垂盆草总黄酮的酶法提取及其抑菌活性

目的研究垂盆草总黄酮的酶法提取工艺及其抑菌作用。方法用酶解和煎煮相结合的方法,以总黄酮得率为指标,通过正交实验优选出最佳提取工艺,用平板打孔法考察垂盆草总黄酮的抑菌作用。结果垂盆草总黄酮的最佳酶解工艺条件是酶解温度50℃,酶解pH 6.0,酶用量0.6%,酶解时间1.5 h,其中酶解温度是显著影响因素。总黄酮得率可达3.471%。垂盆草总黄酮提取液对大肠杆菌、金黄色葡萄球菌、枯草杆菌和产气杆菌都有不同程度的抑菌作用,对四联球菌作用不明显。结论该实验得到的垂盆草总黄酮的提取工艺合理可行,提取率高,提取得到的总黄酮具有一定的抑菌作用。     

Examination of model enzyme and penetration systems in relation to antibacterial activity

Recent work has shown that the activity of cephalosporins in inhibiting exocellular DD-peptidases from Streptomyces R61 and Actinomadura R39 are, at best, only poorly related to minimum inhibitory concentrations against pathogenic isolates. Taking into account the rate at which cephalosporins diffuse through porin channels, such as exist in certain Gram-negative organisms, does not help in establishing a relationship between MIC data and the kinetic data on the model enzymes. Most published cell wall permeability studies, the porin ones being a principal exception, have not examined long enough series of structurally related compounds to establish property-activity relationships.     

Examination of antibacterial activity of the photoactivated arginine haematoporphyrin derivative.

The antibacterial photodynamic effect of arginine haematoporphyrin derivative (HpD-Arg2) was investigated using two methods. The effect proved to be highly antibacterial when it was employed against P. aeruginosa and S. aureus cells floating in the nutrient broth. The reduction of approximately four logarithms of CFU ml-1 after light exposition, as compared to a dark control, was observed. In the second step of the study the photodynamic effect was employed against the same strains of bacteria after their colonization on isolated mouse muscles. In this case the antibacterial effect was observed as well. However, the reduction of CFU ml-1 achieved was much lower and reached one logarithm only. The optimal concentration of photoactivated HpD-Arg2 for S. aureus and P. aeruginosa was 25 microg ml-1 and 800 microg ml-1 for the floating bacteria, and 200 microg ml-1 and 1000 microg ml-1 for sessile bacteria, respectively. We have concluded from our study that the antibacterial effect investigated may offer, in the future, an alternative method for treatment of the tissues superficially infected with pathogens resistant to antibiotics. However, further studies in this field are necessary.     

Antitubercular activity of new coumarins

The present article describes a series of 21 N ′‐benzylidene‐2‐oxo‐2H‐chromene‐3‐carbohydrazides 4a–4v , which were synthesized and evaluated for their cell viabilities in non‐infected and Mycobacterium bovis Bacillus Calmette–Guerin‐infected macrophages. Subsequently, the non‐cytotoxic compounds 4c, 4g, 4h, 4j, 4l and 4t were assessed against Mycobacterium tuberculosis ATCC 27294 using the microplate Alamar Blue assay and the activity expressed as the minimum inhibitory concentration in μg/mL. These compounds exhibited a significant activity (50–100 μg/mL) when compared to the first‐line drugs, such as pyrazinamide (PZA >100 μg/mL). These results could be considered a good starting point for further studies to develop new lead compounds to treat multidrug‐resistant tuberculosis.     

Antiproliferative, cytotoxic and antitumour activity of coumarins isolated from Calophyllum brasiliense

Among the eight Calophyllum species found on the American continent, Calophyllum brasiliense is the most widely distributed. Chemical analysis of this species has shown the presence of xanthones with cancer chemopreventive properties and antifungal activity. Recently, three new coumarins with antineoplastic properties have been found. In this study, we have evaluated the biological effects of the antiproliferative activity of coumarins isolated from C. brasiliense on the survival, cell cycle and apoptosis of cells in-vitro and their antitumour effects in mice. The cytological study showed that coumarins from C. brasiliense reduce the survival of BMK cells (baby mouse kidney cells) by inducing apoptosis and, to a lesser degree, necrosis. The cell cycle was arrested in S-phase and the division of BMK cells was inhibited. Coumarins had caused a reduction of experimental tumours in 83% of animals by the end of the treatment. Therefore, coumarins have the potential to be used alone or in combination with other antineoplastic drugs, and they might increase the effectiveness of other treatments for cancer.     

