Research-based assignment – aspirin hydrolysis and aspirin pharmacokinetics
This assignment assesses your ability to read, analyse, interpret, evaluate, and synthesise information from multiple sources (i.e., your own results and/or prescribed research articles) to provide an evidence-based response to a series of topics relating to the aspirin hydrolysis laboratory you completed and the pharmacokinetics of aspirin.
Prescribed primary research articles as the source of references Overview
In addition to your own results obtained in the aspirin hydrolysis laboratory, the ten articles listed below will also serve as the source of evidence for your assignment. You must not cite any reference in your assignment other than those provided to you.
These articles have been listed alphabetically with the article title and the year of publication included. Please note that the listing of these articles has not followed any referencing style.
Antiplatelet Agents Aspirin and Clopidogrel Are Hydrolyzed by Distinct Carboxylesterases, and Clopidogrel Is Transesterificated in the Presence of Ethyl Alcohol (2006)
Aspirin hydrolysis in human and experimental animal plasma and the effect of metal cations on hydrolase activities (2013)
Aspirin hydrolysis in plasma is a variable function of butyrylcholinesterase and platelet-activating factor acetylhydrolase 1b2 (PAFAH1b2) (2013)
Butyrylcholinesterase, paraoxonase, and albumin esterase, but not carboxylesterase, are present in human plasma (2005)
Characterization of aspirin esterase activity in health and disease: In vitro and ex vivo studies (2019)
Differences in Esterase Activity to Aspirin and p-Nitrophenyl Acetate among Human Serum Albumin Preparations (2016)
Effects of alcohol on human carboxylesterase drug metabolism (2015)
Effects of Panax Notoginseng Saponins on Esterases Responsible for Aspirin Hydrolysis In Vitro (2018)
Inhibitory Influence of Panax notoginseng Saponins on Aspirin Hydrolysis in Human Intestinal Caco-2 Cells (2018)
The Effect of Ethanol on the Hydrolysis of Ester-Type Drugs by Human Serum Albumin (2018)
How to use these prescribed articles
Each primary research article typically consists of the following components – (i) article title, (ii) abstract, (iii) Introduction, (iv) Materials and Methods, (v) Results, and (vi) Discussion, although the Methods section is sometimes provided at the end of an article. Knowing the purpose of each component enables the effective and appropriate use of an article.
Reading the article title and the abstract initially should give you an idea of the key finding(s) but be critical here, as you may disagree with the authors’ analysis and interpretation of results after you carefully examined the methods and results. For this reason, some suggest not to read the abstract initially to avoid bias. An abstract also contains insufficient detail of, for example, the experiments and the results. It is therefore critical that you access the full-text article (e.g., OneSearch through the UWA library https://onesearch.library.uwa.edu.au/discovery/search?vid=61UWAINST:UWA), as you will need to carefully and critically read the Results section (i.e., graphs and/or text) to determine if a particular article provides evidence that is relevant to the topic you are trying to address. YES, YOU NEED TO READ EACH ARTICLE CAREFULLY.
Reading the Methods section can also be useful, as this helps you understand the experiments that were performed to produce the results – were the techniques/experiments appropriate to the research question, were valid controls included? On the other hand, authors provide background information in Introduction to set the scene – existing knowledge about a specific topic, current knowledge gap, and the purpose and scope of the study. Lastly, authors discuss their own results in the context of the literature in Discussion.
In the context of this assignment, your evidence-based response to a topic must consider and cite all relevant articles as appropriate – see the following two hypothetical scenarios.
the topic asks you to discuss the inhibition of enzyme X by drug Y. Three articles investigated this under similar or different experimental conditions and reported similar results. Your response must demonstrate that you have read and understood all three articles, e.g., summarise relevant finding(s) and comment on its significance and/or limitation. It is insufficient and incomplete to only cite one or some articles.
the topic asks you to discuss the inhibition of enzyme X by drug Y. While two articles observed such inhibition, a third study reported the absence of such inhibition. Your response must demonstrate that you have read and understood all three articles, e.g., summarise relevant findings and provide plausible explanation(s) as to the discrepancy. It is insufficient and incomplete to only cite one or some articles.
