Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches

Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic α-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.

Download Full-text

Novel cholinesterase inhibitory effect of α-spinasterol isolated from the leaves of Acacia auriculiformis A. CUNN Ex. Benth (Fabaceae)

Tropical Journal of Pharmaceutical Research ◽

10.4314/tjpr.v19i7.20 ◽

2020 ◽

Vol 19 (7) ◽

pp. 1473-1479

Author(s):

Bilqis A. Lawal ◽

Aniefiok Udobre ◽

Taiwo O. Elufioye ◽

Augustine A. Ahmadu ◽

Bolatito Olanipekun

Keyword(s):

Ascorbic Acid ◽

Free Radical ◽

Antioxidant Activities ◽

Radical Scavenging ◽

Inhibitory Effect ◽

Free Radical Scavenging ◽

Acacia Auriculiformis ◽

Ic50 Value ◽

Potent Inhibitory Effect

Purpose: To investigate the in vitro anticholinesterase, α-glucosidase and antioxidant activities of α-spinasterol isolated from Acacia auriculiformis leaves.Methods: The powdered leaves of Acacia auriculiformis were extracted with 70 % ethanol and the dried hydroalcoholic extract was suspended in water and partitioned with ethyl acetate and n-butanol to give their soluble fractions. The in vitro inhibitory activities of α-spinasterol were determined against cholinesterase and, α-glucosidase enzymes, and free radical scavenging potentials using (1,1-diphenyl-2-picrylhydarzyl (DPPH) and 2,2-azino-bis (3-Ethylbenzothiazoline-6-sulphonic acid (ABTS) antioxidantassays.Results: The compound, α-spinasterol, exhibited moderate anticholinesterase activity (IC50 value of 44.19±2.59 μg/mL which was significantly different at (p < 0.05) when compared to the standard galanthamine (IC50 value of 1.73 ± 1.10 μg/mL). It also displayed a good α-glucosidase inhibitory activity with IC``` value of 8.65 ± 1.71μg/mL which was not significantly different when compared to the standard, acarbose with IC50 value of 2.79±0.81 μg/mL. This compound, however, exhibited weak free radical scavenging activities at 26.93 ± 0.00 and 35.16 ±.0.26 % inhibition of DPPH+ and ABTS+ radicals as compared to ascorbic acid and Trolox (73.88 ± 0.04 and 99.82 ± 0.00%) respectively.Conclusion: The results show that α-spinasterol isolated from Acacia auriculiformis exerts potent inhibitory effect against cholinesterase enzyme which might serve as a lead in the search for drugs against Alzheimer disease and diabetes mellitus. Keywords: Acacia auriculiformis, α-Spinasterol, Galanthamine, Acarbose, Trolox, Ascorbic acid

Download Full-text

Regulation of Ascorbic acid by gonadotropins in rat Ovary

10.1101/665752 ◽

2019 ◽

Author(s):

Shah Saddad Hussain ◽

Taruna Arora ◽

Madan Mohan Chaturvedi ◽

Sharmila Basu-Modak ◽

Rajesh Chaudhary ◽

...

Keyword(s):

