Studies on the total synthesis of tenuifoliside B

An Exploratory Study of the Enzymatic Hydroxycinnamoylation of Sucrose and Its Derivatives

Phenylpropanoid sucrose esters are a large and important group of natural substances with significant therapeutic potential. This work describes a pilot study of the enzymatic hydroxycinnamoylation of sucrose and its derivatives which was carried out with the aim of obtaining precursors of natural phenylpropanoid sucrose esters, e.g., vanicoside B. In addition to sucrose, some chemically prepared sucrose acetonides and substituted 3'-O-cinnamates were subjected to enzymatic transesterification with vinyl esters of coumaric, ferulic and 3,4,5-trimethoxycinnamic acid. Commercial enzyme preparations of Lipozyme TL IM lipase and Pentopan 500 BG exhibiting feruloyl esterase activity were tested as biocatalysts in these reactions. The substrate specificity of the used biocatalysts for the donor and acceptor as well as the regioselectivity of the reactions were evaluated and discussed. Surprisingly, Lipozyme TL IM catalyzed the cinnamoylation of sucrose derivatives more to the 1'-OH and 4'-OH positions than to the 6'-OH when the 3'-OH was free and the 6-OH was blocked by isopropylidene. In this case, Pentopan reacted comparably to 1'-OH and 6'-OH positions. If sucrose 3'-O-coumarate was used as an acceptor, in the case of feruloylation with Lipozyme in CH3CN, 6-O-ferulate was the main product (63%). Pentopan feruloylated sucrose 3'-O-coumarate comparably well at the 6-OH and 6'-OH positions (77%). When a proton-donor solvent was used, migration of the 3'-O-cinnamoyl group from fructose to the 2-OH position of glucose was observed. The enzyme hydroxycinnamoylations studied can shorten the targeted syntheses of various phenylpropanoid sucrose esters.

Orthogonal Approach for the Precise Synthesis of Phenylpropanoid Sucrose Esters

Phenylpropanoid sucrose esters (PSEs) are plant-derived metabolites that exist widely in medicinal plants and possess important bioactivities. Their precise synthesis is challenging due to the distinct and diverse substitution patterns...

Potential Herb-Drug Interactions in the Management of Age-Related Cognitive Dysfunction

Late-life mild cognitive impairment and dementia represent a significant burden on healthcare systems and a unique challenge to medicine due to the currently limited treatment options. Plant phytochemicals have been considered in alternative, or complementary, prevention and treatment strategies. Herbals are consumed as such, or as food supplements, whose consumption has recently increased. However, these products are not exempt from adverse effects and pharmacological interactions, presenting a special risk in aged, polymedicated individuals. Understanding pharmacokinetic and pharmacodynamic interactions is warranted to avoid undesirable adverse drug reactions, which may result in unwanted side-effects or therapeutic failure. The present study reviews the potential interactions between selected bioactive compounds (170) used by seniors for cognitive enhancement and representative drugs of 10 pharmacotherapeutic classes commonly prescribed to the middle-aged adults, often multimorbid and polymedicated, to anticipate and prevent risks arising from their co-administration. A literature review was conducted to identify mutual targets affected (inhibition/induction/substrate), the frequency of which was taken as a measure of potential interaction. Although a limited number of drugs were studied, from this work, interaction with other drugs affecting the same targets may be anticipated and prevented, constituting a valuable tool for healthcare professionals in clinical practice.