Intermolecular And Surface Forces

Women are particularly susceptible to malaria during first and second pregnancies, even though they may have developed immunity over years of residence in endemic areas. Plasmodium falciparum-infected red blood cells (IRBCs) were obtained from human placentas. These IRBCs bound to purified chondroitin sulfate A (CSA) but not to other extracellular matrix proteins or to other known IRBC receptors. IRBCs from nonpregnant donors did not bind to CSA. Placental IRBCs adhered to sections of fresh-frozen human placenta with an anatomic distribution similar to that of naturally infected placentas, and this adhesion was competitively inhibited by purified CSA. Thus, adhesion to CSA appears to select for a subpopulation of parasites that causes maternal malaria.

https://science.sciencemag.org/content/sci/272/5267/1502.full.pdf

Adherence of Plasmodium falciparum to Chondroitin Sulfate A in the Human Placenta

The ADAM metalloproteinases.

Theeffects of four extracting solvents [absolute ethanol, absolute methanol, aqueous ethanol (ethanol: water, 80:20 v/v) and aqueous methanol (methanol: water, 80:20 v/v)] and two extraction techniques (shaking and reflux) on the antioxidant activity of extracts of barks of Azadirachta indica, Acacia nilotica, Eugenia jambolana, Terminalia arjuna, leaves and roots of Moringa oleifera, fruit of Ficus religiosa,and leaves of Aloe barbadensis were investigated. The tested plant materials contained appreciable amounts of total phenolic contents (0.31-16.5 g GAE /100g DW), total flavonoid (2.63-8.66 g CE/100g DW); reducing power at 10 mg/mL extract concentration (1.36-2.91), DPPH(.) scavenging capacity (37.2-86.6%), and percent inhibition of linoleic acid (66.0-90.6%). Generally higher extract yields, phenolic contents and plant material antioxidant activity were obtained using aqueous organic solvents, as compared to the respective absolute organic solvents. Although higher extract yields were obtained by the refluxing extraction technique, in general higher amounts of total phenolic contents and better antioxidant activity were found in the extracts prepared using a shaker.

https://www.mdpi.com/1420-3049/14/6/2167/pdf

Effect of extraction solvent/technique on the antioxidant activity of selected medicinal plant extracts.

The chemical structures of the primary cell walls of the grasses and their progenitors differ from those of all other flowering plant species. They vary in the complex glycans that interlace and cross-link the cellulose microfibrils to form a strong framework, in the nature of the gel matrix surrounding this framework, and in the types of aromatic substances and structural proteins that covalently cross-link the primary and secondary walls and lock cells into shape. This review focuses on the chemistry of the unique polysaccharides, aromatic substances, and proteins of the grasses and how these structural elements are synthesized and assembled into dynamic and functional cell walls. Despite wide differences in wall composition, the developmental physiology of grasses is similar to that of all flowering plants. Grass cells respond similarly to environmental cues and growth regulators, exhibit the same alterations in physical properties of the wall to allow cell growth, and possess similar patterns of wall biogenesis during the development of specific cell and tissue types. Possible unifying mechanisms of growth are suggested to explain how grasses perform the same wall functions as other plants but with different constituents and architecture.

Structure and biogenesis of the cell walls of grasses

Adherence of Plasmodium falciparum-infected erythrocytes to cerebral postcapillary venular endothelium is believed to be a critical step in the development of cerebral malaria. Some of the possible receptors mediating adherence have been identified, but the process of adherence in vivo is poorly understood. We investigated the role of carbohydrate ligands in adherence, and we identified chondroitin sulfate (CS) as a specific receptor for P. falciparum-infected erythrocytes. Parasitized cells bound to Chinese hamster ovary (CHO) cells and C32 melanoma cells in a chondroitin sulfate-dependent manner, whereas glycosylation mutants lacking chondroitin sulfate A (CSA) supported little or no binding. Chondroitinase treatment of wild-type CHO cells reduced binding by up to 90%. Soluble CSA inhibited binding to CHO cells by 99.2 +/- 0.2% at 10 mg/ml and by 72.5 +/- 3.8% at 1 mg/ml, whereas a range of other glycosaminoglycans such as heparan sulfate had no effect. Parasite lines selected for increased binding to CHO cells and most patient isolates bound specifically to immobilized CSA. We conclude that P. falciparum can express or expose proteins at the surface of the infected erythrocyte that mediate specific binding to CSA. This mechanism of adherence may contribute to the pathogenesis of P. falciparum malaria, but has wider implications as an example of an infectious agent with the capacity to bind specifically to cell-associated or immobilized CS.