Ascorbic Acid ◽

Specific Activity ◽

Inhibitory Effect ◽

Female Rats ◽

Transcriptional Level ◽

Immature Female ◽

Serum Gonadotropin ◽

Rat Ovary ◽

Dose Dependent

AbstractThe dose dependent depletion of ovarian Ascorbic acid (AA) in rat ovaries, has been used as a bioassay for measurement of Luteinizing Hormone (LH). However, the mechanism of action of gonadotropin (LH, FSH) on ascorbic acid depletion is not completely clear in biochemical terms. To elucidate the mechanism, we looked for the pathways; one, where L-GulonateDehydrogenase (L-GuDH) catalyzes the conversion of L-Gulonic acid (L-GuA) to L-Xylulose, and, in the second the pathway conversion of L-GuA to AA, in a cats, dogs and Rats. Kinetic analysis of the enzyme L-GuDHin vitroshowed the inhibitory effect of AA on L-GuDH. Therefore, we hypothesized that gonadotropins (FSH and LH) may regulate the L-GuDH maintain level of AA in ovary. LH administration to super-ovulated immature female rats caused depletion of ovarian AA but did not result in any change in the specific activity of the ovarian L-GuDH. Further, we administrated a surrogate FSH like hormone (PMSG) to immature female rats which, resulted in increased specific activity of ovarian L-GuDH. However, microarray data on RNA from ovaries exposed to FSH like hormone such as Pregnant Mare serum Gonadotropin (PMSG) did not reveal any increased expression of L-GuDH transcript. It is therefore concluded from the results obtained that; that neither LH, in decreasing the ovarian AA, nor FSH, in increasing the ovarian AA do so by regulating the activity of enzyme L-GuDH at transcriptional level. The results obtained have also been discussed by giving emphasis on the mechanism of ovarian ascorbic acid regulation of LH and FSH.

Download Full-text

In Vitro Effects of Doxycycline on Replication of Feline Coronavirus

Pathogens ◽

10.3390/pathogens10030312 ◽

2021 ◽

Vol 10 (3) ◽

pp. 312

Author(s):

Magdalena Dunowska ◽

Sayani Ghosh

Keyword(s):

Inhibitory Concentration ◽

Infectious Virus ◽

Treatment Options ◽

Inhibitory Effect ◽

Virus Titration ◽

Reverse Transcription Quantitative Pcr ◽

In Vitro Effects ◽

Dose Dependent ◽

Feline Coronavirus

Feline infectious peritonitis (FIP) is a sporadic fatal disease of cats caused by a virulent variant of feline coronavirus (FCoV), referred to as FIP virus (FIPV). Treatment options are limited, and most of the affected cats die or are euthanized. Anecdotally, doxycycline has been used to treat FIP-affected cats, but there are currently no data to support or discourage such treatment. The aim of this study was to establish whether doxycycline inhibits replication of FIPV in vitro. The virus was cultured in Crandell-Rees feline kidney cells with various concentrations of doxycycline (0 to 50 µg/mL). The level of FIPV in cultures was determined by virus titration and FCoV-specific reverse-transcription quantitative PCR. Cell viability was also monitored. There was no difference in the level of infectious virus or viral RNA between doxycycline-treated and untreated cultures at 3, 12- and 18-hours post-infection. However, at 24 h, the growth of FIPV was inhibited by approximately two logs in cultures with >10 µg/mL doxycycline. This inhibition was dose-dependent, with inhibitory concentration 50% (IC50) 4.1 µg/mL and IC90 5.4 µg/mL. Our data suggest that doxycycline has some inhibitory effect on FIPV replication in vitro, which supports future clinical trials of its use for the treatment of FIP-affected cats.

Download Full-text

In vitro study on the effect of cornin on the activity of cytochrome P450 enzymes

BMC Complementary Medicine and Therapies ◽

10.1186/s12906-021-03309-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Qun Zhang ◽

Zengqiang Qu ◽

Yanqing Zhou ◽

Jin Zhou ◽

Junwei Yang ◽

...

Keyword(s):

