Showing papers by "Jon Clardy published in 1987"
239 citations
TL;DR: A novel alkaloid, prianosin A (1), with potent antineoplastic activity has been isolated from the Okinawan marine sponge Prianos melanos as mentioned in this paper.
82 citations
TL;DR: The ophiobolin characterized as 6-epiophiobolin A is selectively toxic to corn bearing Texas-male-sterile (Tms) cytoplasm when assayed in a dark CO(2) fixation assay, suggesting it is plausible that these ophiOBolins had a role in the 1970 corn-blight epidemic in North America.
Abstract: Drechslera maydis, the causal agent of Southern corn leaf blight, and Drechslera sorghicola, the causal agent of leaf spot on Johnson grass, produce a series of phytotoxic sesterterpenoids. These sesterterpenoids belong to the ophiobolin family. One of them, ophiobolin I, was characterized by x-ray diffraction and served as a crucial reference compound for characterizing four other ophiobolins. All of the ophiobolins studied produce characteristic lesions on host plants at concentrations of 1 mM to 1 μM. The ophiobolin characterized as 6-epiophiobolin A is selectively toxic to corn bearing Texas-male-sterile (Tms) cytoplasm when assayed in a dark CO2 fixation assay. It is plausible that these ophiobolins had a role in the 1970 corn-blight epidemic in North America.
66 citations
TL;DR: A new species of acorn worm, recently discovered in deep underwater caves off the island of Maui, yielded after Chromatographic separation of the acetone extract the following secondary metabolites: (4 S,5 R,6 S,)-4-acetoxy-2.6-dibromo-5-hydroxy- cyclohex-2-enone (11), its C-6 epimer (12), (1 R,4 S,5 R,6 S )-4- acetoxy- 2.5-dihydroxy-cyclo
52 citations
TL;DR: Oxidation of a plausible biological precursor for the spirocyclic systems of aerothionin and psammaplysin-A is described.
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TL;DR: Scleroderolide, a yellow pigment produced by the Scleroderris canker fungus Gremmeniellaabietina (Lagerb.) Morelet, is shown to possess structure 1. The structure was determined by an X-ray crystallographic study of the racemic monoacetate 1a. The crystal of 1a belongs to the triclinic system space group P1, the R-factor converged to 0.047 for the 1957 observed reflections as discussed by the authors.
Abstract: Scleroderolide, a yellow pigment produced by the Scleroderris canker fungus Gremmeniellaabietina (Lagerb.) Morelet, is shown to possess structure 1. The structure was determined by an X-ray crystallographic study of the racemic monoacetate 1a. The crystal of 1a belongs to the triclinic system space group, P1, the R-factor converged to 0.047 for the 1957 observed reflections. Scleroderolide occurs mainly as the levorotatory enantiomer (S configuration at C-2′) although on one occasion it was obtained in partially racemic form. The absolute stereochemistry of the levorotatory form was determined by transformation of (−)-sclerodione (5) of known absolute configuration into (−)-scleroderolide. The absolute configuration of (−)-sclerodione was established by correlation with (−)-sclerodin (3). The diacetyl derivative of scleroderolide (1b) shows interesting temperature dependent nuclear magnetic resonance spectral properties due to restricted rotation of the C-4 O-acetyl group. Oxidation of the red pigment scl...
24 citations
TL;DR: Chilenone B was isolated from the red marine alga Laurencia chilensis, and its structure was determined by x-ray diffraction and spectroscopic techniques.
TL;DR: In this article, a partir de l'hexahydro-5,6,7,8,9,10 dimethano,5,8:7,10benzocyclooctenediol-7, 8 via l'isopropylidenedioxy-3a,6a iodomethyl-2 selenocyanatomethsyl-5 perhydro pentalene.
Abstract: Synthese a partir de l'hexahydro-5,6,7,8,9,10 dimethano-5,8:7,10benzocyclooctenediol-7,8 via l'isopropylidenedioxy-3a,6a iodomethyl-2 selenocyanatomethyl-5 perhydro pentalene. Etude RX du sel de methylselenonium du compose du titre
TL;DR: The structure of aspirochlorine has been revised to the novel epidithiopiperazine-2, 5-dione1 on the basis of chemical, spectroscopic, and x-ray crystallographic experiments as mentioned in this paper.
TL;DR: The structure of a new polyether antibiotic portmicin has been determined as shown in Fig. 1 by using new NMR tecnniques, HMBC and HOHAHA as discussed by the authors.
TL;DR: In this article, a novel antimicrobial pyranone has been obtained from very polar extracts of the encrusting gorgonian Briareum polyanthes, which were used to develop two possible structures; x-ray diffraction studies established the structure and relative stereochemistry.
TL;DR: The structure of gersolide, a diterpenoid isolated from extracts of the soft coral Gersemia rubiformis, has been solved via single crystal x-ray diffraction analysis as mentioned in this paper.
TL;DR: An unusual tetracyclic polyketal has been isolated from the red alga Laurencia chilensis as mentioned in this paper, which was established by x-ray diffraction and spectral methods.
TL;DR: In this paper, the addition of phosphorus compounds to 3O-alkyl-5,6-dideoxy-1,2-O-isopropylidene-6-C-nitro-α-D-xylo-hexo-5-(Z)-enofuranoses was first investigated by X-ray crystallographic analysis of the adduct.
Abstract: Stereochemical control of the addition of phosphorus compounds to 3-O-alkyl-5,6-dideoxy-1,2-O-isopropylidene-6-C-nitro-α-D-xylo-hexo-5-(Z)-enofuranoses was first investigated by X-ray crystallographic analysis of the adduct.
TL;DR: A new diterpene, β-dictalediol monoacetate ( ), has been isolated from a brown alga X-ray crystal structure studies of have revealed the existence of two polymorphic modifications.
TL;DR: The crystal and molecular structures of tricyclo[7.2.1.04,11-.06,10]-dodeca-2, 7-diene-5,12-dione (6) have been determined.