1-1-diphenyl-2-picrylhydrazyl and magnolol

Aristolochic acids (AA) are nephrotoxic agents found in Aristolochia species whose consumption leads to the onset of a progressive tubulointerstitial fibrosis. This AA-nephropathy was first reported during the Belgian outbreak of the 1990's in which more than a hundred patients consumed slimming pills containing an Aristolochia species and Magnolia officinalis. The patients developed an end-stage kidney disease requiring dialysis or transplantation. Magnolol and honokiol are bioactive compounds from M. officinalis known for their potent antioxidant activity. As they can alleviate oxidative stress, we investigated their respective effects on AA-mediated tubulotoxicity using HK-2 cells. Magnolol and honokiol were able to reduce the oxidative stress associated with AA-treatment. Cytotoxicity alleviation was further investigated and overall cell viability measurements unexpectedly revealed that both compounds worsened the survival of AA-treated cells. Flow cytometry analyses of annexin V/PI stained cells indicated that the lignans efficiently prevented AA-induced apoptosis; but favored necrosis. Microscopy observations highlighted extensive vacuolization; other types of cell death, including autophagy, paraptosis or accelerated senescence were excluded. Ki-67 index and cell cycle analysis indicated that both magnolol and honokiol inhibited proliferation by blocking the cell cycle at the G1 phase; they also prevented the AA-induced G2/M arrest.

Topics: Aristolochic Acids; Biphenyl Compounds; Cell Cycle; Cell Line; Free Radical Scavengers; Humans; Kidney Tubules; Lignans; Molecular Structure; Oxidative Stress; Picrates

In the course of screening for neuroprotective natural products, Magnoliae Cortex showed potent inhibition of hippocampal neuronal HT22 cell death. Obovatol, honokiol, and magnolol were isolated from the ethanolic extract of Magnoliae Cortex. Isolated compounds obovatol, honokiol, and magnolol were protective against 5mM glutamate-induced cell death. When cells were stressed using glutamate, cell viability decreased to 16.98±4.58% over the control (100.00±10.15%). In contrast, 10 μM obovatol, 10 μM honokiol, and 50 μM magnolol increased cell viability to 91.80±1.70%, 93.59±1.93%, and 85.36±7.40%, respectively. The neuroprotective effects of obovatol and honokiol were attributable to the inhibition of intracellular reactive oxygen species production, followed by protection of the mitochondrial membrane potential (ΔΨm), recovery of Bcl-2 and Bid levels, inhibition of apoptosis-inducing factor expression, and phosphorylation of mitogen-activated protein kinases such as p38 kinases, extracellular signal-regulated kinases, and c-Jun N-terminal kinases. On the contrary, magnolol did not show any significant effect on the ΔΨm and apoptotic factors. Among three compounds, obovatol most strongly scavenged 2,2-diphenyl-1-picrylhydrazyl radicals and inhibited the elevation of intracellular reactive oxygen species levels in glutamate-stressed HT22 cells. These data suggest that obovatol and honokiol may have clinical applications for preventing neurodegenerative disorders.

Topics: Animals; Apoptosis; Apoptosis Inducing Factor; BH3 Interacting Domain Death Agonist Protein; Biphenyl Compounds; Cell Death; Cell Line; Cell Survival; Extracellular Signal-Regulated MAP Kinases; Glutamic Acid; JNK Mitogen-Activated Protein Kinases; Lignans; Magnoliaceae; Membrane Potential, Mitochondrial; Mice; Neurons; Neuroprotective Agents; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Phenyl Ethers; Phosphorylation; Picrates; Plant Extracts; Reactive Oxygen Species; Signal Transduction

To evaluate the antioxidant capacity and quality of traditional Chinese medicines using TLC-bioautography.. Two chromatograms of each crude drug sample were obtained, after developing, by spraying with 1,1-diphenyl-2-picrylhydrazyl (DPPH) solution in ethanol and classical stained reagents, separately. The images sprayed with DPPH solution were captured under light after the plates were heated at 40 degrees C for 30 min, and scanned using video scan software to get peak areas of active compounds.. Total peak areas of the spots on TLC were calculated to evaluate the antioxidant capacity of the tested crude drugs from different habitats and sources. The results indicated that Radix Linderae cultivated in Tiantai (Zhejiang province), Cortex Magnoliae Officinalis cultivated in Liangshan (Sichuan province), and Fructus Perillae acquired in Shanghai have the highest scavenging properties towards DPPH in their respective TLC-autographic assays. Norisoboldine, magnolol and honokiol, luteolin, apigenin and an unknown compound "U" proved to be the major antioxidant components in the corresponding crude drugs as they contribute the dominating peak areas to the total ones.. TLC-bioautography can not only be used for screening of the components with antioxidant potency but also for the purpose of quality evaluation of traditional Chinese medicines at the same time, and the method proved to be selective, simple and reproducible.

