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At least 649 records · Page 36Linked to original sources
PubMed2000

A sleep inducing factor from common Indian toad (Bufo melanostictus, Schneider) skin extract.

Bufo melanostictus (common Indian toad) acquire different bioactive substances in their skin during their life-time in wide ecological habitat. Earlier investigation from this laboratory revealed that toad (B. melanostictus) skin extract (TSE) posses different bioactive compounds of different diversity (Das, M., Auddy, B. and Gomes, A., 1996. Pharmacological study of the toad skin extract on experimental animals. Indian J. Pharmacol. 28, 72-76). Among these sleep induction and sleep potentiation indicated the possibility of sleep inducing factor(s) in TSE. One such sleep inducing factor (SIF) was isolated and purified by neutral alumina column chromatography followed by HPLC. Spectroscopy (UV, IR, FAB-MASS) study indicated that the sleep inducing factor was a 880 Dalton conjugated aromatic compound with a hydroxyl and carbonyl functional group. Biological study showed that SIF produced no lethality in male albino mice upto the dose of 8 mg/kg, i.v. Cyproheptadine antagonised SIF induced contraction of isolated smooth muscle indicating histamine/serotonin receptor mediated action of SIF. EEG studies showed that SIF increased sleep and decreased awakening condition of freely moving rats. Biochemical studies showed that SIF produced significant alteration of brain biogenic amine levels, monoamine oxidase (MAO) and tryptophan hydroxylase (TH) activity. This may be the reason of SIF induced sleep, although the SIF induced sleep mechanism needs further detail investigation.

Animals↗
PubMed1997

Marine microorganisms as a source of new natural products.

Over the past decade, marine microorganisms have become recognized as an important and untapped resource for novel bioactive compounds. The oceans cover greater than 70% of the earth's surface and, taking this into account by volume, represent better than 95% of the biosphere. Given this fact, the oceans present themselves as an unexplored area of opportunity for the discovery of pharmacologically active compounds. In this review, data have been presented to illustrate the diversity of microorganisms living in the sea and the plethora of chemical compounds that have been discovered from them. However, it is important to pursue basic research on the marine environment in order to permit the continued isolation of unique microorganisms. There is still limited knowledge of the physiological requirements of most marine microorganisms, and a greater understanding of their conditions for growth will offer new insights into the complex world of marine microbiology. Clearly, a greater investment in the development of marine biotechnology will produce novel compounds that may contribute significantly toward drug development over the next decade.

Animals↗
PubMed2003

The biodiversity of microbial cytochromes P450.

The cytochrome P450 (CYP) superfamily of genes and proteins are well known for their involvement in pharmacology and toxicology, but also increasingly for their importance and diversity in microbes. The extent of diversity has only recently become apparent with the emergence of data from whole genome sequencing projects and the coming years will reveal even more information on the diversity in microbial eukaryotes. This review seeks to describe the historical development of these studies and to highlight the importance of the genes and proteins. CYPs are deeply involved in the development of strategies for deterrence and attraction as well as detoxification. As such, there is intense interest in pathways of secondary metabolism that include CYPs in oxidative tailoring of antibiotics, sometimes influencing potency as bioactive compounds. Further to this is interest in CYPs in metabolism of xenobiotics for use as carbon sources for microbial growth and as biotransformation agents or in bioremediation. CYPs are also current and potential drug targets; compounds inhibiting CYP are antifungal and anti-protozoan agents, and potentially similar compounds may be useful against some bacterial diseases such as tuberculosis. Of note is the diversity of CYP requirements within an organism, ranging from Escherichia coli that has no CYPs as in many bacteria, to Mycobacterium smegmatis that has 40 representing 1% of coding genes. The basidiomycete fungus Phanerochaete chrysosporium surprised all when it was found to contain a hundred or more CYPs. The functional genomic investigation of these orphan CYPs is a major challenge for the future.

Bacteria↗
PubMed2006

Stably transformed insect cell lines: tools for expression of secreted and membrane-anchored proteins and high-throughput screening platforms for drug and insecticide discovery.

