共查询到20条相似文献,搜索用时 46 毫秒
1.
Ralton LD Bestwick CS Milne L Duthie S Kong Thoo Lin P 《Chemico-biological interactions》2009,177(1):1-6
Bisnaphthalimido compounds bisintercalate to DNA via the major groove and are potentially potent cancer therapeutics. We incorporated natural polyamines as linkers connecting the two-naphthalimido ring moieties to create a series of novel soluble cytotoxic bisnaphthalimidopropyl polyamines (BNIPPs). Here, we determined the cytotoxicity of bisnaphthalimidopropyl spermidine (BNIPSpd) towards Caco-2 and HT-29 colon adenocarcinoma cells revealing an IC50 value of 0.15 and 1.64 μM after 48 h exposure within Caco-2 and HT-29 cells, respectively. After 4 h, ≥0.5 μM BNIPSpd treatment-induced significant DNA damage. After 24 h exposure a concentration-dependent increase in active caspase-3 expression, chromatin condensation and internucleosomal DNA fragmentation identified apoptosis as the principal manifestation for the cytotoxicity within both cell lines. By 24 h exposure, there was also a significant decline in cellular spermine and spermidine levels. It is concluded that bisnaphthalimidopropyl spermidine (BNIPSpd) toxicity primarily results from apoptosis and that BNISpd has potential to be further developed as an anti-tumour agent. 相似文献
2.
Bis-naphthalimidopropyl spermidine (BNIPSpd), spermine (BNIPSpm) and oxa-spermine (BNIPOSpm) showed high in vitro cytotoxicity against human breast cancer MCF-7 cells with IC(50) values of 1.38, 2.91 and 8.45 microM, respectively. These compounds were found to effectively displace the intercalating agent ethidium bromide bound to the calf thymus DNA using fluorimetric methods (C(50) 0.08-0.12 microM) and their apparent equilibrium binding constants (K(app)) were calculated to be in the range of 10.5-18 x 10(7) M(-1). Furthermore, strong stabilisation of calf thymus DNA duplex in the presence of bis-naphthalimidopropyl polyamine derivatives (BNIPSpd, BNIPSpm and BNIPOSpm) was observed by UV spectrophotometric analysis (T(m)=93.3-97 degrees C compared with 75 degrees C for calf thymus DNA without drug). Because of their inherent fluorescence, these compounds were localised preferentially inside the nucleus as evidenced by their direct observation under the fluorescence microscope. The results obtained suggest that the cytotoxic activity of the bis-naphthalimidopropyl polyamines may be in part, caused by their effects on DNA. 相似文献
3.
Soltani F Mosaffa F Iranshahi M Karimi G Malekaneh M Haghighi F Behravan J 《Cell biology and toxicology》2009,25(3):291-296
The protective properties of a prenylated coumarin, umbelliprenin (UMB), on the human lymphocytes DNA lesions were tested.
Lymphocytes were isolated from blood samples taken from healthy volunteers. DNA breaks and resistance to H2O2-induced damage were measured using a single-cell microgel electrophoresis technique under alkaline conditions (comet assay).
Human lymphocytes were incubated in UMB (10, 25, 50, 100, 200, and 400 μM) alone or a combination of different concentrations
of UMB (10, 25, 50, 100, 200, and 400 μM) and 25 μM H2O2. Untreated cells, ascorbic acid (AA; 25, 50, 100, 200, and 400 μM) and H2O2 (25 μM) were considered as negative control, positive control, and the standard antioxidant agent for our study, respectively.
Single cells were analyzed with “TriTek Cometscore version 1.5” software. The DNA damage was expressed as percent tail DNA.
UMB exhibited a concentration-dependent increase in protection activity against DNA damage induced by 25 μM H2O2 (from 67.28% to 39.17%). The antigenotoxic activity of AA, in the range 0–50 μM, was greater than that of UMB. However, no
significant difference (p > 0.05) in the protective activity was found between UMB and AA at concentrations of approximately higher than 50 μM. 相似文献
4.