Topics: Alkaloids; Antioxidants; Biphenyl Compounds; China; Chromatography, Thin Layer; Drugs, Chinese Herbal; Hydrazines; Lignans; Lindera; Luteolin; Magnolia; Perilla; Picrates; Plants, Medicinal; Quality Control; Reproducibility of Results

Propionibacterium acnes, an anaerobic pathogen, plays an important role in the pathogenesis of acne and seems to initiate the inflammatory process by producing proinflammatory cytokines. In order to demonstrate the anti-inflammatory effects and action mechanisms of magnolol and honokiol, several methods were employed. Through DPPH and SOD activity assays, we found that although both magnolol and honokiol have antioxidant activities, honokiol has relatively stronger antioxidant activities than magnolol {[for DPPH assay, % of DPPH bleaching of magnolol and honokiol (500 microM magnolol: 19.8%; 500 microM honokiol: 67.3%)]; [for SOD assay, SOD activity (200 microM magnolol: 53.4%; 200 microM honokiol: 64.3%)]}. Moreover, the production of interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) induced by P. acnes in THP-1 cells, a human monocytic cell line, was reduced by magnolol and honokiol {[for IL-8 (10 microM magnolol: 42.7% inhibition; 10 microM honokiol: 51.4% inhibition)]; [for TNF-alpha (10 microM magnolol: 20.3% inhibition; 10 microM honokiol: 39.0% inhibition)]}. Cyclooxygenase-2 (Cox-2) activity was also suppressed by them [(15 microM magnolol: 45.8% inhibition), (15 microM honokiol: 66.3% inhibition)]. Using a nuclear factor-kappaB (NF-kappaB) luciferase reporter assay system and Western analysis, we identified that magnolol and honokiol exert their anti-inflammatory effects by inhibiting the NF-kappaB element, which exists in Cox-2, IL-8, and TNF-alpha promoters [(15 microM magnolol: 44.8% inhibition), (15 microM honokiol: 42.3% inhibition)]. Of particular note is that magnolol and honokiol operate downstream of the MEKK-1 molecule. Together with their previously known antibacterial activity against P. acnes and based on these results, we suggest that magnolol and honokiol may be introduced as possible acne-mitigating agents.

Topics: Anti-Bacterial Agents; Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Biphenyl Compounds; Cytokines; Humans; Interleukin-8; Lignans; Magnolia; MAP Kinase Kinase Kinase 1; Microbial Sensitivity Tests; Monocytes; NF-kappa B; Phytotherapy; Picrates; Plant Extracts; Propionibacterium acnes; Superoxide Dismutase; Tumor Necrosis Factor-alpha

We have investigated the developdment of potential antioxidants based on magnolol, a naturally occurring biphenolic obtained from the bark of Magnolia officinalis. A series of aminomethylated derivatives of magnolol were synthesized under the aromatic Mannich reaction. In-vitro testing for diphenyl-p-picrylhydrazyl (DPPH) scavenging and chemiluminescence assays in whole cell models revealed that the pyrrolidyl-containing magnolols (2b (5,5'-diallyl-3-(pyrrolidin-1-ylmethyl)-biphenyl-2,2'-diol), 3a (5,5'-diallyl-3,3'-bis-(pyrrolidin-1-ylmethyl)-biphenyl-2,2'-diol) and 4c (5,5'-diallyl-3-(morphorin-4-ylmethyl)-3'-(pyrrolidin-1-ylmethyl)-biphenyl-2,2'-diol)) displayed promising free radical scavenging effects as compared with magnolol. The results from compound 4c indicated that the naturally occurring component was suitable to be a lead compound toward promising antioxidants.

Topics: Biphenyl Compounds; Free Radical Scavengers; Hydrazines; Lignans; Luminescent Measurements; Magnolia; Picrates; Plant Bark; Plant Oils