Chong-Kil Lee

Therapeutic applications of compounds in the Magnolia family

The bark and/or seed cones of the Magnolia tree have been used in traditional herbal medicines in Korea, China and Japan. Bioactive ingredients such as magnolol, honokiol, 4-O-methylhonokiol and obovatol have received great attention, judging by the large number of investigators who have studied their pharmacological effects for the treatment of various diseases. Recently, many investigators reported the anti-cancer, anti-stress, anti-anxiety, anti-depressant, anti-oxidant, anti-inflammatory and hepatoprotective effects as well as toxicities and pharmacokinetics data, however, the mechanisms underlying these pharmacological activities are not clear. The aim of this study was to review a variety of experimental and clinical reports and, describe the effectiveness, toxicities and pharmacokinetics, and possible mechanisms of Magnolia and/or its constituents.

Neuroprotective effects of chlorogenic acid on scopolamine-induced amnesia via anti-acetylcholinesterase and anti-oxidative activities in mice.

Chlorogenic acid is a major polyphenolic component of many plants and beverages, and is particularly abundant in coffee. We evaluated the neuroprotective effects of chlorogenic acid on learning and memory impairment induced by scopolamine (0.5 mg/kg, i.p.), a muscarinic antagonist, using the Y-maze, passive avoidance, and Morris water maze tests. The chlorogenic acid significantly improved the impairment of short-term or working memory induced by scopolamine in the Y-maze test, and significantly reversed cognitive impairments in mice as measured by the passive avoidance test. In addition, chlorogenic acid decreased escape latencies in the Morris water maze test. In a probe trial session, chlorogenic acid increased the latency time in the target quadrant in a dose-dependent manner. Ex vivo, chlorogenic acid inhibited acetylcholinesterase activity in the hippocampus and frontal cortex. Chlorogenic acid also decreased malondialdehyde levels in the hippocampus and frontal cortex. In vitro, chlorogenic acid was found to inhibit acetylcholinesterase activity (IC₅₀=98.17 μg/ml) and free radical scavenging activity (IC₅₀=3.09 μg/ml) in a dose-dependent manner. These results indicate that chlorogenic acid may exert anti-amnesic activity via inhibition of acetylcholinesterase and malondialdehyde in the hippocampus and frontal cortex.

Acemannan purified from Aloe vera induces phenotypic and functional maturation of immature dendritic cells.

Acemannan, a major carbohydrate fraction of Aloe vera gel, has been known to have antiviral and antitumoral activities in vivo through activation of immune responses. The present study was set out to define the immunomodulatory activity of acemannan on dendritic cells (DCs), which are the most important accessory cells for the initiation of primary immune responses. Immature DCs were generated from mouse bone marrow (BM) cells by culturing in a medium supplemented with GM-CSF and IL-4, and then stimulated with acemannan, sulfated acemannan, and LPS, respectively. The resultant DCs were examined for phenotypic and functional properties. Phenotypic analysis for the expression of class II MHC molecules and major co-stimulatory molecules such as B7-1, B7-2, CD40 and CD54 confirmed that acemannan could induce maturation of immature DCs. Functional maturation of immature DCs was supported by increased allogeneic mixed lymphocyte reaction (MLR) and IL-12 production. The differentiation-inducing activity of acemannan was almost completely abolished by chemical sulfation. Based on these results, we propose that the adjuvant activity of acemannan is at least in part due to its capacity to promote differentiation of immature DCs.

Antiviral activities of various water and methanol soluble substances isolated from Ganoderma lucidum

In order to find antiviral substances from basidiomycetes, two water soluble substances, GLhw and GLlw, and eight methanol soluble substances, GLMe-1-8, were prepared from carpophores of Ganoderma lucidum. These substances were examined for their activities against five strains of pathogenic viruses such as herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), influenza A virus (Flu A) and vesicular stomatitis virus (VSV) Indiana and New Jersey strains in vitro. Antiviral activities were evaluated by the cytopathic effect (CPE) inhibition assay and plaque reduction assay. Five substances, GLhw, GLMe-1, -2, -4 and -7 significantly inhibited the cytopathic effects of HSV and VSV. In the plaque reduction assay, GLhw inhibited plaque formation of HSV-2 with 50% effective concentrations (EC50) of 590 and 580 microg/ml in Vero and HEp-2 cells, and its selectivity indices (SI) were 13.32 and 16.26. GLMe-4 did not exhibit cytotoxicity up to 1000 microg/ml, while it exhibited potent antiviral activity on the VSV New Jersey strain with an SI of more than 5.43. These results indicate the possibility of development of antiviral agents from basidiomycetous fungi.