Cytochrome P450 ◽

Drug Interaction ◽

Liver Microsomes ◽

In Vitro Study ◽

Inhibitory Effect ◽

Dependent Manner ◽

Cytochrome P450 Enzymes ◽

Drug Drug Interaction ◽

Dose Dependent

Abstract Background Cornin is a commonly used herb in cardiology for its cardioprotective effect. The effect of herbs on the activity of cytochrome P450 enzymes (CYP450s) can induce adverse drug-drug interaction even treatment failure. Therefore, it is necessary to investigate the effect of cornin on the activity of CYP450s, which can provide more guidance for the clinical application of cornin. Methods Cornin (100 μM) was incubated with eight isoforms of CYP450s, including CYP1A2, 2A6, 3A4, 2C8, 2C9, 2C19, 2D6, and 2E1, in pooled human liver microsomes. The inhibition model and corresponding parameters were also investigated. Results Cornin exerted significant inhibitory effect on the activity of CYP3A4, 2C9, and 2E1 in a dose-dependent manner with the IC50 values of 9.20, 22.91, and 14.28 μM, respectively (p < 0.05). Cornin inhibited the activity of CYP3A4 non-competitively with the Ki value of 4.69 μM, while the inhibition of CYP2C9 and 2E1 by cornin was competitive with the Ki value of 11.31 and 6.54 μM, respectively. Additionally, the inhibition of CYP3A4 by cornin was found to be time-dependent with the KI/Kinact value of 6.40/0.055 min− 1·μM− 1. Conclusions The inhibitory effect of cornin on the activity of CYP3A4, 2C9, and 2E1 indicated the potential drug-drug interaction between cornin and drugs metabolized by these CYP450s, which needs further investigation and validation.

Download Full-text

Immunomodulatory activities of whey fractions in efferent prefemoral lymph of sheep

Journal of Dairy Research ◽

10.1017/s0022029900031757 ◽

1996 ◽

Vol 63 (2) ◽

pp. 257-267 ◽

Cited By ~ 12

Author(s):

Chun W. Wong ◽

Geoffrey O. Regester ◽

Geoffrey L. Francis ◽

Dennis L. Watson

Keyword(s):

Immune Responses ◽

Bovine Milk ◽

Inhibitory Effect ◽

Dependent Manner ◽

Milk Whey ◽

Significant Difference ◽

Lymphocyte Phenotypes ◽

Dose Dependent

SummaryStudies on the immunomodulatory activities of ruminant milk and colostral whey fractions were undertaken. By comparing with boiled colostral whey in a preliminary experiment, a putative heat-labile immunostimulatory factor for antibody responses was found to be present in ovine colostral whey. Studies were then undertaken in sheep in which the efferent prefemoral lymphatic ducts were cannulated bilaterally, and immune responses in the node were measured following subcutaneous injection in the flank fold of whey protein preparations of various purities. A significant sustained decline of efferent lymphocyte output was observed following injection with autologous crude milk whey or colostral whey preparations, but no changes were observed in interferon-gamma levels in lymph plasma. Two bovine milk whey fractions (lactoperoxidase and lactoferrin) of high purity were compared in bilaterally cannulated sheep. A transient decline over the first 6 h was seen in the efferent lymphocyte output and lymph flow rate after injection of both fractions. A significant difference was seen between the two fractions in interferongamma levels in lymph at 6 h after injection. However, no significant changes in the proportion of the various efferent lymphocyte phenotypes were seen following either treatment. Whereas both fractions showed a significant inhibitory effect in a dose-dependent manner on the proliferative response of T lymphocytes, but not B lymphocytes, to mitogenic stimulation in vitro, no similar changes were seen following in vivo stimulation with these two fractions.

Download Full-text

Mobilization of Fibrinogen Receptor Sites on Human Platelets Stimulated with ADP is Prevented by Prostacyclin

10.1055/s-0039-1687387 ◽

1979 ◽

Author(s):

J. Hawiger ◽

S. Parkinson ◽

S. Timmons

Keyword(s):

Inhibitory Effect ◽

Human Platelets ◽

Affinity Constant ◽

Human Fibrinogen ◽

Fibrinogen Receptor ◽

Receptor Sites ◽

Plasma Factor ◽

Potent Inhibitory Effect

Fibrinogen is a plasma factor required for aggregation of human platelets by ADP. The mechanism of platelet-ADP-fibrinogen interaction was studied by measuring the equilibrium binding of 125I-fibrinogen to human platelets separated from plasma proteins. Binding of 125I-fibrinogen to platelets not stimulated with ADP was low and unaffected by an excess of unlabel led fibrinogen. However, when platelets were stimulated with 4μM of ADP, there was an eightfold increase In the number of available binding sites for human fibrinogen, with affinity constant of 1.9 x 109M-1. This striking increase in fibrinogen receptor sites on human platelets was specific for ADP as contrasted to ATP, AMP, and adenosine. Prostacyclin (Prostaglandin I2, PGI2), a novel prostaglandin produced by the blood vessel wall, completely blocked this ADP-induced increase in fibrinogen receptor sites on human platelets. The effect of PGI2 was prompt and concentration dependent, reaching maximum at 10-9M. 6-keto PGF2 a stable derivative ot PGI2, did not have such an effect. Thus movement of fibrinogen receptor sites on human platelet membrane stimulated with ADP is prevented by PGI2. This represents a new biologic property of this vascular hormone and contributes to better understanding of its potent inhibitory effect in vitro and in vivo on ADP-induced platelet aggregation requiring mobilization of fibrinogen receptor.