In vitro effect of malathion and diazinon on oocytes fertilization and embryo development in porcine
Yvonne Ducolomb Eduardo Casas Alejandra Valdez Guadalupe González Mario Altamirano-Lozano Miguel Betancourt 《Cell biology and toxicology》2009,25(6):623-633
Diazinon and malathion are commonly used organophosphate insecticides in agriculture, industry, and in veterinary medicine
as an ectoparasiticide. The importance to carry out in vitro reproductive toxicology assays lies on the need of knowing the
alterations these insecticides may cause at cellular level, since they are endocrine disruptors that interfere with reproductive
functions. The aim of this study was to evaluate in vitro oocyte viability, fertilization, and embryo development with different
concentrations of diazinon and malathion. For in vitro fertilization (IVF), porcine oocytes and sperm were co-incubated for
7 h with increasing concentrations (50, 100, and 500 μM) of diazinon and malathion. For embryo development, fertilized oocytes
were cultured in medium containing the same insecticide concentrations during 96 h for embryo development and 144 h for morulae
formation. Diazinon did not affect oocyte viability and embryo divisions but decreased IVF (fertilization inhibition50 = 502 μM) and morulae formation (morulae inhibition50 = 344 μM). Malathion affected all the studied parameters: lethal concentration50 = 1 mM, fertilization inhibition50 = 443 μM, development inhibition50 = 375 μM, and morulae inhibition50 = 216 μM. The results of this study indicate that diazinon and malathion used in commercial formulation could be toxic, producing
impairment in in vitro fertilization and embryo development. This is an approach for further investigations to find out cell
damage mechanisms produced by these widely used insecticides. 相似文献
5.
Siwek A Stączek P Wujec M Stefańska J Kosikowska U Malm A Jankowski S Paneth P 《Journal of molecular modeling》2011,17(9):2297-2303
4-Benzoyl-1-(4-methyl-imidazol-5-yl)-carbonylthiosemicarbazide (1) was synthesized, and its antibacterial and type IIA topoisomerase (DNA gyrase and topoisomerase IV) activity evaluated.
(1) was found to have high therapeutic potential against opportunistic Gram-positive bacteria, and inhibitory activity against
topoisomerase IV (IC50 = 90 μM) but not against DNA gyrase. An increase in activity against topoisomerase IV (IC50 = 14 μM) was observed when the imidazole moiety of (1) was replaced with the indole group in 4-benzoyl-1-(indol-2-yl)-carbonylthiosemicarbazide (2). However, (2) showed only weak antibacterial activity. Although the results of the bacterial type IIA topoisomerases inhibition study
did not parallel antibacterial activities, our observations strongly imply that a 4-benzoylthiosemicarbazide scaffold can
be developed into an efficient Gram-positive antibacterial targeting topoisomerase IV. The difference in activity against
type IIA topoisomerases between (1) and (2) was further investigated by docking studies, which suggested that these compounds target the ATP binding pocket. 相似文献
6.
