Gualamycin, a novel acaricide produced by Streptomyces sp. NK11687. II. Structural elucidation.

A novel acaricide, gualamycin was isolated from the culture broth of Streptomyces sp. NK11687. The structure of gualamycin was determined to be (2R,3S,4S)-2-O-[4-O-(2-amino-2-deoxy-beta-D-gulopyranosyl)-alpha-D - galactopyranosyl]-2,3,4-trihydroxy-4-[(2S,3S,4S,5S)-3,4-dihydroxy-5-hydr oxy - methylpyrrolidin-2-yl] butanoic acid by FAB-MS, 1H and 13C NMR, COSY, HMQC, HMBC, IR, X-ray crystallographic analyses and synthetic studies.

Pironetin, a novel plant growth regulator produced by Streptomyces sp. NK10958. II. Structural elucidation.

A novel plant growth regulator, pironetin was isolated from the culture broth of Streptomyces sp. NK10958. The structure of pironetin was determined to be (5R,6R)-5-ethyl- 5,6-dihydro-6-[(E)-(2R,3S,4R,5S)-2-hydroxy-4-methoxy-3,5-dimethyl-7- nonenyl]-2H-pyran-2-one by FAB-MS, 1H and 13C NMR, COSY, COLOC, DEPT, IR, X-ray crystallographic analyses and adapted Mosher's method.

Structures and solid state tautomeric forms of two novel antileukemic tropoloisoquinoline alkaloids, pareirubrines A and B, from Cissampelos pareira.

Two novel tropoloisoquinoline alkaloids, Pareirubrines A and B, have been isolated as antileukemic substances from Cissampelos pareira (Menispermaceae), together with the same skeleton alkaloids, grandirubrine and isoimerubrine. Their structures were elucidated by nuclear magnetic resonance (NMR) studies, and their solid state tautomeric forms were examined by X-ray crystallographic analysis.

Reactions of vitamin E and its model compound 2,2,5,7,8-pentamethylchroman-6-ol with ozone.

Reaction of vitamin E [(R,R,R)-alpha-tocopherol] with ozone in acetonitrile yielded alpha-tocopheryl quinone and its precursor 8a-hydroxytocopherone, which accounted for approximately 30% of the products at < 50% alpha-tocopherol oxidation. In addition, two novel products were identified as epimers of 10-acetyl-7-(4',8',12'-trimethyltridecyl)-3,4,7-trimethyl-2-oxo- 1,6-dioxaspiro[4.5]-deca-3,9-diene. These spiro products were formed in equal amounts in a combined yield of approximately 33% after complete alpha-tocopherol oxidation. Ozonation of the vitamin E model compound 2,2,5,7,8-pentamethylchroman-6-ol yielded an analogous spiro product, 10-acetyl-3,4,7,7-tetramethyl-2-oxo-1,6-dioxaspiro[4.5]deca-3,9-di ene, whose structure was confirmed by X-ray crystallography. The spiro products may be formed by ozone addition to the chroman ring and subsequent rearrangement to ring-opened hydroxyacid products, which yield spiro products by ring closure due to dehydration. Novel spiro products formed by ozonation of vitamin E may be unique markers of ozone interaction with lipid structures that contain vitamin E.

Benastatins A and B, new inhibitors of glutathione S-transferase, produced by Streptomyces sp. MI384-DF12. II. Structure determination of benastatins A and B.

Benastatins A and B, new inhibitors of glutathione S-transferase, have been isolated from the culture broth of Streptomyces sp. MI384-DF12. By X-ray crystallography, benastatin A was determined to be 8,13-dihydro-1,7,9,11-tetrahydroxy-13-dimethyl-8-oxo-3-pentyl- benzo[a]naphthacene-2-carboxylic acid. The structure of benastatin B was elucidated by NMR studies.

Biologically active constituents of Magnolia salicifolia: inhibitors of induced histamine release from rat mast cells.

The extracts of the flower buds of Magnolia salicifolia showed remarkable anti-allergy effects in passive cutaneous anaphylaxis (PCA) test. The bioactive constituents of this medicinal drug were isolated by monitoring their activities with an in vitro bioassay system measuring inhibitory effects on induced histamine release from rat mast cells. Of the ten isolated compounds magnosalicin is a new compound of neolignan structure. In addition to the isolated compounds samples of coumarins and lignans were evaluated their biological activities with the in vitro bioassay.

Biologically active constituents of Arnebia euchroma: structure of arnebinol, an ansa-type monoterpenylbenzenoid with inhibitory activity on prostaglandin biosynthesis.

Three phenolic compounds were isolated from the roots of Arnebia euchroma as inhibitors of in vitro prostaglandin biosynthesis. Two known compounds were identified as shikonofurans and des-O-methyllasiodiplodin. The other new compound was named arnebinol and its structure was elucidated as a novel ansa-type monoterpenylbenzenoid derivative.

Biologically active constituents of Arnebia euchroma: structures of new monoterpenylbenzoquinones: arnebinone and arnebifuranone.

Two quinonic compounds, arnebinone and arnebifuranone, were isolated from the roots of Arnebia euchroma and their structures were elucidated on the basis of spectral evidence. Arnebionone is a monoterpenyl-benzoquinone in which the monoterpene moiety forms a fused ring to the benzoquinone. Arnebifuranone is another monoterpenylbenzoquinone with a furan ring containing side chain which is bonded to the benzoquinone at the head carbon of C10 moiety originating from the geranyl moiety of geranylhydroquinone.

