Lignans and flavonoids are plant compounds with potential health benefits. Lignans are dimers of phenylpropanoids found in flaxseed and other foods. When consumed, lignan precursors are converted by gut bacteria into enterolactone and enterodiol, which have weak estrogenic activity and other biological effects. Flavonoids are polyphenols that include subclasses like flavones, flavonols, flavanones, and anthocyanins found in fruits and vegetables. They are associated with reduced disease risk due to their antioxidant and anti-inflammatory properties. Both lignans and flavonoids are derived from phenylalanine through the shikimate pathway and undergo enzymatic conversions in their
Unit II Introduction to secondary metabolite
Phenylpropanoids and Flavonoids: Lignans, Tea, Ruta
For video lecture join to youtube channel snehal chakorkar
Unit II Introduction to secondary metabolite
Phenylpropanoids and Flavonoids: Lignans, Tea, Ruta
For video lecture join to youtube channel snehal chakorkar
Pharmacognosy
Final year B.Pharm
University of Mumbai
Phenylpropanoids are a diverse group of natural products composed of thousands of different compounds, synthesized from the primary metabolites, phenylalanine or tyrosine amino acids, through a series of enzymatic reactions. ... 4-Coumaryl Co-A serves as the common precursor to flavonoid and phenolic acids biosynthesis.
Utilization of radioactive isotopes in the investigation of biogenetic studiesMs. Pooja Bhandare
Isotopes: TWO TYPES OF ISOTOPES,Radioactive isotopes.
Stable isotopes, Radiolabelled Tracers ( Radiolabelled compounds), Radiotracer Technique, Steps in Tracer Technique,
Selection of Radioisotopes.
Preparation of Radioisotopes.
Introduction/Insertion of Radiolabelled compound in biological system (Plant part) Seperation and determination of labelled compound in various biochemical reaction, Preparation of labelled compounds : Insertion of Radiolabelled compound in plant part, Root feeding, Stem feeding, Direct Injection, Floating Methods, Spray technique, Separation or Isolation of Radiolabelled compound and detection of radioisotope labelled compound. Detection and assay of Radioactive labelled compound, Detector system used (Analysis of Isotopic content). Method in Tracer Technique,
Precursor – Product sequence
Double and Multiple Labelling
. Competitive Feeding,Sequential Analysis
Applications of Tracer Technique
Isolation, Identification and Analysis of PhytoconstituentsDr. Siddhi Upadhyay
Isolation, Identification and Analysis of Phytoconstituents
a) Terpenoids: Menthol, Citral, Artemisin
b) Glycosides: Glycyrhetinic acid & Rutin
c) Alkaloids: Atropine,Quinine,Reserpine,Caffeine
d) Resins: Podophyllotoxin, Curcumin
Commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid.
It is an important biochemical metabolite in plants and microorganisms.
Its name comes from the Japanese flower shikimi the Japanese star anise, Illicium anisatum), from which it was first isolated in 1885 by Johan Fredrik Eykman.
The elucidation of its structure was made nearly 50 years later.
Shikimic acid is also the glycoside part of some hydrolysable tannins.
The shikimate pathway is a seven step metabolic route used by bacteria, fungi, algae, parasites, and plants for the biosynthesis of aromatic amino acids (phenylalanine, tyrosine, and tryptophan).
This pathway is not found in animals; therefore, phenylalanine and tryptophan represent essential amino acids that must be obtained from the animal's diet
Animals can synthesize tyrosine from phenylalanine, and therefore is not an essential amino acid except for individuals unable to hydroxylate phenylalanine to tyrosine).
