Michio Onjo

Phenolic compounds from the leaves of Psidium guajava II. Quercetin and its glycosides

0009-3130/12/4803-0477 2012 Springer Science+Business Media, Inc. 1) Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, 890-0065, Kagoshima, Japan, e-mail: parkbj71@mail.goo.ne.jp; 2) Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, 350-0283, Saitama, Japan; 3) Harunire Bio Laboratory Co., Ltd., 603-2 Hakuyo-cho, 090-0013, Kitami, Japan; 4) Dept. of Bio-Health Technology, Kangwon National University, 200-701, Chuncheon, Korea; 5) Korea National University of Agricultural & Fisheries, 445-893, Hwasung, Korea. Published in Khimiya Prirodnykh Soedinenii, No. 3, May–June, 2012, pp. 429–431. Original article submitted February 1, 2011. Chemistry of Natural Compounds, Vol. 48, No. 3, July, 2012 [Russian original No. 3, May–June, 2012]

INDUCTION OF SPROUTING IN DORMANT YAM (DIOSCOREA SPP.) TUBERS WITH INHIBITORS OF GIBBERELLINS

SUMMARY Ar eliable means to induce sprouting in dormant seed tubers of yams (Dioscorea species) is required to enhance flexibility in planting date and rate of propagation of the crop. Experiments were conducted to assess the potential of two gibberellin inhibitors, Uniconazole-P and Prohexadione-calcium, to induce sprouting in tubers from three varieties ofD. rotundata and four ofD. alata .U niconazole-P and Prohexadionecalcium shortened the period of dormancy in tubers of some varieties. In others, they either had no effect or extended dormancy. The varietal responses were also influenced by whether the tubers were treated at harvest (before shoot senescence) or four weeks after harvest by which time shoots had senesced fully. Tubers stored in darkness at a constant temperature of 30 ◦ Cs prouted earlier but lost weight faster than did those stored under natural daylight and ambient temperature. The apparent slow action of Uniconazole-P and Prohexadione-calcium, and their variable effectiveness in relation to variety, would limit their usefulness in seed or breeding programmes, or in determining treatment timing and the best storage environment for the tubers after treatment.

Structural Basis of Cucumisin Protease Activity Regulation by Its Propeptide

Cucumisin [EC 3.4.21.25], a subtilisin-like serine endopeptidase, was isolated from melon fruit, Cucumis melo L. Mature cucumisin (67 kDa, 621 residues) is produced by removal of the propeptide (10 kDa, 88 residues) from the cucumisin precursor by subsequence processing. It is reported that cucumisin is inhibited by its own propeptide. The crystal structure of mature cucumisin is reported to be composed of three domains: the subtilisin-like catalytic domain, the protease-associated domain and the C-terminal fibronectin-III-like domain. In this study, the crystal structure of the mature cucumisin•propeptide complex was determined by the molecular replacement method and refined at 1.95 Å resolution. In this complex, the propeptide had a domain of the &agr;–&bgr; sandwich motif with four-stranded antiparallel &bgr;-sheets, two helices and a strand of the C-terminal region. The &bgr;-sheets of the propeptide bind to two parallel surface helices of cucumisin through hydrophobic interaction and 27 hydrogen bonds. The C-terminus of the propeptide binds to the cleft of the active site as peptide substrates. The inhibitory assay suggested that the C-terminal seven residues of the propeptide do not inhibit the cucumisin activity. The crystal structure of the cucumisin•propeptide complex revealed the regulation mechanism of cucumisin activity.

Phenolic compounds from the leaves of Psidium guajava. I. Hydrolysable tannins and benzophenone glycosides

0009-3130/11/4704-0632 2011 Springer Science+Business Media, Inc. 1) Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan, e-mail: parkbj71@mail.goo.ne.jp; 2) Harunire Bio Laboratory Co., Ltd., 603-2 Hakuyo-cho, Kitami, 090-0013, Japan; 3) Korea National University of Agricultural & Fisheries, Hwasung, 445-893, Korea; 4) Department of Bio-Health Technology, Kangwon National University, Chuncheon, 200-701, Korea. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 557–559, July– August, 2011. Original article submitted March 24, 2010. Chemistry of Natural Compounds, Vol. 47, No. 4, September, 2011 [Russian original No. 4, July–August, 2011]

Novel steroidal saponins from Dioscorea esculenta (Togedokoro)

Fifteen steroidal saponins 1–15, which include 4 furostanol glycosides 1–3 and 15, and 11 spirostanol glycosides 4–14, were isolated from the tubers and leaves of lesser yam (Dioscorea esculenta, Togedokoro). Their structures were identified by nuclear magnetic resonance and liquid chromatography mass spectroscopy. Four steroidal saponins 9, 11, 14, and 15 were found to be novel compounds. Steroidal saponins from Dioscorea esculenta.