Insect cell-based expression systems are prominent amongst current expression platforms for their ability to express virtually all types of heterologous recombinant proteins. Stably transformed insect cell lines represent an attractive alternative to the baculovirus expression system, particularly for the production of secreted and membrane-anchored proteins. For this reason, transformed insect cell systems are receiving increased attention from the research community and the biotechnology industry. In this article, we review recent developments in the field of insect cell-based expression from two main perspectives, the production of secreted and membrane-anchored proteins and the establishment of novel methodological tools for the identification of bioactive compounds that can be used as research reagents and leads for new pharmaceuticals and insecticides.

Animals↗
PubMedDate not supplied

Etiologies, observations and reporting of estuarine finfish lesions.

Lesions in estuarine finfish are associated with a variety of organisms including parasites and bacterial, viral, and fungal infectious agents. In addition, trauma, suboptimal water quality, and other abiotic stress factors may result in the loss of homeostasis. We have observed solitary ulcerative lesions on menhaden sampled from the Chesapeake Bay, Maryland, the Pimlico River, North Carolina, and the St. Johns River, Florida. Histologically, the lesions demonstrated a marked chronic inflammatory infiltrate and granulomas in response to fungal hyphae throughout large areas of exposed necrotic muscle. Gram-negative rod-shaped bacteria were also observed in the lesions, a common finding in ulcers of aquatic organisms. Similar observations in menhaden and other species have been described previously in the literature as ulcerative mycosis, mycotic granulomatosis, red spot disease, and epizootic ulcerative syndrome. Despite the many different known causes of fish lesions, the popular press and the scientific literature have recently emphasized Pfiesteria piscicida and other Pfiesteria-like dinoflagellates (and their bioactive compounds) as the primary causative agent for finfish lesions, particularly mycotic granulomatous ulcers in Atlantic menhaden. While some laboratory data suggest that Pfiesteria may play a role in field-observed lesions, much more cause-and-effect evidence is needed to determine the importance of other risk factors, both alone or and in combination with Pfiesteria. In order to better understand the etiology of lesion initiation and progression in estuarine finfish, accurate assessments of environmental conditions collected on appropriate temporal and spatial scales, and fish morphological indicators consistent with gross and histological pathologic terminology, should be used for reporting fish lesion observations and kills. Further, this outlook will help to avoid bias and may foster a broader perspective for examining the health of estuarine systems in general.

Animals↗
PubMed2002

New polymeric carriers for controlled drug delivery following inhalation or injection.

Inhalation is gaining increasing acceptance as a convenient, reproducible, and non-invasive method of drug delivery to the lung tissue and/or the systemic circulation. However, sustained drug release following inhalation remains elusive, due in part to the lack of appropriate materials designed specifically for use in the lungs to control the release of bioactive compounds. To address this problem, we have synthesized a new family of ether-anhydride copolymers composed entirely of FDA-approved monomers, including polyethylene glycol (PEG). Sebacic acid, a hydrophobic monomer, was copolymerized with PEG in order to produce water-insoluble polymers capable of providing continuous drug release kinetics following immersion in an aqueous environment. Various amounts of PEG (5-50% by mass) were incorporated into the backbone of the new polymers to allow tuning of particle surface properties for potentially enhanced aerosolization efficiency and to decrease particle clearance rates by phagocytosis in the deep lung. The preparation of large porous particles with these new polymers was systematically approached, utilizing central composite design, to develop improved particle physical properties for deep lung delivery. Microparticles containing model drugs were made with sizes suitable for deposition in various regions of the lung following inhalation as a dry powder. Due to such properties as surface erosion (leading to continuous drug release profiles), erosion times ranging from hours to days (allowing control over drug delivery duration), and ability to incorporate up to 50% PEG in their backbone, these new systems may also find application as "stealth" carriers for therapeutic compounds following intravenous injection.

Administration, Inhalation↗
PubMed1999

Development of a calcium phosphate-gelatin composite as a bone substitute and its use in drug release.