Pharmacognosy of Atropa belladona, biological source, geographical source, chemical constituents, uses, morphology of leaves, flower, fruits of belladona, deadly night shade leaves, chemical test, microscopy, T.S of leaves
When
food containing, lignan precursors are
consumed they are converted to the enterolignans,
enterodiol and enterolactone by bacteria that
normally colonize the human intestine
Enterodiol
and enterolactone have weak estrogenic
activity but may also exert biological effects through
nonestrogenic mechanisms
Because
enterodiol and enterolactone can mimic
some of the effects of estrogens, their plant derived
lignan precursors are classified as phytoestrogens
Lignan
precursors that have been identified in the
human diet include pinoresinol, lariciresinol,
secoisolariciresinol, matairesinol and others
When food containing, lignan precursors are consumed they are converted to the enterolignans, enterodiol and enterolactone, by bacteria that normally colonize the human intestine.
Enterodiol and enterolactone have weak estrogenic activity but may also exert biological effects through nonestrogenic mechanisms.
Because enterodiol and enterolactone can mimic some of the effects of estrogens, their plant-derived lignan precursors are classified as phytoestrogens.
Lignan precursors that have been identified in the human diet include pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, and others
Pharmacognosy
Final year B.Pharm
University of Mumbai
Phenylpropanoids are a diverse group of natural products composed of thousands of different compounds, synthesized from the primary metabolites, phenylalanine or tyrosine amino acids, through a series of enzymatic reactions. ... 4-Coumaryl Co-A serves as the common precursor to flavonoid and phenolic acids biosynthesis.
Utilization of radioactive isotopes in the investigation of biogenetic studiesMs. Pooja Bhandare
Isotopes: TWO TYPES OF ISOTOPES,Radioactive isotopes.
Stable isotopes, Radiolabelled Tracers ( Radiolabelled compounds), Radiotracer Technique, Steps in Tracer Technique,
Selection of Radioisotopes.
Preparation of Radioisotopes.
Introduction/Insertion of Radiolabelled compound in biological system (Plant part) Seperation and determination of labelled compound in various biochemical reaction, Preparation of labelled compounds : Insertion of Radiolabelled compound in plant part, Root feeding, Stem feeding, Direct Injection, Floating Methods, Spray technique, Separation or Isolation of Radiolabelled compound and detection of radioisotope labelled compound. Detection and assay of Radioactive labelled compound, Detector system used (Analysis of Isotopic content). Method in Tracer Technique,
Precursor – Product sequence
Double and Multiple Labelling
. Competitive Feeding,Sequential Analysis
Applications of Tracer Technique
Isolation, Identification and Analysis of PhytoconstituentsDr. Siddhi Upadhyay
Isolation, Identification and Analysis of Phytoconstituents
a) Terpenoids: Menthol, Citral, Artemisin
b) Glycosides: Glycyrhetinic acid & Rutin
c) Alkaloids: Atropine,Quinine,Reserpine,Caffeine
d) Resins: Podophyllotoxin, Curcumin
Commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid.
It is an important biochemical metabolite in plants and microorganisms.
Its name comes from the Japanese flower shikimi the Japanese star anise, Illicium anisatum), from which it was first isolated in 1885 by Johan Fredrik Eykman.
The elucidation of its structure was made nearly 50 years later.
Shikimic acid is also the glycoside part of some hydrolysable tannins.
The shikimate pathway is a seven step metabolic route used by bacteria, fungi, algae, parasites, and plants for the biosynthesis of aromatic amino acids (phenylalanine, tyrosine, and tryptophan).
This pathway is not found in animals; therefore, phenylalanine and tryptophan represent essential amino acids that must be obtained from the animal's diet
Animals can synthesize tyrosine from phenylalanine, and therefore is not an essential amino acid except for individuals unable to hydroxylate phenylalanine to tyrosine).
Pharmacognosy of Atropa belladona, biological source, geographical source, chemical constituents, uses, morphology of leaves, flower, fruits of belladona, deadly night shade leaves, chemical test, microscopy, T.S of leaves
When
food containing, lignan precursors are
consumed they are converted to the enterolignans,
enterodiol and enterolactone by bacteria that
normally colonize the human intestine
Enterodiol
and enterolactone have weak estrogenic
activity but may also exert biological effects through
nonestrogenic mechanisms
Because
enterodiol and enterolactone can mimic
some of the effects of estrogens, their plant derived
lignan precursors are classified as phytoestrogens
Lignan
precursors that have been identified in the
human diet include pinoresinol, lariciresinol,
secoisolariciresinol, matairesinol and others
When food containing, lignan precursors are consumed they are converted to the enterolignans, enterodiol and enterolactone, by bacteria that normally colonize the human intestine.
