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Biomedical subjects

M E Wall

Publications and source records attributed to M E Wall.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Acquisition of incidental information during instruction for a response-chain skill.

We examined the acquisition of incidental information and observational learning of incidental information by adolescents with moderate intellectual disabilities during school-directed systematic instruction. Effectiveness of constant time-delay instruction for vocational-skill acquisition was evaluated within a multiple-probe design across six dyads. Dyadic instructional arrangements allowed the assessment of incidental information acquired through observation. The constant time-delay procedure was effective in teaching the target vocational skill. In addition, participants acquired and retained approximately 50% of the incidental information to which they were exposed during the consequent events of constant time-delay instruction either through direct verbal presentation or through observation of their peers' instruction.

Adolescent↗
PubMedDate not supplied

Plant antitumor agents, 19. Novel triterpenes from Maprounea africana.

Four new pentacyclic triterpenes have been isolated from Maprounea africana. These triterpenes are members of the previously unknown urs-12-en-29-oic acid series. The structures of these compounds were deduced from spectral and chemical evidence. The parent compound, maprounic acid, was identified as 3B-hydroxyurs-12-en-29-oic acid. The remaining three triterpenes were identified as maprounic acid 3-p-hydroxybenzoate, 7 beta-hydroxymaprounic acid 3-p-hydroxybenzoate, and 2 alpha-hydroxymaprounic acid 2,3-bis-p-hydroxybenzoate. Of the four triterpenes, only the 7 beta-hydroxy derivative exhibited in vivo P-388 activity.

Acetylation↗
PubMedDate not supplied

Plant antitumor agents, 21. Flavones, coumarins, and an alkaloid from Sargentia greggii.

Investigation of the MeOH extracts of Sargentia greggii (Rutaceae) led to the isolation of two known flavones, zapotin and 5,6,2'-trimethoxyflavone, and a new flavone, 5,6,2',3',4',6'-hexamethoxyflavone (1), whose structure was established by spectral data and confirmed by total synthesis. In addition, two known coumarins, 3-(alpha,alpha-dimethylallyl) herniarin and seselin, and a new coumarin, O-geranylosthenol (3), have been isolated from this plant. The structure of 3 was deduced from spectral data. Although the crude extracts displayed KB activity, none of the crystalline compounds were significantly active.

Alkaloids↗
PubMedDate not supplied

Plant antitumor agents, 27. Isolation, structure, and structure activity relationships of alkaloids from Fagara macrophylla.

The known alkaloids nitidine chloride [1] and 6-oxynitidine [2] and a new compound 6-methoxy-5,6-dihydronitidine [3] have been isolated from Fagara macrophylla. Compound 3 was the major product and was shown to be an artifact. The alkaloids 1 and 3 have been interconverted by treatment of 1 under basic conditions or 3 under acidic conditions. On sublimation 1 and 3 formed 8,9-dimethoxy-2,3-methylenedioxybenzo[c]phenanthridine [4] which could then be converted to 5,6-dihydronitidine [5]. The alkaloids 1 and 3 are about equipotent in P-388 mouse leukemia, giving high T/C values of 240-260% at doses of 30-50 mg/kg. The other compounds were inactive. The structural requirement for antitumor activity in the phenanthridine series is the ability to form a C-6 iminium ion.

Alkaloids↗
PubMedDate not supplied

Indoles in edible members of the Cruciferae.

Antimutagenic fractions from collards yielded indole-3-carboxaldehyde [4] and traces of indole-3-acetonitrile [2]. The compounds had no antimutagenic activity. An analytical procedure for various indoles in plants was developed based on reversed-phase hplc. The indoles studied included the 3-carbinol 1, the acetonitrile 2, the carboxaldehyde 4, the 3-carboxylic acid 5, and the 3-acetic acid 6. Many Cruciferae and non-Cruciferae were analyzed. The latter did not contain measurable quantities of these compounds. In the case of the Cruciferae--with the exception of collards, which consistently indicated the presence of the aldehyde 4--major indole found was the nitrile 2. Although a particularly careful search for the carbinol 1 was conducted, only trace levels were noted. A review of the literature indicates that the content and occurrence of this indole in plants have been heavily overestimated. Because of the low levels found in the Cruciferae, our studies indicate that the role of the compound as a dietary factor may be questionable.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Plant antimutagenic agents, 1. General bioassay and isolation procedures.

An antimutagenic assay in Salmonella typhimurium has been utilized for a study of the inhibition of the mutagenic activity of 2-aminoanthracene in the presence of the Ames S-9 metabolic activation preparation by crude organic solvent extracts of plant materials. More than 2000 extracts representing 39 families have been tested to date. Confirmed inhibitory activity has been found in 80 samples. More than 60% were nontoxic. Methods for isolation and characterization of pure compounds are presented. Of particular interest is the utilization of large scale preparative hplc for rapid purification of inhibitory chromatographic fractions that were still highly impure.

