This document discusses the role of antioxidants in health and disease. It defines free radicals and describes how they are produced endogenously through metabolism and exogenously through environmental factors. Free radicals can cause oxidative damage but are balanced by the body's antioxidant defense system, which includes antioxidant enzymes like catalase and glutathione peroxidase, chain breaking antioxidants like vitamin E and beta-carotene, and transition metal binding proteins. The document outlines the sources and roles of various reactive oxygen species and antioxidants in the body.
in this presentation, the light is focused on discussing the Reactive oxygen species, oxidative stress, how it forms, how it affects the body and what are the diseases that correlate with oxidative stress.
nevertheless, how it can be balanced by the antioxidants and what is their role in oxidative stress.
Antioxidants are molecules capable of reducing the causes or effects of oxidative stress. Oxidative stress can be caused by environmental factors, disease, infection, inflammation, aging (ROS production). The body produces some endogenous antioxidants, but dietary antioxidants may provide additional line of defense. Flavonoids & other polyphenolics, Vitamins C & E, and Carotenoids are the most common dietary antioxidants. Many herbs and botanicals also contain antioxidants.
Any molecule containing one or more unpaired electrons. These unpaired electrons readily form free radical molecules which are chemically reactive and highly unstable.
Oxidative Stress in Aging and Human Diseases - Exploring the MechanismsQIAGEN
Many modern diseases, including cancer, cardiovascular disease, diabetes, liver disease, arthritis and neurodegenerative disease are related to aging, and aging is closely linked to oxidative stress. Intensive research is being conducted to understand the antioxidant defense mechanism, the mechanisms of aging itself, as well as their roles in human diseases. This slidedeck provides an update on how oxidative stress is linked to aging and how inflammation leads to aging through DNA damage, telomere dysfunction, cellular senescence and oxidative stress. Recent progress on the health benefits of antioxidants and examination of their potential mechanisms in the prevention and treatment of chronic diseases are also covered. Various assay technologies to tackle the complex signaling pathways in this process will be introduced. Learn how you can apply these advanced tools to your research!
in this presentation, the light is focused on discussing the Reactive oxygen species, oxidative stress, how it forms, how it affects the body and what are the diseases that correlate with oxidative stress.
nevertheless, how it can be balanced by the antioxidants and what is their role in oxidative stress.
Antioxidants are molecules capable of reducing the causes or effects of oxidative stress. Oxidative stress can be caused by environmental factors, disease, infection, inflammation, aging (ROS production). The body produces some endogenous antioxidants, but dietary antioxidants may provide additional line of defense. Flavonoids & other polyphenolics, Vitamins C & E, and Carotenoids are the most common dietary antioxidants. Many herbs and botanicals also contain antioxidants.
Any molecule containing one or more unpaired electrons. These unpaired electrons readily form free radical molecules which are chemically reactive and highly unstable.
Oxidative Stress in Aging and Human Diseases - Exploring the MechanismsQIAGEN
Many modern diseases, including cancer, cardiovascular disease, diabetes, liver disease, arthritis and neurodegenerative disease are related to aging, and aging is closely linked to oxidative stress. Intensive research is being conducted to understand the antioxidant defense mechanism, the mechanisms of aging itself, as well as their roles in human diseases. This slidedeck provides an update on how oxidative stress is linked to aging and how inflammation leads to aging through DNA damage, telomere dysfunction, cellular senescence and oxidative stress. Recent progress on the health benefits of antioxidants and examination of their potential mechanisms in the prevention and treatment of chronic diseases are also covered. Various assay technologies to tackle the complex signaling pathways in this process will be introduced. Learn how you can apply these advanced tools to your research!
Free radicals in human diseases and the roleMohammed Sakr
Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Free radicals are a main cause of cardiovascular diseases, cancer, aging and immune defense disorders. Foods like berries and carrot protect us against free radicals.
Free radicals in human diseases and the roleMohammed Sakr
Free radicals reactive oxygen species and reactive nitrogen species are generated by our body by various endogenous systems, exposure to different physiochemical conditions or pathological states. A balance between free radicals and antioxidants is necessary for proper physiological function. If free radicals overwhelm the body's ability to regulate them, a condition known as oxidative stress ensues. Free radicals thus adversely alter lipids, proteins, and DNA and trigger a number of human diseases. Free radicals are a main cause of cardiovascular diseases, cancer, aging and immune defense disorders. Foods like berries and carrot protect us against free radicals.
definition, properties, types of free radical, neurodegenerative disorder, cardiovascular disease, and cancer due to free radicals, importance of antioxidants and their role.