Cytotoxic and antibacterial flavonoids from dragon's blood of Dracaena cambodiana

Chemical studies on the constituents from the dragon's blood of Dracaena cambodiana led to the discovery of three new flavonoid derivatives (1- 3) and six known compounds (4- 9). The structures of the three new compounds were elucidated by NMR and MS spectroscopic analyses. All compounds were evaluated for their growth inhibitory activity against human cell lines K-562, SMMC-7721, and SGC-7901, as well as antibacterial activities against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). As a result, compounds 1, 2, 5, 7, and 9 showed cytotoxicity against K-562, SMMC-7721, and SGC-7901 cell lines. All these compounds were observed to exhibit antibacterial activities against S. aureus, and compounds 1- 4, 6, 8, and 9 were observed to exhibit antibacterial activity against MRSA.     

Cytotoxic activity of coumarins from Micromelum minutum

The crude petroleum ether and chloroform extracts of Micromelum minutum (G. Frost.) Wright & Arn (Rutaceae) showed strong cytotoxic activity when tested against a T-lymphoblastic leukemia cell line. Further fractionation of the extracts resulted in the isolation of five new coumarins 3″,4″-dihydrocapnolactone, 2′,3′-epoxyisocapnolactone, 8-hydroxyisocapnolactone-29,39-diol, 8-hydroxy-3″,4″-dihydrocapnolactone-29,39-diol and 8,4″-dihydroxy-3″,4″-dihydrocapnolactone-29,39-diol, and two triterpenes. Some of these compounds were strongly active against T-lymphoblastic leukemia (CEM-SS), promyeolocytic leukemia (HL60), cervical cancer (HeLa) and liver cancer (HepG2) cell lines. 8-Hydroxyisocapnolactone-29,39-diol was found to be the most active with IC₅₀ values of 2.9, 2.5, 6.9, and 5.9 μg/ml, respectively. This was followed by 2′,3′-epoxyisocapnolactone. When evaluated against the normal mouse fibroblast (3T3) cell line, 8-hydroxyisocapnolactone-29,39-diol was found to be inactive, hence it could serve as a valuable lead for further design and synthesis of more active analogues.     

香豆素类化合物的药理研究进展

通过查阅相关文献,对香豆素类化合物药理作用的研究现状进行综述。香豆素类化合物具有镇痛抗炎、抗艾滋病、抗肿瘤、抗氧化、降压、抗心律失常等多方面的生物活性,为香豆素类化合物的深入研究提供参考。     

Antitumor-promoting activity of coumarins from citrus plants

In order to identify antitumor-promoting agents, we performed primary in vitro screening of 31 coumarins isolated from 11 plants of the Citrus species (Rutaceae), examining their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Some of the 8-substituted coumarins, 8-formyl-7-hydroxycoumarin (5), osthenol (7), demethylauraptenol (8), osthenon (9) and dihydroosthenon (10), were found to significantly inhibit EBV-EA activation (IC50: 129-207 mol ratio/32 pmol TPA). Osthenol (7) exhibited a marked inhibitory effect on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.     

Synthesis and evaluation of anticancer activity of some imidazothiazolyl,imidazobenzothiazolyl and dihydroimidazothiazolyl coumarins

A series of 6-(2H-1-benzopyran-2-one-3-yl)imidazo[2,1-b]thiazoles (1), 2-(2H-1-benzopyran-2-one-3-yl)imidazo[2,1-b]benzothiazoles (2) and 3-(2H-1-benzopyran-2-one-3-yl)-5,6-dihydroimidazo[2,1-b]thiazoles (3) have been synthesized and evaluated for anticancer activity in vitro. The compounds showed very good activity against different tumor cell lines.     

