Yasunobu Asao

Publications (9)19.4 Total impact

• Source

  Available from: Toshio Morikawa

  Article: Oleanane-type triterpene oligoglycosides with pancreatic lipase inhibitory activity from the pericarps of Sapindus rarak.

  Toshio Morikawa, Yuanyuan Xie, Yasunobu Asao, Masaki Okamoto, Chihiro Yamashita, Osamu Muraoka, Hisashi Matsuda, Yutana Pongpiriyadacha, Dan Yuan, Masayuki Yoshikawa
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  ABSTRACT: The methanolic extract from the pericarps of Sapindus rarak DC. was found to show pancreatic lipase inhibitory activity (IC50=ca. 614 microg/mL). From the extract, oleanane-type triterpene oligoglycosides, rarasaponins I-III (1-3), and raraoside A (4), were isolated together with 13 known saponins and four known sesquiterpene glycosides. Among them, several saponin constituents including rarasaponins I (1, IC50=131microM) and II (2, 172microM), and raraoside A (4, 151microM) inhibited pancreatic lipase activity, which were stronger than that of theasaponin E(1) (270microM).
  Phytochemistry 08/2009; 70(9):1166-72. · 3.35 Impact Factor
• Article: Antidiabetogenic constituents from the Thai traditional medicine Cotylelobium melanoxylon.

  Hisashi Matsuda, Yasunobu Asao, Seikou Nakamura, Makoto Hamao, Sachiko Sugimoto, Masako Hongo, Yutana Pongpiriyadacha, Masayuki Yoshikawa
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  ABSTRACT: The methanolic extracts from the wood and bark of Cotylelobium melanoxylon were found to inhibit plasma glucose elevation after sucrose loading in rats and triglyceride elevation after olive oil loading in mice. A new stilbene dimer, melanoxylin A, together with the known stilbene dimers [(+)-ampelopsin F, (+)-isoampelopsin F, and (+)-epsilon-viniferin] and a trimer (vaticanol G) and a lignan [(+)-lyoniresinol] were isolated from the wood extract, and a new stilbene trimer, melanoxylin B, together with the known stilbene dimers [(+)-epsilon-viniferin and cis-(+)-epsilon-viniferin] and trimers (vaticanols A, E, and G) were isolated from the bark extract of C. melanoxylon. The principal constituents, vaticanols A, E, and/or G, inhibited plasma glucose and triglyceride elevation after sucrose loading in rats and olive oil loading in mice, respectively. In addition, vaticanols A, E, and/or G inhibited the enzyme activities of rat intestinal alpha-glucosidase, porcine pancreatic lipase, and rat lens aldose reductase.
  CHEMICAL & PHARMACEUTICAL BULLETIN 06/2009; 57(5):487-94. · 1.59 Impact Factor
• Article: Structures of acetylated oleanane-type triterpene saponins, rarasaponins IV, V, and VI, and anti-hyperlipidemic constituents from the pericarps of Sapindus rarak.

  Yasunobu Asao, Toshio Morikawa, Yuanyuan Xie, Masaki Okamoto, Makoto Hamao, Hisashi Matsuda, Osamu Muraoka, Dan Yuan, Masayuki Yoshikawa
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  ABSTRACT: The methanolic extract and its saponin fraction (methanol-eluted fraction) of the pericarps of Sapindus rarak DC. were found to suppress plasma triglyceride elevation in olive oil-treated mice. From the active fraction, three new acylated oleanane-type triterpene saponins, rarasaponins IV (1), V (2), and VI (3), were isolated. The structures of 1-3 were elucidated on the basis of chemical and spectroscopic evidence. The principle saponin constituents, hederagenin 3-O-alpha-L-arabinopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside (4) and hederagenin 3-O-(3,4-di-O-acetyl-alpha-L-arabinopyranosyl)-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside (5), showed inhibitory effects on plasma triglyceride elevation at a dose of 200 mg/kg, per os.
  CHEMICAL & PHARMACEUTICAL BULLETIN 02/2009; 57(2):198-203. · 1.59 Impact Factor
• Article: Medicinal flowers. XV. The structures of noroleanane- and oleanane-type triterpene oligoglycosides with gastroprotective and platelet aggregation activities from flower buds of Camellia japonica.

