scholarly journals Potential Antidiabetic Effects of Extracts from Four Medicinal Plants Used in Burkina Faso by Inhibition of Alpha-Amylase

Diabetology ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 250-258
Author(s):  
Judith N. Semporé ◽  
Mamounata Diao ◽  
Lassina Ouattara ◽  
Paulin Ouoba ◽  
Windmi Kagambega ◽  
...  
Keyword(s):  
Plant Extracts ◽  
Competitive Inhibition ◽  
Inhibitory Effect ◽  
Rice Starch ◽  
Inhibitory Effects ◽  
Sclerocarya Birrea ◽  
Dependent Inhibition ◽  
Phytochemical Compounds ◽  
Dose Dependent Inhibition ◽  
Liquid Fractionation

Background: The purpose of this study was to evaluate α-amylase inhibitory effects of hydroethanolic extracts of bark from Daniella oliveri, Sclerocarya birrea, Maranthes polyandra, and Pteleopsis suberosa to fight type-II diabetes. Methods: Compound extractions were performed by hydroethanol maceration followed by liquid-liquid fractionation with solvents. TLC profiling was carried out with different fractions. The inhibitory effects of plant extracts on α-amylase activity were determined using rice starch as a substrate. Results: TLC profiling of different fractions showed different phytochemical compounds. The hydroethanolic plant extracts exhibited dose-dependent inhibition of α-amylase. D. oliveri displayed competitive inhibition, M. polyandra and S. birrea showed uncompetitive inhibition and Pteleopsis suberosa exerted mixed-inhibition. M. polyandra extract exerted the highest inhibitory effect (IC50 = 0.5 mg/mL). Conclusions: The barks of M. polyandra exhibit a remarkable α-amylase inhibitory effect which can be a novel source of antidiabetic molecules.

FSH-induced aromatase activity in porcine granulosa cells: non-competitive inhibition by non-aromatizable androgens

1986 ◽  
Vol 108 (3) ◽  
pp. 335-341 ◽  
Author(s):  
W. K. Chan ◽  
C. H. Tan
Keyword(s):  
Induction Period ◽  
Granulosa Cells ◽  
Competitive Inhibition ◽  
Inhibitory Effect ◽  
Reciprocal Relationship ◽  
Test Period ◽  
Aromatase Activity ◽  
Porcine Granulosa Cells ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition

ABSTRACT The aim of this study was to examine the inhibitory effect of the non-aromatizable androgens on FSH-stimulated aromatase activity in porcine granulosa cells. The cells were isolated from medium-sized follicles (4–6 mm) of prepubertal pigs, and cultured under chemically defined conditions in the presence of FSH (1 μg/ml, NIADDK-oFSH-S13) with and without the androgens for an initial 48-h induction period. Subsequently, the spent medium was replaced with fresh medium containing only testosterone as substrate and the cells were reincubated for a further 6 h. The conversion of this steroid to oestradiol-17β during this latter 'test' period was taken as a measure of the aromatase activity. The addition of 5α-dihydrotestosterone (DHT) into cultures of FSH-stimulated cells during the induction period resulted in a definite dose-dependent inhibition (30–70%) of the aromatase activity expressed in the test period. This inhibitory action, of the mixed non-competitive type, is characterized by a decrease in the apparent Vmax and an increase in the Km value, suggestive of an androgen inhibition of FSH-stimulated aromatase synthesis. This inhibition was also shown by the other 5α- and 5β-reduced androgens: 5β-androstanedione was the most effective, while DHT was the least. Other steroids such as pregnenolone and progesterone were inhibitory, but testosterone and diethylstilboestrol were stimulatory. These results suggest an important mechanism for the intrafollicular control of oestrogen synthesis, involving a possible reciprocal relationship between aromatase and 5α-reductase activities. J. Endocr. (1986) 108, 335–341

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.

Inhibition of Yeast Growth by Tryptamine and Recovery with Tryptophan

2020 ◽  
Vol 16 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Chandrika Kadkol ◽  
Ian Macreadie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Competitive Inhibition ◽  
Yeast Species ◽  
Inhibitory Effect ◽  
The Body ◽  
Inhibitory Effects ◽  
Trna Synthetases ◽  
Fermentative Growth ◽  
Biogenic Monoamine

Background: Tryptamine, a biogenic monoamine that is present in trace levels in the mammalian central nervous system, has probable roles as a neurotransmitter and/or a neuromodulator and may be associated with various neuropsychiatric disorders. One of the ways tryptamine may affect the body is by the competitive inhibition of the attachment of tryptophan to tryptophanyl tRNA synthetases. Methods: This study has explored the effects of tryptamine on growth of six yeast species (Saccharomyces cerevisiae, Candida glabrata, C. krusei, C. dubliniensis, C. tropicalis and C. lusitaniae) in media with glucose or ethanol as the carbon source, as well as recovery of growth inhibition by the addition of tryptophan. Results: Tryptamine was found to have an inhibitory effect on respiratory growth of all yeast species when grown with ethanol as the carbon source. Tryptamine also inhibited fermentative growth of Saccharomyces cerevisiae, C. krusei and C. tropicalis with glucose as the carbon source. In most cases the inhibitory effects were reduced by added tryptophan. Conclusion: The results obtained in this study are consistent with tryptamine competing with tryptophan to bind mitochondrial and cytoplasmic tryptophanyl tRNA synthetases in yeast: effects on mitochondrial and cytoplasmic protein synthesis can be studied as a function of growth with glucose or ethanol as a carbon source. Of the yeast species tested, there is variation in the sensitivity to tryptamine and the rescue by tryptophan. The current study suggests appropriate yeast strains and approaches for further studies.

