Yeong Ro Lee

Protein adsorption of dialdehyde cellulose-crosslinked chitosan with high amino group contents

Crosslinked chitosan was prepared by Schiff base formation between the aldehyde groups of dialdehyde cellulose (DAC) and the amino groups of chitosan and a subsequent reduction. DAC was obtained through periodate oxidation of cellulose and solubilization in hot water at 100°C for 1h. Three grades of DAC-crosslinked chitosan were prepared by adding various amounts DAC. The degrees of crosslinking as determined by amino group content were 3.8, 8.3, and 12.1%, respectively. DAC-crosslinked chitosan showed higher stability in the pH 2-9 range and no cytotoxicity was identified over the course of a 21-day long-term stability test. Also, DAC-crosslinked chitosan showed remarkably high bovine serum albumin (BSA) adsorption capacity at pH 5.5 as a result of the increased amino group content, due to the reaction between DAC and chitosan molecular chains occurring at multiple points even though DAC-crosslinked chitosan showed a lower degree of crosslinking.

Amelioration of Auditory Response by DA9801 in Diabetic Mouse

Diabetes mellitus (DM) is a metabolic disease that involves disorders such as diabetic retinopathy, diabetic neuropathy, and diabetic hearing loss. Recently, neurotrophin has become a treatment target that has shown to be an attractive alternative in recovering auditory function altered by DM. The aim of this study was to evaluate the effect of DA9801, a mixture of Dioscorea nipponica and Dioscorea japonica extracts, in the auditory function damage produced in a STZ-induced diabetic model and to provide evidence of the mechanisms involved in enhancing these protective effects. We found a potential application of DA9801 on hearing impairment in the STZ-induced diabetic model, demonstrated by reducing the deterioration produced by DM in ABR threshold in response to clicks and normalizing wave I–IV latencies and Pa latencies in AMLR. We also show evidence that these effects might be elicited by inducing NGF related through Nr3c1 and Akt. Therefore, this result suggests that the neuroprotective effects of DA9801 on the auditory damage produced by DM may be affected by NGF increase resulting from Nr3c1 via Akt transformation.

The Effects of Panax ginseng and Panax quinquefolius on Thermoregulation in Animal Models

We devised a study using animal models of hyperthermia and hypothermia and also attempted to accurately assess the effects of Panax ginseng (PG) and Panax quinquefolius (PQ) on body temperature using these models. In addition, we investigated the effects of PG and PQ in our animal models in high and low temperature environments. The results of our experiments show that mice with normothermia, hyperthermia, and hypothermia maintained their body temperatures after a certain period in accordance with the condition of each animal model. In our experiments of body temperature change in models of normal, low, or high room temperature, the hyperthermic model did not show any body temperature change in either the PG- or PQ-administered group. In the normal and low room temperature models, the group administered PG maintained body temperature, while the body temperature of the PQ-administered group was lower than or similar to that of the control group. In conclusion, the fact that PG increases body temperature could not be verified until now. We also showed that the effect of maintaining body temperature in the PG-administered group was superior in a hypothermia-prone low temperature environment.

Enhanced antidiabetic efficacy and safety of compound K⁄β-cyclodextrin inclusion complex in zebrafish

Background 20(S)-Protopanaxadiol 20-O-D-glucopyranoside, also called compound K (CK), exerts antidiabetic effects that are mediated by insulin secretion through adenosine triphosphate (ATP)-sensitive potassium (KATP) channels in pancreatic β-cells. However, the antidiabetic effects of CK may be limited because of its low bioavailability. Methods In this study, we aimed to enhance the antidiabetic activity and lower the toxicity of CK by including it with β-cyclodextrin (CD) (CD-CK), and to determine whether the CD-CK compound enhanced pancreatic islet recovery, compared to CK alone, in an alloxan-induced diabetic zebrafish model. Furthermore, we confirmed the toxicity of CD-CK relative to CK alone by morphological changes, mitochondrial damage, and TdT-UTP nick end labeling (TUNEL) assays, and determined the ratio between the toxic and therapeutic dose for both compounds to verify the relative safety of CK and CD-CK. Results The CD-CK conjugate (EC50 = 2.158μM) enhanced the recovery of pancreatic islets, compared to CK alone (EC50 = 7.221μM), as assessed in alloxan-induced diabetic zebrafish larvae. In addition, CD-CK (LC50 = 20.68μM) was less toxic than CK alone (LC50 = 14.24μM). The therapeutic index of CK and CD-CK was 1.98 and 9.58, respectively. Conclusion The CD-CK inclusion complex enhanced the recovery of damaged pancreatic islets in diabetic zebrafish. The CD-CK inclusion complex has potential as an effective antidiabetic efficacy with lower toxicity.

Regulatory effect of hydroquinone–tetraethylene glycol conjugates on zebrafish pigmentation

We synthesized two hydroquinone-tetraethylene glycol conjugates (HQ-TGs) and investigated their logP, photophysical stability, and redox chemical stability. HQ-TGs are a little more hydrophilic than hydroquinone (HQ) and show an enhanced photophysical and redox chemical stability compared with HQ. In addition we studied the effect of HQ-TGs on cell viability and on zebrafish pigmentation. MTT assay in HF-16 cells showed HQ-TGs are less cytotoxic than HQ. The phenotype-based image analysis of zebrafish larvae suggests that HQ-TGs suppress the pigmentation of zebrafish in a dose-dependent manner. The comparative experiments on stability, cytotoxicity, and zebrafish pigmentation between HQ and HQ-TGs suggest that mono tetraethylene glycol-functionalization of HQ is an alternative solution to overcome the adverse effect of HQ.

Skin depigmenting action of silkworm (Bombyx mori L.) droppings in zebrafish

The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.

Panax ginseng (Korea Red Ginseng) repairs diabetic sensorineural damage through promotion of the nerve growth factor pathway in diabetic zebrafish

Background Diabetic sensorineural damage is a complication of the sensory neural system, resulting from long-term hyperglycemia. Red ginseng (RG) has shown efficacy for treatment of various diseases, including diabetes mellitus; however, there is little research about its benefit for treating sensorineural damage. Therefore, we aim to evaluate RG efficacy in alloxan-induced diabetic neuromast (AIDN) zebrafish. Methods In this study, we developed and validated an AIDN zebrafish model. To assess RG effectiveness, we observed morphological changes in live neuromast zebrafish. Also, zebrafish has been observed to have an ultrastructure of hair-cell cilia under scanning electron microscopy. Thus, we recorded these physiological traits to assess hair cell function. Finally, we confirmed that RG promoted neuromast recovery via nerve growth factor signaling pathway markers. Results First, we established an AIDN zebrafish model. Using this model, we showed via live neuromast imaging that RG fostered recovery of sensorineural damage. Damaged hair cell cilia were recovered in AIDN zebrafish. Furthermore, RG rescued damaged hair cell function through cell membrane ion balance. Conclusion Our data suggest that RG potentially facilitates recovery in AIDN zebrafish, and its mechanism seems to be promotion of the nerve growth factor pathway through increased expression of topomyosin receptor kinase A, transient receptor potential channel vanilloid subfamily type 1, and mitogen-activated protein kinase phosphorylation.