Justicidin B, a bioactive trace lignan from the seeds of Sesbania drummondii.
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Animals↗
Biomedical subjects
C J Chang
Publications and source records attributed to C J Chang.
3,3',5'-Tri-O-methylpiceatannol and 4,3',5'-tri-O-methylpiceatannol: improvements over piceatannol in bioactivity.
Piceatannol (3,4,3',5'-tetrahydroxy-trans-stilbene) (NSC 365798) has recently been isolated and was subsequently synthesized for NCI tumor panel testing as a new antileukemic natural product from the seeds of Euphorbia lagascae. During the synthesis, a bioactive reaction mixture of several partially O-methylated piceatannol analogues was obtained. This mixture has now been maximized and subjected to bioactivity-directed fractionation, using brine shrimp lethality, to yield 3,3',5'-tri-O-methylpiceatannol (NSC 381281); this new compound has improved stability and better bioactivity in several systems than piceatannol itself. To confirm the structure, 5 was synthesized from vanillin. In addition, the isovanillin analogue, 4,3',5'-tri-O-methylpiceatannol (NSC 381864), another new compound, was synthesized and found to be bioactive.
Animals↗
Novel chromones from Spathelia sorbifolia.
Three new chromones, namely 10-(2',3'-dihydroxy-3'-methylbutanyl)-spatheliachromen, 10-(1',2',3'-trihydroxy-3'-methylbutanyl)spatheliachromen, and 6-(3'-hydroxy-3'-methyl-trans-but-1'-enyl)-O-methylisospatheliachrome n were isolated from the 10% aqueous MeOH extract of the twigs and leaves of Spathelia sorbifolia, together with five known chromones. Compound 2, the known spatheliabischromen, and 5-O-methylsorbifolin showed cytotoxicity against 9PS cells in culture.
Acetylation↗
Biosynthesis of the ansamycin antibiotic ansatrienin (mycotrienin) by Streptomyces collinus.
The biosynthesis of ansatrienin (mycotrienin) has been studied in radioactive and stable isotope feeding experiments with Streptomyces collinus Tü 1892. The m-C7N unit of the ansa ring is efficiently and specifically derived from 3-amino-5-hydroxybenzoic acid; shikimic acid is not incorporated into this part of the molecule but does label the cyclohexanecarboyxlic acid moiety, providing all seven of its carbon atoms. Incorporation of methionine confirms origin of the methoxy group by transmethylation. The D-alanine moiety is derived directly from D-alanine rather than L-alanine. The terminal steps in the conversion of shikimic acid into cyclohexanecarboyxlic acid seem to be sequential reduction of 2,5-dihydrobenzoic acid and cyclohexene-1-carboxylic acid as evidenced by feeding experiments and the detection of a new ansatrienin containing a 1-cyclohexene instead of the cyclohexane moiety.
Chemical Phenomena↗
New xanthones from Psorospermum febrifugum.
The isolation and structural determination of two new xanthone derivatives, 1,2,4-trimethoxy-3,8-dihydroxyxanthone, 1,2,4-trimethoxy-3-hydroxyxanthone and a known 2-methoxy-3-hydroxyxanthone from Psorospermum febrifugum var. ferrugineum are reported. The structures were elucidated by extensive analysis of 1H and 13C nmr, ms, and chemical correlations.
Hexanes↗
New cytotoxic aristolactams from Pararistolochia flos-avis.
Two new aristolactams, aristolactam-FI [1] and -FII [2], were isolated from active extracts of Pararistolochia flos-avis. Their structures were elucidated on the basis of nmr, ms, uv, and ir spectral data. Aristolactam-I [3] and -AII [4] were also isolated from this plant. Aristolactam-AII showed cytotoxicity against PS and KB cells in culture.
Acetylation↗
Bioactive components of Allamanda schottii.
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Animals↗
Bullatacin and bullatacinone: two highly potent bioactive acetogenins from Annona bullata.
