Aqueous homogenate of fresh Ulva lactuca for ameliorating nutrient deficiency—A nutraceutical alternative to using whole seaweeds

Abstract

The green seaweed Ulva lactuca has food value but owing to the presence of high fibers in the form of soluble polysaccharides, its organic matter has reportedly low digestibility. However, owing to high elemental content and presence of bioactive molecules, a strategy to make chemical-free extract was conceived to partition it into mineral rich fraction by homogenizing the fresh seaweed with water, followed by filtering and lyophilizing the extract into powder form (LPAH), thus also lowering the carbohydrate (12 g 100 g−1) and protein (4.32 g 100 g−1) content in it compared to dried whole seaweed. The LPAH was mineral rich and a modest dose of 7.2 g day−1 is capable of fulfilling about 20, 4, 98 and 33 % of the recommended daily allowances of sodium, potassium, iron and boron, respectively. Using the state-of-the-art analytical techniques, the LPAH was characterized and was found to be rich in several known bioactive compounds. It contained phenols (179.99 mg GAE 100 g−1), flavonoids (47.88 mg QE 100 g−1), carotenoids (7.58 mg g−1), and ascorbate (2046.43 μg g−1). The dosage contemplated could also suffice 18 % of ascorbic acid requirement of the human body. The LPAH also showed antioxidant activities such as, DPPH (601.65 μg TE g−1), ABTS (89.77 μg TE g−1), FRAP (154.31 μg TE g−1), TAC (54.57 μg AA g−1). 26 metabolites and 16 amino acids were identified and quantified using GCMS and HPLC, however, none of the amino acids was sufficient enough to act as a protein substitute or supplement. Using LC-HRMS-MS/MS, 43 known bioactive compounds such as Dioncophylline C, hericenone B, alpha-hydroxy-N-desmethyltamoxifen, kni-102, dibenzo pentapehene, proglumide, capsite were identified in the methanolic extract of LPAH, suggesting its nutraceutical value for functional food applications.