The effects of Ginkgo biloba extract on lipopolysaccharide-induced inflammation in vitro and in vivo

Inhibition of Endotoxin-Induced Uveitis by Methylprednisolone Acetate Nanosuspension in Rabbits

PURPOSE

In this study, nanoformulations of methylprednisolone acetate (MPA) were formulated by using a copolymer of poly(ethylacrylate, methyl-methacrylate and chlorotrimethyl-ammonioethyl methacrylate) to study their impacts on the inhibition of inflammatory symptoms in rabbits with endotoxin-induced uveitis (EIU).

METHODS

A modified quasiemulsion solvent diffusion technique was used for the preparation of the nanoparticles. The drug-release profiles and physicochemical characteristics of the nanoformulations were studied by means of X-ray crystallography, differential scanning calorimetry, and Fourier transform infrared spectroscopy. Particle-size analysis yielded mean diameters of approximately 380, 460, and 580 (nm) for copolymer nanoparticles at the ratios of 1:2.5, 1:5, and 1:10, respectively. Major clinical symptoms of EIU (e.g., morphologic changes, leukocytes numbers, and protein levels within the aqueous humor) were examined.

RESULTS

Upon the physicochemical characterizations, no crystal changes or chemical interactions were observed for the copolymer nanoparticles. The 1:2.5 ratio of drug polymer resulted in the most controlled release of MPA. The in vivo examinations revealed that the endotoxin-induced inflammation can be inhibited by the copolymer nanosuspension more significantly than by the microsuspension of MPA itself in the rabbits with EIU.

CONCLUSIONS

Based on our findings, we suggest that the copolymer nanosuspension may favor the localized, controlled ocular delivery of MPA for the prevention of inflammatory symptoms in ocular diseases.

Glycoprotein isolated from Ulmus davidiana Nakai regulates expression of iNOS and COX-2 in vivo and in vitro

This study was carried out to investigate the anti-inflammatory potential of a 116-kDa glycoprotein isolated from Ulmus davidiana Nakai (UDN glycoprotein, 116 kDa) in lipopolysaccaride (LPS)-treated RAW 264.7 cells and dextran sodium sulfate (DSS)-treated A/J mouse. In LPS (1 microg/ml)-stimulated RAW 264.7 cells, we found that UDN glycoprotein has dose-dependent blocking effects of reactive oxygen species (ROS) and inducible nitric oxide (NO) production. In addition, the results obtained from electrophoretic mobility shift assay (EMSA) and western blot analysis showed that UDN glycoprotein dose-dependently inhibits DNA binding activity of nuclear factor-kappa B (NF-kappaB), and activities of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and manganese-superoxide dismutases (Mn-SOD) in LPS-stimulated RAW 264.7 cells. Similar results after treatment with UDN glycoprotein were also brought in the DSS-stimulated A/J mouse colitis. The increased disease activity index (DAI) and the shortened large intestine in DSS (5%)-treated A/J mouse were normalized by treatment with UDN glycoprotein [40 mg/kg body weight (BW)]. These intestinal protective activities of UDN glycoprotein are caused by blockage of plasmic thiobarbituric acid reactive substances (TBARS) formation, nitric oxide (NO) production, and lactate dehydrogenase (LDH) release, accompanying the inhibition of colonic inflammatory signal mediators (NF-kappaB, iNOS, and COX-2). These results in this study were presumably come from anti-oxidative effect of UDN glycoprotein in either LPS-stimulated RAW 264.7 cells or DSS-stimulated A/J mouse colitis. Therefore, we speculate that UDN glycoprotein has anti-inflammatory potential at the early inflammation stage.

Effects of Ginkgo biloba extract on inflammatory mediators (SOD, MDA, TNF-alpha, NF-kappaBp65, IL-6) in TNBS-induced colitis in rats

Inflammatory mediators play a criticial role in ulcerative colitis immune and inflammatory processes. The aim of the study was to investigate the effects of Ginkgo biloba extract on inflammatory mediators (SOD, MDA, TNF-α, NF-κBp65, IL-6) in TNBS-induced colitis in rats. Colitis in rats was induced by colonic administration with 2,4,6-trinitrobenzene sulfonic acid (TNBS, 150 mg/kg). EGB in doses of (50, 100, 200 mg/kg) was administered for 4 weeks to protect colitis. The results showed that EGB could significantly ameliorate macroscopic and histological damage, evidently elevate the activities of SOD and reduce the contents of MDA, inhibit the protein and mRNA expressions of TNF-α, NF-κBp65, and IL-6 in the colon tissues of experimental colitis in a dose-dependent manner compared with the model group. We concluded that the probable mechanisms of EGB ameliorated inflammatory injury in TNBS-induced colitis in rats by its modulation of inflammatory mediators and antioxidation

