Phytochemical Profiling of Tagetes Erecta L. Flowers at Various Blooming Stages Through Optimized Extraction of Bioactive Compounds for the Development of Functional Juice

Ayesha Siddiqa ^1* Adnan Khaliq ² Dr. Tariq Mehmood ² Muhammad Farhan Jahangir Chughtai ² Ana Maria Sanchez-Migallon ³ Samreen Ahsan ² Amanullah Sabir ^4* Isam A. Mohamed Ahmed ^5*

• ¹ The University of Melbourne, Parkville, Victoria, Australia
• ² Khwaja Fareed University of Engineering and Information Technology (KFUEIT), Rahim Yar Khan, Punjab, Pakistan
• ³ University of Castilla-La Mancha, Ciudad Real, Castilla-La Mancha, Spain
• ⁴ Guangdong Ocean University, Zhanjiang, China
• ⁵ King Saud University, Riyadh, Riyadh, Saudi Arabia

Tagetes erecta L. is a valuable medicinal plant and its edible flowers are a rich source of secondary metabolites that may vary at different blooming stages. The current study aimed to evaluate the phytochemical profile of flowers procured at different stages of blooming from the start of flowering to the end of the season and their antioxidant activities by modifying conventional solvent extraction methods with ultrasound pretreatment and by varying solvents (hexane, ethanol, acetone). The results showed that ultrasound-pretreated samples yielded higher percentages than solvent extraction alone. Functional metabolites were also found to be higher in pre-treated samples at various stages and polar solvents. The highest carotenoid content (427.39 mg/100 g) was observed for the pretreated full-bloom flower samples (MAF-1). Radical scavenging activities were observed highest (DPPH 96.19% and ABTS+ 160.09 mmol TE/100 g) in full-bloom marigold flower samples MAF-1 followed by MEF-1 and MAI-1. A highly significant and positive correlation was observed among all variables of phenolic and antioxidant assays. Radical scavenging activities of samples were positively correlated with carotenoid content, flavonoids, and phenolics. Various bioactive compounds including phenolic acids, flavonoids and carotenoids were quantified by HPLC-DAD. Results showed that the ultrasound acetone extracts of marigold (MAF-1) resulted in higher gallic acid (109 mg/g), quercetin (11.74 mg/g), lutein (1.76 mg/g) and zeaxanthin (2.14 mg/g) followed by MEF-1 > MAI-1>MEI-1. The study results showed that the ultrasound assisted extraction of full-bloom flowers (peak season) resulted in higher bioactive contents. Functional juice was prepared by supplementing these purified extracts in various concentrations (0-10 mg) to juice, which resulted in higher acceptability due to improved sensory characteristics. Study results evident that the marigold bioactive compounds hold good potential for the development of functional foods aiming to control early age-related disorders (ARDs).