Download Full-text

In vitro inhibitory effect of obtusofolin on the activity of CYP3A4, 2C9, and 2E1

BMC Complementary Medicine and Therapies ◽

10.1186/s12906-021-03397-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Na Liu ◽

Ping Chen ◽

Xiaojun Du ◽

Junxia Sun ◽

Shasha Han

Keyword(s):

Human Liver ◽

Competitive Inhibition ◽

Liver Microsomes ◽

Inhibitory Effect ◽

Dependent Manner ◽

Cytochrome P450 Enzymes ◽

Inhibition Model ◽

Dose Dependent

Abstract Background Obtusofolin is the major active ingredient of Catsia tora L., which possesses the activity of improving eyesight and protecting the optic nerve. Investigation on the interaction of obtusofolin with cytochrome P450 enzymes (CYP450s) could provide a reference for the clinical application of obtusofolin. Methods The effect of obtusofolin on the activity of CYP450s was investigated in the presence of 100 μM obtusofolin in pooled human liver microsomes (HLMs) and fitted with the Lineweaver–Burk plots to characterize the specific inhibition model and kinetic parameters. Results Obtusofolin was found to significantly inhibited the activity of CYP3A4, 2C9, and 2E1. In the presence of 0, 2.5, 5, 10, 25, 50, and 100 μM obtusofolin, the inhibition of these CYP450s showed a dose-dependent manner with the IC50 values of 17.1 ± 0.25, 10.8 ± 0.13, and 15.5 ± 0.16 μM, respectively. The inhibition of CYP3A4 was best fitted with the non-competitive inhibition model with the Ki value of 8.82 μM. While the inhibition of CYP2C9 and 2E1 was competitive with the Ki values of 5.54 and 7.79 μM, respectively. After incubating for 0, 5, 10, 15, and 30 min, the inhibition of CYP3A4 was revealed to be time-dependent with the KI value of 4.87 μM− 1 and the Kinact value of 0.0515 min− 1. Conclusions The in vitro inhibitory effect of obtusofolin implying the potential drug-drug interaction between obtusofolin and corresponding substrates, which needs further in vivo validations.

Download Full-text

Long‐term in vitro fermentation of high amylose starch digestion residues by human fecal inocula

The FASEB Journal ◽

10.1096/fasebj.24.1_supplement.720.2 ◽

2010 ◽

Vol 24 (S1) ◽

Author(s):

Li Li ◽

Man‐Yu Yum ◽

Pamela White ◽

Mark Campbell ◽

Suzanne Hendrich

Keyword(s):

Starch Digestion ◽

In Vitro Fermentation ◽

High Amylose

Download Full-text

Ascorbic acid attenuates activation and cytokine production in sepsis-like monocytes

10.1101/2021.04.15.21255504 ◽

2021 ◽

Author(s):

Tobias Schmidt ◽

Robin Kahn ◽

Fredrik Kahn

Keyword(s):

