Ok‑Hwa Kang

Inhibitory effect of kaurane type diterpenoids fromAcanthopanax koreanum on TNF-α secretion from trypsin-stimulated HMC-1 cells

Five known kaurane type diterpenoids, 16αH,17-isovaleryloxy-ent-kauran-19-oic acid (1), 16α-hydroxy-17-isovaleryloxy-ent-kauran-19-oic acid (2), paniculoside-IV (3), 16α-hydroxy-ent-kau-ran-19-oic acid (4), andent-kaur-16-en-19-oic acid (5) were isolated from the root ofAcanthopanax koreanum by repeated column chromatography and reversed phase preparative HPLC. The structures of these compounds were established from physicochemical and spectral data. Among the isolated compounds 16αH,17-isovaleryloxy-ent-kauran-19-oic acid (1) showed potent inhibitory activity (IC50 value, 16.2 uM) on TNF-α secretion from HMC-1, a trypsin-stimulated human leukemic mast cell line.

Methyl gallate from Galla rhois successfully controls clinical isolates of Salmonella infection in both in vitro and in vivo systems.

Galla rhois is a commonly used traditional medicine for the treatment of pathogenic bacteria in Korea as well as in other parts of Asia. Methyl gallate (MG), a major component of Galla Rhois, exhibits strong antibacterial activity, but its mechanism of action against Salmonella spp. is unclear. In the present study, we investigated the antibacterial actions of MG against Salmonella. The antibacterial activity determined by broth dilution method indicated that the antibacterial activity of MG against Salmonella strains ranged from 3.9 to 125 µg/ml. In vitro bacterial viability test indicated that MG significantly decreased the viability of Salmonella over 40% when combined with ATPase inhibitors. The time-kill curves showed that a combined MG and ATPase inhibitors (DCCD and NaN3) treatment reduced the bacterial counts dramatically after 24 h. Oral administration of MG showed a strong anti-bacterial activity against WS-5 infected BALB/c mice. In contrast to the untreated Salmonella infected control animals, MG treated groups showed no clinical symptoms of the disease, such as lethargy and liver damage. It was observed that MG treatment significantly increased the survival of animals from Salmonella infection, while in untreated groups all animal succumbed to disease by the sixth day post infection. Thus, the present study demonstrates the therapeutic ability of MG against Salmonella infections.

In vitro anti‑MRSA activity of carvone with gentamicin

Carvone is one of the naturally occurring monoterpenes, the largest class of secondary metabolites in plants, and exists in two enantiomers, R-carvone (R-car) and S-car. The objective of this study was to investigate the antimicrobial activity of R-car and S-car with gentamicin (GET) against methicillin-resistant Staphylococcus aureus (MRSA). MRSA is a major human pathogen that causes serious problems, including hospital-acquired pneumonia, abscesses and surgical wound infections. Nosocomial MRSA infections often exhibit multidrug resistance. In the present study, antimicrobial susceptibility testing was performed with R-car, S-car and GET using the broth microdilution method. Minimal inhibitory concentration values for R- and S-car against six different strains of S. aureus ranged between 500 and 1,000 μg/ml. Anti-MRSA activity was evaluated using the checkerboard and time-kill assays to investigate the potential synergistic effects of different combinations of the carvone enantiomers and GET. R-car plus S-car, R-car plus GET and S-car plus GET exhibited significant synergistic activity against MRSA. These findings suggest that the single-agent anti-MRSA activities of R-car, S-car and GET are effectively increased through combination therapy. This study showed that carvone may be a potential adjuvant antimicrobial agent.

Synergistic effects of oxyresveratrol in conjunction with antibiotics against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a serious clinical problem worldwide. The aim of the present study was to examine the antimicrobial activity of oxyresveratrol (ORV) against MRSA. The antimicrobial activity of ORV was evaluated against three strains of MRSA and one methicillin-susceptible S. aureus (MSSA) strain using a minimal inhibitory concentration (MIC) assay, MTT colorimetric assay, checkerboard dilution test and time-kill assay. The MIC of ORV for all strains was moderate at 125 µg/ml. Of note, the antimicrobial activity and fractional inhibitory concentration index values of ORV were markedly increased in the presence of a non-growth inhibitory dose of certain antibiotics. Time-kill curves revealed that a combination of ORV with ciprofloxacin or with gentamicin reduced bacterial counts to below the lowest detectable limit after 24 h. These effective combinations may be used as potential antimicrobial regimens for use in the management of MRSA.

