Syntheses and properties of bioactive organo-silicon compounds.
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Determination of lipophilicity and hydrogen-bond donor acidity of bioactive sulphonyl-containing compounds by reversed-phase HPLC and centrifugal partition chromatography and their application to structure-activity relations.
The lipophilic character of two large series of substituted benzenesulphonamides (BzSA) and 4-aminodiphenylsulphones (4-ADS) has been assessed by two chromatographic methods, i.e. reversed-phase HPLC using a relatively novel octadecylpolyvinyl packing and centrifugal counter-current chromatography (CPC). The octadecylpolyvinyl stationary phase proved an interesting alternative to the more common octadecylsilane type stationary phase for obtaining retention parameters correlated to partition coefficients (i.e. log P). The CPC method, being far less time-consuming and markedly more precise than the classical shake-flask method, offers a promising alternative for measuring partition coefficients. The parameter delta log Poct-hep, i.e. log Poctanol minus log Pheptane, was also determined for both congeneric series and was indicative of a similar H-bonding capacity for the SO2NH2 and 4-NH2-C6H4-SO2 groups. QSAR analyses of carbonic anhydrase inhibition by BzSA and antimycobacterial activity of 4-ADS show the capacity of the new lipophilicity parameters to express the hydrophobic component of the drug-enzyme interactions and to reveal a possible role of H-bond donor capacity in governing the antimycobacterial activity of 4-ADS.
Carbonic Anhydrase Inhibitors↗
Analysis and bioactive evaluation of the compounds absorbed into blood after oral administration of the extracts of Vaccinium vitis-idaea in rat.
In order to screen the active constituents of Vaccinium vitis-idaea L., the compounds absorbed into the rat blood after oral administration of ethanol extract of the stems and leaves of V. vitis-idaea (EEV) have been analyzed. Two compounds were detected in the plasma and identified as arbutin and fraxin, which are originally existed in the crude drug. Furthermore, the pharmacological effects of the two compounds involving EEV for curing acute and chronic respiratory tract infection were tested. The results showed that both arbutin and fraxin have the anti-inflammatory, anti-coughing and phlegm-removing effects. Therefore, it was ascertained that the arbutin and fraxin would be the main active constituents of V. vitis-idaea L.
Administration, Oral↗
Diversity and biotechnological potential of the sponge-associated microbial consortia.
Sponges are well known to harbor diverse microbes and represent a significant source of bioactive natural compounds derived from the marine environment. Recent studies of the microbial communities of marine sponges have uncovered previously undescribed species and an array of new chemical compounds. In contrast to natural compounds, studies on enzymes with biotechnological potential from microbes associated with sponges are rare although enzymes with novel activities that have potential medical and biotechnological applications have been identified from sponges and microbes associated with sponges. Both bacteria and fungi have been isolated from a wide range of marine sponge, but the diversity and symbiotic relationship of bacteria has been studied to a greater extent than that of fungi isolated from sponges. Molecular methods (e.g., rDNA, DGGE, and FISH) have revealed a great diversity of the unculturable bacteria and archaea. Metagenomic approaches have identified interesting metabolic pathways responsible for the production of natural compounds and may provide a new avenue to explore the microbial diversity and biotechnological potential of marine sponges. In addition, other eukaryotic organisms such as diatoms and unicellular algae from marine sponges are also being described using these molecular techniques. Many natural compounds derived from sponges are suspected to be of bacterial origin, but only a few studies have provided convincing evidence for symbiotic producers in sponges. Microbes in sponges exist in different associations with sponges including the true symbiosis. Fungi derived from marine sponges represent the single most prolific source of diverse bioactive marine fungal compounds found to date. There is a developing interest in determining the true diversity of fungi present in marine sponges and the nature of the association. Molecular methods will allow scientists to more accurately identify fungal species and determine actual diversity of sponge-associated fungi. This is especially important as greater cooperation between bacteriologists, mycologists, natural product chemists, and bioengineers is needed to provide a well-coordinated effort in studying the diversity, ecology, physiology, and association between bacteria, fungi, and other organisms present in marine sponges.