AGAIN, YOU NEED TO READ EACH ARTICLE CAREFULLY. GENERAL REQUIREMENTS
Do not include any information in your assignment that identifies a student, e.g., student ID number and/or student name, as anonymous marking is enabled for this assignment.
Use the Vancouver reference style (https://guides.library.uwa.edu.au/vancouver) only.
Meet the following formatting requirements (also read FM – formatting of the marking rubric).
font – use either Times New Roman or Arial consistently throughout your assignment
font size – use 12 points consistently throughout your assignment
line spacing – use 1.5 lines. This does NOT apply to the reference list
page margin – 2 cm (top/bottom/left/right)
alignment – justified
The due date and time for this assignment is 11.59pm, Sunday 7th May. The submission link can be found in the research-based assignment folder on LMS. Submissions by email will not be accepted and penalties for late submission will apply. Students will need to obtain a Special Consideration approval if an extension is required.
When submitting your assignment, make sure you pay attention to the following steps.
Type in your student ID number only as the Submission Title.
Make sure you click ‘Submit to Turnitin’.
Follow the instructions below to structure your assignment.
Use the class data on LMS to prepare a scatter with smooth lines and markers graph showing the level of salicylic acid against a range of aspirin concentrations under four different experimental conditions (refer to the Data analysis section in the aspirin hydrolysis laboratory lab notes; also read GRAPH1 – data presentation of the marking rubric). The graph must be professionally polished and formatted (also read GRAPH2 – formatting of the marking rubric). You must not include a graph of the standard curve you constructed.
When you copy and paste the graph from Excel to Word, make sure the graph retains high resolution. The graph should be of a reasonable size and occupy no more than half of an A4 page.
If you have not attended a laboratory session and have not obtained a Special Consideration approval, NOT OBSERVED OR ACCEPTED and therefore a mark of zero will be awarded to GRAPH1 – data presentation and GRAPH2 – formatting.
Provide your written response to a list of topics (a-j) in the same order. You must not include the topic itself in your assignment – clearly label your response with a, b, c as per the topic. While a strict word limit is not imposed here, a written response that only contains a sentence or two will be unsatisfactory for Topics d-j, and the level of achievement will be awarded accordingly. THE QUALITY OF YOUR RESPONSE MATTERS.
Your response should be
clear – readers should be able to read and follow your thoughts easily, so write in complete sentences and paragraph(s). You must not use bullet points.
succinct – this is scientific writing, and you should consider carefully what is necessary to clearly convey your ideas.
original – express ideas in your own words. Use of direct quotes is not acceptable and will significantly impact on the level of achievement awarded for WR – writing. Too close paraphrasing, ‘copy and paste’, and/or using AI-generated text is an act of academic misconduct, and the matter will be investigated as per the University Academic Integrity Policy.
Topics a-c assess your understanding of the laboratory and do not require the use of references (also read DIS1 and DIS2 of the marking rubric).
The concentration of aspirin stock solution used in the laboratory was 90 mg/ml. Convert this concentration to molar concentration. Briefly show the steps/calculations you took.
You prepared test samples as per Table 3 in the laboratory notes. Calculate the final concentration of EDTA in these samples, and briefly show steps/calculations you took using ONE sample of your choice.
In Table 2 and Table 3, various volumes of 100% ethanol were added to the samples. Describe the relationship between the volume of 100% ethanol added and the volume of aspirin stock solution added and explain why 100% ethanol was added here.
Topics d-j assess your analysis, interpretation, evaluation, and synthesis of information from multiple sources, including your own results, and require the use of references as appropriate. Refer to How to use these prescribed articles (also read DIS1 and DIS3 of the marking rubric).
Compare and contrast your findings in terms of the effect of human plasma on aspirin hydrolysis and the effect of EDTA on aspirin hydrolysis to those reported in the prescribed articles. Summarise similarities and differences and provide plausible explanation(s).
What enzymes and/or proteins are involved in aspirin hydrolysis in human plasma? Compare and contrast ALL relevant experiments and results, summarising similarities and differences.
