Deokyeong Choe

Novel derivatives of monascus pigment having a high CETP inhibitory activity

The cholesteryl ester transfer protein (CETP), inhibition of which assists in maintaining a high level of high-density lipoprotein cholesterol in the blood, is a target for anti-atherosclerosis treatments. Orange monascus pigment was produced by a Monascus species in a 5 L jar fermenter and various derivative compounds were synthesised by incorporating 19 different l-amino acids into the orange pigment. Among them, the l-Thr and l-Tyr derivatives exhibited high inhibitory activities against the CETP reaction. The inhibitory activities of the l-Thr and l-Tyr derivatives increased in a dose-dependent manner, resulting in IC50 values of 1.0 and 2.3 μM, respectively. When CETP reactions in the presence of the derivatives were performed, the inhibition modes of the l-Thr and l-Tyr derivatives were non-competitive with inhibition constant (Ki) values of 2.7 and 4.3 μM, respectively.

Synthesis of high-strength microcrystalline cellulose hydrogel by viscosity adjustment

Developing hydrogels with enhanced mechanical strength is desirable for bio-related applications. For such applications, cellulose is a notable biopolymer for hydrogel synthesis due to its inherent strength and stiffness. Here, we report the viscosity-adjusted synthesis of a high-strength hydrogel through the physical entanglement of microcrystalline cellulose (MCC) in a solvent mixture of tetrabutylammonium fluoride/dimethyl sulfoxide (TBAF/DMSO). MCC was strategically dissolved with TBAF in DMSO at a controlled ratio to induce the formation of a liquid crystalline phase (LCP), which was closely related to the viscosity of the cellulose solution. The highest viscosity was obtained at 2.5% MCC and 3.5% TBAF, leading to the strongest high-strength MCC hydrogel (strongest HS-MCC hydrogel). The resulting hydrogel exhibited a high compressive strength of 0.38MPa and a densely packed structure. Consequently, a positive linear correlation was determined between the viscosity of the cellulose solution and the mechanical strength of the HS-MCC hydrogel.

Clinical and Biological Evaluations of Biodegradable Collagen Matrices for Glaucoma Drainage Device Implantation

Purpose To characterize the clinical and biological properties of biodegradable collagen matrices (BCMs) for possible glaucoma drainage device implantation. Methods A total of 68 refractory glaucoma eyes, followed up postoperatively for at least 6 months, were consecutively enrolled after retrospective chart review. The BCM-augmented Ahmed valve implantations (BAAVI) using our Ologen-6 and Ologen-7 valves were performed and compared with a conventional method. Complete surgical success was defined as an IOP of ≤21 mm Hg (IOP 1) or ≤17 mm Hg (IOP 2) without antiglaucoma medications. Qualified success was defined as an IOP ≤21 mm Hg with or without antiglaucoma medications. The biological properties of each BCM were assessed by enzymatic degradation rates via collagenase under ocular physiological conditions. Results The mean ages and preoperative IOPs were similar for the groups. In the conventional, BAAVI with Ologen-6, and BAAVI with Ologen-7 groups, complete success rates with target IOP 1 were 29.2%, 40.0%, and 66.7%; those with target IOP 2 were 12.5%, 30.0%, and 45.8%; qualified success rates were 45.8%, 55.0%, and 75.0%, respectively. The enzymatic degradation rate of Ologen-7 was significantly slower than that of Ologen-6 (12.5 × 10-3 vs. 28.8 × 10-3). Conclusions The surgical success rate was highest in the Ologen-7 BAAVI group, with the lowest dependency on postoperative antiglaucoma medication use compared with the conventional and Ologen-6 BAAVI groups. The clinical results correlated with the different biological and physicochemical properties based on the degree of enzymatic degradation and on the structural morphology.