ginkgetin and bilobetin

Ginkgo biloba L. biflavones were shown to increase cAMP phosphodiesterase activity and to stimulate skin microcirculation. The aim of this study was to investigate whether biflavones were able to stimulate lipolysis in adipocytes. Lipolysis was assayed in fully differentiated 3T3-L1 fat cells in the presence of biflavones at 0.005 - 100 microM. Cell viability was evaluated at 0.5 -100 microM. Theophylline and caffeine were used as reference compounds. Lipolytic activity in untreated cells was 0.62 +/- 0.15 micromoles glycerol/mg DNA/h. All biflavones except sciadopitysin stimulated lipolysis in a concentration-dependent fashion. Maximal stimulation was observed at 0.1 - 0.5 microM. At higher concentrations the effect diminished progressively and was lost at 100 microM. Only a partial loss of cell viability was observed with biflavones at 10 - 100 microM.

Topics: 3T3 Cells; Adipocytes; Animals; Biflavonoids; Caffeine; Cell Survival; Dose-Response Relationship, Drug; Flavonoids; Ginkgo biloba; Lipolysis; Medicine, Chinese Traditional; Mice; Molecular Structure; Plant Extracts; Theophylline

Phospholipase A2 (PLA2) regulates eicosanoid and platelet-activating factor production. It also plays an important role in the regulation of critical mediators in inflammatory diseases in which PLA2 activity is significantly enhanced during sepsis and multiple organ failure. Therefore, inhibitors of PLA2 activity offer themselves as target substances in the development of anti-inflammatory drugs. We identified 2 biflavonoids, bilobetin and ginkgetin, that can inhibit PLA2 activity. In experiments using 2-linol-[1-14C]PE as substrate both substances potently inhibited several kinds of type II 14-kDa PLA2 while inhibiting type I 14-kDa PLA2 to a lesser extent. We tested these PLA2 inhibitors for their ability to inhibit the production of tumor necrosis factor alpha (TNFalpha) and 2 enzymes, inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (COX-2) in an assay system using lipopolysaccharide (LPS)-stimulated Raw264.7 macrophages. In Raw264.7cells, bacterial LPS induced the production of COX-2 and iNOS proteins as well as TNFalpha. The inhibitors consistently inhibited the production of TNFalpha in a dose-dependent manner. Moreover, treatment of the macrophages with bilobetin and ginkgetin shut down the production of nitrite, one of the stable end products of NO released into the culture supernatant. The decrease in NO products was accompanied by a decrease in iNOS protein level as assessed by Western blot probed with specific anti-iNOS antibody. Both inhibitors also reduced the expression of COX-2 protein in the LPS-stimulated cells, which coincided with the reduction in iNOS protein. These results, therefore, suggest that these two sPLA2 inhibitors may be useful for inhibiting the production of inflammatory cytokine and NO production in inflammatory diseases.

Topics: Animals; Biflavonoids; Cell Line; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Depression, Chemical; Flavonoids; Gene Expression Regulation; Ginkgo biloba; Group II Phospholipases A2; Humans; Isoenzymes; Macrophage Activation; Macrophages; Membrane Proteins; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; omega-N-Methylarginine; Phospholipases A; Phospholipases A2; Plants, Medicinal; Prostaglandin-Endoperoxide Synthases; Rats; Tumor Necrosis Factor-alpha

Six flavonoid constituents (quercetin, isorhamnetin, kaempferol, bilobetin, ginkgetin and sciadopitysin) were isolated from Ginkgo biloba leaves and determined by reversed phase HPLC using salvianolic acid B as internal standard. The column employed was Zorbax ODS (150 mm x 4 mm ID, 5 microns). The mobile phase consisted of solvent A (methanol) and solvent B [tetrahydrofuran--water--formic acid (34:65:1)] for gradient elution. The flow rate was 1 ml.min-1 and detection was effected at 350 nm. This method is accurate, rapid and reproducible. Analytical data for various samples were given.

Topics: Biflavonoids; Flavonoids; Ginkgo biloba; Molecular Structure; Plant Leaves; Plants, Medicinal; Quercetin