Publications by authors named "Joung Han Yim"

Alzheimer's disease (AD) remains a significant public health challenge with limited effective treatment options. Ramalin, a compound derived from Antarctic lichens, has shown potential in the treatment of AD because of its strong antioxidant and anti-inflammatory properties. However, its instability and toxicity have hindered the development of Ramalin as a viable therapeutic agent.

View Article and Find Full Text PDF

Ramalin, a strong antioxidant isolated from Antarctic lichens, has been shown to have potential therapeutic effects in the treatment of Alzheimer's disease. However, this compound is readily degraded in aqueous solutions, which restricts its development as a therapeutic agent. With a view toward addressing this problem, in this study, we modified the structure of ramalin to obtain more stable compounds and attempted to identify a derivative with the strongest neuroprotective properties.

View Article and Find Full Text PDF
Article Synopsis
  • Alzheimer's disease (AD) is a serious brain condition characterized by harmful protein buildup, leading to memory loss and cell death, with no current effective treatments available.
  • This study explores new compounds called chloride-substituted Ramalin derivatives, which may help fight AD by targeting the aggregation of tau proteins and inhibiting an enzyme linked to amyloid production.
  • The results show that some derivatives, especially RA-3Cl and RA-4Cl, effectively reduce tau aggregation and BACE-1 enzyme activity, indicating potential for developing new AD therapies.
View Article and Find Full Text PDF
Article Synopsis
  • When cells are frozen, cryoprotective agents (CPAs) help prevent damage from ice crystallization, but high levels can be toxic to cells.
  • Exopolysaccharides (EPSs) from Antarctic bacteria show promise as non-toxic alternatives with similar benefits as traditional CPAs.
  • The study isolated bacteria from the Ross Sea, identified one strain (RosPo-2), and demonstrated that its EPS (p-CY02) effectively protects mammalian cells when combined with dimethyl sulfoxide (DMSO), leading to increased survival rates after freezing.
View Article and Find Full Text PDF

Using mass spectrometry (MS)-guided isolation methods, a new thiodiketopiperazine derivative (1) and exserohilone (2) were isolated from an EtOAc-extract of Setosphaeria rostrata culture medium. The chemical structure of the new compound was elucidated by MS and NMR spectroscopy, and the absolute configurations were established by the quantum mechanical calculations of electronic circular dichroism. All isolated compounds were examined for their effects on reactive oxygen species (ROS) production, matrix metalloproteinase 1 (MMP-1) secretion, and procollagen type I α1 secretion in tumor necrosis factor (TNF)-α-induced human dermal fibroblasts.

View Article and Find Full Text PDF
Article Synopsis
  • - Three new compounds derived from a marine fungus were identified, including simplifusinolide A, 24-epi simplifusinolide A, and simplifusidic acid L, as well as two known compounds (fusidic acid and 16-O-deacetylfusicid acid), using advanced analysis techniques.
  • - The structures of these compounds were confirmed through various scientific methods, including NMR and MS analyses, along with calculations for their absolute configurations.
  • - In laboratory tests, simplifusidic acid L, fusidic acid, and 24-epi simplifusinolide A showed promise as treatments for benign prostatic hyperplasia (BPH) by reducing androgen receptor activity and cell
View Article and Find Full Text PDF

Strategies for reducing inflammation in neurodegenerative diseases have attracted increasing attention. Herein, we discovered and evaluated the neuroprotective potential of fungal metabolites isolated from the Antarctic fungus Pseudogymnoascus sp. (strain SF-7351).

View Article and Find Full Text PDF

Cryopreservation of human red blood cells (RBCs) is vital for regenerative medicine and organ transplantation, but current cryoprotectants (CPAs) like glycerol and hydroxyethyl starch (HES) have limitations. Glycerol requires post-thaw washing due to cell membrane penetration, while HES causes high viscosity. To address these issues, we explored exopolysaccharides (EPS) from Antarctic sp.

View Article and Find Full Text PDF

Cold acclimation refers to a phenomenon in which plants become more tolerant to freezing after exposure to non-lethal low temperatures. (Wahlenb.) Schwaegr is a moss found in the Arctic that can be used to study the freezing tolerance of bryophytes.

View Article and Find Full Text PDF

Alkyl butyrate with fruity flavor is known as an important additive in the food industry. We synthesized various alkyl butyrates from various fatty alcohol and butyric acid using immobilized cutinase (cut). Esterification reaction was performed in a non-aqueous system including heptane, isooctane, hexane, and cyclohexane.

View Article and Find Full Text PDF

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a profound negative impact on patients' quality of life. Four known secondary fungal metabolites were found in the chemical study of the Antarctic fungus sp. SF-7343, including 14-methoxyalternate C (), 5'-methoxy-6-methyl-biphenyl-3,4,3'-triol (), 3,8,10-trihydroxy-4-methoxy-6-methylbenzocoumarin (), and alternariol monomethyl ether ().