Enterodiol and enterolactone have weak estrogenic activity but may also exert biological effects through nonestrogenic mechanisms.
Because enterodiol and enterolactone can mimic some of the effects of estrogens, their plant-derived lignan precursors are classified as phytoestrogens.
Lignan precursors that have been identified in the human diet include pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, and others
Phenyl propanoid pathway by kk sahu sirKAUSHAL SAHU
SYNOPSIS
INTRODUCTION
HISTORY
DEFINITION
PRIMARY VS SECONDARY PLANT METABOLISM
SECONDARY METABOLITES
PHENOLIC COMPOUND
PHENYLPROPANOID PATHWAY METABOLITES
PHENYLPROPANOID BIOSYNTHESIS
BIOCHEMICAL PATHWAYS TO PHENOLIC CLASSES
SOME IMPORTANT PRODUCTS OF PHENYLPROPANOID PATHWAY
LIGNANS AND LIGNINS
FLAVONOIDS
METABOLIC ENGINEERING OF PHENYLPROPANOID PRODUCTION
BIOTECHNOLOGICAL APPLICATIONS
CONCLUSION
REFERENCES
AN INTRODUCTION TOPLANT SECONDARY METABOLITES :ITS APPLICATIONSSupriya Sankranthi
This presentation is about different types of secondary metabolites produced by the plants and thier applications in different fields like medicine,drugs,cosmetics and perfumery,plant defense,role in ecological balance,textile industries.
In fact, many of the drugs available today contain active ingredients extracted from natural products. Since 1994, nearly half of all drugs were discovered using natural products. Furthermore, between 2005 and 2007, there were 13 new drugs based on natural products that entered the commercial market, including the following 5 new products: small molecule ixabepilone, retapamulin, trabectedin, and the peptides exenatide and ziconotide. Clearly, natural product drug discovery programs continue to play a significant role in the clinical development of new therapies in the biopharmaceutical industry.
Is the separation of medicinally active portions of plant (and animal) tissues using selective solvents through standard procedures.
The products so obtained from plants are relatively complex mixtures of metabolites, in liquid or semisolid state or in dry powder form (after removing the solvent), & are intended for oral or external use
The Medicinal plants constitute an effective source of both traditional and modern medicines, herbal medicine has been shown to have genuine utility and about 80% of rural population depends on it as primary health care. [WHO, (2005)]
alkaloids -General methods of structural elucidation of Alkaloids. Structura...ramiah valliappan
General methods of structural
elucidation of Alkaloids. Structural
Elucidation and synthesis of
Papaverine, Quinine and Morphine.
Stereoselective synthesis of
Reserpine. Biosynthesis of Alkaloids.
Sem II, Paper III, Unit II……
This PPT include the description of flavonoids which is useful for pharmacognosy students. It include flavonoids description, classification and identification test.
bhutnashak is india's number one constipation churna .its action starts within 2 to 3 hours after oral use.it provides relief from all types of constipation.it is non habit forming and recommended for all family members.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
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.
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
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
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2 Case Reports of Gastric Ultrasound
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.
2. Lignans
When food containing, lignan precursors are
consumed they are converted to the enterolignans,
enterodiol and enterolactone, by bacteria that
normally colonize the human intestine.
Enterodiol and enterolactone have weak estrogenic
activity but may also exert biological effects through
nonestrogenic mechanisms.
. Because enterodiol and enterolactone can mimic
some of the effects of estrogens, their plant-derived
lignan precursors are classified as phytoestrogens.