This study was carried out to develop a calcium phosphate-gelatin composite implant that would mimic the structure and function of bone for use in filling voids or gaps and to release bioactive compounds like drugs, growth hormones into the implant site to assist healing. XDS analysis of the synthesized calcium phosphate revealed a calcium to phosphorus molar ratio of ca. 2.30, implying a less erodible material than hydroxyapatite (1.67). Release of the antibiotic gentamicin from the implant was with a burst, whether in situ or in vivo, followed by an almost constant release for about three months. It was found that the release rate could be decreased by increasing the density of the gelatin membrane. Upon implantation into rabbit tibia the release duration was substantially shortened (to about 4 weeks) with respect to the in situ tests basically due to the degradation of gelatin. In vivo studies with rabbits confirmed this degradation. The composite was perfectly biocompatible as shown by the histological studies. It, thus, has a great potential as a bone substitute material.

Animals↗
PubMed1993

The significance of the metabolism of the neurohormone melatonin: antioxidative protection and formation of bioactive substances.

Recent findings suggest that the ability of melatonin to enter all body tissues and to be metabolized, enzymatically or nonenzymatically, in any of them results in a spectrum of effects, which exceed substantially those transduced by membrane receptors. These actions comprise the formation of various bioactive compounds such as N-acetylserotonin, 5-methoxytryptamine, N,N-dimethyl-5-methoxytryptamine, 5-methoxytryptophol, cyclic 2-hydroxymelatonin, pinoline, and 5-methoxylated kynuramines. Apart from enzymatic metabolism, nonenzymatic reactions with free radicals, in particular the superoxide anion and the hydroxyl radical, represent a new and significant aspect of melatonin's biological role. Melatonin represents the most potent physiological scavenger of hydroxyl radicals found to date, and recent findings suggest an essential role of this indoleamine for protection from hydroxyl radical-induced carcinogenesis and neurodegeneration.

Animals↗
PubMed1999

Integration of phospholipid and sterol metabolism in mammalian cells.

The lethal consequences of imbalances in lipid and sterol metabolism in human diseases such as atherosclerosis and lipid storage disorders underscores our need to know how cholesterol, phospholipid and sphingolipid metabolism is integrated. Accumulation and abnormal localization of lipids and sterol affects cellular function not only by perturbing membrane activity but also by increasing production of bioactive lipids derived from cholesterol, phospholipids and sphingolipids. For example in the NPC mouse model, accumulation of intracellular cholesterol and sphingomyelin is accompanied by increased sphingosine [187], a potent regular of protein kinase C and cell proliferation [152]. Oxidized LDL has an important role in the pathology of atherosclerosis by promoting foam cell formation and cytotoxicity [65]. 7-Hydroxycholesterol and 7-ketocholesterol are involved in many aspects of oxidized LDL activity including initiation of apoptosis in a number of cell types [188, 189] and enhancing cholesterol accumulation by inhibiting efflux [190]. Oxysterols formed intracellularly or from oxidized lipoproteins could have an important role in regulating lipid metabolism in the foam cell. Bioactive metabolites of phospholipids, such as diglyceride, phosphatidic acid and lysolipids, could also increase in circumstances of elevated deposition and have profound and varied effects on cell physiology. In addition to elucidating mechanisms for integration of lipid metabolism, we should determine when these responses go awry and assess the influence of bioactive compounds formed under these circumstances on cell viability and growth.

Animals↗
PubMed2001

Effect of intracerebral 6-nitronoradrenaline, an endogenous catechol-O-methyltransferase (COMT) inhibitor, on striatal dopamine metabolism in anaesthetised rats.

6-Nitronoradrenaline, a bioactive compound recently identified in the brain, is known to inhibit catechol-O-methyltransferase. To study its effect on dopamine metabolism, it was administered into rat striatum via a microdialysis probe. Other nitrated catechols (6-nitrodopamine, 6-nitro-DOPAC and 5-nitro-HVA) were studied for comparison. Tolcapone, a selective catechol-O-methyltransferase inhibitor, was used as a positive reference compound. Both 6-nitronoradrenaline and tolcapone increased striatal extracellular dopamine levels during the perfusion (at 100 microM concentration but not at 10 microM) and decreased the efflux of homovanillic acid. Tolcapone, but not other nitrated catechols, increased 3,4-dihydroxyphenylacetic acid efflux. None of the compounds inhibited MAO-B activity at 100 microM or lower. At 1 mM, 6-nitrodopamine inhibited MAO-B by 60%. Compared to tolcapone, other nitrated catechols were very weak COMT inhibitors in vitro. Neither tolcapone nor 6-nitronoradrenaline modified the metabolism of L-dopa which was given peripherally. In binding studies, both 6-nitronoradrenaline and other nitrocatechols failed to affect the dopamine transporter even at high micromolar concentrations. In conclusion, exogenous 6-nitronoradrenaline can act as a COMT inhibitor in the striatum and elevate striatal dopamine levels without inhibiting dopamine reuptake. Whether endogenous 6-nitronoradrenaline can be formed also in vivo in the striatum and act as a regulator of dopaminergic tone remains to be determined.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2003

