scholarly journals Discovery of five HIV nucleoside analog reverse-transcriptase inhibitors (NRTIs) as potent inhibitors against the RNA-dependent RNA polymerase (RdRp) of SARS-CoV and 2019-nCoV

2020 ◽  
Author(s):  
Jialei Sun
Keyword(s):  
Rna Polymerase ◽  
Polymerase Activity ◽  
Inhibitory Effects ◽  
Rna Dependent Rna Polymerase ◽  
Nucleotide Analogs ◽  
Dependent Inhibition ◽  
Catalytic Metal ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
Low Activity

AbstractThe outbreak of SARS in 2002-2003 caused by SARS-CoV, and the pandemic of COVID-19 in 2020 caused by 2019-nCoV (SARS-CoV-2), have threatened human health globally and raised the urgency to develop effective antivirals against the viruses. In this study, we expressed and purified the RNA-dependent RNA polymerase (RdRp) nsp12 of SARS-CoV and developed a primer extension assay for the evaluation of nsp12 activity. We found that nsp12 could efficiently extend single-stranded RNA, while having low activity towards double-stranded RNA. Nsp12 required a catalytic metal (Mg2+ or Mn2+) for polymerase activity and the activity was also K+-dependent, while Na+ promoted pyrophosphorylation, the reverse process of polymerization. To identify antivirals against nsp12, a competitive assay was developed containing 4 natural rNTPs and a nucleotide analog, and the inhibitory effects of 24 FDA-approved nucleotide analogs were evaluated in their corresponding active triphosphate forms. Ten of the analogs, including 2 HIV NRTIs, could inhibit the RNA extension of nsp12 by more than 40%. The 10 hits were verified which showed dose-dependent inhibition. In addition, the 24 nucleotide analogs were screened on SARS-CoV primase nsp8 which revealed stavudine and remdesivir were specific inhibitors to nsp12. Furthermore, the 2 HIV NRTIs were evaluated on 2019-nCoV nsp12 which showed inhibition as well. Then we expanded the evaluation to all 8 FDA-approved HIV NRTIs and discovered 5 of them, tenofovir, stavudine, abacavir, zidovudine and zalcitabine, could inhibit the RNA extension by nsp12 of SARS-CoV and 2019-nCoV. In conclusion, 5 FDA-approved HIV NRTIs inhibited the RNA extension by nsp12 and were promising candidates for the treatment of SARS and COVID-19.

scholarly journals Effects of cigarette smoke and its constituents on the adherence of polymorphonuclear leukocytes

1980 ◽  
Vol 29 (3) ◽  
pp. 1096-1101
Author(s):  
R B Bridges ◽  
L Hsieh ◽  
D G Haack
Keyword(s):  
Cigarette Smoke ◽  
Water Soluble ◽  
Inhibitory Effects ◽  
Partial Protection ◽  
Nylon Fiber ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
In Vitro Effects ◽  
Dose Dependent

The in vitro effects of the water-soluble fraction of whole cigarette smoke (WSF) and two alpha, beta-unsaturated aldehydes of cigarette smoke (acrolein and crotonaldehyde) on polymorphonuclear leukocyte (PMNL) adherence were determined with nylon fiber columns. Each of these cigarette smoke constituents caused a dose-dependent inhibition of PMNL adherence. However, at least fivefold higher concentrations of these agents were necessary to inhibit adherence as compared with those necessary to achieve the same level of inhibition of PMNL chemotaxis. Furthermore, inhibition of adherence by WSF could be differentiated from its effects on chemotaxis in that reduced glutathione completely protected chemotaxis from the effects of WSF but only afforded partial protection to PMNL adherence. These data suggest that the inhibitory effects of WSF, acrolein, and crotonaldehyde on PMNL chemotaxis are not due to their inhibition of adherence. Finally, although PMNL adherence is considered to be an integral part of the chemotactic mechanism, differentiation between these two PMNL functions may be possible, since some inhibitors of chemotaxis do not have corresponding inhibitory effects on adherence.