Antimicrobial activity of flavonoids

Flavonoids are ubiquitous in photosynthesising cells and are commonly found in fruit, vegetables, nuts, seeds, stems, flowers, tea, wine, propolis and honey. For centuries, preparations containing these compounds as the principal physiologically active constituents have been used to treat human diseases. Increasingly, this class of natural products is becoming the subject of anti-infective research, and many groups have isolated and identified the structures of flavonoids possessing antifungal, antiviral and antibacterial activity. Moreover, several groups have demonstrated synergy between active flavonoids as well as between flavonoids and existing chemotherapeutics. Reports of activity in the field of antibacterial flavonoid research are widely conflicting, probably owing to inter- and intra-assay variation in susceptibility testing. However, several high-quality investigations have examined the relationship between flavonoid structure and antibacterial activity and these are in close agreement. In addition, numerous research groups have sought to elucidate the antibacterial mechanisms of action of selected flavonoids. The activity of quercetin, for example, has been at least partially attributed to inhibition of DNA gyrase. It has also been proposed that sophoraflavone G and (-)-epigallocatechin gallate inhibit cytoplasmic membrane function, and that licochalcones A and C inhibit energy metabolism. Other flavonoids whose mechanisms of action have been investigated include robinetin, myricetin, apigenin, rutin, galangin, 2,4,2'-trihydroxy-5'-methylchalcone and lonchocarpol A. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.     

Recent advances in understanding the antibacterial properties of flavonoids

Antibiotic resistance is a major global problem and there is a pressing need to develop new therapeutic agents. Flavonoids are a family of plant-derived compounds with potentially exploitable activities, including direct antibacterial activity, synergism with antibiotics, and suppression of bacterial virulence. In this review, recent advances towards understanding these properties are described. Information is presented on the ten most potently antibacterial flavonoids as well as the five most synergistic flavonoid-antibiotic combinations tested in the last 6 years (identified from PubMed and ScienceDirect). Top of these respective lists are panduratin A, with minimum inhibitory concentrations (MICs) of 0.06-2.0 μg/mL against Staphylococcus aureus, and epicatechin gallate, which reduces oxacillin MICs as much as 512-fold. Research seeking to improve such activity and understand structure-activity relationships is discussed. Proposed mechanisms of action are also discussed. In addition to direct and synergistic activities, flavonoids inhibit a number of bacterial virulence factors, including quorum-sensing signal receptors, enzymes and toxins. Evidence of these molecular effects at the cellular level include in vitro inhibition of biofilm formation, inhibition of bacterial attachment to host ligands, and neutralisation of toxicity towards cultured human cells. In vivo evidence of disruption of bacterial pathogenesis includes demonstrated efficacy against Helicobacter pylori infection and S. aureus α-toxin intoxication.     

Synthesis, structure and antibacterial activity of some alkyltriazenopyrazoles

A series of bis-beta-chlorethyl-, dimethyl- and diethyltriazenopyrazoles (I-IV) were synthesized. By the method of IR spectroscopy the most probable transformation form of I was shown. The compounds were tested as antibacterial agents on a series of bacterial species. It was established that only one of them (VI) possessed a low inhibitory effect. All the rest inhibited strongly the growth of Staphylococcus aureaus 209 and E. coli 387.     

Structural requirements of hydroxylated coumarins for in vitro anti-Helicobacter pylori activity

We have previously found that a 7-hydroxycoumarin derivative has potent anti-Helicobacter pylori (H. pylori) activity, comparable with metronidazole. In this report, we describe the structural requirement for the anti-H. pylori activity of several hydroxylated coumarins (1-23). It was found that 7-hydroxy-4-methylcoumarin (6), 6,7-dihydroxy-4-methylcoumarin (8), 6-hydroxy-7-methoxy-4-methylcoumarin (10) and 5,7-dihydroxycyclopentanocoumarin (21) showed comparable anti-H. pylori activity with metronidazole. The presence of 7- and/or 6-hydroxyl groups seems to be essential to display higher anti-H. pylori activity. Their activities depended on the number and position of the hydroxyl group on the benzenoid ring of the coumarin system. Methylation of the hydroxy group generally diminished the activity. In hydroxylated coumarins, the methyl group at C-4 position enhanced the activity. The inhibitory activity of coumarins (1-23) against jack bean urease was examined, but no coumarins showed any inhibition at 160 micrograms/mL.     

Synthesis and pharmacological activity of some alkoxy-substituted benzofurans and coumarins

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