Water-Soluble Melanoidin Pigment as a New Antioxidant Component of Fermented Willowherb Leaves (Epilobium angustifolium)

Abstract

Willowherb (Epilobium angustifolium L., family Onagraceae) is a well-known food and medicinal plant used after fermentation as a source of beverages with high antioxidant potential. Despite this long history of use, only a few papers have described the chemical profile and bioactivity of fermented willowherb tea in general. To understand the basic metabolic differences of non-fermented and fermented E. angustifolium leaves, we used general chemical analysis, high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection assay, and an isolation technique. As a result, the content of 14 chemical groups of compounds was compared in the two plant materials; 59 compounds were detected, including 36 new metabolites; and a new water-soluble phenolic polymer of melanoidin nature was isolated and characterized. The fundamental chemical shifts in fermented E. angustifolium leaves relate mainly to the decrease of ellagitannin content, while there is an increase of melanoidin percentage and saving of the antioxidant potential, despite the significant changes detected. The strong antioxidative properties of the new melanoidin were revealed in a series of in vitro bioassays, and a simulated gastrointestinal and colonic digestion model demonstrated the stability of melanoidin and its antioxidant activity. Finally, we concluded that the new melanoidin is a basic antioxidant of the fermented leaves of E. angustifolium, and it can be recommended for additional study as a promising food and medicinal antioxidant agent.

Fermentation Affects the Antioxidant Activity of Plant-Based Food Material through the Release and Production of Bioactive Components

“…However, they noted that fermented red cabbage is still rich in anthocyanin content. Olennikov et al pointed that novel melanoidin is an essential antioxidant found in the fermented leaves of willowherb with a content of 145.31 ± 4.35 mg per gram dry plant weight, and it is worth further investigation as potential food and medical antioxidant [ 49 ].…”

Metabolites of Siberian Raspberries: LC-MS Profile, Seasonal Variation, Antioxidant Activity and, Thermal Stability of Rubus matsumuranus Phenolome

“…Similar teas are the most popular non-alcoholic beverages in the world due to the large number of health benefits [82,83]. Herbal teas, which are infusions and decoctions from leaves, roots, flowers, and plant seeds, are an important source of phenolic compounds in the human diet [84,85]. To assess the possible use of herbal tea from R. matsumuranus leaves, the phenolic compound content was analysed in infusions and decoctions obtained from extraction with water at different temperatures (Table 2).…”

Polymeric Compounds of Lingonberry Waste: Characterization of Antioxidant and Hypolipidemic Polysaccharides and Polyphenol-Polysaccharide Conjugates from Vaccinium vitis-idaea Press Cake

“…Alkaline hydrolysis of the polysaccharides was performed as previously described using 10% potassium hydroxide solution heating, 80% H 2 SO 4 neutralization, and liquid–liquid extraction with ethyl acetate [ 38 ]. Degradation products were analyzed by high-performance liquid chromatography with photodiode array detection and electrospray ionization triple quadrupole mass spectrometric detection (HPLC–PDA–ESI–tQMS) using an LC-20 Prominence liquid chromatograph coupled with an SPD-M30A photodiode array detector (wavelength range 200–600 nm), and an LCMS 8050 triple quadrupole mass spectrometer (Shimadzu, Columbia, MD, USA) with two-eluent gradient elution [ 39 ].…”