  Masayuki Yoshikawa, Toshio Morikawa, Yasunobu Asao, Emi Fujiwara, Seikou Nakamura, Hisashi Matsuda
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  ABSTRACT: The methanolic extract from the flowers buds of Camellia japonica L. (Theaceae) were found to exhibit potent inhibitory activities on ethanol- or indomethacin-induced gastric mucosal lesions in rats. Through bioassay-guided separation, 28-noroleanane-type triterpene oligoglycosides, camelliosides A, B, and C, and an oleanane-type triterpene oligoglycoside, camellioside D, were isolated from the methanolic extract together with five known compounds. The absolute stereostructures of camelliosides were determined on the basis of chemical and physicochemical evidence, which included the structure revision of the nortriterpene aglycons (camellenodiol and camelledionol). The principal oligoglycosides, camelliosides A and B, showed platelet aggregation activity in addition to the gastroprotective effects on ethanol- or indomethacin-induced gastric mucosal lesions in rats.
  CHEMICAL & PHARMACEUTICAL BULLETIN 05/2007; 55(4):606-12. · 1.59 Impact Factor
• Source

  Available from: Toshio Morikawa

  Article: Medicinal flowers. XII.(1)) New spirostane-type steroid saponins with antidiabetogenic activity from Borassus flabellifer.

  Masayuki Yoshikawa, Fengming Xu, Toshio Morikawa, Yutana Pongpiriyadacha, Seikou Nakamura, Yasunobu Asao, Akira Kumahara, Hisashi Matsuda
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  ABSTRACT: The methanolic extract from the male flowers of Borassus flabellifer was found to inhibit the increase of serum glucose levels in sucrose-loaded rats at a dose of 250 mg/kg, p.o. From the methanolic extract, six new spirostane-type steroid saponins, borassosides A-F (1-6), were isolated together with 23 known constituents. The structures of borassosides (1-6) were elucidated on the basis of chemical and physicochemical evidences. In addition, the principal steroid saponin, dioscin (13), inhibited the increase of serum glucose levels in sucrose-loaded rats at a dose of 50 mg/kg, p.o.
  CHEMICAL & PHARMACEUTICAL BULLETIN 03/2007; 55(2):308-16. · 1.59 Impact Factor
• Article: Rotenoids and flavonoids with anti-invasion of HT1080, anti-proliferation of U937, and differentiation-inducing activity in HL-60 from Erycibe expansa.

  Hisashi Matsuda, Kazutoshi Yoshida, Katsutoshi Miyagawa, Yasunobu Asao, Saya Takayama, Souichi Nakashima, Fengming Xu, Masayuki Yoshikawa
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  ABSTRACT: Principal rotenoids (deguelin, tephrosin, rotenone, and 12a-hydroxyrotenone) (3-30microM) isolated from the stems of Erycibe expansa significantly inhibited invasion of human fibrosarcoma HT1080 cells through Matrigel-coated filters and release of proMMPs-2 and 9. In addition, deguelin and tephrosin showed differentiation-inducing activity in human promyelocytic leukemia HL-60 cells. Furthermore, effects of various constituents isolated from the ethyl acetate-soluble fraction on proliferation of human leukemia U937 cells were examined. As a result, most of isoflavones and several flavans as well as rotenoids showed moderate or substantial anti-proliferative activities.
  Bioorganic & Medicinal Chemistry 03/2007; 15(3):1539-46. · 2.92 Impact Factor
• Article: Nuphar alkaloids with immediately apoptosis-inducing activity from Nuphar pumilum and their structural requirements for the activity.

