Phenolic sucrose esters: evolution, regulation, biosynthesis, and biological functions

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.

The useful biological properties of sucrose esters: Opportunities for the development of new functional foods

Sucrose esters have been deployed as surfactants in many food products since the 1950s. In addition to their useful physical characteristics, sucrose esters also have interesting biological properties that enhance their utility. This review critically examines the broad suite of biological activities that has been attributed to both synthetically-derived and naturally-occurring sucrose esters. These include insecticidal, molluscicidal, plant growth-regulating, anti-microbial, anti-tumor, anti-oxidant, anti-depressive, neuro-protective, anti-inflammatory and anti-plasmodial effects. In addition to providing a summary of the structure-activity profiles of sucrose esters, the various known mechanisms-of action of these compounds are also discussed. Furthermore, since sucrose esters are well-known surfactants, the potential to advantageously apply their industrially desirable physical characteristics in combination with their biological properties is considered. Recent advances in synthetic chemistry that have facilitated the deployment of biologically active sucrose esters as food additives are also described.

Structurally diverse specialized metabolites of maize and their extensive biological functions

Maize originated in southern Mexico and various hybrid varieties have been bred during domestication. All maize tissues are rich in specialized plant metabolites (SPMs), which allow the plants to resist the stresses of herbivores and pathogens or environmental factors. To date, a total of 95 terpenoids, 91 phenolics, 31 alkaloids, and 6 other types of compounds have been identified from maize. Certain volatile sesquiterpenes released by maize plants attract the natural enemies of maize herbivores and provide an indirect defensive function. Kauralexins and dolabralexins are the most abundant diterpenoids in maize and are known to regulate and stabilize the maize rhizosphere microbial community. Benzoxazinoids and benzoxazolinones are the main alkaloids in maize and are found in maize plants at the highest concentrations at the seedling stage. These two kinds of alkaloids directly resist herbivory and pathogenic infection. Phenolics enhance the cross-links between maize cell walls. Meanwhile, SPMs also regulate plant-plant relationships. In conclusion, SPMs in maize show a large diversity of chemical structures and broad-spectrum biological activities. We use these to provide ideas and information to enable the improvement of maize resistances through breeding and to promote the rapid development of the maize industry.