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In this paper, a novel way for high value-added application of lignosulfonate is presented. In this study, we use lignosulfonate nanosheets to fabricate a free-standing, binder-free, ultrathin and light-weight conductive film electrode via vacuum filtration method. The results show that LS is a promising candidate material for the preparation of electrochemical capacitor film electrode. It is worth mentioning that we use non-toxic, pollution-free aqueous solution (water) over organic solvents as the dispersion during the reductive graphene oxide (RGO) preparation process. The electrochemical measurements exhibit that the resistivity of lignosulfonate nanosheets/RGO (LNRGO) film electrode is 0.66 × 10−3 kΩ cm−1. The specific capacitance of the LNRGO film electrode is calculated to be 120 mF cm−2 at the current density of 0.2 mA cm−2, which is approximately 6.67 times larger than that of RGO-water film electrode.

In this study we conducted serial kinetic studies integrated with computational simulations to judge the inhibitory effect of pyrogallol on α-glucosidase, due to the association between this enzyme and the treatment of type 2 diabetes. As a result, we found that pyrogallol bound to the active site of α-glucosidase, interacting with several key residues, such as ASP68, MET69, TYR71, PHE157, PHE158, PHE177, GLN181, HIS348, ASP349, ASP406, VAL407, ASP408, ARG439, and ARG443, which was predicted by performing a protein-ligand docking simulation. Subsequently, we evaluated the inhibitory effect of pyrogallol on α-glucosidase, and found that it induced a mixed type of inhibition in a reversible and quick-binding manner. The relevant kinetic parameters were evaluated to be: IC50=0.72±0.051mM; Ki=0.37±0.018mM. A tertiary conformational change was synchronized with pyrogallol inhibition and modulation of the shape of the active site was correspondingly observed. Our study provides insight into the functional inhibitory role of pyrogallol, which results from its triple-hydroxyl groups interacting with the active site of α-glucosidase. We suggest that compounds similar to pyrogallol (phenolic hydroxyl compounds) which target the key residues of the active site of α-glucosidase could be potential agents for α-glucosidase inhibition.

Due to the finding that inhibition of α-glucosidase is directly associated with treatment of several diseases, the development of a selective inhibitor for targeting α-glucosidase is important. Gallotannin (GT) is a natural ingredient that has been used as a food additive and for medicinal applications. In this study, we performed a computational docking experiment involving the pre-simulation of the binding mechanism of GT, and the effect of GT on α-glucosidase was evaluated with inhibitory kinetics based on its polyphenol properties. The computational simulations indicated that the hydroxyl groups of GT interact with several residues near the α-glucosidase active site (Met69, Tyr71, Phe177, Arg212, Asp214, Glu276, His348, Asp349, and Arg439), which could affect the catalytic function of α-glucosidase by retarding substrate access. Subsequent kinetic experiments showed that GT conspicuously inhibited α-glucosidase in a parabolic mixed-type manner (IC50=1.31±0.03μM;Ki=0.41±0.032μM). Our study provides insight into the inhibition mechanism and binding manner of GT to α-glucosidase. Based on its α-glucosidase-inhibiting effect and its demonstrated safety as a naturally derived compound, GT represents a promising potential agent for treatment of α-glucosidase-associated diseases.

Fucoidans are complex sulfated polysaccharides that have a wide range of biological activities. Previously, we reported the various effects of Fucus vesiculosus fucoidan on tyrosinase and B16 melanoma cells. In this study, to identify fucoidan-targeted proteins in B16 melanoma cells, we performed a proteomics study and integrated enzyme kinetics. We detected 19 candidate proteins dysregulated by fucoidan treatment. Among the probed proteins, the enzyme kinetics of two candidate enzymes, namely lactate dehydrogenase (LDH) as an upregulated protein and superoxide dismutase (SOD) as a downregulated enzyme, were determined. The enzyme kinetics results showed that Fucus vesiculosus fucoidan significantly inhibited LDH catalytic function while it did not affect SOD activity even at a high dose, while only slightly decreased activity (up to 10%) at a low dose. Based on our previous and present observations, fucoidan could inhibit B16 melanoma cells growth via regulating proteins/enzymes expression levels such as LDH and SOD known as cell survival biomarkers. Interestingly, both expression level and enzyme catalytic activity of LDH were regulated by fucoidan, which could directly induce the apoptotic effect on B16 melanoma cells along with SOD downregulation. This study highlights how combining proteomics with enzyme kinetics can yield valuable insights into fucoidan targets.