Animals↗
Prodrugs of nitroxyl as inhibitors of aldehyde dehydrogenase.
In the preceding paper, analogs of chlorpropamide with an OMe substituent on the sulfonamide nitrogen were shown to inhibit aldehyde dehydrogenase (AlDH), and it was postulated that these compounds were bioactivated by O-demethylation to release nitroxyl (HN = O, nitrosyl hydride), which is an inhibitor of AlDH. Further evidence for the production of nitroxyl from compounds with O-acyl instead of OMe on the sulfonamide nitrogen is now presented. Thus, nitrous oxide (N2O), the end product of nitroxyl dimerization and disproportionation, was found to be generated on alkaline or enzymatic hydrolysis of N,O-diacylated N-hydroxyarylsulfonamides. Since the latter compounds strongly inhibit yeast AlDH in vitro after bioactivation by an esterase intrinsic to this enzyme, nitroxyl generated from these compounds must be the common intermediate that inhibits AlDH.
Aldehyde Dehydrogenase↗
Novel anthelmintic compounds and molluscicides from medicinal plants.
This review assesses the role that can be played by allelochemicals (bioactive secondary compounds) from medicinal and other plants in the control of human helminthic diseases. In the search for new anthelmintics among plant allelochemicals, 3 practical issues have considerable significance. They are the range and capacity of anthelmintic bioassays utilised in preclinical studies in vitro on plant extracts, the phenomenon of coexistent allelochemicals with overlapping activity spectra within single plants, and the problem of non-specific cytotoxins among plant allelochemicals. These topics are discussed in the context of the present absence of any clinically useful plant anthelmintics. In the search for new plant molluscicides for schistosomiasis control, the characteristics of a range of molluscicidal plants are measured against those of the synthetic molluscicide of choice, niclosamide, and against the postulated attributes of practically useful plant molluscicides.
Animals↗
Cytotoxic 2',5'-dihydroxychalcones with unexpected antiangiogenic activity.
A series of 2',5'-dihydroxychalcones were synthesized and evaluated for cytotoxicity against tumor cell lines and human umbilical venous endothelial cells (HUVEC). It was found that chalcones with electron-withdrawing substituents on the B ring exhibited potent cytotoxicity against a variety of tumor cell lines while compounds with electron-releasing groups were less potent in general. Those compounds with B ring replaced by extended or heteroaromatic rings exhibited significant bioactivity. Several compounds were shown to have marked cytotoxic selectivity towards HUVECs. Especially, among the synthesized compounds, 2-chloro-2',5'-dihydroxychalcone (2-3) showed the highest selectivity index up to 66 in comparison to HCT116 cells. This compound also exhibited strong inhibitory effects on the HUVEC tube formation in an in vitro model. When administered into BDF1 mice bearing Lewis lung carcinoma cells at 50 mg kg(-1) day(-1), 2-3 was found to inhibit the growth of tumor mass by 60.5%.
Angiogenesis Inhibitors↗
Environmental influences on isoflavones and saponins in soybeans and their role in colon cancer.
Soybeans have long been recognized as an excellent source of high-quality protein. The soybean also contains a wide variety of chemical compounds that have potent bioactivity. Among these compounds are the isoflavones and the saponins. The goal of our research was to quantify isoflavone and saponin concentrations in elite soybean cultivars grown in different environments and to identify a naturally occurring high and low variety that could be used in animal studies of colon cancer. We observed significant environment x genotype interactions for the cultivars and selected 2 that provided the range of concentration for isoflavones and saponins. These were grown in an adequate quantity for animal studies, which are ongoing. We explored the influence of isoflavones and saponins on human colon tumor cells in culture, Caco-2, to determine potential mechanisms through which these compounds influence the carcinogenic process. We observed the inhibition of Caco-2 cell proliferation by isoflavones and saponins, suggesting a protective effect of these compounds in colon cancer. Using purified soy saponins, we found no negative effects on mouse growth, organ weights, or intestinal morphology when the diet contained up to 3% saponins by weight. Hence, soy isoflavones and saponins are likely to be protective of colon cancer and to be well tolerated. Continuing studies will explore the cancer-protective effects of these compounds in animal models.