Lignan precursors that have been identified in the
human diet include pinoresinol, lariciresinol,
secoisolariciresinol, matairesinol, and others
3.
4.
5. Introduction Lignans
The term “Lignan” was first introduced by Haworth (1948) to describe a group of dimeric
phenylpropanoids where two phenylpropanoid molecules are attached by its central
carbon (C8). Lignans are a subgroup of non-flavonoid polyphenols.
They are widely distributed in the plant kingdom, being present in more than 55 plant
families, where they act as antioxidants and defence molecules against pathogenic fungi
and bacteria.
Flowing structure contains
a) Phenylpropanoid and b) Lignan
a) Phenylpropanoid unit; b) Lignan structure
6. Chemical structure of lignans
Their basic chemical structure consists of two phenylpropane unitslinked by a
C-C bond between the central atoms of the respective side chains (position 8
or β), also called β-β’ bond; in these cases the dimers are called neolignans.
Hence, their chemical structure is referred to as (C6-C3)2, and they are included
in the phenylpropanoids group, as well as their precursors:
the hydroxycinnamic acids
Fig. 1 – Phenylpropane unit
7. Lignans can be found in more than 60 families of vascular plants
and have been isolated from different plant parts, exudates and
resins.
Biological activity of Lignans -are Antiviral ,Anticancer ,Cancer
prevention, Anti-inflammatory, antimicrobial ,antioxidant ,
immunosuppressive, Hepatoprotective, Osteoporosis prevention.
Based on their carbon skeleton, cyclization pattern, and the way in
which oxygen is incorporated in the molecule skeleton, they can be
divided into 8 subgroups:
Main subclasses of Lignans- 1.Furofuran, 2.Furan,
3.Dibenzylbutane, 4.Dibenzylbutyrolactol,
5.Dibenzylbutyrolactones, 6.Aryltetralin, 7.Arylnaphtalene,
8.Dibenzocyclooctadienes.
among these subgroups, the furan, dibenzylbutane and
dibenzocyclooctadiene lignans can be further classified in “lignans
with C9 (9´)-oxygen” and “lignans without C9 (9´)-oxygen”
9. They are not present in the free form in nature, but linked to
other molecules, mainly as glycosylated derivatives.
Among the most common lignans, secoisolariciresinol (the most
abundant one), lariciresinol, pinoresinol, matairesinol and 7-
hydroxymatairesinol are found.
Podophyllotoxin , a naturally occurring aryltetralin lignin, is one
of the most important compound due to its high toxicity and current
use as a local antiviral agent . podophyllotoxin, obtained from plants
of the genus Podophyllum ( Berberidaceae family); it is a mitotic
toxin whose derivatives have been used as chemotherapeutic
agents;
Food rich in lignans
The richest dietary source is flaxseed (linseed), that contains mainly
secoisolariciresinol, but also lariciresinol, pinoresinol and
matairesinol in good quantity . They are also found in sesame
seeds, whole grains.
10. Biosynthesis of lignans
The pathway starts from 3 of the 4 most common dietary hydroxycinnamic acids: p-coumaric
acid, sinapic acid, and ferulic acid (caffeic acid is not a precursor of this subgroup
of poyphenols). Therefore, they arise from the shikimic acid pathway, via phenylalanine.
The first three reactions reduce the carboxylic group of the hydroxycinnamates to alcohol
group, with formation of the corresponding alcohols, called monolignols, that is, p-coumaric
alcohol, sinapyl alcohol and coniferyl alcohol. These molecules also enter the pathway of
lignin biosynthesis.
The first step, which leads to the activation of the hydroxycinnamic acids, is catalysed by
hydroxycinnamate:CoA ligases, commonly called p-coumarate:CoA ligases , with formation of
the corresponding hydroxycinnamate-CoAs, namely, feruloil-CoA, p- coumaroyl-CoA and
sinapil-CoA.