Comparison of the inhibitory effects of PYY(3-36) and PYY(1-36) on gastric emptying in rats

2004 ◽  
Vol 287 (5) ◽  
pp. R1064-R1070 ◽  
Author(s):  
Prasanth K. Chelikani ◽  
Alvin C. Haver ◽  
Roger D. Reidelberger
Keyword(s):  
Gastric Emptying ◽  
Intravenous Infusion ◽  
Peptide Yy ◽  
Molecular Forms ◽  
Inhibitory Effects ◽  
Dependent Inhibition ◽  
Order Of Magnitude ◽  
Dose Dependent Inhibition ◽  
Dose Dependent ◽  
The Brain

We compared the effects of the two molecular forms of the brain-gut peptide YY (PYY), PYY(1-36) and PYY(3-36), on gastric emptying. Unanesthetized rats received 20-min intravenous infusions of rat PYY(1-36) (0, 1.7, 5, 17, 50, 100, 170 pmol·kg−1·min−1) and rat PYY(3-36) (0, 0.5, 1.7, 5, 17, 50, 100, 170 pmol·kg−1·min−1), either alone or combined, and gastric emptying of saline was measured during the last 10 min of infusion. For comparison, human PYY(3-36) was administered at 0, 17, and 50 pmol·kg−1·min−1. Gastric emptying was decreased by 11, 24, 26 and 38% in response to 17, 50, 100, and 170 pmol·kg−1·min−1 of rat PYY(1-36); by 10, 26, 41, 53, and 57% in response to 5, 17, 50, 100, and 170 pmol·kg−1·min−1 of rat PYY(3-36); and by 35 and 53% in response to 17 and 50 pmol·kg−1·min−1 of human PYY(3-36), respectively. Estimated ED50s were 470 and 37 pmol·kg−1·min−1 for rat PYY(1-36) and PYY(3-36), respectively. In general, within an experiment, coadministration of PYY(1-36) and PYY(3-36) inhibited gastric emptying by an amount that was comparable to that produced when either peptide was given alone. We conclude that 1) intravenous infusion of PYY(1-36) and PYY(3-36) each produces a dose-dependent inhibition of gastric emptying in rats, 2) PYY(3-36) is an order of magnitude more potent than PYY(1-36) in inhibiting gastric emptying, 3) human PYY(3-36) and rat PYY(3-36) inhibit gastric emptying similarly, and 4) PYY(1-36) and PYY(3-36) do not appear to interact in an additive or synergistic manner to inhibit gastric emptying.

scholarly journals Effects of adenosine, 2-deoxyadenosine and N6-phenylisopropyladenosine on rat islet function and metabolism

1982 ◽  
Vol 204 (3) ◽  
pp. 689-696 ◽  
Author(s):  
Iain L. Campbell ◽  
Keith W. Taylor
Keyword(s):  
Cyclic Amp ◽  
Insulin Release ◽  
Biological Effects ◽  
Insulin Biosynthesis ◽  
Inhibitory Effects ◽  
Marked Inhibition ◽  
Cyclic Amp Accumulation ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Adenosine (1.0–100 μm). N6-phenylisopropyladenosine (0.1–10 μm) and 2-deoxyadenosine (10 mm) all produced a dose-dependent inhibition of glucose-stimulated insulin release. The inhibition of glucose-stimulated insulin release by adenosine and N6-phenylisopropyladenosine was abolished by 3-isobutyl-1-methylxanthine (0.1 mm), whereas 2-deoxyadenosine inhibited insulin release even in the presence of 3-isobutyl-1-methylxanthine. These adenosine nucleosides also inhibited the release of insulin induced by 4-methyl-2-oxopentanoate (20 mm), dl-glyceraldehyde (30 mm) and l-leucine (20 mm). Adenosine (10 μm). N6-phenylisopropyladenosine (10 μm) and 2-deoxyadenosine (10 mm) did not inhibit insulin biosynthesis or [U-14C]glucose oxidation at concentrations of the nucleosides that gave maximal inhibition of insulin release. However, adenosine, 2-deoxyadenosine and N6-phenylisopropyladenosine produced marked inhibition of the glucose-stimulated increases seen in islet cyclic AMP accumulation. Similar to its effects on insulin release, 3-isobutyl-1-methylxanthine (0.1 mm) antagonized the inhibitory effects of cyclic AMP accumulation produced by adenosine and N6-phenylisopropyladenosine, but had no effect on the inhibition of cyclic AMP accumulation seen with 2-deoxyadenosine. These results show that adenosine and its specifically modified analogues, 2-deoxyadenosine and N6-phenylisopropyladenosine, are strong inhibitors of insulin release from rat islets, a function that appears to be the consequence of their ability to inhibit the accumulation of cyclic AMP. It is proposed that the B cells, in common with many other tissues, may possess two different sites at which adenosine nucleosides interact to produce their biological effects; these are the so-called ‘P’ and ‘R’ sites first described by Londos & Wolff [(1977) Proc. Natl. Acad. Sci. U.S.A.74, 5482–5486].