Human kidney 11β-hydroxysteroid dehydrogenase: regulation by adrenocorticotropin?

1996 ◽  
Vol 134 (3) ◽  
pp. 301-307 ◽  
Author(s):  
S Diederich ◽  
M Quinkler ◽  
K Miller ◽  
P Heilmann ◽  
M Schöneshöfer ◽  
...  
Keyword(s):  
Human Kidney ◽  
Kinetic Studies ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effect ◽  
Benjamin Franklin ◽  
Dependent Inhibition ◽  
Direct Inhibitory Effect ◽  
Dose Dependent Inhibition ◽  
Endogenous Substrates ◽  
Radioactive Detection

Diederich S, Quinkler M, Miller K, Heilmann P, Schöneshöfer M, Oelkers W. Human kidney 11βhydroxysteroid dehydrogenase: regulation by adrenocorticotropin? Eur J Endocrinol 1996;134:301–7. ISSN 0804–4643 In ectopic adrenocorticotropin (ACTH) syndrome (EAS) with higher ACTH levels than in pituitary Cushing's syndrome and during ACTH infusion, the ratio of cortisol to cortisone in plasma and urine is increased, suggesting inhibition of renal 11β-hydroxysteroid dehydrogenase (11β-HSD) by ACTH or by ACTH-dependent steroids. Measuring the conversion of cortisol to cortisone by human kidney slices under different conditions, we tested the possibility of 11β-HSD regulation by ACTH and corticosteroids. Slices prepared from unaffected parts of kidneys removed because of renal cell carcinoma were incubated with unlabeled or labeled cortisol, and cortisol and cortisone were quantitated after HPLC separation by UV or radioactive detection. The 11β-HSD activity was not influenced by incubation with increasing concentrations (10−12–10−9 mol/l) of ACTH (1–24 or 1–39) for 1 h. Among 12 ACTH-dependent steroids tested (10−9–10−6 mol/l), only corticosterone (IC50 = 2 × 10−7 mol/l), 18-OH-corticosterone and 11βOH-androstenedione showed a significant dose-dependent inhibition of 11β-HSD activity. The percentage conversion rate of cortisol to cortisone was concentration dependent over the whole range of cortisol concentrations tested (10−8–10−5 mol/l). A direct inhibitory effect of ACTH on 11β-HSD is, therefore, unlikely. The only steroids inhibiting the conversion of cortisol to cortisone are natural substrates for 11β-HSD Kinetic studies show a saturation of the enzyme at high cortisol concentrations. Thus, the reduced percentage renal cortisol inactivation in EAS seems to be due mainly to overload of the enzyme with endogenous substrates (cortisol, corticosterone and others) rather than to direct inhibition of 11β-HSD by ACTH or ACTHdependent steroids, not being substrates of 11β-HSD. S Diederich, Department of Endocrinology, Klinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany

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.

Nickel inhibits endothelin-induced contractions of vascular smooth muscle

1990 ◽  
Vol 258 (6) ◽  
pp. C1025-C1030 ◽  
Author(s):  
K. Blackburn ◽  
R. F. Highsmith
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Isometric Force ◽  
Inhibitory Effect ◽  
Rat Aorta ◽  
Porcine Coronary Artery ◽  
Force Development ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

Endothelin (ET)-induced contractions of vascular smooth muscle (VSM) are dependent on extracellular Ca2+ yet display only partial sensitivity to L-type Ca2+ antagonists. The purpose of this study was to evaluate the effect of nickel (Ni2+), a Ca2+ channel antagonist with clearly documented differential potency toward L- vs. T-type Ca2+ currents on ET-mediated contractions in VSM. Treatment of rings of left anterior descending porcine coronary artery (LAD) with Ni2+ produced a profound dose-dependent inhibition of isometric force development in response to porcine ET (ET-1). At a concentration of 360 microM, Ni2+ exerted a significant inhibitory effect on contracture in response to doses of ET-1 ranging from 3 to 100 nM. In contrast, the same concentration of Ni2+ failed to significantly affect peak force development in response to KCl depolarization (5-77 mM) or to phenylephrine (0.3-30 mM). In addition, 360 microM Ni2+ significantly inhibited the contractile response of rat aorta to 10 nM ET-1. We conclude that ET-1 activates a Ni2(+)-sensitive process in VSM which may signal an additional Ca2+ influx pathway that appears to be functionally distinct from the L-type Ca2+ channel.

