Component – I (A)
Role Name Affiliation
Principal Investigator Dr. Sheela Ramachandran Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore.
Co-Principal Investigators Dr. S.Kowsalya Dr.M.Sylvia Subapriya Dr.G. Bagyalakshmi Mrs.E.Indira
Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore.
Paper Coordinator Dr. S. Thilakavathy Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore.
Content Writer Dr. K. Bhaskarachary Senior Research Officer
Dept. Food Chemistry National Institute of Nutrition Jamai Osmania, Hyderabad – 500007.
Content Reviewer Dr. K. Bhaskarachary Senior Research Officer
Dept. Food Chemistry National Institute of Nutrition Jamai Osmania, Hyderabad – 500007.
Language Editor Dr. K. Bhaskarachary Senior Research Officer
Dept. Food Chemistry National Institute of Nutrition Jamai Osmania, Hyderabad – 500007.
Component-I (B) Description of Module
Items Description of Module
Subject Name Foods and Nutrition
Paper Name Functional Foods and Nutraceuticals
Module Name Allyl-S- Compounds
Module ID F11FN06
Pre-requisites Beneficial effect of garlic extract and
capsicinoids on human health and pharmacological properties
Objectives · To know the concepts of allyl-s-
compounds and its biological properties
· To capsicinoids and its biological properites
· Benifical effect of garlic and chillies on human health and wellness
Keywords Allyl-S- Compounds , allicin, antimicrobial and
antiinsecticidal properties, Sulphur component and Apoptosis
Introduction
This module deals with allyl-s-compounds and capsicinoids, which having wide biological properties. Further these modules deals about beneficial effect of garlic extract and capsicinoids on human health and its pharmacological properties.
Objectives
After completing this module, the learner will be able to
· know the concepts of allyl-s-compounds and its biological properties
· capsicinoids and its biological properites
· Benifical effect of garlic and chillies on human health and wellness
Overview
This module is part of the Food Biotechnology paper. It is designed to give an overview of the allyl-s-compounds and capsicinoids and its biological properties related to useful for human growth and development. . The students will be able to understand the different organic sulfur components present in garlic and its different biological functions.
Allyl-s- compounds:
Allyl-sulfur compounds are organic derivatives of sulfur compounds extensively present in genus allium which consists of garlic (Allium sativum) and Onion (Allium cepa). The allyl sulfur compounds demonstrating immense biological functions which includes anti microbial, anti oxidative and anti cancerous properties which was extensively studied in both in invitro and invivo.
Allyl-s- compounds in garlic:
In garlic, allicin is the first sulfur compound extensively analyzed, a scientist from American organic groups called Cavallito and Baily, isolated this compound in 1944.
Interestingly the compound was generated only during cruched/chopped condition by the activity of allinase, an enzyme which converts stored alliin into allicin which gives pungent smell of
garlic. The allicin having broad spectrum antimicrobial and antiinsecticidal properties and garlic used as defense mechanism against attacks by pests. However allicin is very unstable and converts into series of sulfur compound like diallyldisulfide (DDS), diallyltrisulphide(DTS) etc., which exhibits antibacterial, fungal,viral and antiprotozoal ativity. Several animal studies published between 1995 and 2005 indicate that allicin may reduce atherosclerosis and fat deposition, normalize the lipoprotein balance, decrease blood pressure, have anti-thrombotic and anti-inflammatory activities which have been discussed later part of this chapter.
The general pathway of allyl-s-compounds synthesis in garlic
Chemical structure of widely studied natural organo sulfur compounds (allyl derivatives)
Extraction of allyl-s- compounds from garlic:
Steam distillation, water extraction, drying and pulverizing and alcohol immersion were the major methods used for extraction. In steam method volatile compounds were condensed and collected as garlic oil and more than 20 organo sulfur compounds were analysed in garlic oil.
Among which DAS,DADS and DATS were major components. The garlic oil products were commercialized by blending with other vegetable oils for various purposes.
Biological properties of allyl-s-compounds:
The all biological properties related to garlic, which has been extensively used from 3000yers has credited to organo sulfur compounds which has been extracted as water soluble and oil soluble extracts. Reports from the 19th century describes the presence of diallyl disulfide, trisulfide, and tetrasulfide compounds in steam-distilled garlic oiL In 1944 Cavallito described the isolation of the odoriferous antibacterial substance allicin from extraction of garlic with ethanol at room temperatures obtained from alliin which represents 0.24% of dry garlic.
Research revealed that the cysteine sulfoxide fraction of garlic consists of 85% along with 2%
S-propylcysteine sulfoxide and 13% S-methylcysteine sulfoxide ." Action of allinase on the mixture of 3-5 affords allyl methanethiosulfinate, MeS(0)- SCH2CH=CH2, methyl methanethiosulfinate, MeS(0)SMe, and other mixed or symmetrical thiosulfinates RS(0)SR' (R and R' are variously methyl, propyl, and allyl) found in garlic.
Regulation of NFkb pathway: Invitro studies in human T cells showed that s-allyl cystine having inhibitory effect on nuclear factor kappa b activation, a factors regulate expression of genes encoding proteins in immune function, inflammation and cell growth regulation.