Effects of leukotriene C4 on pancreatic secretion and circulation in dogs

1988 ◽  
Vol 254 (6) ◽  
pp. G849-G855
Author(s):  
S. J. Konturek ◽  
W. Pawlik ◽  
K. Czarnobilski ◽  
P. Gustaw ◽  
J. Jaworek ◽  
...  
Keyword(s):  
Pancreatic Secretion ◽  
Pancreatic Tissue ◽  
Leukotriene C4 ◽  
Inhibitory Effects ◽  
Maximal Inhibition ◽  
Control Value ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Protein Output ◽  
Dose Dependent

In the present study the effects of leukotriene C4 (LTC4) on exocrine pancreatic secretion and pancreatic blood flow were determined. LTC4 given intravenously in various doses ranging from 0.35 to 2.8 nmol.kg-1.h-1 in conscious dogs caused a dose-dependent inhibition of pancreatic HCO-3 and protein responses to exogenous hormones such as secretin, cholecystokinin octapeptide (CCK-8), and bombesin and to endogenous stimulants including meat feeding and duodenal perfusion with oleate. In tests with pancreatic secretion induced by secretin plus CCK, maximal inhibition by LTC4 occurred at a dose of 1.4 nmol.kg-1.h-1 and reached approximately 70% of the control value for HCO-3 output and 45% for protein output. In tests with separate secretin- or CCK-induced secretion, maximal inhibition occurred at a dose of 1.4 nmol.kg-1.h-1 and reached 38 and 66% of the control HCO-3 and protein secretion, respectively. The same dose of LTC4 reduced the postprandial HCO-3 secretion by approximately 80% and protein output by approximately 70%. After administration of indomethacin, the pancreatic secretion declined, but the inhibitory effects of LTC4 remained unchanged. Pancreatic tissue generated two to three times more LTC4 than the gastrointestinal mucosa, and indomethacin caused further increase in this generation, suggesting that LTC4 may contribute to indomethacin-induced pancreatic inhibition. (ABSTRACT TRUNCATED AT 250 WORDS)

Direct antigonadal activity of cannabinoids: suppression of rat granulosa cell functions

1983 ◽  
Vol 244 (2) ◽  
pp. E177-E185 ◽  
Author(s):  
E. Y. Adashi ◽  
P. B. Jones ◽  
A. J. Hsueh
Keyword(s):  
Granulosa Cells ◽  
Plasma Concentrations ◽  
Concomitant Treatment ◽  
Human Beings ◽  
Inhibitory Effects ◽  
Cell Functions ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