Screening of crude extracts of the bark of Annona bullata showed cytotoxic and pesticidal activities. By monitoring with brine-shrimp lethality, two novel, extremely potent acetogenins, bullatacin [1] and bullatacinone [2], were isolated. Spectral and chemical methods identified bullatacin as a diastereomer of asimicin. Bullatacinone represents bullatacin with the lactone cleaved and reformed at the 4-OH. Compounds 1 and 2 show selective cytotoxicities in human tumor cell lines, and certain susceptible cells give ED50 values as low as 10(-12)-10(-15) micrograms/ml. Bullatacin was pesticidal at concentrations as low as 1 ppm, but bullatacinone lacked pesticidal activities. The known compounds liriodenine and (-)-kaur-16-en-19-oic acid were also isolated and were lethal to brine shrimp but were not significantly cytotoxic.
Antineoplastic Agents, Phytogenic↗
Majorenolide and majorynolide: a new pair of cytotoxic and pesticidal alkene-alkyne delta-lactones from Persea major.
From the EtOH extract of the bark of Persea major, two bioactive compounds, majorynolide [1] and majorenolide [2], were isolated by activity-directed fractionation using brine shrimp. Their structures have been elucidated on the basis of spectral data as a pair of new alkene-alkyne delta-lactones, each with an exocyclic alkylidene methine carbon. Both 1 and 2 are moderately cytotoxic, and 2 is selectively pesticidal.
Animals↗
Natural products as a source of potential cancer chemotherapeutic and chemopreventive agents.
Recent advances in the chemistry of novel bioactive natural products are reported. This research is directed to the exploration of plants with confirmed activity in bioassays designed to detect potential cancer chemotherapeutic and chemopreventive agents. Structural work and chemical studies are reported for several cytotoxic agents from the plants Annona densicoma, Annona reticulata, Claopodium crispifolium, Polytrichum obioense, and Psorospermum febrifugum. Studies are also reported based on development of a mammalian cell culture benzo[a]pyrene metabolism assay for the detection of potential anticarcinogenic agents from natural products. In this study a number of isoflavonoids and flavonoids with antimutagenic activity have been discovered.
Animals↗
Bullatacin, bullatacinone, and squamone, a new bioactive acetogenin, from the bark of Annona squamosa.
Activity-directed fractionation of the stem bark of Annona squamosa, monitoring with brine shrimp lethality, led to the isolation of the highly bioactive acetogenins bullatacin [1] and bullatacinone [2], thus demonstrating a new abundant plant source for these potent compounds. A new keto-monotetrahydrofuran acetogenin with a ketolactone terminus, as first seen in bullatacinone [2], was also isolated, characterized by spectral analyses, and named squamone [3]. The cytotoxicities of 3 were increased significantly by reduction of the two keto groups to hydroxyls, and the tetrahydrosquamone [7] and bullatacinone [2] both showed selective cytotoxicities to MCF-7 human breast carcinoma. Liriodenine and (-)-kaur-16-en-19-oic acid were also isolated.
Antineoplastic Agents, Phytogenic↗
Additional bioactive heptenes from Melodorum fruticosum.
Four additional new bioactive heptenes, melodorinol [2], homomelodienone [4], 7-hydroxy-6-hydromelodienone [5], and homoisomelodienone [7] have been isolated from Melodorum fruticosum. These compounds were slightly to significantly cytotoxic to human tumor cell lines. Their structures have been determined by comparison of their 1H-nmr, 13C-nmr, and mass spectral data with those of prototype compounds (acetylmelodorinol [1], melodienone 3, and isomelodienone [6]).
Alkenes↗
Two new styryl lactones, 9-deoxygoniopypyrone and 7-epi-goniofufurone, from Goniothalamus giganteus.