The Fusarium metabolite enniatin B is now recognized as a frequent contaminant of grains used for human foods and animal feeds. Yet, so
far very limited data are available on its toxicity and that of other emerging Fusarium mycotoxins (Jestoi M, 2008, Crit Rev Food Sci Nutr 48:21-49). Thus, the mutagenic/genotoxic potential of enniatin B was investigated
in a battery of short-term tests, and its cytotoxicity compared with that of several other mycotoxins. No mutagenicity was
detected in the Ames assay with four Salmonella typhimurium strains, and in the HPRT (hypoxanthine guanine phosphoribosyl transferase) assay with V79 cells, in either the presence or
absence of an external metabolizing enzyme system (rat liver S9). For other types of genotoxicity, i.e., clastogenicity and
chromosomal damage, studied in V79 cells by means of alkaline single-cell gel electrophoresis (Comet) assay and micronucleus
assay, no significant genotoxic potential of enniatin B was revealed. However, the Fusarium metabolite exerts pronounced time- and concentration-dependent cytotoxic effects in V79 cells as determined by Alamar Blue
reduction and by neutral red uptake assays. For instance, IC20 and IC50 values determined for enniatin B by neutral red assay for 48-h exposure are 1.5 μM and 4 μM. These values are higher than
those of the more potent Fusarium toxin deoxynivalenol (IC20 0.7 μM, IC50 of 0.8 μM), but clearly lower than the IC values of several other mycotoxins tested in parallel. Their ranking of cytotoxicity
in V79 cells was as follows: deoxynivalenol > enniatin B > patulin > ochratoxin A > zearalenone > citrinin. Moreover, enniatin
B was found to induce nuclear fragmentation, a sign of apoptosis, already at low submicromolar concentrations. In summary,
despite an apparent lack of mutagenic and genotoxic activity, enniatin B can cause pronounced cytotoxicity in mammalian cells,
detectable at low micromolar concentrations. 相似文献
7.
Beob G. Kim Julye M. Adams Brian A. Jackson Merlin D. Lindemann 《Biological trace element research》2010,133(2):171-180
Dietary chromium(III) picolinate (CrPic) effects on circulating steroid hormones have been reported in various experimental
animals. However, direct effects of CrPic on adrenocortical steroidogenesis are uncertain. Therefore, the objective was to
determine the effects of CrPic on cortisol and dehydroepiandrosterone sulfate (DHEAs) secretion from H295R cells. In experiment
1, a 24-h exposure to CrPic (0 to 200 μM) had both linear (p < 0.001) and quadratic (p < 0.001) effects on cortisol secretion from forskolin-stimulated cells with the highest cortisol secretion at 0.1 μM of CrPic
and the lowest at 200 μM of CrPic. In experiment 2, a 48-h exposure to CrPic (200 μM) decreased cortisol (p < 0.07) release from forskolin-stimulated cells during a 24-h collection period. In experiment 3, a 48-h exposure to CrPic
(100 μM) decreased cortisol (p < 0.05) and DHEAs (p < 0.01) from forskolin-stimulated cells during a 24-h sampling period. In experiment 4, a 24-h exposure to forskolin followed
by a 24-h exposure to both forskolin and CrPic (100 and 200 μM) decreased both cortisol and DHEAs secretion (p < 0.01). This study suggests that at high concentrations, CrPic inhibits aspects of steroidogenesis in agonist-stimulated
adrenocortical cells. 相似文献
8.
The regeneration of meristematic tissues from sporophytes of Laminaria digitata was studied by protoplast and tissue culture. Sequential treatment of explants in sterile seawater with 1% Betadine for 5 min,
1% commercial bleach for 1–2 min and 2% antibiotic treatment supplemented with 1 μM GeO2 overnight enabled viable explants as high as 55%. Different morphogenetic responses were observed from tissue culture on
media supplemented with plant growth regulators alone or in combination, mainly filamentous calluses up to 50% according to
the media. Dark green compact calluses were observed on two combinations: 4 μM Pi + 2 μM N-(2-chloro-4-pyridyl)-N’-phenylurea
(CPPU) and 0.04 μM Pi + 0.44 μM 6-benzylaminopurine. Thalloid-like structures comparable to adventitious buds were regenerated
on medium supplemented with 4 μM Pi + 0.45 μM zeatin but at low frequency suggesting a strong genotypic effect. Friable calluses
were developed from protoplasts in enriched medium with polyamines and containing 0.40 μM CPPU + 0.45 μM 2,4-dichlorophenoxyacetic
acid. In order to produce protoplasts, a one-step enzymatic protocol was developed and yields reached 22 × 106 protoplasts per gram of fresh weight. 相似文献
9.
