Masayoshi Oyama

Agarwood induced laxative effects via acetylcholine receptors on loperamide-induced constipation in mice.

Agarwood (Aquilaria sinensis, Aquilaria crasna) is well known as an incense in the oriental region such as Thailand, Taiwan, and Cambodia, and is used as a digestive in traditional medicine. We investigated the laxative effects and mechanism of agarwood leaves extracted with ethanol (EEA-1, Aquilaria sinensis; EEA-2, Aquilaria crasna). EEA-1, EEA-2, the main constituents of EEAs (mangiferin, and genkwanin-5-O-primeveroside), and senna increased the frequency and weight of stools in loperamide-induced constipation model mice. EEA-1 and EEA-2 did not induce diarrhea as a side effect, but senna induced severe diarrhea. EEA-1 and senna increased gastro-intestinal (GI) transit in the model mice. EEA-1, but not senna, also increased the intestinal tension of isolated jejunum and ileum in guinea pigs, and the tension increase was blocked by atropine, a muscarinic receptor antagonist, but not by other inhibitors (granicetron, pyrilamine, or bradykinin-antagonist peptide). Furthermore, the increase in frequency and weight of stools induced by EEA-1 were blocked by pre-administration of atropine in the model mice. These findings indicate that EEAs exerted a laxative effect via acetylcholine receptors in the mouse constipation model.

Resveratrol oligomers from Vatica albiramis.

Five new stilbenoids, vatalbinosides A-E (1-5), and 13 known compounds (6-18) were isolated from the stem of Vatica albiramis. The effects of these new compounds on interleukin-1β-induced production of matrix metalloproteinase-1 (MMP-1) in human dermal fibroblasts were examined. Three resveratrol tetramers, (-)-hopeaphenol (6), vaticanol C (13), and stenophyllol C (14), were identified as strong inhibitors of MMP-1 production.

Terpenoids from Chloranthus serratus and their anti-inflammatory activities.

Seven new terpenoids, including two sesquiterpene dimers (1, 2), two norditerpenoids (3, 4), and three sesquiterpenes (5-7), along with six known sesquiterpene dimers and four known sesquiterpenes were isolated from the whole plant of Chloranthus serratus. Their structures and relative configurations were elucidated on the basis of spectroscopic data analysis. The absolute configuration of 1 was determined by the CD exciton chirality method. These isolates were evaluated for their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW264.7 cells. Compound 2 and two known compounds, shizukaols B and D, showed significant anti-inflammatory activities, with IC(50) values of 0.22, 0.15, and 7.22 μM, respectively.

Inhibitory effects of sesquiterpene lactones isolated from Eupatorium chinense L. on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

Sesquiterpene lactones (SQTLs) have been shown to suppress the degranulation as inferred by histamine release in rat basophilic leukemia RBL-2H3 cells. In this study, we isolated the 9 kinds of SQTLs from Eupatorium chinense L. and examined the effects of these SQTLs on the degranulation in RBL-2H3 cells. The chemical structures of two novel compounds (SQTL-3 and 8) were determined. All the SQTLs suppressed the degranulation from Ag-stimulated RBL-2H3 cells. To disclose the inhibitory mechanism of degranulation by SQTLs, we examined the activation of intracellular signaling molecules such as Lyn, Syk, and PLCgammas and intracellular free Ca(2+) concentration ([Ca(2+)]i). None of these SQTLs showed the activation of Syk and PLCgammas. The intracellular free Ca(2+) concentration ([Ca(2+)]i) was elevated by Fc epsilonRI activation, but SQTLs treatment reduced the elevation of [Ca(2+)]i by suppressing Ca(2+) influx. Thus, it was suggested that the suppression of Ag-stimulated degranulation by these SQTLs is mainly due to the decreased Ca(2+) influx. Furthermore, in order to clarify the in vivo effect of SQTL-rich extract, we administered SQTL-rich extract to the type I allergic model mice and measured the passive cutaneous anaphylaxis (PCA) reaction induced by IgE-antigen complex. The SQTLs remarkably suppressed PCA reaction in a dose-dependent manner. Thus, it was suggested that SQTLs would be a candidate as an anti-allergic agent.

Japanese Huperzia serrata extract and the constituent, huperzine A, ameliorate the scopolamine-induced cognitive impairment in mice.