Flow Cytometry ◽

Ascorbic Acid ◽

Cytokine Production ◽

In Vitro Study ◽

Surface Expression ◽

High Dose ◽

Functional Assay ◽

Dependent Manner ◽

Dose Dependent

Objective To investigate the effects of high dose ascorbic acid (AA) on monocyte polarization and cytokine production in vitro Design Experimental in vitro study of cells from healthy subjects and patients with sepsis Setting University research laboratory and academic hospital Subjects Six healthy controls and three patients with sepsis Interventions Monocytes were isolated from whole blood of healthy donors (n=6) and polarized in vitro for 48hrs using LPS or LTA. Polarization was confirmed by surface marker expression using flow cytometry. As a comparison, monocytes were also isolated from septic patients (n=3) and analyzed for polarization markers. The effect of AA on monocyte polarization was evaluated. As a functional assay, AA-treated monocytes were analyzed for cytokine production of TNF and IL-8 by intracellular staining and flow cytometry following activation with LPS or LTA. Measurements and Main Results Both LPS and LTA induced polarization in healthy monocytes in vitro, with increased expression of both pro- (CD40 and PDL1, p<0.05) and anti-inflammatory (CD16 and CD163, p<0.05) polarization markers, with non-significant effects on CD86 and CD206. This pattern resembled, at least partly, that of monocytes from septic patients. Treatment with AA significantly inhibited the upregulation of surface expression of CD16 and CD163 (p<0.05) in a dose dependent manner, but not CD40 or PDL-1. Finally, AA attenuated LPS or LTA-induced cytokine production of IL-8 and TNF in a dose-dependent manner (both p<0.05). Conclusions AA inhibits upregulation of anti-, but not pro-inflammatory related markers in LPS or LTA polarized monocytes. Additionally, AA attenuates cytokine production from in vitro polarized monocytes, displaying functional involvement. This study provides important insight into the immunological effects of high dose AA on monocytes, and potential implications in sepsis.

Download Full-text

Effects of Hydrothermal Treatments on Physicochemical Properties and In Vitro Digestion of Starch

Food Biophysics ◽

10.1007/s11483-021-09687-7 ◽

2021 ◽

Author(s):

Ishita Chakraborty ◽

Indira Govindaraju ◽

Sintu Rongpipi ◽

Krishna Kishore Mahato ◽

Nirmal Mazumder

Keyword(s):

Physicochemical Properties ◽

Water Solubility ◽

Amylose Content ◽

Potato Starch ◽

Brown Rice ◽

Food Products ◽

Enzymatic Digestion ◽

Diabetic Patients ◽

Degree Of Hydrolysis

AbstractStarchy food items such as rice and potato with high carbohydrate content raise blood sugar. Hence, consuming low glycaemic foods is one tool to keep diabetes under control. In this study, potato and brown rice (Njavara rice) starches were subjected to hydrothermal treatments: heat moisture treatment (HMT) and annealing (ANN) to develop starch-based food products fit for consumption by diabetic patients. The effects of hydrothermal treatments on physicochemical properties and in-vitro enzymatic digestion of starch were determined. It was observed that hydrothermal treatments decreased the swelling power (SP)% and increased the water solubility (WS)% of the native starches. Native potato starch (PSN) showed a high SP of 80.33%, while annealed potato starch (PANN) and heat moisture treated potato starch (PHMT) showed SP reduced to 65.33% and 51.66%, respectively. Similarly, the SP % reduced from 64.33% in native brown rice (BRN) to 44.66% in annealed brown rice (BRANN) and 38.33% in heat moisture treated brown rice (BRHMT). WS % increased from 32.86% in PSN to 36.66% in PANN and 40.66% in PHMT. In BRN, the WS % increased from 14.0% to 14.66% in BRANN and 18.33% in BRHMT. Amylose content increased from 13.23% and 14.56% in PSN and BRN to 16.14% in PANN 17.99% in PHMT, 17.33% in BRANN, and 18.98% in BRHMT. The PSN crystallinity index reduced from 33.49 to 30.50% in PANN and 32.60% in PHMT. At 12 h of enzymatic digestion, it was found that the degree of hydrolysis (DoH) of PHMT (31.66%) and PANN (36.82%) reduced when compared to PSN (41.09%). Similarly, BRHMT exhibited the lowest DoH at 12 h compared to BRANN (29.24%) and BRN (35.48%). This study highlights the importance of hydrothermal treatments on starch in developing low glycaemic index commercial starch-based food products.

Download Full-text