-picrylhydrazyl) and by the ferric reduction antioxidant power (FRAP). The bioactive compound quantification of the PMF extracts yielded TPC of approximately 1,217.9 ± 92.05 mg GAE/100 g, TFC of approximately 227.0 ± 13.21 mg CE/100 g, TCC of approximately 128.4 ± 2.88 mg/100 g, BCC of approximately 88.33 ± 0.02 mg/100 g, DPPH of approximately 1,002.2 ± 4.56 μmol TEAC/100 g, and FRAP of approximately 1,314.8 ± 29.00 μmol TEAC/100 g. These findings underscore the potential of using grape pomace digestate as a sustainable cultivation strategy to enhance the bioactive compound profile of Pot Marigold. The significant antioxidant activity demonstrated by the PMF extracts highlights their potential applications in food, nutraceutical, and cosmetic industries, contributing to the valorization of agricultural waste within a circular economy framework.