Animals↗
[Studies on chemical constitutes of green alga Chaetomorpha basiretorsa and their bioactivity].
OBJECTIVE: To study the chemical constituents of Chaetomorpha basiretorsa and screen for bioactive leading compounds. METHOD: Compounds were isolated by normal phase silica gel and Sephadex LH-20 gel column chromatography, reverse phase MPLC and reverse phase HPLC. Their structures were elucidated by spectroscopic methods including MS, IR and 1D, 2D NMR. Cytotoxicity of the compounds was screened by using standard MTT method. The purified compounds' inhibition against proliferation of dog vascular smooth muscle cells was also screened by MTT assay. RESULT: Five compounds were isolated from C. basiretorsa and their structures were identified as euphol (I), loloilide (II), 4-cumylphenol (III), zeaxanthin (IV) and lactucaxanthin (V). CONCLUSION: All these compounds were obtained from this genus for the first time. Compound (III), 4-cumylphenol, was a new nature product. All compounds were inactive (IC50 > 10 microg x mL(-1)) in cytotoxicity screening. In inhibition against proliferation of dog vascular smooth muscle cells test, the cell survival ratio to compound I was (0.32 +/- 0.056)% which indicate its potential anti-atherosclerotic bioactivity.
Animals↗
[Prospect in the study of creating new drugs from Chinese herbal medicine].
This paper concisely describes the prospect in developing new drugs from Chinese herbal medicine. The search for bioactive constituents or leading compounds from natural sources especially from Chinese herbal medicine will be proved to be one of the most effective ways by changing the traditional concept of study on natural drugs using modern ideas. It is well known that plants in China provide a fertile source of natural compounds dealt with biological and structural diversity, which is the best channel to discover bioactive and leading compounds. Many instances have showed that structural transformation and analogues synthesis of known natural compounds or drugs can provide an important way to find new leading compounds. Study of the bioactive principle of Chinese herbal medicine involves an integration of chemical study and bioassay with intensive screening. It should be emphasized that the investigation of bioactive compounds for creating new drugs is the major task of Chinese pharmaceutical industry.
Drug Design↗
Comparison of extraction methods for marker compounds in the essential oil of lemon grass by GC.
A gas chromatography flame ionization detection method for the quantification of bioactive marker compounds (neral, geranial, geraniol, limonene, citronellal, and beta-myrcene) in the essential oil of Cymbopogon citratus (lemon grass) was developed. Four procedures for the extraction of essential oils from C. citratus were compared including solvent extraction, steam distillation extraction, accelerated solvent extraction, and supercritical fluid extraction. Solvent extraction by sonication with nonpolar solvents showed comparable results to the steam distillation method. Several commercial products prepared from C. citratus and Cymbopogon flexuosus were analyzed and compared.
Acyclic Monoterpenes↗
Bioactive substances of plant origin in food--impact on genomics.