Protective effect of ixerisoside A against UVB‑induced pro‑inflammatory cytokine production in human keratinocytes

Human skin is the first line of defense for the protection of the internal organs of the body from different stimuli. Ultraviolet B (UVB), one of the harmful radiations for skin, is widely known to induce abnormally increased cytokine release from keratinocytes leading to inflammatory skin disorders. IL-6 and IL-8 induce an acute-phase response and stimulate leukocyte infiltration in the skin. Previous studies have shown that chronic exposure to UVB radiation increases cyclooxygenase-2 (COX‑2) expression through various cell signaling pathways, resulting in skin cancer. Recent studies have shown that the activation of extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 MAPK is strongly correlated with acute inflammation and development of skin cancer caused by an increased expression of COX-2. Ixerisoside A (IXA) is an active constituent of Ixeris dentata of the Compositae (Asteraceae) family. The effect of IXA on skin inflammation has yet to be elucidated. To determine the anti-inflammatory effects of IXA, we examined its effect on UVB-induced pro-inflammatory cytokine production in human keratinocytes (HaCaT cells) by observing these cells in the presence or absence of IXA. In this study, pro-inflammatory cytokine production was determined by enzyme-linked immunosorbent assay (ELISA), reverse transcription-polymerase chain reaction (rt-pcr), and western blot analysis to evaluate the activation of mitogen-activated protein kinases (MAPKs). IXA inhibited UVB-induced production of the pro-inflammatory cytokines IL-6 and IL-8 in a dose-dependent manner. Moreover, IXA inhibited the expression of COX-2, ERK, JNK, and p38 MAPKs, indicating that the secretion of the pro-inflammatory cytokines IL-6 and IL-8, and COX-2 expression was inhibited by blocking MAPK phosphorylation. These results indicated that IXA potentially protects against UVB-induced skin inflammation.

Synergistic Effect of Brazilein in Combination with Hygromycin-b against Staphylococcus aureus

*Department of Herbal Crop Research, NIHHS, RDA, Eumseong 369-873, Korea.**Department of Oriental Pharmacy, College of Pharmacy and Wonkwang-Oriental Medicines Research Institute,Institute of Biotechnology, Wonkwang University, Iksan 570-749, Korea.***BK21 Plus Team, Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan 570-749, Korea.ABSTRACT : Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality.In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicro-bial activity of brazilein (BRZ) isolated from Caesalpinia sappan L. (Leguminosae) against 8 different strains of Staphylococ-cus aureus (S. aureus). New antimicrobial activity was found using the minimum inhibitory concentrations (MICs), brothdilution as well as checkerboard method. Against the 8 strains, the minimum inhibitory concentrations of BRZ were in therange of 62.5-500㎍/mL. From those results we performed the checkerboard test to determine the synergism of BRZ incombination with Hygromycin-b (HgB) against 4 strains. The combined activity of BRZ and HgB against 4 strains resultedin a fractional inhibitory concentrations index (FICI) ranging from 0.18-0.5. The effect of BRZ with HgB was found to besynergistic. We found that BRZ reduced the MICs of HgB. BRZ and HgB could lead to the development of new combinationantibiotics against MRSA infection. Key Words : Antibacterial Effect, Methicillin-Resistant Staphylococcus aureus, Brazilein, Hygromycin-b

The Anti-Diabetic Effects and Nephroprotective Effect of Black Ginseng Prosapogenin Extract in Streptozotocin-Induced Mice

Background: This study examined the hypoglycemic and kidney protective effect of black ginseng in streptozotocin-induced diabetic mice. Methods and Results: Diabetes was induced by treating mice with streptozotocin (STZ) for four weeks. In vivo studies were performed in order to investigate the hypoglycemic effect of the black ginseng prosapogenin (GBG05-FF) extract. The body weight and blood glucose level were measured. Moreover, after the mice were sacrificed, the kidneys were isolated and histological changes were observed with hematoxylin and eosin staining. Blood urea nitrogen and creatinine levels were also measured. The results showed that administration of black ginseng increased body weight. Compared to blood glucose levels in STZ mice, blood glucose levels were reduced by 48% in STZ mice supplemented with 300 mg/kg of black ginseng, and by 69% in STZ mice supplemented with 900 mg/kg. Furthermore, histopathological examination of STZ mouse kidneys revealed, changes in the kidneys, epithelial cell damages, inflammatory cell infiltration and glomerulus hypertrophy. However, a significant reduction of glomerular water droplets (indicative of glomerulus hypertrophy) was observed in the kidneys of STZ mice supplemented with black ginseng extract. Conclusions: These results suggest that black prosapogenin (GBG05-FF) ginseng extract has a significant hypoglycemic effect and can be used as an anti-diabetic substance and renal protective agents as part of dietary supplements or novel drugs.