Biomedical subjects

R Bye

Publications and source records attributed to R Bye.

At least 19 recordsLinked to original sources

PubMed2001

Bioactive oleanolic acid saponins and other constituents from the roots of Viguiera decurrens.

The bisdesmoside oleanolic acid saponin, 3-0-(methyl-beta-D-glucuronopyranosiduronoate)-28-0-beta-D-glucopyranosyl-oleanolate along with nine known compounds (two diterpenic acids, one chromene, three triterpenes, one steroidal glycoside, and two monodesmoside oleanolic acid saponins), were obtained from Viguiera decurrens roots. The chemical structure of the bisdesmoside oleanolic saponin was determined by chemical and NMR spectral evidence. A mixture of monodesmoside saponins displayed cytotoxic activity against P388 and COLON cell lines (ED50= 2.3 and 3.6 microg/ml, respectively). Two of the known compounds showed insecticidal activity against the Mexican bean beetle larvae (Epilachna varivestis).

Asteraceae↗

PubMed2001

New modified eremophilanes from the roots of Psacalium radulifolium.

The investigation of the chemical constituents from the roots of Psacalium radulifolium, a member of the matarique complex of medicinal plants, which includes several members of the Asteraceae, resulted in the isolation of four new modified eremophilanes: radulifolin A (4), epi-radulifolin A (5), radulifolin B (6), and radulifolin C (7), together with the known natural substances cacalol, cacalone, epi-cacalone, O-methyl-1,2-dehydrocacalol, adenostin A, decompostin, and neoadenostylone. Antimicrobial evaluation of the extracts and the isolated compounds indicated that cacalol was the major active compound.

Asteraceae↗

PubMed2001

Antiinflammatory constituents from Heterotheca inuloides.

Three new compounds, cadalen-15-oic acid (1), 3,7-dihydroxy-3(4H)-isocadalen-4-one (2), and dicadalenol (3), were isolated from the aerial parts of Heterotheca inuloides (Mexican arnica), together with the known compounds 7-hydroxycadalene (4), 7-hydroxy-4alphaH-3,4-dihydrocadalene (5), 1alpha-hydroxy-1(4H)-isocadalen-4-one (6), 1alpha-hydroxy-4alphaH-1,2,3,4-tetrahydrocadalen-15-oic acid (7), 7-(3,3-dimethylallyloxy)coumarin, caryolan-1,9beta-diol, and quercetin. The structures of the new compounds were elucidated by spectroscopic methods. The antiinflammatory activities of the extracts and the isolated compounds were evaluated by determining the inhibition of TPA-induced mouse ear edema. The natural products 3, caryolan-1,9beta-diol, and quercetin were the most active substances tested and displayed dose-dependent activities.

Animals↗

PubMed2001

Biological and mechanistic activities of xanthorrizol and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol isolated from Iostephane heterophylla.

Xanthorrizol (1) and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol (2) were identified as the principal antimicrobial components of a CH(2)Cl(2)-MeOH (1:1) extract derived from Iostephane heterophylla. Compound 2 is a new natural product, but has been synthesized. Both compounds exhibited low level activity (MICs of 16-32 microg/mL) against methicillin-resistant staphylococci and vancomycin-resistant enterococci. They were either inactive or poorly active against Gram-negative bacteria and yeast. Mechanistic studies performed in Escherichia coli imp suggested nonspecific inhibition of DNA, RNA, and protein synthesis by both of these compounds. Compound 1 was tested in an in vivo model; it did not provide protection to mice infected with Staphylococcus aureus.

Animals↗

PubMed2001

Geranins C and D, additional new antiprotozoal A-type proanthocyanidins from Geranium niveum.

Two new additional A-type proanthocyanidins have been isolated from Geranium niveum. Their structures were determined by spectroscopic, chemical and chiroptical methods as epi-afzelechin-(4beta-->8,2beta-->O-->7)-gallocatechin (1) and epi-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin (2). Proanthocyanidins 1 and 2 were given the trivial names of geranins C and D, respectively. Compound 2 showed moderate antiprotozoal activity against Entamoeba histolytica and Giardia lamblia, whereas 1 exhibited weak activity toward E. histolytica.

