The interaction between bovine serum albumin and [6]-,[8]- and [10]-gingerol: An effective strategy to improve the solubility and stability of gingerol

Exploring gingerol glucosides with enhanced anti-inflammatory activity through a newly identified α-glucosidase (ArG) from Agrobacterium radiobacter DSM 30147

Gingerols are phenolic biomedical compounds found in ginger (Zingiber officinale) whose low aqueous solubility limits their medical application. To improve their solubility and produce novel glucosides, an α-glucosidase (glycoside hydrolase) from Agrobacterium radiobacter DSM 30147 (ArG) was subcloned, expressed, purified, and then confirmed to have additional α-glycosyltransferase activity. After optimization, the ArG could glycosylate gingerols into three mono-glucosides based on the length of their acyl side chains. Compound 1 yielded 63.0 %, compound 2 yielded 26.9 %, and compound 3 yielded 4.37 %. The production yield of the gingerol glucosides optimally increased in 50 mM phosphate buffer (pH 6) with 50 % (w/v) maltose and 1000 mM Li+ at 40 °C for an 24-h incubation. The structures of purified compound 1 and compound 2 were determined as 6-gingerol-5-O-α-glucoside (1) and novel 8-gingerol-5-O-α-glucoside (2), respectively, using nucleic magnetic resonance and mass spectral analyses. The aqueous solubility of the gingerol glucosides was greatly improved. Further assays showed that, unusually, 6-gingerol-5-O-α-glucoside had 10-fold higher anti-inflammatory activity (IC50 value of 15.3 ± 0.5 μM) than 6-gingerol, while the novel 8-gingerol-5-O-α-glucoside retained 42.7 % activity (IC50 value of 106 ± 4 μM) compared with 8-gingerol. The new α-glucosidase (ArG) was confirmed to have acidic α-glycosyltransferase activity and could be applied in the production of α-glycosyl derivatives. The 6-gingerol-5-O-α-glucoside can be applied as a clinical drug for anti-inflammatory activity.

Novel Type of Slowly Digested Starch Complex with Antioxidant Properties

With the increasing number of diabetic patients in the world, there is an urgent requirement to reduce the incidence of diabetes. It is considered that a viable prophylactic treatment for type 2 diabetes mellitus is to reduce starch digestibility and oxidative stress. In this study, a novel type of slowly digested starch [pea starch (PS)-gingerol complex] was fabricated to evaluate its in vitro enzymatic digestibility and antioxidant activities. Theoretical and experimental analyses showed that PS can encapsulate gingerols with long alkyl chains to form starch-gingerol complexes, which are further stacked into a mixture of V6- and V7-crystallites. These complexes, in particular the PS-10-gingerol complex, showed high resistance to amylolysis and good antioxidant activities. This study demonstrates that these novel starch-gingerol complexes have the potential to deliver antioxidants encapsulated in starch with slow-digesting properties and reduce oxidative stress. Moreover, this new type of slowly digested starch with antioxidant properties showed great potential in the prevention of type 2 diabetes.

Modulation of protein-ligand interactions in the presence of ZIF-8: Spectroscopy and molecular dynamics simulation

In this paper, we investigated the protein-ligand interactions in the presence of ZIF-8 using multi-spectroscopic approaches and molecular dynamics simulation. Fluorescence experiments and molecular docking results showed that ZIF-8 did not change the type of quenching and interaction force between ciprofloxacin (CIP) and human serum albumin (HSA), but made the binding constant of HSA-CIP to be smaller, suggesting that ZIF-8 maybe accelerate the dissociation of CIP from HSA-CIP complex. Moreover, the effect of ZIF-8 on the physiological function of HSA was explored. Multi-spectroscopic methods revealed that ZIF-8 did not significantly alter the microenvironment of amino acid groups, but cause a slight decrease in the content of α-helical conformation, and a sparse and flexible structure of the protein backbone. These peculiarities might lead to the diminution of HSA's ability to control drugs. In short, ZIF-8 might enhance drug effect due to affecting the binding of drugs to proteins. However, the present study is only a preliminary investigation of the suitability of ZIF-8 as a drug carrier in vitro, and subsequent in vivo experimental studies will be required to further confirm the idea.

Molecular Recognition Study toward the Mitochondrial Electron Transport Chain Inhibitor Mubritinib and Human Serum Albumin

The ability to bind plasma proteins helps in comprehending relevant aspects related to the pharmacological properties of many drugs. Despite the vital role of the drug mubritinib (MUB) in the prophylaxis of various diseases, its interaction with carrier proteins still needs to be clarified. The present work focuses on the interaction between MUB and Human serum albumin (HSA), investigated by employing multispectroscopic, biochemical, and molecular docking approaches. The results reveal that MUB has quenched HSA intrinsic fluorescence (following a static mechanism) by attaching very close (r = 6.76 Å) and with moderate affinity (Kb ≈ 104 M-1) to the protein site I (mainly by H-bonds, hydrophobic and Van der Waals forces). On one side, the HSA-MUB interaction has been accompanied by a slight disturbance in the HSA chemical environment (around the Trp residue) and protein secondary structure modifications. On another side, MUB competitively inhibits HSA esterase-like activity, which is very similar to other Tyrosine kinase inhibitors, and evidence that protein functional alterations have been triggered by MUB interaction. In summary, all of the presented observations can shed light on diverse pharmacological factors associated with drug administration.

Structural characterization and stability of glycated bovine serum albumin-kaempferol nanocomplexes

Kaempferol (Kae), a flavonoid is endowed with various functions. However, due to its poor water solubility and stability, its application in the food and pharmaceutical fields remains elusive. Emerging reports have emphasized the importance of bovine serum albumin (BSA), and glycosylated BSA (GBSA) prepared in the nature deep eutectic solvent system as drug delivery system carriers. In our study, ultraviolet and fluorescence spectra revealed the higher interactions of BSA and GBSA with Kae. Through analysis of Z-average diameter, zeta-potential, polydispersity index (PDI), encapsulation efficiency (EE), loading capacity (LC) of BSA-Kae nanocomplexes (NPs) and GBSA-Kae NPs, GBSA-Kae NPs showed a higher absolute value of zeta-potential and lower PDI, while its EE and LC were also higher. Structural characterization and stability analysis revealed that GBSA-Kae NPs had more stable properties. This study laid the theoretical foundation for improving the solubility and stability of Kae during its delivery and transport.

10-gingerol, a natural AMPK agonist, suppresses neointimal hyperplasia and inhibits vascular smooth muscle cells proliferation

Background: Abnormal proliferation of vascular smooth muscle cells (VSMCs) in the intimal region is a key event in the development of neointimal hyperplasia. 10-G, a bioactive compound found in ginger,...

Complexation of curcumin with cyclodextrins adjusts its binding to plasma proteins

Curcumin shows poor bioaccessibility due to its poor water solubility that limiting its application in aqueous formulations, and the weak binding to plasma proteins that hindering its transportation to targeted...