We present an analysis of X-ray-induced damage in ΦX174 plasmid DNA, applying doses between D = 250 and 1,500 Gy. To analyse this damage in detail, the distribution of plasmid fragments after irradiation have been determined
by scanning force microscopy. The results show that even for the lowest dose of D = 250 Gy, a significant amount of double-strand breaks are observed. For increasing dose, the percentage of small fragments
increases and is accompanied by a shortening of the average fragment length from < L> = 1,400 nm for a dose of D = 250 Gy to < L> = 1,080 nm after irradiation with D = 1,500 Gy. The most crucial parameter, the average number of double-strand breaks per broken plasmid (<DSBb> ) has been determined for the first time for the applied doses. The results show that the average number of DSBs per broken
plasmid <DSBb> increases almost linearly from a value of <DSBb> = 1.3 after irradiation with D = 250 Gy to <DSBb> = 1.7 after exposure to D = 1,500 Gy. The presented results show that the amount of DSBs induced by X-ray radiation in plasmid DNA can be calculated
with high accuracy by means of scanning force microscopy, providing relevant information regarding the interaction of X-rays
with DNA molecules.
相似文献
M. BrezeanuEmail: |
10.
Alma R. López-Laredo Fanny D. Ramírez-Flores Gabriela Sepúlveda-Jiménez Gabriela Trejo-Tapia 《In vitro cellular & developmental biology. Plant》2009,45(5):550-558
Tecoma stans is a tropical plant from the Americas. Antioxidant activity and both phenolic compound and flavonoid total content were determined
for callus tissue of T. stans cultured in either a set photoperiod or in darkness. Callus lines from three explant types (hypocotyls, stem, and leaf) were
established on B5 culture medium supplemented with 0.5 μM 2,4-D and 5.0 μM kinetin. While leaf-derived callus grew slower
under a 16-h photoperiod (specific growth rate, μ = 0.179 d−1, t
D = 3.9 d) than in darkness (μ = 0.236 d−1, t
D = 2.9 d), it accumulated the highest amount (p < 0.05) of both phenolics (86.6 ± 0.01 mg gallic acid equivalents/g) and flavonoids (339.6 ± 0.06 mg catechin equivalents/g).
Similarly, antioxidant activity was significantly higher (p < 0.05) when callus was cultured in period light than when grown in extended darkness. Antioxidant activity measured with
a 2,20-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS)-based assay was 350.5 ± 15.8 mmol Trolox/g
extract for callus cultured under a defined photoperiod compared to 129.1 ± 7.5 mmol Trolox/g extract from callus cultured
in darkness. Content of phenolic compounds and flavonoids was in agreement with a better antioxidant power (EC50 = 450 μg extract/mg 1,1-diphenyl-2-picrylhydrazyl) and antiradical efficiency. Results of the present study show that calli
of T. stans are a source of compounds with antioxidant activity that is favored by culture under a set photoperiod. 相似文献
11.
Ging Kuo Wang Joanna Calderon Shiow-Jiin Jaw Sho-Ya Wang 《The Journal of membrane biology》2009,229(1):1-9
Articaine is widely used as a local anesthetic (LA) in dentistry, but little is known regarding its blocking actions on Na+ channels. We therefore examined the state-dependent block of articaine first in rat skeletal muscle rNav1.4 Na+ channels expressed in Hek293t cells. Articaine exhibited a weak block of resting rNav1.4 Na+ channels at −140 mV with a 50% inhibitory concentration (IC50) of 378 ± 26 μM (n = 5). The affinity was higher for inactivated Na+ channels measured at −70 mV with an IC50 value of 40.6 ± 2.7 μM (n = 5). The open-channel block by articaine was measured using inactivation-deficient rNav1.4 Na+ channels with an IC50 value of 15.8 ± 1.5 μM (n = 5). Receptor mapping demonstrated that articaine interacted strongly with a D4S6 phenylalanine residue, which is known
to form a part of the LA receptor. Thus the block of rNav1.4 Na+ channels by articaine is via the conserved LA receptor in a highly state-dependent manner, with a ranking order of open (23.9×) > inactivated
(9.3×) > resting (1×) state. Finally, the open-channel block by articaine was likewise measured in inactivation-deficient
hNav1.7 and rNav1.8 Na+ channels, with IC50 values of 8.8 ± 0.1 and 22.0 ± 0.5 μM, respectively (n = 5), indicating that the high-affinity open-channel block by articaine is indeed preserved in neuronal Na+ channel isoforms. 相似文献
12.
