scholarly journals The use of Bayesian methodology in the development and validation of a tiered assessment approach towards prediction of rat acute oral toxicity

2022 ◽  
Author(s):  
James W. Firman ◽  
Mark T. D. Cronin ◽  
Philip H. Rowe ◽  
Elizaveta Semenova ◽  
John E. Doe
Keyword(s):  
In Silico ◽  
Oral Toxicity ◽  
New Approach ◽  
Combining Data ◽  
Assessment Approach ◽  
In Vivo Testing ◽  
Degree Of Confidence ◽  
Development And Validation

AbstractThere exists consensus that the traditional means by which safety of chemicals is assessed—namely through reliance upon apical outcomes obtained following in vivo testing—is increasingly unfit for purpose. Whilst efforts in development of suitable alternatives continue, few have achieved levels of robustness required for regulatory acceptance. An array of “new approach methodologies” (NAM) for determining toxic effect, spanning in vitro and in silico spheres, have by now emerged. It has been suggested, intuitively, that combining data obtained from across these sources might serve to enhance overall confidence in derived judgment. This concept may be formalised in the “tiered assessment” approach, whereby evidence gathered through a sequential NAM testing strategy is exploited so to infer the properties of a compound of interest. Our intention has been to provide an illustration of how such a scheme might be developed and applied within a practical setting—adopting for this purpose the endpoint of rat acute oral lethality. Bayesian statistical inference is drawn upon to enable quantification of degree of confidence that a substance might ultimately belong to one of five LD50-associated toxicity categories. Informing this is evidence acquired both from existing in silico and in vitro resources, alongside a purposely-constructed random forest model and structural alert set. Results indicate that the combination of in silico methodologies provides moderately conservative estimations of hazard, conducive for application in safety assessment, and for which levels of certainty are defined. Accordingly, scope for potential extension of approach to further toxicological endpoints is demonstrated.

Screening of Antibiotics against β-amyloid as Anti-amyloidogenic Agents: A Drug Repurposing Approach

2020 ◽  
Vol 16 ◽  
Author(s):  
Jahangir Alam ◽  
Varun Jaiswal ◽  
Lalit Sharma
Keyword(s):  
In Silico ◽  
Docking Simulation ◽  
Drug Repurposing ◽  
In Vitro Assays ◽  
Contagious Diseases ◽  
Main Culprit ◽  
In Vivo Testing ◽  
Β Amyloid

Background: β-amyloid (Aβ) production and aggregation is the main culprit of Alzheimer’s disease (AD). AD is becoming crisis where no treatment available for halting the disease progression. Antibiotics are used not only to treat infections, but also some of the non-contagious diseases and have found active as anti-amyloidogenic agents. Objective: The work aim’s to investigate anti-amyloidogenic activity of antibiotics as re-purposing agents via inhibiting Aβ aggregation and fibril formation employing in-silico and in-vitro approaches. Mehtods: In-silico screening was designed with receptor and ligand preparation, grid formation, docking simulation and its analysis. Thioflavin T-amyloid binding and protease-digestion studies were intended as in-vitro assays. The pharmacological potential of antibiotics as anti-amyloidogenic agents was assessed by these methods. Results: Paromomycin and Neomycin were identified with higher order of estimated free energy of binding in in-silico sreening. In in-vitro screening, paromomycin significantly (p<0.01) reduced the fluorescence intensity and resistance to tryptic degradation of Aβ(1-42) peptides while neomycin had no or little effect (p<0.01) when compared to control. Results from docking and wet lab studies were found in correlation. Conclusion: Paromomycin exhibited higher anti-Aβ aggregating and defibrillogenic activity than neomycin and leaves an indication for further in-vivo testing and could be a future promising anti-amyloidal candidate for the treatment of several amyloidoses.

1,3,4-Thiadiazolo (3,2-Α) Pyrimidine-6-Carbonitrile Scaffold as PARP1 Inhibitors.

2020 ◽  
Vol 21 ◽  
Author(s):  
Elizabeth Eldhose ◽  
Kaviarasan Lakshmanan ◽  
Praveen T. Krishnamurthy ◽  
Kalirajan Rajagopal ◽  
Manal Mohammed ◽  
...  
Keyword(s):  
Anticancer Activity ◽  
In Silico ◽  
Biological Activities ◽  
Docking Study ◽  
Binding Mode ◽  
Oral Toxicity ◽  
Standard Drug ◽  
In Silico Docking