  Hisashi Matsuda, Kazutoshi Yoshida, Katsutoshi Miyagawa, Yumiko Nemoto, Yasunobu Asao, Masayuki Yoshikawa
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  ABSTRACT: The methanolic extract and its alkaloid fraction from the rhizomes of Nuphar pumilum showed cytotoxic effects on human leukemia cell (U937), mouse melanoma cell (B16F10), and human fibroblast (HT1080). Dimeric sesquiterpene thioalkaloids with the 6-hydroxyl group (6-hydroxythiobinupharidine, 6,6'-dihydroxythiobinupharidine, 6-hydroxythionuphlutine B) showed substantial cytotoxic activity at a concentration of 10 microM, but dimeric sesquiterpene thioalkaloids lacking the 6-hydroxyl group (thiobinupharidine, thionuphlutine B, 6'-hydroxythionuphlutine B, neothiobinupharidine, thionuphlutine B beta-sulfoxide, and neothiobinupharidine beta-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, 7-epideoxynupharidine, and nupharolutine) showed weak activity. Next, apoptosis-inducing activity of a principal active constituent, 6-hydroxythiobinupharidine, on U937 was examined using morphological observation and DNA fragmentation assay (TUNEL method). Apoptosis of U937 was immediately observed within 1 h after treatment of 6-hydroxythiobinupharidine at 2.5-10 microM.
  Bioorganic & Medicinal Chemistry Letters 04/2006; 16(6):1567-73. · 2.55 Impact Factor
• Article: Potent anti-metastatic activity of dimeric sesquiterpene thioalkaloids from the rhizome of Nuphar pumilum.

  Hisashi Matsuda, Toshio Morikawa, Mamiko Oda, Yasunobu Asao, Masayuki Yoshikawa
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  ABSTRACT: The methanolic extract and its alkaloid fraction from the rhizomes of Nuphar pumilum inhibited invasion of B16 melanoma cells across collagen-coated filters in vitro. Dimeric sesquiterpene thioalkaloids with the 6-hydroxyl group, 6-hydroxythiobinupharidine, 6,6'-dihydroxythiobinupharidine, and 6-hydroxythionuphlutine B, showed potent activity with IC(50) values of 0.029, 0.087, and 0.36 microM, respectively, but dimeric sesquiterpene thioalkaloids lacking the 6-hydroxyl group (thiobinupharidine, neothiobinupharidine, syn-thiobinupharidine sulfoxide, thionuphultine B beta-sulfoxide, and neothiobinupharidine beta-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, deoxynupharidine, 7-epideoxynupharidine, and nupharolutine) showed weak activity. The alkaloid fraction (20 mg/kg/d, po) and the principal dimeric sesquiterpene thioalkaloid 6-hydroxythiobinupharidine (5 mg/kg/d, po) significantly inhibited lung tumor formation by more than 90% 10 days after injection of B16 melanoma cells in mice.
  Bioorganic & Medicinal Chemistry Letters 01/2004; 13(24):4445-9. · 2.55 Impact Factor
• Article: Protective effects of polygodial on gastric mucosal lesions induced by necrotizing agents in rats and the possible mechanisms of action.

  Yutana Pongpiriyadacha, Hisashi Matsuda, Toshio Morikawa, Yasunobu Asao, Masayuki Yoshikawa
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  ABSTRACT: The effects of polygodial isolated from the leaves of Tasmannia lanceolata on necrotizing agents-induced gastric lesions in rats were compared with capsaicin. Polygodial markedly inhibited the gastric mucosal lesions induced by several necrotizing agents, such as ethanol (ED(50)=0.029 mg/kg, p.o.), 0.6 M HCl (ED(50)=0.26 mg/kg, p.o.), and aspirin (ED(50)=0.38 mg/kg, p.o.), and partly inhibited the gastric mucosal lesions induced by indomethacin, but showed no significant effect on acid output in pylorus-ligated rats at doses of 0.05-0.5 mg/kg. The gastroprotection of polygodial was attenuated by pretreatment with indomethacin (10 mg/kg, s.c.), N(G)-nitro-L-arginine methyl ester (70 mg/kg, i.p.), N-ethylmaleimide (10 mg/kg, s.c.) and ruthenium red (3.5 mg/kg, s.c.). Polygodial (0.2 mg/kg, p.o.) increased the amount of reduced glutathione in gastric mucosa of ethanol-treated group. These results suggested that endogenous prostaglandins, nitric oxide, sulfhydryl compounds and vanilloid receptor-mediated effects are involved in the protective effect of polygodial.
  Biological & Pharmaceutical Bulletin 06/2003; 26(5):651-7. · 1.66 Impact Factor