13.
Pier Giovanni Baraldi Mojgan Aghazadeh Tabrizi Francesca Fruttarolo Romeo Romagnoli Delia Preti 《Purinergic signalling》2009,5(1):3-19
Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named
A1, A2A, A2B and A3 (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding
of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective
agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview
of the recent advancements in identifying potent and selective A2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine
ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N
6-, C2-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions.
Compounds 1-deoxy-1-{6-[N′-(furan-2-carbonyl)-hydrazino]-9H-purin-9-yl}-N-ethyl-β-D-ribofuranuronamide (19, hA1
K
i = 1050 nM, hA2A
K
i = 1550 nM, hA2B EC50 = 82 nM, hA3
K
i > 5 μM) and its 2-chloro analogue 23 (hA1
K
i = 3500 nM, hA2A
K
i = 4950 nM, hA2B EC50 = 210 nM, hA3
K
i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay
in Chinese hamster ovary (CHO) cells expressing hA2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide
(BAY-60–6583, hA1, hA2A, hA3 EC50 > 10 μM; hA2B EC50 = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis.
This article has previously been published in issue 4/4, under doi:. 相似文献
14.
Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named
A1, A2A, A2B and A3 (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding
of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective
agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview
of the recent advancements in identifying potent and selective A2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine
ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N
6-, C2-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions.
Compounds 1-deoxy-1-{6-[N′-(furan-2-carbonyl)-hydrazino]-9H-purin-9-yl}-N-ethyl-β-D-ribofuranuronamide (19, hA1
K
i = 1050 nM, hA2A
K
i = 1550 nM, hA2B EC50 = 82 nM, hA3
K
i > 5 μM) and its 2-chloro analogue 23 (hA1
K
i = 3500 nM, hA2A
K
i = 4950 nM, hA2B EC50 = 210 nM, hA3
K
i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay
in Chinese hamster ovary (CHO) cells expressing hA2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide
(BAY-60–6583, hA1, hA2A, hA3 EC50 > 10 μM; hA2B EC50 = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis. 相似文献
15.
Wei XJ Wu J Ni YD Lu LZ Zhao RQ 《In vitro cellular & developmental biology. Animal》2011,47(10):735-741
Previous studies have shown that the in ovo injection of equol can markedly improve the water-holding capacity of muscles
of broilers chickens at 7 wk of age through promotion of the antioxidant status. We aimed to investigate directly the antioxidant
effects of equol on muscle cells in broilers. Muscle cells were separated from leg muscle of embryos on the 11th day of incubation
and treated with equol and H2O2, either alone or together. Cells were pretreated with medium containing 1, 10, or 100 μM equol for 1 h prior to the addition
of 1 mM H2O2 for a further 1 h. Photomicrographs of cells were obtained. Cell viability, malondialdehyde (MDA) content, and L-lactate
dehydrogenase (LDH) activity in the cell supernatant, as well as intracellular total superoxide dismutase (T-SOD) and glutathione
peroxidase (GSH-Px) activities were determined. Treatment with 1 mM H2O2 caused serious damage to cells, indicated by comets with no clear head region but a very apparent tail of DNA fragments.