The direct effects of delta 9-tetrahydrocannabinol (THC) and related cannabinoids on ovarian granulosa cells were studied in vitro. Granulosa cells from immature, hypophysectomized, estrogen-treated rats were cultured for 2 days in an androstenedione-supplemented medium in the presence or absence of follicle-stimulating hormone (FSH) (10 ng/ml) with or without cannabinoids. FSH treatment increased progesterone and estrogen biosynthesis, whereas concomitant treatment with THC led to a dose-dependent inhibition of the FSH-stimulated accumulation of progesterone and estrogen with ED50 values of 3.5 +/- 0.3 X 10(-7) and 1.8 +/- 0.2 X 10(-6) M, respectively. Treatment with related but nonpsychoactive cannabinoids (cannabidiol, cannabinol, cannabigerol, or cannabichromene) was equally effective. The THC-induced inhibition of progesterone production was reversible and was associated with an inhibition of pregnenolone biosynthesis and a decrease of 3 beta-hydroxysteroid dehydrogenase activity. In addition, treatment with THC brought about a dose-dependent inhibition of the FSH-induced increase in luteinizing hormone (LH) receptors. The inhibitory effects of THC were not associated with changes in cell number, protein content, or cell viability. Thus, THC exerts direct inhibitory effects on FSH-dependent functions related to steroidogenesis and the acquisition of LH receptors, all of which are essential to follicular maturation. Because plasma concentrations of THC similar to those used in this study have been reported in human beings, repeated exposure of female users to THC may lead to ovarian dysfunction, due in part, to the direct antigonadal activity to THC.

Neurokinin inhibition of cholinergic myenteric neurons in canine antrum

1990 ◽  
Vol 258 (1) ◽  
pp. G122-G128 ◽  
Author(s):  
E. A. Mayer ◽  
C. B. Koelbel ◽  
W. J. Snape ◽  
G. Vandeventer ◽  
L. Leduc
Keyword(s):  
Myenteric Plexus ◽  
Electrical Field Stimulation ◽  
Neurokinin A ◽  
Inhibitory Effects ◽  
Ach Release ◽  
Myenteric Neurons ◽  
Receptor Agonists ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Neurokinins regulate gastrointestinal motility by interacting with receptors on both muscle layers and on myenteric plexus neurons. To determine if specific neurokinin (NK) receptor agonists can mediate inhibitory effects on myenteric neurons, we studied the effect of the NK-1 agonist substance P methylester (SPME) and the putative endogenous NK-2 receptor ligand neurokinin A (NKA) on [3H]acetylcholine [( 3H]ACh) release induced by electrical field stimulation from muscle strips cut from the canine gastric antrum. SPME but not NKA caused a dose-dependent inhibition of stimulated [3H]ACh release in tissues containing the myenteric plexus. The inhibition was not seen in longitudinal muscle without myenteric plexus. Pretreatment of tissues with indomethacin or antiserum to vasoactive intestinal polypeptide (VIP) but not naloxone or adrenergic or cholingergic blockade abolished the SPME-induced inhibition. Exogenous VIP stimulated the release of prostaglandin E2 (PGE2) from full thickness strips, and both VIP and PGE2 inhibited [3H]ACh release induced by electrical depolarization. These findings suggest that NK-1 receptor agonists can selectively inhibit stimulated [3H]ACh release and that this inhibition may involve the release of VIP and PGE2 from neurons within the myenteric plexus.

Dopaminergic modulation of respiratory motor output in peripherally chemodenervated goats

1998 ◽  
Vol 85 (3) ◽  
pp. 946-954 ◽  
Author(s):  
Ken D. O’Halloran ◽  
Patrick L. Janssen ◽  
Gerald E. Bisgard
Keyword(s):  
Carotid Body ◽  
Inhibitory Effect ◽  
Motor Output ◽  
High Dose ◽  
Inhibitory Effects ◽  
Before And After ◽  
Ventilatory Effect ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

We examined the ventilatory effects of exogenous dopamine (DA) and norepinephrine (NE) administration in chloralose-anesthetized, paralyzed, artificially ventilated adult goats before and after carotid body denervation (CBD). Intravenous (iv) DA bolus injections and slow iv infusions caused dose-dependent inhibition of phrenic nerve activity (PNA) in carotid body (CB)-intact animals during normoxia and hyperoxia but not during hypercapnia. NE administration in CB-intact goats caused dose-dependent inhibition of PNA of similar magnitude to DA trials. The DA D2-receptor agonists quinelorane and quinpirole inhibited PNA, whereas the DA D1-receptor agonist SKF-81297 had no effect. After CBD, the ventilatory depressant effects of DA persisted, but responses were significantly attenuated compared with CB-intact trials. CBD abolished the inhibitory effect of low-dose NE administration but did not alter ventilatory responses to high-dose NE injection. The peripheral DA D2-receptor antagonist domperidone substantially attenuated the inhibitory effects of DA bolus injections and infusions and reversed the inhibitory ventilatory effect of high-dose DA administration to excitation in some animals. The α-adrenoceptor antagonist phentolamine had no effect on DA-induced ventilatory depression. β-Adrenoceptor stimulation with isoproterenol produced similar hemodynamic effects to DA administration but had no effect on PNA. We conclude that DA and NE exert both CB-mediated and non-CB-mediated inhibitory effects on respiratory motor output in anesthetized goats. The ventilatory depressant effects that persist in peripherally chemodenervated animals are DA D2-receptor mediated, but their exact location remains speculative.