Primary cultures from the marine sponge Xestospongia muta (Petrosiidae, Haplosclerida).

In the context of the investigations on the origin and in vitro production of bioactive compounds, primary cultures were developed from ectosomal and choanosomal cell suspensions from the sponge Xestospongia muta. Dissociated cells aggregated and reorganized into a striking reticulated network of cells, typical for X. muta. Moreover, in some cultures an isotropic reticulation of small spicules, very similar to that found in the ectosome of adult sponges, was observed. Phytohaemagglutinin promoted aggregation and the reorganization of the cells. HPLC analyses revealed that straight-chain acetylenic compounds were recovered from short-term cultures and that they were synthesized during culture. Heterotrophic bacteria were assumed to be involved in the process. Together our results established that X. muta would be an excellent experimental model to study, in laboratory conditions, the differentiation of the skeleton and the in vitro biosynthesis of straight-chain acetylenic compounds.

Alkynes↗
PubMed2002

Inhibition of liver metastasis by targeting of immunomodulators using mannosylated liposome carriers.

Mannosylated liposomes were prepared by incorporating cholesten-5-yloxy-N-(4-((1-imino-2-beta-D-thiomannosylethyl)amino)butyl)formamide (Man-C4-Chol) into small unilamellar liposomes consisting of cholesterol and distearoyl phosphatidylcholine (DSPC). The biodistribution of liposomes labeled with [3H]cholesteryl hexadecyl ether was examined in mice. The rate and extent of the hepatic uptake of those [3H]liposomes increased proportionally on increasing the mixing ratio of Man-C4-Chol. Their hepatic uptake was reduced by increasing the administered dose due to the limited number of mannose receptors. The liver uptake of [3H]Man-liposomes was preferentially mediated by liver non-parenchymal cells (NPC) and significantly inhibited by co-injection with an excess of Man-BSA, indicating the involvement of a mannose receptor-mediated mechanism in the hepatic uptake of Man-liposomes. Muramyl dipeptide (MDP), an immunomodulator, was also incorporated into the liposomes and its inhibitory effect in an experimental liver metastasis model was examined. In contrast to free MDP treatment, which showed little effect on the inhibition of metastasis, liposomal MDP significantly reduced the number of metastatic colonies in the liver. Active targeting of MDP to liver NPC by Man-liposomes resulted in more effective inhibition than delivery of MDP by liposomes without mannose. Treatment with MDP/Man-liposomes further increased the survival of the tumor-bearing mice. These results suggest that Man-liposomes are effective carriers for targeted delivery of bioactive compounds to liver NPC.

Adjuvants, Immunologic↗
PubMed2001

Leishmaniasis phytotherapy. Nature's leadership against an ancient disease.

The use of phytotherapy to treat human diseases has its roots in pre-historical times. Despite the modern advances achieved in the field of synthetic chemistry, the most efficient drugs available have their genesis directly or indirectly related with the vegetal kingdom. Indigenous communities have long used plant extracts to treat illnesses. Many of these extracts have shown effective action, with new bioactive compounds being extracted and screened every year. These extracts have also proven to be good sources of therapeutic agents to the treatment of Leishmaniasis. This work highlights some of these agents, while trying to emphasize the importance of plants as a source of new and powerful drugs against this widespread disease.

Animals↗
PubMed2001

Purification and identification of active antibacterial components in Carpobrotus edulis L.