Sodium cromoglycate: evidence of tachykinin antagonist activity in the human skin

1993 ◽  
Vol 75 (1) ◽  
pp. 167-172 ◽  
Author(s):  
D. C. Crossman ◽  
M. R. Dashwood ◽  
G. W. Taylor ◽  
R. Wellings ◽  
R. W. Fuller
Keyword(s):  
Sodium Cromoglycate ◽  
Human Skin ◽  
High Performance ◽  
Gel Filtration ◽  
Inhibitory Effect ◽  
Intradermal Injection ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Dose Dependent

The mechanism of action of the antiasthmatic drug sodium cromoglycate (SCG) is unclear. One possibility is that SCG antagonizes the effects of the tachykinin substance P (SP), an agent known to cause airway edema. However, when SP is inhaled by humans, it has no demonstrable effect on airway function; therefore, the possibility that SCG prevents SP-induced changes in microvascular permeability was examined in human skin in vivo where potent edema-producing effects are seen. SCG (5–500 nmol) caused significant (P < 0.05) dose-dependent inhibition of SP-induced edema (wheal) formation when coadministered by intradermal injection. There was no effect on the nonreceptor-mediated flare response. SCG also significantly (P < 0.05) inhibited the wheal response to the related tachykinin neurokinin B but had no inhibitory effect on the cutaneous responses to histamine and prostaglandin E2. In addition, SCG (0.1–10 mM) caused dose-dependent inhibition of binding of SP labeled with 125I-labeled Bolton-Hunter to a number of tissues known to contain SP binding sites, as assessed by autoradiography. These concentrations were equivalent to the final concentrations of SCG found to inhibit the wheal response in the skin. The possibility that SCG interacted with SP was investigated both by gel filtration and high-performance liquid chromatography. No strong interaction was demonstrated with an 8,000 M excess of SCG under both hydrophobic and hydrophilic conditions. These results raise the possibility that SCG may have tachykinin antagonist properties.

Apolipoprotein AIV: a potent endogenous inhibitor of lipid oxidation

1998 ◽  
Vol 274 (5) ◽  
pp. H1836-H1840 ◽  
Author(s):  
Xiaofa Qin ◽  
Debi K. Swertfeger ◽  
Shuqin Zheng ◽  
David Y. Hui ◽  
Patrick Tso
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Inhibitory Effect ◽  
Lipoprotein Oxidation ◽  
Atherogenic Lipid Profile ◽  
Dependent Inhibition ◽  
Dose Dependent Inhibition ◽  
Endogenous Antioxidant ◽  
Knockout Animals

Overexpression of apolipoprotein (apo) AIV in transgenic mice confers significant protection against atherosclerosis in apoE knockout animals even in the presence of a more severe atherogenic lipid profile. Because lipoprotein oxidation has been recognized to be pivotal in development of atherosclerosis, the antioxidative activity of apoAIV was investigated. Fasting intestinal lymph was used to mimic conditions in the interstitial fluid, the potential site for lipoprotein oxidation in vivo. ApoAIV (10 μg/ml) significantly inhibited copper-mediated oxidation of lymph. This inhibitory effect was further evaluated using purified low-density lipoprotein. Addition of apoAIV (2.5 μg/ml) increased the time of 50% conjugated diene formation by 2.4-fold, whereas apoE or BSA did not show such a protection even at 20 μg/ml. Addition of apoAIV during the propagation phase also resulted in a dose-dependent inhibition. ApoAIV also protected macrophage-induced oxidation of fasting lymph. These results provide the first evidence that apoAIV is a potent endogenous antioxidant.

Inhibition of Tyrosinase by Protocatechuic Aldehyde

2004 ◽  
Vol 32 (01) ◽  
pp. 97-103 ◽  
Author(s):  
Jae Kyung No ◽  
Min Sun Kim ◽  
You Jung Kim ◽  
Song Ja Bae ◽  
Jae Sue Choi ◽  
...  
Keyword(s):  
Competitive Inhibition ◽  
Salvia Miltiorrhiza ◽  
Inhibitory Effect ◽  
Tyrosinase Activity ◽  
Medical Problems ◽  
Melanin Biosynthesis ◽  
Rate Limiting Step ◽  
Protocatechuic Aldehyde ◽  
Dependent Inhibition ◽  
Potent Inhibitory Effect

The purpose of this study was to determine the inhibitory action of protocatechuic aldehyde (PCA) on tyrosinase activity. PCA is one of the compounds found in the root of Salvia miltiorrhiza. Our study documented that PCA has a potent inhibitory effect on tyrosinase, which catalyzes the rate-limiting step of melanin biosynthesis. Although melanin biosynthesis has an essential function normally in human skin for defense against ultraviolet light of the sun, its abnormal activity as seen in pigmentation disorder could lead to serious medical problems. Our data showed that PCA, with concentrations ranging from 1×10-5 M to 8×10-5 M , exhibited dose-dependent inhibition of the enzyme activity with 50% of inhibition at 19.92×10-6 M . A further kinetic analysis on PCA inactivation of tyrosinase activity revealed a competitive inhibition of the enzyme at the L-tyrosine binding site. The findings of our present study merit further research on the applicability of PCA as a potential agent for treatment of pigmentation disorder.

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