Two new styryl lactones, 9-deoxygoniopypyrone [1] and 7-epi-goniofufurone [3], and a known styryl lactone, goniodiol [5], were isolated from the stem bark of Goniothalamus giganteus. The structures were elucidated by ir, ms, 1H-nmr, 13C-nmr, and 1H-1H COSY spectra; the relative configurations were determined by X-ray crystallographic analysis. Unlike goniopypyrone [2] and goniofufurone [4], neither of the new styryl lactones 1 and 3 showed significant bioactivities to human tumor cells. However, goniodiol [5] showed significant and selective cytotoxicity against human lung tumor cells (A-549).
Animals↗
The complete hrp gene cluster of Pseudomonas syringae pv. syringae 61 includes two blocks of genes required for harpinPss secretion that are arranged colinearly with Yersinia ysc homologs.
Pseudomonas syringae pv. syringae 61 contains a 25-kb hrp cluster that is sufficient to elicit the hypersensitive response (HR) in nonhost plants. Previous studies have shown that mutations in complementation groups VIII, IX, and XI in the hrp cluster abolished the ability of the bacterium to cause the HR. The sequence of a 3.7-kb SmaI-SstI fragment covering groups VIII and IX now reveals five open reading frames (ORFs) in the same transcript, designated as hrpU, hrpW, hrpO, hrpX, and hrpY, and predicted to encode proteins of 14,795, 23,211, 9,381, 28,489, and 39,957 Da, respectively. The hrpU, hrpW, hrpO, hrpX, and hrpY genes are homologous and arranged colinearly with the yscQ/spa33/spaO, yscR/spa24/spaP, yscS/spa9/spaQ, yscT/spa29/spaR, and yscU/spa40/spaS genes of Yersinia spp., Shigella flexneri, and Salmonella typhimurium, respectively. These proteins also show similarity to Fli/Flh proteins of Bacillus and enteric bacteria. The Ysc and Spa proteins are involved in the secretion of virulence factors, like the Yop and Ipa proteins. Fli/Flh proteins are involved in flagellar biogenesis. The sequence of a 2.9-kb EcoRV-EcoRI DNA fragment containing mainly group XI revealed five ORFs, designated hrpC, hrpD, hrpE, hrpF, and hrpG, predicted to encode proteins of 29,096, 15,184, 21,525, 7,959, and 13,919 Da, respectively. The first three genes belong to an operon containing hrpZ, which encodes an extracellular protein that elicits the HR. hrpF and hrpG are two potential ORFs upstream of hrpH in the hrpH operon. HrpC is homologous to Yersinia YscJ, Pseudomonas solanacearum HrpI, Xanthomonas compestris pv. vesicatoria HrpB3, and Rhizobium fredii NolT. HrpE is similar to YscL of Yersinia spp. P. s. pv. syringae 61 Hrp proteins are most similar to Ysc proteins among those homologs. TnphoA insertions in hrpC, hrpE, hrpW, hrpX, and hrpY abolished the ability of P. s.pv. syringae 61 to secrete HrpZ (harpinPss), as determined by immunoblot analysis of cell-bound and culture supernatant fractions. Thus, many of the proteins required for flagellar biogenesis and virulence protein secretion in plant and animal pathogens may have a common ancestry.
Amino Acid Sequence↗
The association of vitamin b 12 and folate blood levels with mortality and cardiovascular morbidity incidence in the old old: the Bronx aging study.