Possible mode of antiviral activity of acidic protein bound polysaccharide isolated from Ganoderma lucidum on herpes simplex viruses.

Two protein bound polysaccharides, a neutral protein bound polysaccharide (NPBP) and an acidic protein bound polysaccharide (APBP), were isolated from water soluble substances of Ganoderma lucidum by EtOH precipitation and DEAE-cellulose column chromatography. Their antiviral activities against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) were then investigated by plaque reduction assay. APBP exhibited more potent HSV-1 and HSV-2 antiviral activity than NPBP with 50% effective concentration (EC(50)) of 300-520 microg/ml. In order to examine the possible mode of the antiviral activity of APBP its virucidal effect, antiviral activity in preincubation, attachment and penetration assay were tested with HSV-1 and HSV-2. APBP was found to have a direct virucidal effect on HSV-1 and HSV-2. APBP did not induce IFN or IFN-like materials in vitro and is not expected to induce a change from a normal state to an antiviral state. APBP in concentrations of 100 and 90 microg/ml inhibited up to 50% of the attachment of HSV-1 and HSV-2 to Vero cells and was also found to prevent penetration of both types of HSV into Vero cells. These results show that the antiherpetic activity of APBP seems to be related to its binding with HSV-specific glycoproteins responsible for the attachment and penetration, and APBP impedes the complex interactions of viruses with cell plasma membranes.

Antiherpetic activities of various protein bound polysaccharides isolated from Ganoderma lucidum

To investigate antiherpetic substances from Ganoderma lucidum, various protein bound polysaccharides, GLhw, GLhw-01, GLhw-02, GLhw-03, were isolated by activity-guided isolation from water soluble substances of the carpophores. These substances were examined for their antiviral activities against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduction assay in vitro. Among them, the acidic protein bound polysaccharide, GLhw-02 of a brownish substance, exhibited the most potent antherpetic activity with 50% effective concentrations (EC50) of 300 approximately 520 microg/ml in Vero and HEp-2 cells, and its selectivity indices (SI) were more than 20. GLhw-02 was identified to consist mainly of polysaccharide (approximately 40.6%) and protein (approximately 7.80%) by anthrone test and Lowry-Folin test, and showed the usual molar ratio (C:H:O = 1:2:1) of carbohydrates by elemental analysis. These results suggest that GLhw-02 possesses the possibility of being developed from a new antiherpetic agent.

Immunomodulatory activity of betulinic acid by producing pro-inflammatory cytokines and activation of macrophages.

Betulinic acid (BA), a pentacyclic triterpene isolated fromLycopus lucidus, has been reported to be a selective inducer of apoptosis in various human cancer and shown anti-inflammatory and immunomodulatory properties. We postulated that BA modulates the immunomodulatory properties at least two groups of protein mediators of inflammation, interlukin-1β (IL-1β) and the tumor necrosis factor-a (TNF-α) on the basis of the critical role of the monocytes and tissue macrophages in inflammatory and immune responses. TNF-α and IL-1β were produced by BA in a dose dependent manner at concentration of 0.625 and 10 μg/mL. The production of NO associated withiNOS was inhibited when treated with LPS at the concentration of 2.5 to 20 μg/mL of BA whereas COX-2 expression was decreased at 2.5 to 20 μg/mL. These modulations of inflammatory mediators were examined in LPS-stimulated RAW 264.7 cells and peritoneal macrophages. The morphology of macrophage was also examined and enhanced surface CD 40 molecule was expressed when treated BA at 0.625–5 ¼g/mL with or without LPS. Furthermore, BA (20 μg/mL) enhanced apoptosis by producing DNA ladder in the RAW 264.7 cells. Our results indicated that BA induced activation of macrophage and pro-inflammatory cytokines. This may provide a molecular basis for the ability of BA to mediate macrophage, suppress inflammation, and modulate the immune response.