In the past decade, substantial progress has been made concerning our knowledge of bioactive components in plant foods and their links to health. Human diets of plant origin contain many hundreds of compounds which cannot be considered as nutrients, but appear to play a role in the maintenance of health. These substances are called nutraceuticals. In some cases where the disease process is at least partially understood, elements of protection can be related to a single compound or structurally related group of compounds in the diet. Bioactive components of food which are of special interest include the following groups: polyphenols, phytoestrogens, phytosterols, phytates and polyunsaturated fatty acids. Most of them are featured by antioxidant properties. In the first part of this review, we indicate the main groups of bioactive compounds giving a description of their localisation, chemical properties and biological actions. Recently, it was shown, however, that the bioavailability of potential antioxidants from plant foods is generally too low to have any substantial direct effect on reactive oxygen species. As a result of that it is postulated that dietary compounds, even in very low concentrations, may have a far greater impact than previously appreciated on the regulation of gene expression. The second part of this paper concerns the action of the literally most important bioactive substances on the molecular mechanisms of the control of genes which in turn affect cellular metabolism. A few current studies on the action of selected nutraceuticals on the activity of transcription factors such as AP-1, NF-kappaB, SREBPs, PPARs as final targets in the signal transduction cascade and gene regulation are included. A detailed analysis of numerous factors of dietary origin with their targets is far beyond the scope of this paper. However, continuing research on the effects of nutraceuticals on gene expression should provide insight into the mechanisms of prevention of diseases such as obesity, diabetes, atherosclerosis, hypertension and cancer by dietary manipulations.
Animals↗
Marine pharmacology in 2003-2004: anti-tumour and cytotoxic compounds.
During 2003 and 2004, marine pharmacology research directed towards the discovery and development of novel anti-tumour agents was published in 163 peer-reviewed articles. The purpose of this review is to present a structured assessment of the anti-tumour and cytotoxic properties of 150 marine natural products, many of which are novel compounds that belong to diverse structural classes, including polyketides, terpenes, steroids and peptides. The organisms yielding these bioactive marine compounds include invertebrate animals, algae, fungi and bacteria. Anti-tumour pharmacological studies were conducted with 31 structurally defined marine natural products in a number of experimental and clinical models that further defined their mechanisms of action. Particularly potent in vitro cytotoxicity data generated with murine and human tumour cell lines was reported for 119 novel marine chemicals with as yet undetermined mechanisms of action. Noteworthy is the fact that marine anti-cancer research was sustained by a global collaborative effort, involving researchers from Australia, Austria, Canada, China, Egypt, France, Germany, Italy, Japan, Mexico, the Netherlands, New Zealand, Papua New Guinea, the Philippines, South Africa, South Korea, Spain, Switzerland, Taiwan, Thailand and the United States of America (USA). Finally, this 2003-2004 overview of the marine pharmacology literature highlights the fact that the discovery of novel marine anti-tumour agents continued at the same pace as during 1998-2002.
Antineoplastic Agents↗
The potential impact of novel investigational compounds on human fertility.
There is considerable concern that the incidence of infertility in humans may be increasing, in some instances due to the action of bioactive xenobiotic compounds found in our environment; for example, high concentrations of xenobiotics with estrogenic activity can interfere with normal testicular function and fertility. However, recent studies have shown that very low concentrations of several estrogenic xenobiotics can have subtle, unexpected effects on sperm function. When tested in vitro, these compounds stimulate spermatozoa to become fertile very quickly, but continued stimulation causes them to burn out and lose fertilising ability; similar responses occurring in vivo could reduce fertility. In contrast, several other compounds, structurally related to amfetamine, have been shown to act on spermatozoa in vitro in a positive manner, stimulating cells to 'switch on' quickly and then preventing burnout so that they maintain fertilising potential; similar responses occurring in vivo could enhance fertility. These results could have implications for either reducing or enhancing natural fertility.
Animals↗
Potentiation by isoniazid of relaxation induced by nitrovasodilators in rat aorta.