Background: 1,3,4-thiadiazolo pyrimidine is a lead molécule which is versatile for a wide variety of biological activities and in continuation of our interest in establishing some novel heterocyclic compounds for antitumor activity. Objective: The objective of the study was to synthesize series of 5-amino-7-(substituted aldehyde)-2[(naphthalene-2-yloxy)methyl] - [1,3,4]thiadiazolo-[3,2-α]-pyrimidine-6- carbonitrile derivative and evaluated for their possible in vitro and in vivo anticancer activity. Methods: Herein we report the synthetic scheme which was followed for the preparation of a series of title compounds B1- B9 is outlined in the scheme 1. The intermediate 5-[(naphthalen-2- yloxy)methyl]-1,3,4-thiadiazolo-2-amine was prepared by heating 2-naphthoxyacetic acid and thiosemicarbazide in presence of phosphoryl chloride at a temperature of 65 - 750C. The obtained compound reacted with malononitrile and appropriate amount of aromatic and heteroaromatic aldehydes in refluxing ethanol yielded 5-amino-7-(substituted aldehyde)-2[(naphthalene-2-yloxy)methyl] -[1,3,4]thiadiazolo-[3,2-α]-pyrimidine-6- carbonitrile derivatives (B1 – B9). The purity of synthesized compounds ensured by various spectral analysis. Results: In in-silico molecular docking studies compounds B3 and B9 show binding affinity like known PARP1 inhibitor olaparib. The cellular evaluation indicates that the anticancer activity of compounds B1, B3, B9 is significant when compared to standard drug (olaparib) against MDA-MB-232 cell line and compounds B3, B6, B7 are most active against MCF-7 cell lines. The most active compound B3 was subjected to acute oral toxicity studies by OECD 423 guidelines and in-vivo anti-cancer studies were carried out using DMBA induced model. Conclusion: The in-silico docking study of the newly synthesized compounds were performed, the results showed good binding mode in the active site of PARP1 enzyme. In-silico ADME properties of synthesized compounds were also studied and showed good drug like properties.

scholarly journals Toxicological Screening of Four Bioactive Citroflavonoids: In Vitro, In Vivo, and In Silico Approaches

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5959
Author(s):  
Rolffy Ortiz-Andrade ◽  
Jesús Alfredo Araujo-León ◽  
Amanda Sánchez-Recillas ◽  
Gabriel Navarrete-Vazquez ◽  
Avel Adolfo González-Sánchez ◽  
...  
Keyword(s):  
Acute Toxicity ◽  
Cell Lines ◽  
In Silico ◽  
Low Risk ◽  
Oral Toxicity ◽  
Toxicological Effects ◽  
Ld50 Value ◽  
Preclinical Safety

Many studies describe different pharmacological effects of flavonoids on experimental animals and humans. Nevertheless, few ones are confirming the safety of these compounds for therapeutic purposes. This study aimed to investigate the preclinical safety of naringenin, naringin, hesperidin, and quercetin by in vivo, in vitro, and in silico approaches. For this, an MTT-based cytotoxicity assay in VERO and MDCK cell lines was performed. In addition, acute toxicity was evaluated on Wistar rats by OECD Guidelines for the Testing of Chemicals (Test No. 423: Acute Oral Toxicity-Class Method). Furthermore, we used the ACD/Tox Suite to predict toxicological parameters such as hERG channel blockade, CYP450 inhibition, and acute toxicity in animals. The results showed that quercetin was slightly more cytotoxic on cell lines (IC50 of 219.44 ± 7.22 mM and 465.41 ± 7.44 mM, respectively) than the other citroflavonoids. All flavonoids exhibited an LD50 value > 2000 mg/kg, which classifies them as low-risk substances as OECD guidelines established. Similarly, predicted LD50 was LD50 > 300 to 2000 mg/kg for all flavonoids as acute toxicity assay estimated. Data suggests that all these flavonoids did not show significant toxicological effects, and they were classified as low-risk, useful substances for drug development.

Regulatory Genotoxicity Testing: A Critical Appraisal

1995 ◽  
Vol 23 (3) ◽  
pp. 352-379
Author(s):  
Robert D. Combes
Keyword(s):  
Data Interpretation ◽  
In Vitro Tests ◽  
Negative Results ◽  
Testing Strategies ◽  
Current Controversy ◽  
In Vivo Testing ◽  
Development And Validation ◽  
Genotoxicity Testing