Every component of the eye is vulnerable to damage from ROI, particularly retina. There are several reasons for the vulnerability of the retina, including high concentrations of polyunsaturated fatty acid (PUFA), constant exposure to visible light, high consumption of oxygen, an abundance of photosensitisers in the neurosensory retina and the RPE, the process of phagocytosis by the RPE which is known to generate hydrogen peroxide.
Free radical reactions are expected to produce progressive adverse changes that accumulate with age throughout the body. Such “normal” changes with age are relatively common to all.
However, superimposed on this common pattern are patterns influenced by genetics and environmental differences that modulate free radical damage.
These are manifested as diseases at certain ages determined by genetic and environmental factors.
Cancer and atherosclerosis, two major causes of death, are salient “free radical” diseases. Cancer initiation and promotion is associated with chromosomal defects and oncogene activation. It is possible that endogenous free radical reactions, like those initiated by ionizing radiation, may result in tumor formation.
A brief introduction about Pharmacology of free radicals, generation of free radicals, Antioxidants, Free radicals causing disorders such as cancer diabetes, neuro degenerative disorders such as Parkisonism's Disease
This presentation introduces a brief and rapid review for an important research area (oxidative stress) and its relation to liver fibrosis.
Liver fibrosis is very important for us as we are facing a very dangerous and continuously growing problem in Egypt, HEPATIC PATIENTS COMPLICATIONS.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
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micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
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This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
1. Role of Antioxidant in Health
and Disease
By-Dr Amit Gupta
PG-2
Deptt of Pharmacology
2. Contents
• Free radicals
• Antioxidant defense system
• Methods of Total antioxidant capacity assessment
• Conclusion
3. Free Radicals
• It is a molecular species having an unpaired electron
and thus is a highly reactive entity (being unstable)
• Free radicals are constantly produced in human
system during metabolism or deliberately during the
process of phagocytosis
4. • Apart from these, free radicals can also be generated
from toxic enviromental pollutants, ionizing
radiations, ozone, heavy metal poisoning, cigarette
smoking and chronic alcohol intake
• Free radicals being highly reactive can oxidise
biomolecules leading to tissue injury and cell death
5. • Now it is proved that free radicals on one hand have
key role in many fundamental cellular reactions and
on the other hand, they are important in the
pathophysiology of common diseases including
atherosclerosis, chronic renal failure, and diabetes
mellitus
• Thus free radicals have dual role
6. • To stabilize itself, a free radical may donate its
unpaired electron or may accept one from other
biomolecule transforming a non-radical to another
free radical to set up disastrous chain reaction
• Thus initiation, propagation, and termination of chain
reaction occurs
10. • Free radicals can be negatively or positively charged
or may be electrically neutral
• H2O2, HOCl are neutral and such agents which are
not free radicals in true sense are called as Reactive
Oxygen Species ( ROS)
11. Endogenous free radicals
The most important free radicals in the body are-
1. singlet oxygen (O2), hydroxyl radical (OH-),
nitric oxide (NO), hypochlorous acid (HOCl),
hydrogen peroxide (H2O2) and the superoxide
radical (O2-)
2. Carbon-centered free radicals
13. Superoxide (O2-)
• Superoxide (O2-) is produced by the addition of a single
electron to oxygen
• Major source of superoxide is from the electron transfer
chain of the mitochondria
• Also produced during metabolism of drugs by CYP 450 e.g
of paracetamol or alcohol
• Some enzymes also catalyzes superoxide formation e.g
superoxide and hydrogen peroxide are produced during
oxidation of hypoxanthine to xanthine and uric acid
14. Hydrogen peroxide(H2O2)
• Hydrogen peroxide(H2O2) is not a free radical but
falls in the category of reactive oxygen species
• It is a powerful oxidising agent
• It is the main source of hydroxyl (OH-) radicals
• It is also involved in the production of HOCl by
neutrophils.