Animals↗

PubMed2000

Day surgery for older people (70+): selection versus outcome effects.

As length of Australian hospital stays decreased, concerns were raised about benefits of shorter stays for older people. We investigated personal characteristics, perceived health outcomes (SF-36) and service use of day-only and other patients aged 70+, at one and 12 weeks after hospital discharge. Day-only patients were younger, had better self-reported health, were selected for orthopaedic, gastrointestinal and ophthalmic procedures and used similar levels of formal and informal services after discharge as people with longer stays. There was no evidence of ill effects of day surgery for older people, but improved selection and information giving procedures can improve outcomes.

Journal Article↗

PubMed2000

New phenylethanoids from Buddleja cordata subsp. cordata.

Bioassay-guided fractionation of a crude extract of the stem bark of Buddleja cordata subsp. cordata with significant antimycobacterial activity led to the isolation of a mixture composed by ten new long-chain esters of 2[4'-hydroxyphenyl]-ethanol (1-10), along with the lichen metabolites methyl beta-orcinolcarboxylate (11) and beta-orcinolcarboxylate (12). Extensive HPLC allowed the separation of the major components of the mixture, which were characterized by spectral means as 2[4'-hydroxyphenyl]-ethyl stearate (3), 2[4'-hydroxyphenyl]-ethyl behenate (6), and 2[4'-hydroxyphenyl]-ethyl lignocerate (8). The minor esters were identified as 2[4'-hydroxyphenyl]-ethyl palmitate (1), 2[4'-hydroxyphenyl]-ethyl heptadecanoate (2), 2[4'-hydroxyphenyl]-ethyl nonadecanoate (4), 2[4'-hydroxyphenyl]-ethyl arachidate (5), 2[4'-hydroxyphenyl]-ethyl tricosanoate (7), 2[4'-hydroxyphenyl]-ethyl pentacosanoate (9), and 2[4'-hydroxyphenyl]-ethyl hexacosanoate (10) by GC-MS analysis of the methyl esters derivatives of the fatty acids obtained by alkaline hydrolysis of the mixture. Compound 8 exhibited moderate antibacterial activity against Mycobacterium tuberculosis (MIC = 64 micrograms/ml).

Glucosides↗

PubMed2000

Phytotoxic compounds from Xanthocephalum gymnospermoides var. eradiatum.

Investigation of the aerial parts of Xanthocephalum gymnospermoides var eradiatum led to the isolation of two new labdane-type of diterpenes, namely, 8 alpha,13S-epoxylabdane-14S,15-diol (1) and methyl grindelate (2). In addition, grindelic acid (3), 7 alpha, 8 alpha-epoxygrindelic acid (4), 7 alpha-hydroxy-8(17)dehydrogrindelic acid (5), 17-hydroxygrindelic acid (6) and 4,5-epoxy-beta-caryophyllene (7) were obtained. The isolated compounds were characterized by spectral means. The absolute configuration of compound 1 was established by chemical correlation with 8 alpha,13S-epoxy-15-nor-labdan-14-oic acid methyl ester of known absolute stereochemistry and by using the advanced Mosher's ester methodology. The results of the present investigation indicated that the known compound barbatol (8) could be an enantiomer of compound 1. Compounds 1-3 and 7 caused significant inhibition of the radicle growth of seedlings of Amaranthus hypochondriacus.

Asteraceae↗

PubMed1999

Geranins A and B, new antiprotozoal A-type proanthocyanidins from Geranium niveum.

Bioassay-guided fractionation of the antiprotozoal extract of Geranium niveum led to the isolation of two new A-type proanthocyanidins, epi-afzelechin-(4beta-->8, 2beta-->O-->7)-afzelechin (1) and epi-catechin-(4beta-->8, 2beta-->O-->7)-afzelechin (2). Compounds 1 and 2 were given the trivial names of geranins A and B, respectively. In addition, five known compounds, mahuannin B (3), reynoutrin (4), hyperin (5), methyl gallate (6), and 3-beta-caffeoyl-12-oleanen-28-oic acid (7), were obtained. The structures of the new proanthocyanidins were elucidated by spectroscopic and chemical methods as well as CD measurements. Compounds 1, 2, and 4-7 were tested against axenically grown trophozoites of Giardia lamblia and Entamoeba histolytica.