This review considers current approaches to regulatory genotoxicity testing, focusing on how the use of animals can be further replaced, reduced and refined. The complementary roles of in vitro and in vivo testing, and the justification for using animals, are discussed in detail. Recommendations are made for improvements and further work, in the light of the considerable current controversy surrounding the composition and deployment of testing strategies, and the interpretation of the data generated, particularly for carcinogenicity prediction. The major problems are the oversensitivity of in vitro tests and the insensitivity of in vivo assays. On the basis of an analysis of some published databases, it is concluded that there is insufficient support for using in vivo genotoxicity assays for screening. Also, it is questionable whether the scientific benefits of using such assays always outweigh the costs to the animals involved. The considerable efforts being made to harmonise in vivo protocols and to develop improved methods for detecting genotoxicity are discussed. It is recommended that more emphasis be placed on characterising genotoxins in vitro, especially for mechanisms of activity, to optimise the benefits of any confirmatory animal tests.. Also, regulatory agencies are urged to require better-designed and more-scientifically sound protocols, in which animal numbers are minimised and data interpretation, particularly that of negative results, is facilitated. Lastly, in the development and validation of transgenic rodent systems, emphasis should be placed on developing protocols in which other acute toxicity and metabolism endpoints can be measured simultaneously with in vivo mutagenesis, while minimising animal numbers.

scholarly journals Development and validation of phosphonate-based inhibitors and activitiy-based probes (ABPs) for detection and pharmacological targeting of kallikreins

2021 ◽  
Author(s):  
Ευάγγελος Μπισύρης
Keyword(s):  
In Silico ◽  
Theranostic Agents ◽  
Development And Validation