View Article and Find Full Text PDF

Recently, microorganisms and their metabolites in the Antarctic marine environment have attracted attention as useful sources for novel therapeutics, including anticancer drugs. Here, we investigated the effects of citromycin, isolated from the Antarctic marine-derived fungus, sp., on human ovarian cancer cells.

View Article and Find Full Text PDF

Microglia play a significant role in immune defense and tissue repair in the central nervous system (CNS). Microglial activation and the resulting neuroinflammation play a key role in the pathogenesis of neurodegenerative disorders. Recently, inflammation reduction strategies in neurodegenerative diseases have attracted increasing attention.

View Article and Find Full Text PDF

A lipolytic enzyme (Rcut) was discovered from the Rhodococcusstrain (RosL12) isolated from the Antarctic Ross Sea. The corresponding gene composed of 651 bases encoding 216 amino acids. It was found to be a cutinase gene through BLAST search.

View Article and Find Full Text PDF
Article Synopsis
  • - The cause of Alzheimer's disease (AD) is not well understood, and there is currently no effective cure or treatment to halt its progression.
  • - The study explored the therapeutic potential of ramalin, a compound derived from Antarctic lichen, for treating AD, highlighting its antioxidant, BACE-1 inhibition, and anti-inflammatory properties.
  • - Ramalin and its synthesized derivatives show promise as potential treatments by targeting multiple pathways related to Alzheimer's disease.
View Article and Find Full Text PDF

Chemical investigation of the Antarctic lichen-derived fungal strain sp. SF-7394 yielded a new amphilectane-type diterpene, acrepseudoterin (), and a new acorane-type sesquiterpene glycoside, isocordycepoloside A (). In addition, three known fungal metabolites, (-)-ternatin (), [D-Leu]-ternatin (), and pseurotin A (), were isolated from the EtOAc extract of the fungal strain.

View Article and Find Full Text PDF

Chemical investigation of the Antarctic fungi sp. SF-7343 revealed four known secondary fungal metabolites: alternate C (), altenusin (), alternariol (), and altenuene (). The compound structures were identified primarily by NMR and MS analyses.

View Article and Find Full Text PDF

A new α-pyrone analog, arthrifuranone A (1) was isolated from an EtOAc-extract of Arthrinium pseudosinense culture medium. The isolation workflow was guided by a Molecular Networking-based dereplication strategy. The chemical structure of the new compound was elucidated using MS and NMR spectroscopic techniques, and the absolute configuration was established by the Mosher's method and gauge-including atomic orbital NMR chemical shift calculations, followed by DP4 + analysis.

View Article and Find Full Text PDF

iTRAQ proteomic profiling was conducted to examine the proteomic responses of the Antarctic copepod Tigriopus kingsejongensis under ultraviolet B (UVB) exposure. Of the 5507 proteins identified, 3479 proteins were annotated and classified into 25 groups using clusters of orthologous genes analysis. After exposing the T.

View Article and Find Full Text PDF

Eight new naphtho[1,2-c]furan derivatives (1-8) along with six known analogues (9-14) were isolated from culture medium of the basidiomycete Basidioradulum radula. The structures of these compounds were identified using spectroscopic analysis, and their absolute configurations were resolved using X-ray diffraction, ECD, and VCD. Compounds 7 and 14 inhibited the cell viability of human prostate cancer DU-145 cells with IC values of 7.

View Article and Find Full Text PDF

Inflammation is a vital process that maintains tissue homeostasis. However, it is widely known that uncontrolled inflammation can contribute to the development of various diseases. This study aimed to discover anti-inflammatory metabolites from Penicillium bialowiezense.

View Article and Find Full Text PDF

(UA) is a member of the family Umbilicariaceae. To the best of our knowledge, no studies on its anti-inflammatory effects have been reported yet. In the present study, we examined its ability to suppress inflammatory responses and the molecular mechanisms underlying these abilities using lipopolysaccharide- (LPS-) stimulated RAW 264.

View Article and Find Full Text PDF

The aim of the present study was to determine the anti-inflammatory effect of an extracts isolated from the lichen. Amandinea sp. was collected from the Antarctic and extracted with methanol.

View Article and Find Full Text PDF

Heat shock proteins (Hsp) are class of conserved and ubiquitous stress proteins present in all living organisms from primitive to higher level. Various studies have demonstrated multiple cellular functions of Hsp in living organisms as an important biomarker in response to abiotic and biotic stressors including temperature, salinity, pH, hypoxia, environmental pollutants, and pathogens. However, full understanding on the mechanism and pathway involved in the induction of Hsp still remains challenging, especially in aquatic invertebrates.

View Article and Find Full Text PDF