Pretreatment with low (1 μM) but not high concentrations of equol (10 μM) inhibited cell damage, while 100 μM equol caused
more serious damage than H2O2 alone. Pretreatment with 1 μM equol had no effect on cell viability, while pretreatment with 10 and 100 μM equol significantly
decreased cell viability in a dose-dependent manner. Compared with H2O2 alone, pretreatment with low-dosage equol markedly decreased LDH activity and MDA production in the supernatant, significantly
increased intracellular T-SOD activity (P < 0.05) and tended to increase intracellular GSH-Px activity (0.05 < P < 0.1). Pretreatment with high-dosage equol (10 and 100 μM) significantly enhanced LDH activity, but had no effect on MDA
content, T-SOD or GSH-Px activity induced by H2O2, except for an obvious increase in GSH-Px activity caused by 10 μM equol. These results indicate that equol at low dosage
can prevent skeletal muscle cell damage induced by H2O2, while pretreatment with high-dosage equol shows a synergistic effect with H2O2 in inducing cell damage. 相似文献
16.
Gabrielová E Jabůrek M Gažák R Vostálová J Ježek J Křen V Modrianský M 《Journal of bioenergetics and biomembranes》2010,42(6):499-509
Reactive oxygen species (ROS) originating from mitochondria are perceived as a factor contributing to cell aging and means
have been sought to attenuate ROS formation with the aim of extending the cell lifespan. Silybin and dehydrosilybin, two polyphenolic
compounds, display a plethora of biological effects generally ascribed to their known antioxidant capacity. When investigating
the cytoprotective effects of these two compounds in the primary cell cultures of neonatal rat cardiomyocytes, we noted the
ability of dehydrosilybin to de-energize the cells by monitoring JC-1 fluorescence. Experiments evaluating oxygen consumption
and membrane potential revealed that dehydrosilybin uncouples the respiration of isolated rat heart mitochondria albeit with
a much lower potency than synthetic uncouplers. Furthermore, dehydrosilybin revealed a very high potency in suppressing ROS
formation in isolated rat heart mitochondria with IC50 = 0.15 μM. It is far more effective than its effect in a purely chemical system generating superoxide or in cells capable
of oxidative burst, where the IC50 for dehydrosilybin exceeds 50 μM. Dehydrosilybin also attenuated ROS formation caused by rotenone in the primary cultures
of neonatal rat cardiomyocytes. We infer that the apparent uncoupler-like activity of dehydrosilybin is the basis of its ROS
modulation effect in neonatal rat cardiomyocytes and leads us to propose a hypothesis on natural ischemia preconditioning
by dietary polyphenols. 相似文献
17.
Aminoglycosides are polycationic antibiotics that have been shown to block a variety of cation channels. The inhibitory effect
of externally applied aminoglycosides on P2X2 receptor currents was examined after heterologous expression in Xenopus laevis oocytes using the two-electrode voltage-clamp technique. All of the aminoglycosides tested inhibited the ATP-evoked responses
with potencies ranging from 71 μM to 2 mM (IC50 values). The ranked order of potency was streptomycin > gentamicin > neomycin > paromomycin > kanamycin. The inhibition of
P2X receptor currents was independent of the ATP concentration used for the activation, which is compatible with a noncompetitive
mechanism. The inhibition was voltage-dependent and was reduced at more positive membrane potentials. To examine whether the
current block was dependent on the receptor conformation, the aminoglycoside effect on a non-desensitizing P2X2-X1 receptor
chimera was analyzed. The results from these measurements suggest that inhibition is caused by an open pore block that locks
the P2X receptor chimera in an open nonconducting state from which the agonist dissociation is slow. We also demonstrate that
the P2X2-X1 chimera can serve as a tool to directly test whether an antagonist acts competitively or not. 相似文献
18.