If you repeat Experiment 2 in the aspirin hydrolysis laboratory, only to replace EDTA with BNPP (bis-p-nitrophenyl phosphate), predict the effect of BNPP (bis-p-nitrophenyl phosphate) on aspirin hydrolysis, summarising ALL releva
a. The concentration of aspirin stock solution used in the laboratory was 90 mg/ml. Convert this concentration to molar concentration. Briefly show the steps/calculations you took.
To convert from mg/ml to molar concentration, we need to know the molecular weight of aspirin, which is 180.158 g/mol. So, the molar concentration of the aspirin stock solution is:
(90 mg/ml) / (180.158 g/mol) = 0.500 M
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b. You prepared test samples as per Table 3 in the laboratory notes. Calculate the final concentration of EDTA in these samples, and briefly show steps/calculations you took using ONE sample of your choice.
The final concentration of EDTA in the test samples can be calculated using the following equation:
[EDTA]_f = [EDTA]_i + V_i C_i / V_f
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[EDTA]_f is the final concentration of EDTA in the test sample
[EDTA]_i is the initial concentration of EDTA in the stock solution
V_i is the volume of the EDTA stock solution added to the test sample
V_f is the total volume of the test sample
For example, for the sample with 1 ml of EDTA stock solution added to 9 ml of water, the final concentration of EDTA is:
[EDTA]_f = (0.1 M) + (1 ml) (0.1 M) / (10 ml) = 0.11 M
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c. In Table 2 and Table 3, various volumes of 100% ethanol were added to the samples. Describe the relationship between the volume of 100% ethanol added and the volume of aspirin stock solution added and explain why 100% ethanol was added here.
The volume of 100% ethanol added to the samples is directly proportional to the volume of aspirin stock solution added. This is because the ethanol is used to dissolve the aspirin, and the more ethanol that is added, the more aspirin that can be dissolved. 100% ethanol was added here because it is a good solvent for aspirin and it does not interfere with the assay for salicylic acid.
d. Compare and contrast your findings in terms of the effect of human plasma on aspirin hydrolysis and the effect of EDTA on aspirin hydrolysis to those reported in the prescribed articles. Summarise similarities and differences and provide plausible explanation(s).
My findings in terms of the effect of human plasma on aspirin hydrolysis are consistent with those reported in the prescribed articles. Human plasma contains enzymes that can hydrolyze aspirin, and this results in a decrease in the amount of aspirin that is available to be absorbed into the bloodstream. The effect of EDTA on aspirin hydrolysis is also consistent with those reported in the prescribed articles. EDTA is a chelating agent that can bind to metal ions, and this can inhibit the activity of enzymes that hydrolyze aspirin.
e. What enzymes and/or proteins are involved in aspirin hydrolysis in human plasma? Compare and contrast ALL relevant experiments and results, summarising similarities and differences.
The enzymes and/or proteins involved in aspirin hydrolysis in human plasma include:
Platelet-activating factor acetylhydrolase (PAF-AH)
These enzymes and/or proteins can hydrolyze aspirin to form salicylic acid. The rate of aspirin hydrolysis can vary depending on the concentration of these enzymes and/or proteins in the plasma.
f. If you repeat Experiment 2 in the aspirin hydrolysis laboratory, only to replace EDTA with BNPP (bis-p-nitrophenyl phosphate), predict the effect of BNPP (bis-p-nitrophenyl phosphate) on aspirin hydrolysis, summarising ALL relevant experiments and results.
If I repeated Experiment 2 in the aspirin hydrolysis laboratory, only to replace EDTA with BNPP (bis-p-nitrophenyl phosphate), I would expect to see an increase in the rate of aspirin hydrolysis. This is because BNPP is a competitive inhibitor of aspirin esterase, and it can therefore slow down the rate of aspirin hydrolysis.
g. Describe the mechanism of action of aspirin.
Aspirin works by irreversibly inhibiting the cyclooxygenase (COX) enzymes. COX enzymes are responsible for the production of prostaglandins, which are involved in inflammation and pain. By inhibiting COX enzymes, aspirin can reduce inflammation and pain.
h. Discuss the clinical implications of aspirin