Στην παρούσα διδακτορική διατριβή περιγράφεται ο σχεδιασμός και η σύνθεση ενός νέου ιχνηθέτη ενεργότητας (activity-based probe, ABP) και αναστολέων ειδικών για την καλλικρεΐνη 7 (KLK7), καθώς και η αποτίμηση των θεραπευτικών ιδιοτήτων τους in vivo. Η KLK7 είναι μία σερινοπρωτεάση η οποία έχει μελετηθεί ιδιαίτερα για τον ενεργό της ρόλο στην φλεγμονή και την αποφολίδωση του δέρματος, καθώς και σε διάφορους τύπους καρκίνου. Οι ιχνηθέτες ενεργότητας (ABPs) είναι μικρά μόρια ικανά να αναγνωρίζουν ειδικά τις καταλυτικώς ενεργές μορφές των ενζύμων. Η ιδιότητά τους αυτή, τους καθιστά μοναδικά και ιδιαίτερα χρήσιμα εργαλεία για την ανίχνευση και την ποσοτικοποίηση του ενεργού κλάσματος του ενζύμου, καθώς επίσης και για την in vivo απεικόνιση της ενζυμικής δραστηριότητας, με πολυάριθμες εφαρμογές στην βιοχημική ανάλυση, αλλά και στην μοριακή διάγνωση. Σημειώνεται ότι τα αντισώματα, που χρησιμοποιούνται στις διάφορες ανοσοδοκιμές, αναγνωρίζουν την ολική ποσότητα του ενζύμου στην οποία περιλαμβάνονται και ενζυμικώς ανενεργές μορφές, όπως για παράδειγμα προένζυμα, σύμπλοκα ενζύμου-αναστολέα, κολοβωμένες πρωτεΐνες που έχουν απωλέσει την ενζυμική ενεργότητα, κλπ. Για τον σχεδιασμό του ιχνηθέτη της KLK7 εφαρμόσαμε μια in silico προσέγγιση για τον προσδιορισμό ενός νέου υποστρώματος ειδικού για την KLK7. Τροποποίηση του πεπτιδικού υποστρώματος έδωσε τον φωσφωνικό αναστολέα (Boc-Phe-PheP-(OPh)2), ειδικό για την KLK7, ενώ ο ειδικός ιχνηθέτης ενεργότητας (biotin-X-X-Phe-PheP-(OPh)2) παρήχθη με βιοτινυλίωση του αναστολέα. Επιπλέον, συντέθηκε ένας ιχνηθέτης ABP με απόσβεση φθορισμού (KLK7-qABP, όπου q: quenched), ο οποίος αξιολογήθηκε in vitro με καθιερωμένες αναλυτικές μεθόδους, αλλά και με μία νέα μεθοδολογία ιστοχημικής ανάλυσης ενζύμων, την ακτιβογραφία (activography) (Pampalakis et al., Chem Commun (Camb) 53: 3246-3248, 2017). Πειραματικά δείχθηκε ότι ο ιχνηθέτης KLK7-ABP ανιχνεύει την ενεργή μορφή της ανθρώπινης KLK7, καθώς και την ενδογενή ανθρώπινη KLK7 και την Klk7 του ποντικού, σε εκχυλίσματα κυττάρων και βιοψίες δέρματος, αντίστοιχα. Οι θεραπευτικές δυνατότητες του αναστολέα και του ιχνηθέτη της KLK7 καταδείχθηκαν in vivo χρησιμοποιώντας ποντικούς Spink5-/-Klk5-/-. Το σύνδρομο Netherton είναι μια (ενίοτε θανατηφόρα) μορφή ιχθύωσης, η οποία χαρακτηρίζεται από παθολογική υπεραποφολίδωση του δέρματος και ιδιοσυστατικά ενεργοποιημένη φλεγμονή στην επιδερμίδα, με αποτέλεσμα την εκτεταμένη βλάβη του δερματικού φραγμού. Η νόσος οφείλεται στην ανεπάρκεια του αναστολέα σερινοπρωτεασών LEKTI λόγω μεταλλάξεων στο αντίστοιχο γονίδιο SPINK5, με αποτέλεσμα την έκτοπη ενεργοποίηση της πρωτεόλυσης στην επιδερμίδα των ασθενών με σύνδρομο Netherton, αλλά και των ποντικών Spink5-/- που αναπαράγουν την ανθρώπινη νόσο, και αποτελούν καθιερωμένο πρότυπο για την μελέτη του συνδρόμου Netherton και της ατοπικής δερματίτιδας. Επίσης, έχει δειχθεί ότι η πρωτεάση KLK7 είναι ενεργοποιημένη στο δέρμα των ποντικών Spink5-/-Klk5-/-, στους οποίους έχει αδρανοποιηθεί η πρωτεάση Klk5, και εμπλέκεται αιτιολογικά στην παθολογία του δέρματος (Furio et al., 2015; Kasparek el al., 2017). Επομένως οι ποντικοί αυτοί αποτελούν ιδανικό πρότυπο για την δοκιμή και αξιολόγηση αναστολέων της πρωτεάσης Klk7. Επιδερμική χορήγηση τόσο του αναστολέα όσο και του ABP της KLK7 εξασθένισε σημαντικά την φλεγμονή και την υπεραποφολίδωση του δέρματος. Τα δεδομένα αυτά παρέχουν προκλινικές ενδείξεις για την δυνητική θεραπευτική και διαγνωστική (θεραποδιαγνωστική / therapeutic and diagnostic: theranostic) χρήση του KLK7-ABP σε δερματικές παθολογίες, καθώς και σε καρκίνους των ωοθηκών και του παγκρέατος, όπου επίσης εμπλέκεται η KLK7. Με την ίδια στρατηγική αναπτύχθηκε ένας ΑΒΡ για την KLK6 (biotin-dPEG®4-His-Ile-Val-ArgP-(OPh)2) με σκοπό την ανίχνευση και ποσοτικό προσδιορισμό της ενεργούς KLK6 σε βιολογικά και κλινικά δείγματα, δεδομένου ότι η KLK6 εμπλέκεται στις νόσους Alzheimer και Parkinson, καθώς και σε διάφορους τύπους καρκίνων. Μέχρι σήμερα, ο ρόλος θεραποδιαγνωστικών ABPs για τις κυστεϊνοπρωτεϊνάσες καθεψίνες έχει μελετηθεί και αξιολογηθεί σε καρκίνους και καρδιαγγειακές παθήσεις (Ben-Nun et al., 2015; Weiss-Sadan et al., 2019). Στην παρούσα διατριβή, για πρώτη φορά αναπτύχθηκαν και αξιολογήθηκαν νέοι αναστολείς-ABPs για την KLK7 (Bisyris et al, 2021a and 2021b) και την KLK6 με διττές λειτουργίες φιλοξενούμενες σε έναν πεπτιδικό σκελετό, δηλαδή αναστολέα και ιχνηθέτη, και με ποικίλες δυνατές θεραποδιαγνωστικές εφαρμογές. Η εφαρμογή τους στην στόχευση των καλλικρεϊνών, την μεγαλύτερη οικογένεια σερινοπρωτεασών του ανθρώπινου γονιδιώματος, η οποία καταδείχθηκε στην παρούσα διατριβή, διευρύνει γενικότερα την χρήση των ABPs ως θεραποδιαγνωστικών μέσων (theranostic agents).