Animals↗

PubMed1999

Orizabins V-VIII, tetrasaccharide glycolipids from the Mexican scammony root (Ipomoea orizabensis).

An extensive investigation of the so-called jalapin resinoid obtained from roots of the Mexican scammony, Ipomoea orizabensis, using high field NMR spectroscopy led to the characterization of six glycosides, including the known scammonins I (1) and II (2) and four new tetrasaccharides of jalapinolic acid, orizabins V-VIII (3-6). All the isolates (1-6) were found to be weakly cytotoxic toward human oral epidermoid carcinoma (KB).

Antineoplastic Agents, Phytogenic↗

PubMed1999

Postacute care for older aboriginal people: an exploratory-descriptive study.

Many Aboriginal people reside in rural and remote Australia. Aboriginal health workers were the informants in this exploratory-descriptive study, which explored issues pertaining to postacute care for older Aboriginal people. Qualitative analysis of interview data revealed several issues were viewed as being of crucial importance in the provision of effective postacute services to older Aboriginal people. These were: (i) identification of Aboriginality; (ii) perceived racism and stereotypical attitudes among hospital staff and healthcare workers; and (iii) effective discharge planning. Other issues which were believed to impact upon service use were identified as: (i) availability of services; (ii) knowledge of services and level of use; and (iii) the notion of mainstream versus Aboriginal-specific services. Findings are discussed in relation to available literature. Implications for further research are drawn from the findings of this exploratory study.

Aged↗

PubMed1998

A comparative study of the analgesic and anti-inflammatory activities of pectolinarin isolated from Cirsium subcoriaceum and linarin isolated from Buddleia cordata.

The dried aqueous extract of aerial parts of Cirsium subcoriaceum (Asteraceae) and its major flavonoid glycoside, pectolinarin, have been evaluated for analgesic and anti-inflammatory effects in mice and rats, respectively. Both the extract and pectolinarin exerted significant and dose-dependent analgesic and anti-inflammatory activities. Also, the anti-inflammatory activities of an aqueous extract of Buddleia cordata and its principal glycoside linarin were evaluated. The results of pharmacological testing proved that linarin is a better anti-inflammatory agent than pectolinarin and indomethacin. On the other hand, pectolinarin exerted a better analgesic effect than linarin.

Analgesics↗

PubMed1997

Smooth muscle relaxing flavonoids and terpenoids from Conyza filaginoides.

Activity-guided fractionation of the smooth muscle relaxing, chloroform-methanol (1:1) extract of Conyza filaginoides (D.C.) Hieron (Asteraceae) led to the isolation of three flavonoids (quercetin 3-glucoside, rutin, and pinostrobin), one sterol (alpha-spinasterol), a sesquiterpenoid (beta-caryophyllene 4,5-alpha-oxide), and two triterpenoids (erythrodiol and 3-beta-tridecanoyloxy-28-hydroxyolean-12-ene). 3-beta-Tridecanoyloxy-28-hydroxy-olean-12-ene is a new naturally occurring terpenoid. All the isolated compounds induced a concentration-dependent inhibition of the spontaneous contractions of rat ileum. The spasmolytic activity exhibited by the extract and active principles tends to support the traditional use of C filaginoides as an antispasmodic agent.

Animals↗

PubMed1996

Phytogrowth-inhibitory and antifungal constituents of Helianthella quinquenervis.

Investigation on the roots of Helianthella quinquenervis (Hook.) A. Gray (Asteraceae), led to the isolation of one new benzofuran (6-methoxy-tremetone (1)) and a new prenylacetophenone (4-beta-D-(glucopyranosyloxy)-3-[3-methoxy-trans-isopenten-1 -yl] acetophenone (3)). In addition, 6-hydroxy-3-methoxytremetone (2), encecalin (6), euparin (5), demethylencecalin (4), and angelic acid were obtained. Structural assignments of the isolated compounds were based on spectroscopic and spectrometric analysis. Natural products 1-4 showed marginal cytotoxicity against three human tumor cell lines [MCF-7, A-549, and HT-29]. Compounds 4 and 6 inhibited the radicle growth of Amaranthus hypochondriacus and Echinochloa crusgalli. Furthermore, substances 4-6 exhibited antifungal activity against Trichophyton mentagrophytes.