New antitumor principles, casearins A-F, for Casearia sylvestris Sw. (Flacourtiaceae).

New antitumor clerodane diterpenes, named casearins A-F, have been isolated from the leaves of Casearia sylvestris Sw. (Flacourtiaceae). These structures have been completely elucidated by two dimensional nuclear magnetic resonance, circular dichroism spectroscopy, X-ray analysis, and chemical evidences.

Production, isolation and structure determination of a novel beta-glucosidase inhibitor, cyclophellitol, from Phellinus sp.

In the course of our screening of beta-glucosidase inhibitor, a culture filtrate of a mushroom, Phellinus sp. strongly inhibited the enzyme activity. The active substance was isolated through charcoal separation, column chromatography and crystallization. Spectroscopic and crystallographic analysis revealed that it had a novel cyclitol structure, (1S,2R,3S,4R,5R,6R)-5-hydroxymethyl-7-oxabicyclo[4,1,0]heptane-2,3,4-tri ol, and we named it cyclophellitol. It inhibited almond-derived beta-glucosidase with an IC50 of 0.8 micrograms/ml.

Structure of strychnine hydrochloride sesquihydrate.

C21H23N2O2+.Cl-.1.5H2O, Mr = 397.90, monoclinic, P2(1), a = 7.617 (1), b = 32.463 (2), c = 7.849 (1) A, beta = 90.40 (2) degrees, V = 1940.8 (4) A3 Z = 4, Dm = 1.39, Dx = 1.36 g cm-3, lambda (Cu K alpha) = 1.5418 A, mu = 19.724 cm-1, F(000) = 844, final R = 0.047 for 3368 observed reflections. Strychnine hydrochloride is a naturally occurring alkaloid in its protonated form. One of the N atoms accepts the proton from hydrochloric acid changing its hybridization to sp3. The indole N atom is sp2 hybridized with its lone-pair electron involved in conjugation with the carbonyl group. The hydrogen bonds form a complex zigzag network which stabilizes the structure.

Structure of thiolactomycin.

[4R,(2E,5E)]-3-Hydroxy-2,4,6-trimethyl-2,5,7-octatriene-4-thiol ide, C11H14O2S, Mr = 210.30, hexagonal, P6(5), a = b = 9.8514 (6), c = 19.954 (1) A, V = 1677.1 A3, Z = 6, Dx = 1.249 g cm-3, lambda(Cu K alpha) = 1.5418 A, u = 23.07 cm-1, F(000) = 672, T = 298 K, R = 0.028 for 1021 unique reflections [Fo2 greater than 2 sigma(Fo2)]. The absolute configuration was determined by the Bijvoet method. The thiolactone ring is planar with S-C bond distances of 1.774 (3) and 1.856 (3) A, and C-S-C angle of 93.3 (1) degrees. The angle between least-squares planes for the thiolactone and butadienyl groups is 101.7 degrees.

Thrazarine, a new antitumor antibiotic. II. Physico-chemical properties and structure determination.

A new antitumor antibiotic thrazarine was soluble in water and positive to anisaldehyde-sulfuric acid and ninhydrin color reactions. The absolute structure of thrazarine was determined to be O-[3R)-2-diazo-3-hydroxybutyryl)-L-serine by acid hydrolysis, spectroscopic analysis and X-ray crystallographic analysis. Structurally, thrazarine was a new member of azaserine group antibiotics.

Structure of a modified cytosine: an antiviral nucleoside analog, homo-Ara-C.

Homo-Ara-C [5'-(hydroxymethyl)-5'-deoxy-1-beta-D-arabinofuranosyl-3H- cytosine], C10H16N3O5, Mr = 258.25, P2,2,2, a = 8.261 (2), b = 19.644 (4), c = 6.993 (6) A, V = 1134.8 A3, Z = 4, Dx = 1.511 g cm-3, lambda (Cu Ka) = 1.5418 A, mu = 10.5 cm-1, F(000) = 548, T = 288 K, final R = 0.053 for 1189 observed reflections. Conformational features of the nucleoside include a glycosidic bond conformation in the anti range, a ribose moiety in the 2E [C(2')-endo] form like 5'-N3-Ara-C, 5-NO2-Ara-U and Ara-C and a C(5')-C(6') bond that is gauche to C(4')-O(4') but trans to C(4')-C(3').

A receptor model for tumor promoters: rational superposition of teleocidins and phorbol esters.

Four 12-O-tetradecanoyl-13-O-acetylphorbol-type tumor promoters--teleocidin, phorbol ester, aplysiatoxin, and ingenol ester--are superposed in an attempt to understand their common biological activity on the assumption that they may bind to the same receptor site. A method using three-dimensional computer graphics was applied for superposing molecules and receptor mapping. The main feature of the method is that molecules are superposed in terms of spatial arrangement of physical and chemical properties but not in terms of the atomic positions as in conventional methods. This led to successful extraction of common structural features required for potent tumor-promoting activity: two hydrogen donors, a hydrogen acceptor, and a large lipophilic group. Their mutual spatial arrangements are most important for biological activity.