Recent In Vitro and In Silico Advances in the Understanding of Intranasal Drug Delivery

2020 ◽  
Vol 26 ◽  
Author(s):  
John Chen ◽  
Andrew Martin ◽  
Warren H. Finlay
Keyword(s):  
Drug Delivery ◽  
In Silico ◽  
Local Drug Delivery ◽  
In Vivo Studies ◽  
Intranasal Drug Delivery ◽  
Nasal Sprays ◽  
In Silico Studies ◽  
Drug Delivery Devices

Background: Many drugs are delivered intranasally for local or systemic effect, typically in the form of droplets or aerosols. Because of the high cost of in vivo studies, drug developers and researchers often turn to in vitro or in silico testing when first evaluating the behavior and properties of intranasal drug delivery devices and formulations. Recent advances in manufacturing and computer technologies have allowed for increasingly realistic and sophisticated in vitro and in silico reconstructions of the human nasal airways. Objective: To perform a summary of advances in understanding of intranasal drug delivery based on recent in vitro and in silico studies. Conclusion: The turbinates are a common target for local drug delivery applications, and while nasal sprays are able to reach this region, there is currently no broad consensus across the in vitro and in silico literature concerning optimal parameters for device design, formulation properties and patient technique which would maximize turbinate deposition. Nebulizers are able to more easily target the turbinates, but come with the disadvantage of significant lung deposition. Targeting of the olfactory region of the nasal cavity has been explored for potential treatment of central nervous system conditions. Conventional intranasal devices, such as nasal sprays and nebulizers, deliver very little dose to the olfactory region. Recent progress in our understanding of intranasal delivery will be useful in the development of the next generation of intranasal drug delivery devices.

In-silico Studies of Isolated Phytoalkaloid Against Lipoxygenase: Study Based on Possible Correlation

2018 ◽  
Vol 21 (3) ◽  
pp. 215-221
Author(s):  
Haroon Khan ◽  
Muhammad Zafar ◽  
Helena Den-Haan ◽  
Horacio Perez-Sanchez ◽  
Mohammad Amjad Kamal
Keyword(s):  
In Silico ◽  
Docking Studies ◽  
In Vivo Studies ◽  
In Vitro Assays ◽  
Chronic Obstructive ◽  
Lipoxygenase Inhibitors ◽  
Lipoxygenase Inhibition ◽  
In Silico Studies

Aim and Objective: Lipoxygenase (LOX) enzymes play an important role in the pathophysiology of several inflammatory and allergic diseases including bronchial asthma, allergic rhinitis, atopic dermatitis, allergic conjunctivitis, rheumatoid arthritis and chronic obstructive pulmonary disease. Inhibitors of the LOX are believed to be an ideal approach in the treatment of diseases caused by its over-expression. In this regard, several synthetic and natural agents are under investigation worldwide. Alkaloids are the most thoroughly investigated class of natural compounds with outstanding past in clinically useful drugs. In this article, we have discussed various alkaloids of plant origin that have already shown lipoxygenase inhibition in-vitro with possible correlation in in silico studies. Materials and Methods: Molecular docking studies were performed using MOE (Molecular Operating Environment) software. Among the ten reported LOX alkaloids inhibitors, derived from plant, compounds 4, 2, 3 and 1 showed excellent docking scores and receptor sensitivity. Result and Conclusion: These compounds already exhibited in vitro lipoxygenase inhibition and the MOE results strongly correlated with the experimental results. On the basis of these in vitro assays and computer aided results, we suggest that these compounds need further detail in vivo studies and clinical trial for the discovery of new more effective and safe lipoxygenase inhibitors. In conclusion, these results might be useful in the design of new and potential lipoxygenase (LOX) inhibitors.

In Silico Assessment of ADME Properties: Advances in Caco-2 Cell Monolayer Permeability Modeling

2019 ◽  
Vol 18 (26) ◽  
pp. 2209-2229 ◽  
Author(s):  
Hai Pham-The ◽  
Miguel Á. Cabrera-Pérez ◽  
Nguyen-Hai Nam ◽  
Juan A. Castillo-Garit ◽  
Bakhtiyor Rasulev ◽  
...  
Keyword(s):  
Intestinal Absorption ◽  
In Silico ◽  
Review Paper ◽  
Cell Monolayer ◽  
Cell Permeability ◽  
Drug Substances ◽  
Wide Range ◽  
Modeling Techniques

One of the main goals of in silico Caco-2 cell permeability models is to identify those drug substances with high intestinal absorption in human (HIA). For more than a decade, several in silico Caco-2 models have been made, applying a wide range of modeling techniques; nevertheless, their capacity for intestinal absorption extrapolation is still doubtful. There are three main problems related to the modest capacity of obtained models, including the existence of inter- and/or intra-laboratory variability of recollected data, the influence of the metabolism mechanism, and the inconsistent in vitro-in vivo correlation (IVIVC) of Caco-2 cell permeability. This review paper intends to sum up the recent advances and limitations of current modeling approaches, and revealed some possible solutions to improve the applicability of in silico Caco-2 permeability models for absorption property profiling, taking into account the above-mentioned issues.

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