Kabir ME Krishnaswamy S Miyamoto M Furuichi Y Komiyama T 《Applied microbiology and biotechnology》2011,90(2):553-564
Phage-display and competitive panning elution leads to the identification of minimum-sized antigen binders together with conventional
antibodies from a mouse cDNA library constructed from HM-1 killer toxin neutralizing monoclonal antibody (nmAb-KT). Antigen-specific
altered camelid-like single-domain heavy chain antibody (scFv K2) and a conventional antibody (scFv K1) have been isolated
against the idiotypic antigen nmAb-KT. The objectives of the study were to examine (1) their properties as compared to conventional
antibodies and also (2) their antifungal activity against different pathogenic and non-pathogenic fungal species. The alternative
small antigen-binder, i.e., the single-domain heavy chain antibody, was originated from a conventional mouse scFv phage library
through somatic hyper-mutation while selection against antigen. This single-domain antibody fragment was well expressed in
bacteria and specifically bound with the idiotypic antigen nmAb-KT and had a high stability and solubility. Experimental data
showed that the binding affinity for this single-domain antibody was 272-fold higher (K
d = 1.07 × 10−10 M) and antifungal activity was three- to fivefold more efficient (IC50 = 0.46 × 10−6 to 1.17 × 10−6 M) than that for the conventional antibody (K
d = 2.91 × 10−8 M and IC50 = 2.14 × 10−6 to 3.78 × 10−6 M). The derived single-domain antibody might be an ideal scaffold for anti-idiotypic antibody therapy and the development
of smaller peptides or peptide mimetic drugs due to their less complex antigen-binding site. We expect that such single-domain
synthetic antibodies will find their way into a number of biotechnological or medical applications. 相似文献
19.
DNA methyltransferase 1 (DNMT1) is an emerging target for the treatment of cancer, brain disorders, and other diseases. Currently,
there are only a few DNMT1 inhibitors with potential application as therapeutic agents or research tools. 5,5-Methylenedisalicylic
acid is a novel scaffold previously identified by virtual screening with detectable although weak inhibitory activity of DNMT1
in biochemical assays. Herein, we report enzyme inhibition of a structurally related compound, trimethylaurintricarboxylic
acid (NSC97317) that showed a low micromolar inhibition of DNMT1 (IC50 = 4.79 μM). Docking studies of the new inhibitor with the catalytic domain of DNMT1 suggest that NSC97317 can bind into the
catalytic site. Interactions with amino acid residues that participate in the mechanism of DNA methylation contribute to the
binding recognition. In addition, NSC97317 had a good match with a structure-based pharmacophore model recently developed
for inhibitors of DNMT1. Trimethylaurintricarboxylic acid can be a valuable biochemical tool to study DNMT1 inhibition in
cancer and other diseases related to DNA methylation. 相似文献
20.
Mary Chebib Navnath Gavande Kit Yee Wong Anna Park Isabella Premoli Kenneth N. Mewett Robin D. Allan Rujee K. Duke Graham A. R. Johnston Jane R. Hanrahan 《Neurochemical research》2009,34(10):1704-1711
GABAC receptors play a role in myopia, memory-related disorders and circadian rhythms signifying a need to develop potent and selective
agents for this class of receptors. Guanidino analogs related to glycine, β-alanine and taurine were evaluated at human ρ1GABAC receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. Of the 12 analogs tested, 8 analogs were active as antagonists and the remaining
were inactive. (S)-2-Guanidinopropionic acid (IC50 = 2.2 μM) and guanidinoacetic acid (IC50 = 5.4 μM; K
B = 7.75 μM [pK
B = 5.11 ± 0.06]) were the most potent being competitive antagonists at this receptor. In contrast, the β-alanine and GABA
guanidino analogs showed reduced activity, indicating the distance between the carboxyl carbon and terminal nitrogen of the
guanidino group is critical for activity. Substituting the C2-position of guanidinoacetic acid with various alkyl groups reduced
activity indicating that steric effects may impact on activity. The results of this study contribute to the structure–activity-relationship
profile required in developing novel therapeutic agents. 相似文献