Anthracenes↗
PubMedDate not supplied

Plant antimutagenic agents, 2. Flavonoids.

A number of known prenylated flavonoids were isolated from Psoralea corylifolia using an assay procedure based on inhibition of the mutagenic action of 2-aminoanthracene on Salmonella typhimurium (T-98). All of these compounds were toxic rather than antimutagenic or desmutagenic. Bakuchiol [17], a known prenylated phenolic terpene, was also isolated; its activity was not due to toxicity. Biochanin A [4], a known isoflavone, was similarly isolated from Cicer arientinum and was active and nontoxic. Some of the above flavonoids were studied for inhibition of the mutagenicity of several different mutagens with results depending upon the structure of the flavonoid and the mutagen.

Anthracenes↗
PubMedDate not supplied

Plant antimutagenic agents, 3. Coumarins.

Several coumarins were isolated from crude plant extracts by means of an antimutagenic assay procedure. These coumarins included psoralen from Psoralea corylifolia and imperatorin and osthol from Selinum monniere. Studies of structure-activity relationships of these and several other available coumarins were carried out with four mutagens. All of the coumarins were nontoxic and in particular showed high activity in the inhibition of the mutagenicity of benzo[a]pyrene.

Benzo(a)pyrene↗
PubMedDate not supplied

Plant antimutagenic agents, 4. Isolation and structure elucidation of maesol, an inactive constituent of Maesa spp.

Maesol, a novel dimeric phenol, was isolated from seeds of Maesa montana and Maesa indica. Maesol was shown to have the formula C28H42O4 with structure 1, a dimeric, symmetrical 1,12-bis(3,3'-dihydroxy-4,4'-dimethyl-5,5'-dimethoxyphenyl)dodecane. It is the first compound with such structure to be isolated from plant material. Structure elucidation was based largely on 1H- and 13C-nmr techniques and comparison with a known synthetic isomeric dimer 3. Although crude extracts showed strong inhibition of 2-aminoanthracene activity against Salmonella typhimurium (T-98), the pure compound was inactive when tested for inhibition of the mutagenic activity of several mutagens.

2-Acetylaminofluorene↗
PubMedDate not supplied

Plant antimutagenic agents, 5. Isolation and structure of two new isoflavones, fremontin and fremontone from Psorothamnus fremontii.

Two new isoflavones, fremontin and fremontone, were isolated from roots of Psorothamnus fremontii (Fabaceae), a desert plant. Compound 1 has the structure 5'-(alpha, alpha-dimethylallyl)-5,7,2',4'-tetrahydroxyisoflavone; compound 2 is similar but also contains the 3'-(gamma,gamma-dimethylallyl) substituent. The alpha,alpha-dimethylallyl substituent is rarely observed, and the combination of the alpha,alpha- and gamma,gamma-dimethylallyl substituents is unprecedented. Both 1 and 2 were nontoxic toward Salmonella typhimurium and were both highly active in the inhibition of mutagenicity of ethyl methanesulfonate (EMS) at all concentrations tested. Compound 2 was more active than 1 in the inhibition of mutagenicity of 2-aminoanthracene (2AN) and acetylaminofluorene (AAF) toward S. typhimurium.

Animals↗
PubMedDate not supplied

Plant antimutagens, 6. Intricatin and intricatinol, new antimutagenic homoisoflavonoids from Hoffmanosseggia intricata.

Intricatin [1] and intricatinol [2] are new homoisoflavonoids isolated from a desert plant Hoffmanosseggia intricata, which was collected in Baja California, Mexico. The structures of the compounds were elucidated using a variety of spectroscopic techniques. The structure of 1 was shown to be 7,4'-dimethoxy-8-hydroxyhomoisoflavone, and 2 was shown to be 4'-methoxy-7,8-dihydroxyhomoisoflavone. Both compounds 1 and 2 displayed activity in the inhibition of the mutagenicity of 2AN toward Salmonella typhimurium (T98). Compound 2 was much more active than 1 in the case of the inhibition of the mutagenicity of AAF toward S. typhimurium (T98) and the inhibition of EMS towards S. typhimurium (T100). Compounds 1 and 2 are the first examples of antimutagenic activity in homoisoflavones.

Animals↗
PubMedDate not supplied

Plant antimutagenic agents, 7. Structure and antimutagenic properties of cymobarbatol and 4-isocymobarbatol, new cymopols from green alga (Cymopolia barbata).

Two new compounds, cymobarbatol and 4-isocymobarbatol, were isolated from the marine alga Cymopolia barbata. The complete structures and absolute stereochemistries of these compounds were elucidated by a variety of spectroscopic techniques and X-ray crystallography. Both compounds were found to be nontoxic over a broad concentration range to Salmonella typhimurium strains T-98 and T-100. Both compounds exhibited strong inhibition of the mutagenicity of 2-aminoanthracene and ethyl methanesulfonate toward, respectively, the T-98 strain plus a metabolic activator and T-100.

Benzopyrans↗