Kazuyuki Hori

Carvacrol, a component of thyme oil, activates PPARα and γ and suppresses COX-2 expression

Cyclooxygenase-2 (COX-2), the rate-limiting enzyme in prostaglandin biosynthesis, plays a key role in inflammation and circulatory homeostasis. Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors belonging to the nuclear receptor superfamily and are involved in the control of COX-2 expression, and vice versa. Here, we show that COX-2 promoter activity was suppressed by essential oils derived from thyme, clove, rose, eucalyptus, fennel, and bergamot in cell-based transfection assays using bovine arterial endothelial cells. Moreover, from thyme oil, we identified carvacrol as a major component of the suppressor of COX-2 expression and an activator of PPARα and γ. PPARγ-dependent suppression of COX-2 promoter activity was observed in response to carvacrol treatment. In human macrophage-like U937 cells, carvacrol suppressed lipopolysaccharide-induced COX-2 mRNA and protein expression, suggesting that carvacrol regulates COX-2 expression through its agonistic effect on PPARγ. These results may be important in understanding the antiinflammatory and antilifestyle-related disease properties of carvacrol.

Anti-leukemia activities of Lup-28-al-20(29)-en-3-one, a lupane triterpene

The cytotoxicities of 11 lupane series triterpenes against 3 human leukemias, 2 melanomas, 2 neuroblastomas and normal fibroblast cells were examined. Lupane triterpenes with a carbonyl group at C-17 (7-11) showed inhibitory effects on leukemia, melanoma and neuroblastoma cell growth. Lup-28-al-20(29)-en-3-one (8) markedly inhibited the cell growth of 3 leukemias to a greater extent than the other human cancers and normal lung fibroblast cells. The cytotoxicity profiles of 8 against human cancer cells showed that its cytotoxic effect against 3 lung cancer cell lines was strong and the cytotoxic effects against osteosarcoma, breast cancer and urinary bladder cancer cells were very weak. The morphological observations of leukemia nuclei and the gel electrophoresis analysis of DNA extracted from 8-treated leukemia cells revealed that 8 induced leukemia cell apoptosis. Furthermore, we investigated the cytotoxic effects of 8 on adriamycin (ADM)- and vincristine (VCR)-resistant K562 (K562/ADM and K562/VCR) cells. K562/ADM and K562/VCR cells showed greater resistance toward ADM and VCR when compared to parent K562 cells. However, 8 inhibited the drug-resistant K562 cell growth to the same extent as K562 cells by the induction of apoptosis.

Isolation of Human Renin Inhibitor from Soybean: Soyasaponin I Is the Novel Human Renin Inhibitor in Soybean

We found human renin inhibitory activity in soybean and isolated the active compound, soybean renin inhibitor (SRI). The physico-chemical data on the isolated SRI were identical with those of soyasaponin I. SRI showed significant inhibition against recombinant human renin, with an IC50 value of 30 μg/ml. Kinetic studies with SRI indicated partial noncompetitive inhibition, with a Ki value of 37.5 μM. On the other hand, SRI weakly inhibited pepsin, papain, and bromeline activities, but did not inhibit other proteinases, such as trypsin, kallikrein, angiotensin converting enzyme, and aminopeptidase M. Moreover, a significant (p<0.05) decrease in the systolic blood pressure of spontaneously hypertensive rats was observed when partially purified SRI was orally administrated at 40 mg/kg/d for 7 weeks. This is the first demonstration of a renin inhibitor from soybean, soyasaponin I.

Citronellol and Geraniol, Components of Rose Oil, Activate Peroxisome Proliferator-Activated Receptor α and γ and Suppress Cyclooxygenase-2 Expression

We evaluated the effects of rose oil on the peroxisome proliferator-activated receptor (PPAR) and cyclooxygenase-2 (COX-2). Citronellol and geraniol, the major components of rose oil, activated PPARα and γ, and suppressed LPS-induced COX-2 expression in cell culture assays, although the PPARγ-dependent suppression of COX-2 promoter activity was evident only with citronellol, indicating that citronellol and geraniol were the active components of rose oil.

Reduction of blood pressure by soybean saponins, renin inhibitors from soybean, in spontaneously hypertensive rats.

