Hitting the sweet spot: A systematic review of the bioactivity and health benefits of phenolic glycosides from medicinally used plants

Abstract

Phenolic acid and flavonoid glycosides form a varied class of naturally occurring compounds, characterised by high polarity-resulting from the glycone moiety-and the presence of multiple phenol functionalities, which often leads to strong antioxidant activity.Phenolic glycosides, and in particular flavonoid glycosides, may possess strong bioactive properties with broad spectrum activity. This systematic literature review provides a detailed overview of 28 studies examining the biological activity of phenolic and flavonoid glycosides from plant sources, highlighting the potential of these compounds as therapeutic agents. The activity of glycosides depends upon the biological activity type, identity of the aglycone and the identity and specific location of the glycone moiety. From studies reporting the activity of both glycosides and their respective aglycones, phenolic glycosides appear to generally be a storage/reserve pool of precursors of more bioactive compounds. The glycosylated compounds are likely to be more bioavailable compared to their aglycone forms, due to the presence of the sugar moieties. Hydrolysis of the glycoside in the in vivo environment would release the free aglycone, potentiating their biological activity. However, further high-quality studies are needed to firmly establish the clinical efficacy of glycosides from many of the plant species studied.

UHPLC–MS/MS Analysis on Flavonoids Composition in Astragalus membranaceus and Their Antioxidant Activity

“…Methoxylated flavonoids and their glycosides, such as calycosin and calycosin-7- O - β -D-glucoside, were the major bioactive constituents of A. membranaceus due to their superior bioactivities [ 8 , 9 ]. After glycosylation and methylation, the reactivity and solubility of the flavonoids usually improved and thereby so did their absorption and bioactivity [ 10 ]. Many methoxyl flavones and flavonoid glycosides have been proved the superior antioxidant activities [ 11 , 12 ].…”

Enzymatic Biosynthesis of Simple Phenolic Glycosides as Potential Anti-Melanogenic Antioxidants

“…Simple phenolics (SPs) belong to phytochemicals that exist in a variety of forms in the kingdom of Plantae and are low-molecular-weight biomaterials that possess a wide range of biologically beneficial properties [ 1 ]. For instance, hydroxytyrosol (or 3,4-dihydroxyphenyl ethanol; depicted in Figure 1 ), which exists as a main component in olive leaves or processed olive oil, and its glycoside oleuropein ( Figure 1 ) are reported to show, at the in vitro level, antioxidant activities that prevent oxidation of fats and nucleic acids, antimicrobial activities against some microorganisms, platelet aggregation inhibitory activities and endothelial dysfunction preventative activities [ 2 , 3 , 4 , 5 ].…”

“…In the meantime, the SP aglycones tend to display advances in their in vivo absorption and metabolism rates, and when they are combined as formulations, their chemical stability is known to decline. However, when it comes to their corresponding glycosides, although their bio-absorption rate is not as high, their solubility and bioavailability can be enhanced more than aglycones [ 1 , 3 , 16 , 18 ]. In this regard, several studies [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ] in which various organic or enzymatic synthesis methods were employed have consistently reported the manufacture of a series of SP glycosides.…”

Caerulines A and B, Flavonol Diacylglycosides from Persea caerulea

“…18 Furthermore, flavonoids can exist as glycosides, in which sugar residues act as a decisive factor in their architectural complexity and bioactivity. 20 Such flavonoid transformation is endogenously accomplished by glycosyltransferases, which can create interesting and highly diverse compounds with broad or specialized functions. 21 The sugar moiety can be essential for glycoside bioactivity in some cases, but its pharmacokinetics and bioavailability could usually be enhanced by glycosylation.…”

“…Previous structure–activity relationship surveys disclosed that particular substitution patterns of hydroxy groups and hydrophobic substituents (e.g., alkyl/prenyl, alkylamino, and additional oxygen- or nitrogen-containing heterocyclic moieties) usually positively influence the antibacterial activity of flavonoids, but an activity reduction is often observed if the active hydroxy groups are methylated . Furthermore, flavonoids can exist as glycosides, in which sugar residues act as a decisive factor in their architectural complexity and bioactivity . Such flavonoid transformation is endogenously accomplished by glycosyltransferases, which can create interesting and highly diverse compounds with broad or specialized functions .…”