The influence of isoniazid (ISO) preincubation on the relaxant effects of a group of nitrovasodilators was examined in norepinephrine-contracted rat aortic rings with and without endothelium. ISO displaced to the left the dose-response curves to all nitrovasodilators and increased the negative logarithm of their median effective concentration (EC50) values. Potentiation was minimal with sodium nitrite and increased progressively with sodium nitroprusside, nitroglycerin (NTG), and isosorbide dinitrate. The phenomenon occurred in rings with and without endothelium and was not seen with the nitric oxide-releasing agent acetylcholine or with the nonspecific vasodilator hydralazine. These results confirm previous observations of potentiation of NTG vasorelaxation by ISO and extend them to other nitrovasodilators. Potentiation is attributed to the previously postulated inhibition by ISO of pyridoxal-requiring enzymes involved in the breakdown of homocysteine, leading to its intracellular accumulation. Increased availability of this sulfhydryl donor would lead in turn to enhanced bioactivation and vasorelaxant effects of nitrovasodilators. The different degrees of potentiation observed would be related to the sulfhydryl requirement of each compound for bioactivation. Alternatively, enhanced bioactivation of the nitrovasodilators could be due to induction by ISO of P-450 enzymes involved in this process.
Animals↗
Sorting out bioactivity in flavonoid mixtures.
Natural polyphenolic compounds, including flavonoids, which are synthesized by plants, have repeatedly been linked to multiple health benefits, but specific bioactive compounds or individualized roles have been difficult to interpret or to assign. This limitation has prevented the development of robust dietary recommendations. This paper describes a plant-cell-culture production approach that provides uniform yields of abundant natural mixtures of flavonoids from small molecules to high molecular weight oligomers and polymers. The flavonoids correspond to compounds produced in nature by the same plant genotypes; but, through elicitation tactics, the levels and the profiles of the flavonoid yield can be enhanced, and isolation from cell cultures is more rapid and streamlined than isolation from in vivo plant tissues. Introduction of (14)C sucrose to the cell-culture medium enabled the recovery and the identification of biolabeled flavonoid mixtures, which could be easily tracked in serum of rats after gavage. The biolabeled materials are now being investigated to determine tissue localization, structures of bioactive components, and the interactions between flavonoid components that contribute to bioactive potential.
Animals↗
Hepatic metabolism and bioactivation of mycotoxins and plant toxins.
The intoxication of livestock from ingested feed contaminated with naturally occurring toxicants is of great economic importance. Certain toxicants require enzymatic bioactivation before harmful effects are exhibited. In the liver, the cytochrome P-450 dependent mixed function oxidase (MFO) system normally metabolizes foreign compounds (xenobiotics) into more polar, more excretable and less toxic metabolites. During metabolism of aflatoxins and pyrrolizidine alkaloids (PA), oxidized metabolites are highly reactive with cellular components and are more toxic than the parent compounds. Hepatic bioactivation is of considerable importance because active metabolites are formed directly within the tissues of the animal. In addition, the MFO system has only limited specificity and is dependent on many factors including diet, age, sex, species and environmental influences. The interrelationship of these factors on aflatoxicosis and pyrrolizidine alkaloidosis are often responsible for the chronic nature and difficult etiology of these diseases. A better understanding of the factors affecting metabolism and bioactivation of these toxicants may lead to the development of techniques for protecting animals that are subjected to contaminated feeds.
Aflatoxins↗
The effects of S9 mix from rat oesophagus, salivary gland, and liver on the mutagenicity of the rat oesophageal carcinogen N-nitroso-N-methylaniline in the Salmonella typhimurium assay.
The present study examines the feasibility of using the Salmonella typhimurium plate-incorporation assay of Ames for detecting target-organ specificity with N-nitroso-N-methylaniline (NMA), a compound for which the target site for tumour formation in the rat is the oesophagus. Thus it was anticipated that the oesophagus would bioactivate this compound. The compound has been investigated using S9 from Aroclor- and NMA-induced rat oesophagus, salivary gland and liver in the presence and absence of the co-mutagen, norharman. No response to NMA was seen with oesophageal S9 even though benzo[a]pyrene produced a dose-related increase in revertants in strain TA98 and TA100. No response to NMA was seen with salivary-gland S9. However, a response was produced with Aroclor-induced rat-liver S9 in the presence of norharman and with NMA-induced rat-liver S9 in the absence of norharman.
Animals↗