Oral administration of Ginkgo biloba extract, EGb-761 inhibits thermal hyperalgesia in rodent models of inflammatory and post-surgical pain

BACKGROUND AND PURPOSE

Studies in vitro suggest that the standardised extract of Ginkgo biloba, EGb-761 has anti-inflammatory properties and modulatory effects on key pain-related molecules. This study investigated the analgesic and anti-inflammatory effects of EGb-761 on carrageenan-induced inflammatory and hindpaw incisional pain.

EXPERIMENTAL APPROACH

Adult male Wistar rats (n=6-10/group; 250-420 g) were injected intradermally with carrageenan into the left hindpaw or anaesthetised with isoflurane (2%) and a longitudinal 1 cm incision was made through the skin, fascia and plantaris muscle of the hindpaw. EGb-761 (3, 10, 30, 100 or 300 mg kg(-1)), diclofenac (5 mg kg(-1)) or drug-vehicle was administered 3 h post-carrageenan/post-surgery. Hindpaw withdrawal latency (in seconds) to thermal stimulation, response threshold (in grams) to mechanical stimulation and paw volume were measured.

KEY RESULTS

Carrageenan induced significant mechanical allodynia, thermal hyperalgesia and paw oedema at 6 h post-carrageenan, while paw incision surgery induced significant mechanical allodynia and thermal hyperalgesia at 6 and 24 h post-surgery. Administration of EGb-761 dose-dependently inhibited thermal hyperalgesia and was equally effective as diclofenac (5 mg kg(-1)) in both the carrageenan and hindpaw incision model. EGb-761 had no effect on carrageenan- or incision-induced mechanical allodynia or paw oedema. Diclofenac significantly reduced mechanical allodynia in both models and carrageenan-induced paw oedema.

CONCLUSIONS AND IMPLICATIONS

EGb-761 dose-dependently alleviates acute inflammatory and surgically induced thermal hyperalgesia and is comparable to diclofenac, a commonly prescribed non-steroidal anti-inflammatory drug. This indicates that EGb-761 has analgesic potential in acute inflammatory pain.

Protective effects of ginkgo biloba against acetaminophen-induced toxicity in mice

BACKGROUND

The analgesic acetaminophen (AAP) causes a potentially fatal, hepatic centrilobular necrosis when taken in overdose. It was reported that these toxic effects of AAP are due to oxidative reactions that take place during its metabolism.

OBJECTIVE

In this study, we aimed to investigate the possible beneficial effect of Ginkgo biloba (EGb), an antioxidant agent, against AAP toxicity in mice.

METHODS

Balb/c mice were injected i.p. with: (1) vehicle, control (C) group; (2) a single dose of 50 mg/kg Ginkgo biloba extract, EGb group; (3) a single dose of 900 mg/kg i.p. acetaminophen, AAP group, and (4) EGb, in a dose of 50 mg/kg after AAP injection, AAP + EGb group. Serum ALT, AST, and tumor necrosis factor-alpha (TNF-alpha) levels in blood and glutathione (GSH), malondialdehyde (MDA) levels, myeloperoxidase (MPO) activity, and collagen contents in liver tissues were measured. Formation of reactive oxygen species in hepatic tissue samples was monitored by using chemiluminescence (CL) technique with luminol and lusigenin probe. Tissues were also examined microscopically.

RESULTS

ALT, AST levels, and TNF-alpha were increased significantly (p < 0.001) after AAP treatment, and reduced with EGb. Acetaminophen caused a significant (p < 0.05-0.001) decrease in GSH levels while MDA levels and MPO activity were increased (p < 0.001) in liver tissues. These changes were reversed by EGb treatment. Furthermore, luminol and lusigenin CL levels in the AAP group increased dramatically compared to control and reduced by EGb treatment (p < 0.01).

CONCLUSION

Our results implicate that AAP causes oxidative damage in hepatic tissues and Ginkgo biloba extract, by its antioxidant effects protects the tissues. Therefore, its therapeutic role as a "tissue injury-limiting agent" must be further elucidated in drug-induced oxidative damage.