/pdf/chondroitin-sulfate-a-is-a-cell-surface-receptor-for-1g3p9pqv66.pdf

Chondroitin sulfate A is a cell surface receptor for Plasmodium falciparum-infected erythrocytes.

Antioxidant activity of hot water extract from the fruit of the Doum palm, Hyphaene thebaica

Effective use of reducing agents and nanoparticle encapsulation in stabilizing catechins in alkaline solution

Epimedium brevicornum leaves water extract exerted a potent and specific inhibition against yeast α-glucosidase, with 50% inhibition of activity (IC50) at 11.8 μmol/L (or 2.01 μg) Gallic Acid Equivalent (GAE)/mL. Several major flavonols from the leaves were evaluated for inhibitory activity. Baohuoside I exhibited strong inhibition against the α-glucosidase while icariin and epimedin A, B and C were weak or inactive. All compounds were inactive against pancreatic α-amylase. The IC50 of baohuoside I was 28.9 μmol/L and its kinetic mode of inhibition was of the mixed type inhibition, with K1 (inhibition constant for the formation of the baohuoside-enzyme complex) and K2 (inhibition constant for the formation of the baohuoside-enzyme–substrate complex) of 12.4 and 31.7 μmol/L, respectively. Since its K1 was lower than its K2, it would indicate that baohuoside I tends to bind more easily and firmly to the free enzyme than to the enzyme–substrate complex. The fact that icariin, which has no free C4′-OH and C7-OH, showed weak inhibition while baohuoside I, which has no free C4′-OH but free C7-OH, showed strong inhibition, indicates the primary importance of the A-ring C7-OH for α-glucosidase inhibitory activity.

Evaluation of α-glucosidase inhibition potential of some flavonoids from Epimedium brevicornum

The gut microbiota plays a prominent role in human health. Alterations in the gut microbiota are linked to the development of chronic diseases such as obesity, inflammatory bowel disease, metabolic syndrome, and certain cancers. We know that diet plays an important role to initiate, shape, and modulate the gut microbiota. Long-term dietary patterns are shown to be closely related with the gut microbiota enterotypes, specifically long-term consumption of carbohydrates (related to Prevotella abundance) or a diet rich in protein and animal fats (correlated to Bacteroides). Short-term consumption of solely animal- or plant-based diets have rapid and reproducible modulatory effects on the human gut microbiota. These alterations in microbiota profile by dietary alterations can be due to impact of different dietary macronutrients, carbohydrates, protein, and fat, which have diverse modulatory effects on gut microbial composition. Food-derived phenolics, which encompass structural variants of flavonoids, hydroxybenzoic acids, hydroxycinnamic acids, coumarins, stilbenes, ellagitannins, and lignans can modify the gut microbiota. Gut microbes have been shown to act on dietary fibers and phenolics to produce functional metabolites that contribute to gut health. Here, we discuss recent studies on the impacts of phenolics and phenolic fiber-rich foods on the human gut microbiota and provide an insight into potential synergistic roles between their bacterial metabolic products in the regulation of the intestinal microbiota.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12563

Ken Ng

Papers

Chondroitin sulfate A is a cell surface receptor for Plasmodium falciparum-infected erythrocytes.

Antioxidant activity of hot water extract from the fruit of the Doum palm, Hyphaene thebaica

Effective use of reducing agents and nanoparticle encapsulation in stabilizing catechins in alkaline solution

Evaluation of α-glucosidase inhibition potential of some flavonoids from Epimedium brevicornum

Modulation of the human gut microbiota by phenolics and phenolic fiber-rich foods.