15. • In biological systems hydrogen peroxide is generated
by the production of superoxide
O2 + O2⁻+ 2H⁺ = H2O2 + O2
• The above reaction is called a dismutation reaction as
the radical reactants produce non- radical products
16. Hydroxyl radical (OH-)
• Hydroxyl radical (OH-) is probably the final mediator
of most free radical induced tissue damage
• The reason for this is that the hydroxyl radical reacts,
with extremely high rate constants, with almost every
type of molecule found in living cells
17. • Hydroxyl radical formation in vivo mainly occur by
transition metal catalysed decomposition of
superoxide and hydrogen peroxide
Fe2+ + H2O2 = Fe3+ + OH + OH−
• This reaction is called as Fenton’s reaction described
in 1894
18. Singlet oxygen
• Singlet oxygen (O2) is an electronically excited and
mutagenic form of oxygen
• It is similar to normal oxygen but it has an extra
electron
• It is generated by input of energy like radiation or
sunlight
• This free radical is involved in joint diseases (like
arthritis) and eye diseases
19. Peroxy-nitrite
• Cytotoxicity of NO is due to formation of
peroxynitrite
• It is produced by the reaction of nitric oxide with
superoxide NO + O2- = ONOO-
• Because of its oxidizing properties, peroxy-nitrite can
damage a wide array of molecules in cells, including
DNA and proteins and results in cell apoptosis
20. Hypochlorous acid
• Activated polymorphonuclear cells produce HOCl as a
major bactericidal agent
• This reaction occurs in the neutrophilic lysosomal
vesicles and helps in the killing of bacteria and viruses
• HOCl may cross cell membrane so it may contribute to
tissue damage during the inflammatory process
21. Promoters of free radical
• Several transition metals have variable oxidation
numbers which accordingly can accept or donate
electrons e.g Fe, Cu
• As a result, these metals serve as excellent promoters
of free radical
Fe3+ + e- = Fe2+
Cu2+ + e- = Cu+
22. EXOGENOUS FREE RADICALS
• Drugs: A number of drugs can increase the production of free
radicals e.g nitrofurantoin, antineoplastic agents as
bleomycin, anthracyclines (adriamycin) and methotrexate
• Radiation
• Tobacco smoking
• Inorganic particles e.g asbestos, silica, quartz
• Gases e.g ozone
• Pesticides, exhaust fumes
23. Role of Free radicals
• Body’s immune system’s cells purposefully create them to
neutralize viruses and bacteria
• In absence of free radicals body’s defense system will become
weak
• Normally, the body can handle free radicals, but if antioxidants
are unavailable, or if the free-radical production becomes
excessive, damage to tissues can occur
• Of particular importance is that free radical damage
accumulates with age.
24. • Free radicals are imlicated in many diseases e.g
autoimmune diseases, RA, carcinogenesis
• CNS- Parkinson’s disease, Alzheimer’s disease,
Huntington’s disease, MS
• CVS- MI, Ischaemic reperfusion injury,
atherosclerosis
25. • Endocrine- DM
• GIT- Peptic ulcer, cirrhosis, pancreatitis
• Renal- Nephrotoxicity due to aminoglycosides and
heavy metals
• RS- Toxicity due to cigarette smoke, asbestos, silia
• Eyes- Cataract, Retinopathy
26. Antioxidant Defense system
• An antioxidant can be defined as: “any substance that,
when present in low concentrations compared to that
of an oxidisable substrate, significantly delays or
inhibits the oxidation of that substrate”.
