Phytochemical Composition and Antioxidant Activity of Pot Marigold (Calendula officinalis): The Impact of Light...

This study evaluated the impact of colored shade nets (control, pearl, red, and blue) on the phytochemical composition and antioxidant activity of two pot marigold (Calendula officinalis L.) varieties: the 'Springer mix' from Italy and a 'domestic' variety from Serbia. Phytochemical parameters assessed included total extractive matter (TEM), total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity measured by DPPH and FRAP assays. The results indicate that colored shade nets significantly enhanced the accumulation of bioactive compounds and antioxidant activity, particularly in the 'domestic' Serbian variety, which consistently outperformed the Italian 'Springer mix'. Blue nets notably improved extract yield and radical scavenging activity, red nets promoted flavonoid synthesis, while control conditions led to the highest TPC. The 'domestic' Serbian variety exhibited exceptionally high TPC (68.21 mg GAE/g dry extract) and TFC (55.55 mg RE/g dry extract) content. Correspondingly, potent antioxidant activity was observed, with EC₅₀ values as low as 0.065 mg/mL under blue net conditions. Principal component analysis further validated the superior phytochemical profile of the Serbian variety. These findings demonstrate the effectiveness of light spectrum manipulation in enhancing the medicinal quality of pot marigold and underscore the potential of Serbian germplasm for high-value cultivation in phytopharmaceutical applications.