scholarly journals Ethanol Extract ofAlismatis rhizomeInhibits Adipocyte Differentiation of OP9 Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yeon-Ju Park ◽  
Mi-Seong Kim ◽  
Ha-Rim Kim ◽  
Jeong-Mi Kim ◽  
Jin-Ki Hwang ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Adipocyte Differentiation ◽  
Ethanol Extract ◽  
Clonal Expansion ◽  
Inhibitory Effects ◽  
Alisma Orientale ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Mitotic Clonal Expansion ◽  
Dose Dependent

The rhizome ofAlisma orientale (Alismatis rhizome)has been used in Asia for promoting diuresis to eliminate dampness from the lower-jiaoand to expel heat. In this study, an ethanol extract of the rhizome ofAlisma orientale(AOE) was prepared and its effects on adipocyte differentiation of OP9 cells were investigated. Treatment with AOE in a differentiation medium for 5 days resulted in dose-dependent inhibition of lipid droplet formation in OP9 cells. Furthermore, AOE significantly inhibited adipocyte differentiation by downregulating the expression of the master transcription factor of adipogenesis, peroxisome proliferation-activity receptorγ(PPARγ), and related genes, including CCAAT/enhancer binding proteinβ(C/EBPβ), fatty acid-binding protein (aP2), and fatty acid synthase (FAS). AOE exerted its inhibitory effects primarily during the early adipogenesis stage (days 1-2), at which time it also exerted dose-dependent inhibition of the expression of C/EBPβ, a protein related to the inhibition of mitotic clonal expansion. Additionally, AOE decreased the expression of autophagy-related proteins, including beclin 1, and the autophagy-related genes, (Atg)7andAtg12. Our results indicate that AOE’s inhibitory effects on adipocyte differentiation of OP9 cells are mediated by reduced C/EBPβexpression, causing inhibition of mitotic clonal expansion and autophagy.

Differences between antigenic determinants of pig and cat zona pellucida proteins

Reproduction ◽  
2000 ◽  
pp. 15-23 ◽  
Author(s):  
K Jewgenow ◽  
M Rohleder ◽  
I Wegner
Keyword(s):  
In Vitro Fertilization ◽  
Zona Pellucida ◽  
Antigenic Determinants ◽  
Vitro Fertilization ◽  
Contraceptive Vaccine ◽  
Sperm Binding ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Despite many efforts, the control of reproduction in feral cat populations is still a problem in urban regions around the world. Immunocontraception is a promising approach; thus the present study examined the suitability of the widely used pig zona pellucida proteins (pZP) for contraception in feral domestic cats. Purified zona pellucida proteins obtained from pig and cat ovaries were used to produce highly specific antisera in rabbits. Antibodies against pZP raised in rabbits or lions were not effective inhibitors of either in vitro sperm binding (cat spermatozoa to cat oocytes) or in vitro fertilization in cats, whereas antibodies against feline zona pellucida proteins (fZP) raised in rabbits showed a dose-dependent inhibition of in vitro fertilization. Immunoelectrophoresis, ELISA and immunohistology of ovaries confirmed these results, showing crossreactivity of anti-fZP sera to fZP and to a lesser extent to pZP, but no interaction of anti-pZP sera with fZP. It is concluded that cat and pig zonae pellucidae express a very small number of shared antigenic determinants, making the use of pZP vaccine in cats questionable. A contraceptive vaccine based on feline zona pellucida determinants will be a better choice for the control of reproduction in feral cats if immunogenity can be achieved.

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