“Sweet Flavonoids”: Glycosidase-Catalyzed Modifications

Abstract

Natural flavonoids, especially in their glycosylated forms, are the most abundant phenolic compounds found in plants, fruit, and vegetables. They exhibit a large variety of beneficial physiological effects, which makes them generally interesting in a broad spectrum of scientific areas. In this review, we focus on recent advances in the modifications of the glycosidic parts of various flavonoids employing glycosidases, covering both selective trimming of the sugar moieties and glycosylation of flavonoid aglycones by natural and mutant glycosidases. Glycosylation of flavonoids strongly enhances their water solubility and thus increases their bioavailability. Antioxidant and most biological activities are usually less pronounced in glycosides, but some specific bioactivities are enhanced. The presence of l-rhamnose (6-deoxy-α-l-mannopyranose) in rhamnosides, rutinosides (rutin, hesperidin) and neohesperidosides (naringin) plays an important role in properties of flavonoid glycosides, which can be considered as “pro-drugs”. The natural hydrolytic activity of glycosidases is widely employed in biotechnological deglycosylation processes producing respective aglycones or partially deglycosylated flavonoids. Moreover, deglycosylation is quite commonly used in the food industry aiming at the improvement of sensoric properties of beverages such as debittering of citrus juices or enhancement of wine aromas. Therefore, natural and mutant glycosidases are excellent tools for modifications of flavonoid glycosides.

Evaluation of Two Major Rhodiola Species and the Systemic Changing Characteristics of Metabolites of Rhodiola crenulata in Different Altitudes by Chemical Methods Combined with UPLC-QqQ-MS-Based Metabolomics

“…Regarding human beneficial effects, flavonoids are usually restrained by their low bioavailability due to undesirable water solubility, and this defect can be overcome by glycosylation [ 41 , 45 ], thus broadening applications for human health. For instance, hesperetin 7- O -glucoside has been reported to be superior to hesperetin and hesperidin for inhibiting human intestinal maltase [ 46 ], and the bioactivity of catechins is largely determined by the degree of gallate derivatization [ 47 ]. These facts suggest that Rhodiola crenulata growing at the higher elevation may possess more advantages for human health applications in the case of flavonoids.…”

Potential Inhibitors for Novel Coronavirus Protease Identified by Virtual Screening of 606 Million Compounds

“…The binding profile of these compounds is depicted in Figure S7. Natural compounds such as flavonoids were previously tested as inhibitors of the main protease of SARS-CoV and their effectiveness was demonstrated [18,36]. The Persian walnut (Juglans regia) and japanese cypress (Chamaecyparis obtusa) among others are known to produce glycosides of (−)-taxofolin offering a natural resource for its extraction.…”

Potential Inhibitors for Novel Coronavirus Protease Identified by Virtual Screening of 606 Million Compounds

“…18 In contrast to other proposed inhibitors for SARS-CoV-2, 18 the availability of compounds is denoted as either for sale, in stock or on demand in the ZINC database (Tables S2 and S3) show an increased bioavailability compared to the aglycon. 29 In the organism, these glycosides are cleaved off by β-glucosidase in the gastrointestinal tract or liver. 30,31 Since the aglycon already exhibits acceptable pharmacokinetics in rabbits, 32 glycoyslated (-)-taxifolin will likely display improved bioavailability as well.…”