• They are substances that protect other chemicals of
the body from damaging oxidation reactions by
reacting with free radicals
27. • During this reaction the antioxidant sacrifices itself
by becoming oxidized
• However, antioxidant supply is not unlimited
• Therefore, there is a constant need to replenish
antioxidant resources, whether endogenously or
exogenously
28. • Antioxidant system is divided into three main groups:
1.Antioxidant enzymes
2.Chain breaking antioxidants
3.Transition metal binding proteins
29. Antioxidant Enzymes
Catalase
• First antioxidant enzyme to be characterized
• It catalyses the two stage conversion of hydrogen
peroxide to water and oxygen:
catalase–Fe(III) + H2O2 = compound I
compound I + H2O2 = catalase–Fe(III) +2H2O + O2
30. • Catalase consists of a haem group and a molecule of
NADPH
• Catalase is largely located within cells in peroxisomes,
which also contain most of the enzymes capable of
generating hydrogen peroxide
• Greatest activity is present in liver and erythrocytes
31. Glutathione peroxidase and glutathione reductase
• Glutathione peroxidase catalyze the oxidation of
glutathione at the expense of a hydroperoxide,
ROOH + 2GSH = GSSG + H2O + ROH
• Glutathione peroxidases requires selenium for its
activity
• Predominant subcellular distribution is in the cytosol
and mitochondria
32. • Highest availability is in liver
• Main scavenger of hydrogen
• Activity of the enzyme is dependent on the constant
availability of reduced glutathione. This is made
possible by glutathione reductase
GSSG + NADPH + H+ = 2GSH + NADP+
• NADPH is supplied by pentose phosphate pathway
33. • Any competing pathway that utilises NADPH (such
as the aldose reductase pathway) might lead to a
deficiency of reduced glutathione and hence impair
the action of glutathione peroxidase
34. Superoxide dismutase
• Superoxide dismutase catalyze the dismutation
of superoxide to hydrogen peroxide:
O2− + O2− + 2H+ = H2O2 + O2
• The hydrogen peroxide must then be removed by
catalase or glutathione peroxidase
• There are three forms of superoxide dismutase in
mammalian tissues:
35. (1) Copper zinc superoxide dismutase (CuZnSOD):
• It is found in the cytoplasm of all cells
• It contains catalytically active copper and zinc atom
(2) Manganese superoxide dismutase
(3) Extracellular superoxide dismutase (ECSOD):
• EC-SOD is a secretory copper and zinc containing
SOD distinct from the CuZnSOD described above
36. • EC-SOD is synthesised by fibroblasts and endothelial
cells
• EC-SOD might play a role in the regulation of
vascular tone, because endothelial derived relaxing
factor (nitric oxide or a closely related compound) is
is neutralized in the plasma by superoxide
37. Chain Breaking Antioxidants
• Such antioxidants can be conveniently divided into
lipid phase and aqueous phase antioxidants
1. Lipid phase antioxidants
• These antioxidants scavenge radicals in membranes
and lipoprotein particles and are crucial in preventing
lipid peroxidation
• Most important of these is Vit E
38. • They react rapidly with peroxyl radicals and hence
act to break the chain reaction of lipid peroxidation
• Besides, Vit.E also stabilizes cell membrane so its
deficiency may cause hemolysis and peripheral
neuropathy
• Vitamin E also inhibits the conversion of nitrites in
smoked and pickled foods to nitrosamines in the
stomach
• Nitrosamines are strong tumor promoters
39. Beta Carotene
Fontbonne A, Charles MA, Juhan-Vague I et al. The effect of metformin on the metabolic
abnormalities associated with upper-body fat distribution. BIGPRO Study Group. Diabetes
Care. 1996;19(9):920.
• Carotenoids are pigmented micronutrients present in
fruits and vegetables
• Carotenoids are precursors of vitamin A and also have
antioxidant effects
• Beta-carotene is the most widely studied
• It is composed of two molecules of vitamin A
(retinol) joined together
40. • Dietary beta-carotene is converted to retinol at the
level of the intestinal mucosa.
• Beta-carotene scavenges singlet oxygen, free radicals
and inhibits lipid peroxidation
• Carotenoids also have been reported to have a
number of other biologic actions, including immuno-
enhancement, inhibition of mutagenesis and
regression of premalignant lesions
41. Flavanoids
• Flavonoids are a large group of polyphenolic
antioxidants found in many fruits, vegetables, and
beverages such as tea and wine e.g quercetin
• Epidemiological studies suggest an inverse relation
between flavonoid intake and incidence of chronic
diseases such as coronary heart disease (CHD)
42. Ubiquinol-10
• Ubiquinol-10 (reduced coenzyme Q10) is an effective
chain breaking antioxidant
• Whenever plasma or isolated low density lipoprotein
(LDL) cholesterol is exposed to radicals, ubiquinol-
10 is the first antioxidant to be consumed, suggesting
