Measuring polyphenols metabolism in mankai duckweed: a novel aquatic and amino rich plant protein source

The duckweed Mankai, is based on a specific strain of Wolffia globosa, one of the smallest plants on earth, belonging to the family Lemnaceae. Mankai is being considered as a high-quality substitute for animal protein, and a potential source of vitamin B12 and iron. In fact, it contains all 9 essential amino acids and its protein profile is extremely close to that of egg. Recently, it has been granted GRAS status, and chosen as a test food in a long-term intervention DIRECT-PLUS (ClinicalTrials.gov identifier (NCT number): NCT03020186). Our role will be to determine and compare the metabolic fate of Mankai polyphenols in plasma and urine of 300 volunteers suffering from cardiometabolic disease randomly assigned to physical activity (PA), PA + MED diet, or PA + green-MED diet (enriched with Mankai). However, molecular characterization of phenolic composition of Mankai plant has not previously been reported. Therefore, our initial measurements of total phenolic content determined by Folin-Ciocalteu assay classifies Mankai amongst the foods highest in polyphenols content (860.67 mg/kg). Then, we characterized the polyphenols profile using an UHPLC-ESI-MS/MS system, identifying 26 different polyphenols. One of the main advantages of Mankai is its hydroponic cultivation that optimizes yield throughout the year. Light source, water and mineral management can influence the composition of phenolic content. Our analysis has been done in 10 different plant batches treated with 2 different treatments to assess how quality of light may play a major role in the accumulation of secondary plant compounds. Notably, led light seems to enhance the glycated form of luteolin and quercetin compared to sunlight and the aglycone form of luteolin and quercetin are higher in sunlight treatment. The present analysis confirms the high polyphenol status of Mankai, profiles its major polyphenol components and provides new information on how production process in terms of light quality determines polyphenol content.