Animals↗

PubMed1996

Analgesic and antipyretic activities of an aqueous extract and of the flavone linarin of Buddleia cordata.

The dried aqueous extract of leaves of Buddleia cordata (loganiaceae) and its main flavonoid glycoside, linarin, have been evaluated for analgesic and antipyretic effects in mice and rats, respectively. Both the extract and linarin exerted significant and dose-dependent analgesic and antipyretic activities, the first being obtained against a chemical stimulus (writhing a test in mice) and the second being obtained by a pyretogenic stimulus (yeast-induced hyperthermia test). Furthermore, the response of the animals in the hot plate test was modified by linarin and an aqueous extract. These activities were similar to that showed by morphine sulfate (MS) and they were inhibited by naxolone pretreatment, a specific morphinic antagonist compound. These findings lead to the conclusion that the aqueous extract and linarin exert central analgesic properties. On the other hand, linarin was shown to be responsible for the antipyretic activity of this species.

Analgesics↗

PubMed1995

Biochemically active sesquiterpene lactones from Ratibida mexicana.

Bioactivity-directed fractionation of the methanol extract of the roots of Ratibida mexicana resulted in the isolation of two bioactive sesquiterpene lactones, isoalloalantolactone and elema-1,3,11-trien-8,12-olide. Both compounds caused a significant inhibition of the radicle growth of Amaranthus hypochondriacus and Echinochloa crus-galli, exerted moderate cytotoxic activity against three different solid tumour cell lines and inhibited significantly the radial growth of three phytopathogenic fungi. Isoalloalantolactone also caused the inhibition of ATP synthesis, proton uptake and electron transport (basal, phosphorylating and uncoupled) from water to methylviologen, therefore acting as a Hill's reaction inhibitor. The lactone did not affect photosystem I but inhibited photosystem II. The site of inhibition of isoalloalantolactone is located in the span of P680 to QA redox enzymes because the uncoupled electron transport from water to silicomolybdate and, from DPC to DCIP are inhibited approximately to the same extent.

Antifungal Agents↗

PubMed1995

Vasoactive effects of aqueous extracts from five Mexican medicinal plants on isolated rat aorta.

The present investigation describes the effects of aqueous extracts from Chiranthodendron pentadactylon flowers, Galphimia glauca leaves and flowers, Ipomoea stans roots, Juglans regia leaves and Taxodium mucronatum aerial parts on isolated rat thoracic aorta precontracted by noradrenaline (NA). In all cases, the aqueous extracts (0.5-12 mg/ml) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by NA in rat aorta. The most active extract was that of G. glauca flowers. These findings indicate that the active principle(s) present in the crude extracts can exert a vasorelaxant effect.

Animals↗

PubMed1994

Hepatotoxic pyrrolizidine alkaloids in the Mexican medicinal plant Packera candidissima (Asteraceae: Senecioneae).

A study of the hepatotoxic pyrrolizidine alkaloids (PAs) contained in Packera candidissima (Greene) Weber & Löve (Senecio candidissimus Greene), a Mexican medicinal plant used for the treatment of kidney ailments and noted for its antiseptic properties, is reported. Analysis by TLC and GC-MS have shown the presence in high levels of both PAs and their N-oxides in the root (0.76% dry weight) and the aerial parts (0.36% dry weight) of the plant material. GC-MS analysis showed the presence of senecionine, integerrimine, retrorsine, and usaramine in the aerial parts. The root was found to contain senkirkine as the major component. These results indicate that users of this herb are at high risk of poisoning, especially members of certain cultural groups in Northern Mexico and the Hispanic population in the southwestern United States. In addition, two sesquiterpenes, neoadenostylone and epineoadenostylone were identified from the neutral extracts of this plant material. The 6 alpha-angeloyloxy-9-oxo-delta 10(1)-furanoeremophilane is reported for the first time as a natural product.

Antineoplastic Agents, Phytogenic↗