The effect of commercial purified soybean saponin on renin activity and blood pressure was investigated. Soybean saponin significantly inhibited human renin in vitro with IC50=59.9 μg/ml. Orally administered soybean saponin at 80 mg/kg of body weight per day to spontaneously hypertensive rats for 8 weeks significantly decreased the blood pressure.

Refolding and Activation of Human Prorenin Expressed in Escherichia coli: Application of Recombinant Human Renin for Inhibitor Screening

Human prorenin was expressed in Escherichia coli as a fusion protein of thioredoxin. The chimeric protein, which accumulated insoluble inclusion bodies, was solubilized in 4 M guanidine–HCl and refolded by an arginine-detergent buffer system and by systematic dialysis. The refolded fusion prorenin was activated by trypsin. The antiserum against human kidney renin specifically inhibited the recombinant human renin activity. Using the recombinant human renin, we screened its inhibitory activity in fermented soybean paste (miso) and demonstrated that miso contained renin inhibitory activity derived from soybean. The IC50 values for soybean and steamed soybean extracts were determined to be 1.9 and 1.6 mg/ml, respectively. This is the first demonstration of renin inhibitory activity in miso and soybean.

Suppression of Murine Preadipocyte Differentiation and Reduction of Visceral Fat Accumulation by a Petasites japonicus Ethanol Extract in Mice Fed a High-Fat Diet

We investigated in this study the anti-obesity effect of an extract of Petasites japonicus (a culinary vegetable from Eastern Asia) on a murine adipocyte cell line (3T3-L1) and on diet-induced obesity-prone mice. An ethanol extract of P. japonicus. (PJET) suppressed 3T3-L1 preadipocyte differentiation; however, a hot water extract of P. japonicus (PJHW) exhibited no effect on cell differentiation. PJET significantly attenuated three adipogenetic transcription factors, peroxisome proliferator-activated receptor γ2, CCAAT/enhancer-binding protein and sterol regulatory element-binding protein 1C, at the mRNA level and suppressed the gene expression of fatty acid synthetase. An experiment with diet-induced obesity-prone C57BL/6J mice showed that PJET lowered the body weight gain and visceral fat tissue accumulation, and ameliorated the plasma cholesterol concentration. These findings suggest that P. japonicus might be an effective food against obesity.

An external flavonoid and its dimer from the fern Oreopteris quelpaertensis

Abstract From the frond of Oreopteris quelpaertensis , a novel chalcone-like product has been isolated as a mixture of keto—enol tautomeric isomers, along with its dimeric form, and their structures were determined by extensive 2D NMR spectroscopy or X-ray diffraction. Isoquercitrin was also obtained from this fern.

Lupane triterpenes with a carbonyl group at C-20 induce cancer cell apoptosis

We evaluated the effects of various lupane triterpenes on B16 2F2 mouse melanoma cell differentiation and proliferation. All of the compounds tested (numbered 1–6) induced melanogenesis of B16 2F2 cells, a marker of melanoma cell differentiation. Compounds 4–6, which have a carbonyl group at C-20, markedly inhibited the growth of B16 2F2 cells by the induction of apoptosis. Cytotoxic profiles of these lupane triterpenes against human cancer cells demonstrated that compounds 4–6 showed inhibitory effects on the proliferations of leukemia and lung cancer cells, to a greater extent than other cancer and normal fibroblast cells. These results suggest that the carbonyl group at C-20 of lupane triterpenes played important roles in their apoptosis-inducing activity against cancer cells.

Anti-melanogenic Activity of Ergosterol Peroxide from Ganoderma lucidum on a Mouse Melanoma Cell Line

MeOH extracts of Ganoderma lucidum showed an inhibitory effect on melanin biosynthesis of a mouse melanoma cell line, B16 10F7. We isolated an active compound from the extract. Physical and chemical data of the active compound were identical to those of ergosterol peroxide. Ergosterol peroxide decreased melanin pigment accumulation over 1 μg/ml by the suppression of melanogenic enzyme in B16 10F7 cells. However, ergosterol, a typical steroid in mushrooms, did not show a marked inhibitory effect on B16 10F7 cell melanogenesis at the same concentrations.