its important role in preventing the propagation of
lipid peroxidation
43. Aqueous phase chain breaking antioxidants
• These antioxidants will directly scavenge radicals
present in the aqueous compartment
• Most important antioxidant of this type is vitamin C
(ascorbate)
• Its best known role is as a cofactor for prolyl and
lysyl oxidases in the synthesis of collagen
• Ascorbate has been shown to scavenge superoxide,
hydrogen peroxide, the hydroxyl radical
44. Uric acid
• Uric acid efficiently scavenges free radicals
• Urate is important in providing protection against
certain oxidizing agents such as Ozone
• It has been suggested that the increase in life span
occurred during human evolution is partly explained
by the protective action provided by uric acid in
human plasma
45. Albumin
• Albumin, predominant plasma protein has several
sulphydryl groups and a single cysteine residue
• This chemical structure is responsible for the
antioxidant effect of albumin
• Due to this, albumin plays important role in
transporting free fatty acids in the blood
• In addition, albumin has the capacity to bind copper
ions and will inhibit copper dependent lipid
peroxidation and hydroxyl radical formation
46. Interactions between chain breaking
antioxidants
• It is vital to remember that in vivo, complex
interactions between antioxidants occur e.g ascorbate
helps in regenerating alpha-tocopherol and glutahione
helps in regenerating ascorbate
• Therefore, it becomes difficult to predict how
antioxidants will function in vivo and which
antioxidant is more important than other
47. Transition metal binding proteins
• Transition metal binding proteins (ferritin, transferrin,
lactoferrin, and caeruloplasmin) act as a crucial
component of the antioxidant defence system
• By sequestering iron and copper, they inhibit the
formation of the hydroxyl radical
48. Melatonin
• Melatonin is a powerful antioxidant
• Melatonin easily crosses cell membranes and the
blood-brain barrier
• Melatonin, once oxidized, cannot be reduced to its
former state. Therefore, it has been referred as
terminal (or suicidal) antioxidant
49. Agents augmenting endogenous antioxidants
• N-acetylcysteine is a glutathione precursor while
ebselen is a congener of glutathione peroxidase
• Both augments endogenous glutathione peroxidase
activity
• Former is used as antioxiant in treating paracetamol
toxicity
50. Exogenous(Pharmacological antioxidants)
• Several pharmaceutical agents have been found to
exert an antioxidant effect
1. Xanthine oxidase inhibitors: e.g. allopurinol
2. NADPH inhibitors: e.g. adenosine
3. Albumin
4.Inhibitors of iron redox cycling: deferoxamine,
apotransferrin
5. Statins
51. Plant Sources
• Garlic, grape fruit juice, soyabean, turmeric
(cucurminoids), tomato (lycopene) contains
bioflavinoids which possess good antooxidant
properties
• These are claimed to reduce the risk of
atherosclerosis, MI and various cancers
52. • Spirulina is a blue-green algae with excellent
antioxidant properties
• It is a good source of SOD, beta-carotene and B-
complex vitamins
53. Are antioxidants really beneficial?
• Large clinical trials with a limited number of
antioxidants detected no benefit and even suggested
that excess supplementation with certain antioxidants
may be harmful
• Antioxidant supplements have no clear effect on the
risk of chronic diseases such as cancer and heart
disease in the long run
54. • Because antioxidants that are reducing agents can
also act as pro-oxidants
• For example, vitamin C has antioxidant activity when
it reduces oxidizing substances such as hydrogen
peroxide, however, it will also reduce metal ions that
generate free radicals
• Other example of pro-oxidants are vit E, uric acid
56. Antioxidant
capacity assay
Principle of the method End-product
determination
Spectrometry
DPPH(2,2-diphenyl-1-
Picrylhydrazyl)
Antioxidant reaction
with an organic
radical
Colorimetry
FRAP (ferric reducing
antioxidant power)
Antioxidant reaction
with a Fe(III) complex
Colorimetry
PFRAP(potassium
ferricyanide reducing
power)
Potassium ferricyanide
reduction by
antioxidants and
subsequent reaction
of potassium
ferrocyanide with Fe3+
Colorimetry
Spectrometric Techniques
57. Antioxidant
capacity assay
Principle of the method End-product
determination
CUPRAC(cupric
reducing antioxidant
power)
Cu (II) reduction to Cu
(I) by antioxidants
Colorimetry
TRAP(total peroxyl
radical trapping
antioxidant parameter)
Antioxidant capacity to
scavenge luminol-
derived peroxyl radicals
Chemiluminescence
quenching
62. REFERENCES
• HL sharma, KK sharma. Principles of Pharmacology.
2nd ed.2011;p 901
• Katzung BG, Trevor AJ. Basics and clinical
pharmacology. 13th ed.McGraw Hill
education:2015;p664-5
• For various trial details (https://clinicaltrials.gov)