Huperzia serrata has been used as a Chinese folk medicine for many years. It contains huperzine A, which has a protective effect against memory deficits in animal models; however, it is unclear if H. serrata extract exerts any effects in Alzheimer’s disease (AD) models. We used H. serrata collected in Japan and determined its huperzine A content using HPLC. We determined its inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity. H. serrata extract (30 mg/kg/day) and donepezil (10 mg/kg/day) were orally administrated for 7 days. After repeated administration, we performed the Y-maze and passive avoidance tests. H. serrata extract contained 0.5% huperzine A; H. serrata extract inhibited AChE, but not BuChE. H. serrata extract ameliorated cognitive function in mice. These results indicate that Japanese H. serrata extract ameliorates cognitive function deficits by inhibiting AChE. Therefore, H. serrata extract may be valuable for the prevention or treatment of dementia in AD. Repeated treatment with Huperzia serrata extract (30 mg/kg/day) for six or seven days ameliorated the memory impairment induced by scopolamine in the two behavioral tests.

Sesquiterpenes from the aerial part of Chloranthus japonicus and their cytotoxicities

Four new sesquiterpenes, chlorajapolides F-I (1-4), along with nine known terpenoids (5-13) were isolated from the aerial part of Chloranthus japonicus. Their structures were elucidated on the basis of spectroscopic analysis, and a lindenane sesquiterpene, named 9-hydroxy-heterogorgiolide, previously isolated from the C. japonicus, was revised as its 8-epimer (1a). Moreover, methanol extract (ME), EtOAc fraction (EF), water fraction (WF), and all isolates (1a, 1-13) were evaluated for their cytotoxicities using two human cancer cell lines.

Structure-activity relationship of flavonoids as potent inhibitors of carbonyl reductase 1 (CBR1).

Human carbonyl reductase 1 (CBR1), a member of the short-chain dehydrogenase/reductase superfamily, reduces a variety of carbonyl compounds including therapeutic drugs. CBR1 is involved in the reduction of the anthracycline anticancer drugs to their less anticancer C-13 hydroxy metabolites, which are cardiotoxic. CBR1 inhibitors are thought to be promising agents for adjuvant therapy with twofold beneficial effect in prolonging the anticancer efficacy of the anthracyclines while decreasing cardiotoxicity, a side effect of the drugs. In this study, we evaluated 27 flavonoids for their inhibitory activities of CBR1 in order to explore the structure-activity relationship (SAR). Among them, luteolin (2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-1-benzopyran-4-one) showed the most potent inhibition (IC5095nM), which is also more potent compared to all known classes of CBR1 inhibitors. The inhibition of luteolin was noncompetitive with respect to the substrate in the NADPH-dependent reduction direction, but CBR1 exhibited moderate NADP(+)-dependent dehydrogenase activity for some alicyclic alcohols, in which the luteolin inhibition was competitive with respect to the alcohol substrate (Ki59nM). The SAR of the flavonoids indicated that the 7-hydroxy group of luteolin was responsible for the potent inhibition of CBR1. The molecular docking of luteolin in CBR1-NADPH complex showed that theflavonoid binds to the substrate-binding cleft, in which its 7-hydroxy group formed a H-bond with main-chain oxygen of Met234, in addition to H-bond interactions (of its 5-hydroxy and 4-carbonyl groups with catalytically important residues Tyr193 and/or Ser139) and a π-stacking interaction (between its phenyl ring and Trp229).

Anti-inflammatory sesquiterpenes and sesquiterpene dimers from Chloranthus fortunei

A novel lindenane sesquiterpene with an unprecedented 18-membered triester ring, named chlorafortulide (1), along with one known lindenane sesquiterpene (2) and nine known lindenane sesquiterpene dimers (3–11), was isolated from the whole plant of Chloranthus fortunei. Their structures and relative configurations were elucidated on the basis of spectroscopic analysis. All the isolates were evaluated for their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW264.7 cells. Henriol D (4), shizukaols E (8), G (9), M (10), and O (11) showed significant anti-inflammatory activities with IC50 values of 1.90, 3.68, 1.95, 7.01, and 1.95 μM, respectively.

Novel zierane- and guaiane-type sesquiterpenes from the root of Melicope denhamii.

Two novel zierane‐type sesquiterpenes, named melicodenones A and B (1 and 2, resp.), and three new guaiane‐type sesquiterpenes, named melicodenones C–E (3–5), were isolated from the root of Melicope denhamii (Seem.) T. G. Hartley together with zierone (6). Their structures were established by extensive NMR‐spectroscopic analyses. Compounds 1–6 were tested for cytotoxicity using human colon cancer DLD‐1 cells, and melicodenone A (1) was found to exhibit moderate activity.

Analysis of licorice-induced pseudoaldosteronism in the Japanese Adverse Drug Event Report database

We analyzed the association of age, sex, and dosage with licorice‐associated pseudoaldosteronism using spontaneous adverse event reports.