OBJECTIVE: An elevated homocysteine level in the blood has been identified as an independent risk factor for vascular disease, including coronary atherosclerosis and venoembolic disease. A deficiency of vitamins B ( 6 ), B ( 12 ), or folate in the blood can cause increased blood levels of homocysteine. We set out to determine whether there was a relationship between blood levels of folate and B ( 12 ) and the subsequent development of cardiovascular disease and mortality in old old ambulatory men and women. DESIGN: Four hundred forty subjects (mean age, 79 years; 64% female) were followed in the Bronx Longitudinal Aging Study, a prospective study of 10 years duration, designed to assess risk factors for cardiovascular and cerebrovascular diseases and dementia in an ambulatory old old cohort. METHODS: Serum levels of vitamin B ( 12 ) and folate were measured and related to the incidence of total all-cause mortality, stroke, myocardial infarction, coronary heart disease, and cardiovascular disease. RESULTS: No statistical gender- or age-related differences were found in the mean levels of folate or B ( 12 ). The concentration of folate in the blood was not related to the incidence of mortality, myocardial infarction, stroke, or overall cardiovascular disease. However, by logistical regression and Cox proportional-hazards regression analyses, there was an increased incidence of mortality and coronary heart disease in those subjects having increased vitamin B ( 12 ) levels in the blood. Each 100-pg increase in B ( 12 ) was associated with a 10% increase in mortality and coronary heart disease incidence. CONCLUSION: These results suggest that in elderly subjects, vitamin B ( 12 ) supplementation should not be routinely provided unless there are clear indications for doing so (a deficiency state), and then only to replace enough B ( 12 ) to correct the deficiency. A suggested treatment paradigm is provided for managing vitamin deficiency states and hyperhomocysteinemia in elderly subjects.
Aged↗
Elevated nitric oxide level in aqueous humor of patients with acute angle-closure glaucoma.
Nitric oxide, a noxious and free-radical gas, plays a key role in vasodilatation, inflammation, immunity, and neurotoxicity. Studies have shown that a recently detected NO synthase inducible isoform, found in astrocytes in the optic nerve heads of glaucoma patients, could stimulate excessive production of NO. The purpose of our study was to elucidate the role of NO production in the pathogenesis of glaucoma. We measured the concentrations of NO in aqueous humor from 11 patients with acute angle-closure glaucoma (AACG) and 14 patients with cataract. All samples were collected from patients who were free of any other systemic disease. Utilizing a chemiluminescence assay, we found that in AACG patients the NO levels in aqueous humor samples (83.2 +/- 6.7 microM) were significantly higher than in cataract patients (27.1 +/- 3.6 microM; p < 0.001). We therefore concluded that excessive NO in AACG patients reflects the degree of ocular impairment demonstrated by concomitant retinal cell and optic nerve cell damage.
Acute Disease↗
Further studies on the biosynthesis of granaticin.
Experiments with cerulenin-inhibited cultures of S. violaceoruber showed conversion of dihydrogranaticin (II) into granaticin (I), but not vice versa, confirming an earlier conclusion that II is the biosynthetic precursor of I. Feeding of CH3(13)C18O2Na followed by 13C-NMR analysis of the product by the 18O shift method indicated the expected incorporation of 18O at carbons 1, 11 and 13 of I and showed that the oxygen of the pyran ring originates from C-3 and not from C-15. Analysis of I biosynthesized from 13C2H3COONa by 13C[1H, 2H] triple resonance NMR spectroscopy showed the incorporation of one atom of deuterium each at C-2 and C-4. C-16 carried a maximum of 2, not 3, atoms of deuterium. These results are discussed in terms of biosynthetic mechanisms.
Acetates↗
Substrate utilization in defined media.
Substrate utilization in defined media for two flower spiroplasmas (S. floricola and FS SR-3) and honeybee spiroplasma (HBS AS-576) was investigated. Glucose, fructose, and mannose were utilized by all three spiroplasmas. In addition, HBS (AS-576) could ferment trehalose; FS (SR-3), sucrose; and S. floricola, trehalose, sucrose, and raffinose. The three spiroplasmas varied greatly in growth requirements for amino acids. Only S. floricola utilized arginine. HBS (AS-576) required at least one purine and one pyrimidine base for growth, while both flower spiroplasmas grew with only one base in the medium. Oleic acid, cholesterol, and BSA were essential to all three spiroplasmas. Palmitic acid, which was non-essential, promoted growth significantly.
Amino Acids↗