Pterostilbene, a natural dimethylated analog of resveratrol, inhibits rat aortic vascular smooth muscle cell proliferation by blocking Akt-dependent pathway.

Vascular smooth muscle cells (VSMCs) are the main cellular component in the arterial wall, and abnormal proliferation of VSMCs plays a central role in the pathogenesis of atherosclerosis and restenosis after angioplasty, and possibly in the development of hypertension. Pterostilbene, a natural dimethylated analog of resveratrol, is known to have diverse pharmacological activities including anti-cancer, anti-inflammation and anti-oxidant activities. The present study was designed to investigate the effects of pterostilbene on platelet-derived growth factor (PDGF)-BB-induced VSMCs proliferation as well as the molecular mechanisms of the antiproliferative effects. The cell growth of VSMCs was determined by cell counting and [(3)H]thymidine incorporation assays. Pterostilbene significantly inhibited the DNA synthesis and proliferation of PDGF-BB-stimulated VSMCs in a concentration-dependent manner. The inhibition percentages of pterostilbene at 1, 3 and 5microM to VSMCs proliferation were 68.5, 80.7 and 94.6%, respectively. The DNA synthesis of pterostilbene at 1, 3 and 5microM in VSMCs was inhibited by 47.4, 76.7 and 100%, respectively. Pterostilbene inhibited the PDGF-BB-stimulated phosphorylation of Akt kinase. However, pterostilbene did not change the expression of extracellular signal-related kinase (ERK) 1/2, PLCgamma1, phosphatidylinositol (PI)3 kinase and PDGF-Rbeta phosphorylation. In addition, pterostilbene down-regulated the cell cycle-related proteins including the expression of cyclin-dependent kinase (CDK) 2, cyclin E, CDK4, cyclin D1, retinoblastoma (Rb) proteins and proliferative cell nuclear antigen (PCNA). These findings suggest that the inhibition of pterostilbene to the cell proliferation and DNA synthesis of PDGF-BB-stimulated VSMCs may be mediated by the suppression of Akt kinase. Furthermore, pterostilbene may be a potential anti-proliferative agent for the treatment of atherosclerosis and angioplasty restenosis.

Anti-inflammatory function of arctiin by inhibiting COX-2 expression via NF-κB pathways

BackgroundArctiin, isolated from Forsythia suspensa has been reported to have anti-inflammatory, anti-oxidant, antibacterial, and antiviral effects in vitro. However, there has been a lack of studies regarding its effects on immunological activity. The aim of this study is to investigate the anti-inflammatory potential and possible mechanisms of arctiin in LPS-induced macrophages.MethodsWe investigated the mRNA and protein levels of proinflammatory cytokines through RT-PCR and western blot analysis, followed by a FACS analysis for surface molecule changes.ResultsArctiin dose dependently decreased the production of NO and proinflammatory cytokines such as IL-1β, IL-6, TNF-α, and PGE2, and it reduced the gene and protein levels as determined by RT-PCR and western blot analysis, respectively. The expression of co-stimulatory molecules such as B7-1 and B7-2 were also inhibited by arctiin. Furthermore, the activation of the nuclear transcription factor, NF-κB in macrophages was inhibited by arctiin.ConclusionTaken together these results provide evidence of the bioactivity of arctiin in inflammatory diseases and suggest that arctiin may exert anti-inflammatory effect by inhibiting the pro-inflammatory mediators through the inactivation of NF-kB.

In vivo evidence of the immunomodulatory activity of orally administered Aloe vera gel

The gels of Aloe species contain immunomodulatory components such as aloctin A and acemannan. Most studies on these gels were performed in in vitro cell culture systems. Although several studies examined their immunomodulatory activity in vivo, the route of administration was intraperitoneal or intramuscular. Here, we evaluated the in vivo immunomodulatory activity of processed Aloe vera gel (PAG) in mice. Oral administration of PAG significantly reduced the growth of C. albicans in the spleen and kidney following intravenous injection of C. albicans in normal mice. PAG administration also reduced the growth of C. albicans in streptozotocin-induced diabetic mice. PAG administration did not increase ovalbumin (OVA)-specific cytotoxic T lymphocyte (CTL) generation in normal mice, but did increase it in high-fat-diet induced diabetic mice. These findings provide the first clear evidence for the immunomodulatory activity of orally administered Aloe vera gel.