In the second step, a NADPH-dependent cinnamoyl-CoA: oxidoreductase, also called
cinnamoyl-CoA reductase catalyzes the formation of the corresponding aldehydes, and the
release of coenzyme A.
In the last step, a NADPH-dependent cinnamyl alcohol dehydrogenase, also called monolignol
dehydrogenase , catalyzes the reduction of the aldehyde group to an alcohol group, with the
formation of the aforementioned monolignols.
11. The next step, the dimerization of monolignols, involves the
intervention of stereoselective mechanisms, or, more precisely,
enantioselective mechanisms. plant lignans exists as (+)- or (-)-
enantiomers,
Hydroxycinnamic acids (hydroxycinnamates) are a class of
aromatic acids or phenylpropanoids having a C6–C3 skeleton.
These compounds are hydroxy derivatives of cinnamic acid.
13. Flavonoids
Flavonoids are the most abundant polyphenols in human diet, over 4000 have
been identified. Latin word flavus meaning yellow, their color in nature. many of
which are responsible for the attractive colors of flowers, fruits and leaves. In
plants, these compounds afford protection against ultraviolet radiation,
pathogens, and herbivores .
In fruits and vegetables, they are usually found in the form of glycosides and
sometimes as acylglycosides . characterized by the flavan nucleus
Chemically, flavonoids have the general structure of a 15-carbon skeleton, which
consists of two phenyl rings (A and B) and heterocyclic ring (C).
flavan nucleus
14. Classification of flavonoids-
They can be subdivided into different subgroups depending on the
carbon of the C ring on which B ring is attached, and the degree of
unsaturation and oxidation of the C ring.
Flavonoids in which B ring is linked in position 3 of the ring C are
called isoflavones;
those in which B ring is linked in position 4, neoflavonoids,
while those in which the B ring is linked in position 2 can be further
subdivided into several subgroups on the basis of the structural
features of the C ring. These subgroup are: flavones, flavonols or
catechins, flavanones, flavanonols, and anthocyanins.
Finally, flavonoids with open C ring are called chalcones.
15. A) Anthoxanthins
1.flavone- Flavones are mainly found in cereals and herbs
eg luteolin,apigenin,tangeritin
2.Flavonol or 3-hydroxyflavone-
Foods rich in flavonols-The major sources in human diet
are:fruit;vegetables;beverages such as red wine and tea.
eg.Quercetin,kaempferol,myricetin,fisetin,galangin,isorhamnetin,pachypodo
l,rhamnazin,pyranoflavonols,furanoflavonols
16. B) Flavanones: type of flavonoids, are various aromatic, colorless
ketones derived from flavone that often occur in plants as glycosides.
Flavanone-eg. Hesperetin,naringenin,eriodictyol,homoeriodictyol
C)Flavanonols:class of flavonoids that use the 3-hydroxy-2,3-dihydro-2-
phenylchromen-4-one (IUPAC name) backbone.
Flavanonol or 3-hydroxyflavanone or 2,3-dihydroflavonol eg.taxifolin
or dehydroquercetin,dihydrokaempferol
17. D) Flavans - The flavans are benzopyran derivatives that use the 2-phenyl-3,4-dihydro-2H-
chromene skeleton include
1. flavan-3-ols (flavanols),- examples are catechin, gallocatechin, catechin 3-gallate,
gallocatechin 3-gallate,epicatechins.
2. flavan-4-ols
3.flavan-3,4-diols.
flavan-3-ols flavan-4-ols flavan-3,4-diols
18. D) Anthocyanidins - anthocyanidins are the aglycones of
anthocyanins; Anthocyanins are a very large group of red-
blue plant pigments. Anthocyanins occur in all higher
plants, mostly in flowers and fruits but also in leaves,
stems, and roots. They are very good antioxidants
Health benefits of flavonoids-Their regular consumption is
associated with reduced risk of a number of chronic
diseases, including cancer, cardiovascular disease (CVD)
and neurodegenerative disorders. thy are good
antioxidant and anti-inflammatory ,