Very little is known about the chemical composition of Carpobrotus edulis, also known as Hotnotsfig or sourfig. However, some claims have been made in the past by traditional healers, regarding its usage as a medicinal plant. In this investigation it was initially illustrated that a crude methanolic extract of the plant exhibits strong anti-bacterial activity. Subsequently, the crude extract was fractionated by means of liquid-liquid chromatography, tannins removed by means of LH20 column chromatography and bioactive fractions with antibacterial properties isolated by means of preparative thin layer chromatography. Five bioactive compounds, individually or collectively responsible for the antibacterial property of C. edulis, were purified from an active ethyl acetate fraction. These compounds were initially identified as flavanoids using standard fingerprinting methods and eventually identified as rutin, neohesperidin, hyperoside, cactichin and ferulic acid using flavanoid standards. A sixth flavanoid with antibacterial activity was also purified but could not be identified in this way. The latter is currently isolated in larger volume for identification through nuclear magnetic resonance spectroscopy.

Anti-Infective Agents↗
PubMed2002

Ethnophysiology and herbal treatments of intestinal worms in Dominica, West Indies.

In rural Dominican ethnophysiology worms reside in a human organ called the 'worm bag'. Unchecked, worms can cause illness by growing in size and number, spreading out of the worm bag and into other organs. In this study of 'bush medicine', we use a measure of cognitive salience in free-listing tasks, which reveals five plants commonly used to treat intestinal worms. These were Ambrosia hispida (Asteraceae), Aristolochia trilobata (Aristlochiaceae), Chenopodium ambrosioides (Chenopodiaceae), Portulaca oleracea (Portulacaceae), and Artemisia absinthium (Asteraceae). Bioactive compounds appear to be present in all of these plants. The cognitive salience of these plant remedies coupled with evidence of biochemical properties suggest that they provide efficacious treatments for controlling intestinal parasite loads.

Dominica↗
PubMed1999

Antimicrobial properties of alkamides present in flavouring plants traditionally used in Mesoamerica: affinin and capsaicin.

The bioactive amides affinin and capsaicin isolated respectively from Heliopsis longipes roots and Capsicum spp fruits, were assayed for activity against Escherichia coli, Pseudomonas solanacearum, Bacillus subtilis and Saccharomyces cerevisicae suspension cultures. The alkamide affinin inhibited growth of E. coli and S. cerevisiae at concentrations as low as 25 microg/ml. Higher concentrations of affinin were necessary to inhibit growth of P. solanacearum and B. subtilis. However. high concentrations of capsaicin only retarded the growth of E. coli and P. solanacearum, whereas growth of B. subtilis was strongly inhibited and that of S. cerevisiae was initially enhanced. Results are discussed in relation to previous reports concerning crude extract and to the molecular structures of the bioactive compounds.

Amides↗
PubMed2004

Structure and interactions in covalently and ionically crosslinked chitosan hydrogels for biomedical applications.

This review presents a critical analysis of covalently and ionically crosslinked chitosan hydrogels and related networks for medical or pharmaceutical applications. The structural basis of these hydrogels is discussed with reference to the specific chemical interactions, which dictate gel formation. The synthesis and chemistry of these hydrogels is discussed using specific pharmaceutical examples. Covalent crosslinking leads to formation of hydrogels with a permanent network structure, since irreversible chemical links are formed. This type of linkage allows absorption of water and/or bioactive compounds without dissolution and permits drug release by diffusion. pH-controlled drug delivery is made possible by the addition of another polymer. Ionically crosslinked hydrogels are generally considered as biocompatible and well-tolerated. Their non-permanent network is formed by reversible links. Ionically crosslinked chitosan hydrogels exhibit a higher swelling sensitivity to pH changes compared to covalently crosslinked chitosan hydrogels. This extends their potential application, since dissolution can occur in extreme acidic or basic pH conditions.

Biomedical Technology↗
PubMed2000

Chemoinformatics - similarity and diversity in chemical libraries.

Molecular similarity and molecular diversity techniques lie at the heart of attempts to design structurally diverse combinatorial libraries for the identification of novel bioactive compounds. Recent advances include the development of new types of selection algorithm, the validation of such algorithms, the use of filtering systems to screen out undesirable molecules prior to the design of a library, and the integration of similarity and diversity analysis with other methods for computer-aided molecular design.

Algorithms↗