Evaluation of antioxidant activity and inhibitory effect on nitric oxide production of some common vegetables

The objectives of this study were to study the antioxidant activities and nitric oxide (NO) scavenging effects of vegetables in vitro systems and to study the inhibitory effects of vegetables on the NO production and NO-induced DNA damage in RAW 264.7 macrophage. The results indicated that water extracts from Indian lotus, Jew's ear, shiitake, eggplant, and winter mushroom showed stronger antioxidant activity and free-radical-scavenging ability than that of other vegetable extracts. The scavenging effects of vegetable extracts on NO derived from sodium nitroprusside (SNP) were in decreasing order of water spinach > Indian lotus > eggplant and garland chrysanthemum. In the macrophage model system, the water extracts from fresh daylily flower, sponge gourd, pea sprout, and eggplant exhibited over 80% inhibition on NO generation stimulated by lipopolysaccharide. The extract from fresh daylily flower that expressed the strongest inhibition on NO production was attributed to the ability to reduce the inducible nitric oxide synthase (iNOS) induction. However, the extracts from pea sprout and eggplant suppressed the NO production by scavenging on NO and inactivating toward iNOS enzyme. In addition, the water extracts from fresh daylily flower, sponge gourd, pea sprout, and eggplant also showed over 40% inhibitory effect on DNA damage induced by SNP in RAW 264.7 macrophage. The data also indicated that eggplant and pea sprout extracts contained higher total phenolic compounds, anthocyanins, and ascorbic acids and appeared to be responsible for their antioxidant activities and scavenging effects on NO derived from SNP.

Suppressive Effect of Punica granatum on the Production of Tumor Necrosis Factor (Tnf) in BV2 Microglial Cells

While the anti-oxidant properties of Punica granatum methanol extract (PGMF) are well documented, little is known concerning the anti-inflammatory effect of Punica granatum. PGMF was pretreated in BV2 microglial cells and cells were stimulated to induce inflammation by lipopolysaccharide (LPS). The effect of PGME on the production and expression of tumor necrosis factor alpha (Tnf, previously known as Tnf alpha) was determined by enzyme-linked immunosorbent assay (ELISA), western blotting, and reverse transcription-polymerase chain reaction (RT-PCR). In addition, the expression of nuclear factor kappa b (Nfkappab) was measured using an electrophoretic mobility shift assay (EMSA). By ELISA, PGME at the concentrations of 1, 5, 10, and 50 microg/ml inhibited Tnf production in LPS-stimulated cells by 30.2, 42.3, 57.6, and 88.4%, respectively, compared to LPS-stimulated cells. The LPS-stimulated Tnf production was reduced with a dose-dependent manner. Immuno blot and RT-PCR analyses revealed that PGME of 5 and 50 microg/ml inhibited the expression of both protein and mRNA levels of Tnf compared to LPS-stimulated cells. EMSA revealed that PGME of 5 and 50 microg/ml blocked the LPS-stimulated activation of Nfkappab. These data suggest that PGME may suppress LPS-stimulated Tnf production through inhibition of Nfkappab in BV2 microglia cells.

Neuroinflammation: a potential therapeutic target

The increased appreciation of the importance of glial cell-propagated inflammation (termed 'neuroinflammation') in the progression of pathophysiology for diverse neurodegenerative diseases, has heightened interest in the rapid discovery of neuroinflammation-targeted therapeutics. Efforts include searches among existing drugs approved for other uses, as well as development of novel synthetic compounds that selectively downregulate neuroinflammatory responses. The use of existing drugs to target neuroinflammation has largely met with failure due to lack of efficacy or untoward side effects. However, the de novo development of new classes of therapeutics based on targeting selective aspects of glia activation pathways and glia-mediated pathophysiologies, versus targeting pathways of quantitative importance in non-CNS inflammatory responses, is yielding promising results in preclinical animal models. The authors briefly review selected clinical and preclinical data that reflect the prevailing approaches targeting neuroinflammation as a pathophysiological process contributing to onset or progression of neurodegenerative diseases. The authors conclude with opinions based on recent experimental proofs of concept using preclinical animal models of pathophysiology. The focus is on Alzheimer's disease, but the concepts are transferrable to other neurodegenerative disorders with an inflammatory component.