Antioxidants such as vitamin E derivatives and a-lipoic acid have been shown to inhibit NF-kB activation in human T cells induced by TNF-a and PMA. Further N-acetyl cystine also showed a promising result in HELA cells via inhibiting TNFa and H2o2 effect on oxidative balance. In the past few years several investigators have used both in vivo and in vitro models to show that
garlic compounds protect hepatocytes from lipid peroxidation induced by various oxidants. S- allyl cysteine (SAC), one of the major garlic compounds, was shown to protect vascular endothelial cells from H2O2-induced oxidant injury.
Anti cancerous Properties: A sulfur component of garlic has anticancerous properties and showed anti tumors activity in various cancers models both invivo and invitro. In one of the study three water-soluble sulfur compounds - Sallyl- cysteine (SAC), S-ethyl-cysteine (SEC) and S-propyl-cysteine (SPC) - and three oil-soluble sulfur compounds - diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisullide (DATS) - were examined for their ability to alter the in vitro growth and metabolism of canine mammary tumor cells line 13 (CMT-13). Interestingly, oil soluble compounds having cytostatic impact on CMT-13, and its intensity was proporetional to sulfur content of the compound i.e DATS>DADS>DAS. However water soluble compound doesn’t show any impact on cell multiplication. Further 1uM of DADS is sufficient for total cytostatic function, which prevent multiplication of CMT13.
Evidence for anticarcinogenic effect of Allium vegetables derives from epidemiological data as well as laboratory studies. For example, a population-based, case-control study involving 564 patients with stomach cancer and 1131 controls documented an inverse correlation between dietary intake of Allium vegetables and cancer risk. A more recent population-based, case- control study conducted in Shanghai, China, examined the association between intake of Allium vegetables (garlic, onions, scallions, chives, and leeks) and the risk of prostate cancer. This study, involving 238 cases with histologically confirmed prostate cancer and 471 control subjects, concluded that men with high intake of total Allium vegetables (>10 g/day) had
a statistically significantly lower risk of prostate cancer than those with low intake (<2.2 g/day).
Regulation of apoptosis by Allyl-s-compounds:
Apoptosis is a tightly regulated process of cellular suicide, which is implicated in development, tissue homeostasis of multicellular organisms, and various physiological and pathological conditions. Abnormalities in cell death control can lead to a variety of diseases including cancer.
Pathways leading to apoptosis are initiated either from internal events within the cell (mitochondrial or intrinsic pathway) or at the cell surface (death receptor or extrinsic pathway),
which result in the proteolytic activation of cysteine proteases (caspases). More recently, we compared sensitivities of PC-3 and DU145 human prostate cancer cells to apoptosis induction byDAS,DADS, andDATS. Both cell lines were relatively more sensitive to apoptosis induction by DATS compared with DAS and DADS, suggesting that the oligosulfide chain length affects apoptosis inducing activity of OSCs.Ectopic expression of Bcl-2 in PC-3 cells afforded significant protection against DATS-induced apoptosis underscoring significance of Bcl-2 in cell death by this OSC analogue.
Anti atherogenic process:
Oxidation of low-density lipoprotein (LDL) and activation of the pleiotropic transcription factor nuclear factor kappa B (NF-kB), are often the chemical and molecular alterations associated with the development of the atherosclerotic lesion. Oxidsed-LDL results in foamcell formation via increasing monocyte chemotaxis and decreased macrophage motility results in the production of free radicals and inflammatory cytokines which Interns activates transcription factor, nuclear factor kappa B (NF-kB), in the surrounding endothelial cells of the vascular intima. NF-kB activation has been implicated strongly in increased adhesion molecule production, increased growth factor production and smooth muscle proliferation. The synthetic antioxidants have profound impact on reduction of foamcell formation along with vasodilators. However former had a issue of toxicity at high and chronic consumption. So naturally available antioxidants have higher values and many studies showed antioxidant properties of sulfur containing compounds in garlic, so it might be a naturally promising compound on anti atherosclerosis properties. Further studies are also showed that antioxidant properties of sulfur components of garlic was comparable with standard antioxidant butylated hydroxytoluene in prevention of TBARS formation from oxidized LDL in the presence of copper sulfate. Further reactive oxygen production from mstimulated macrophages was significantly decreased in the presence of garlic components. In addition NFkb factors in nucleus of garlic treated cells were significnalty decreased compare to control cells which were treated with H2O2.
Antioxidative properties:
7 week feeding of diallylsulfide and diallyldisulfide changed rat hepatic glutathione related antioxidant activities by increasing glutathione reductase and decrease in peroxidase activity.
Further studies were also confiremed that disulfide is more potent than mono sulfide and diarryl derivatives were more active than monoarryl derivatives. Invitro studies showed that, S-allyl- cystine is able to scavenge singlet oxygen and hydrogen peroxide, prevents H2O2-induced endothelial cell injury and lipid peroxidation
In addition, TNFa and H2O2 can induce high levels of NF-kB activation in human T lymphocytes, and SAC can inhibit this NF-kB activation. Further SAC reduces ischemic
brain edema in rats by inhibiting lipid peroxidation, and reduces histological damage to the heart and liver in mice treated with doxorubicin, an anticancer drug . Recently, we reported that SAC attenuates carbon tetrachloride (CCl4)-induced pulmonary fibrosis in rats Reduced glutathione (GSH) plays important roles in the protective effect against antioxidative injury, and both N-
acetyl cysteine (NAC) and L-cysteine (Cys) have been reported to act as glutathione prodrugs.
Although hepatoprotective properties of NAC have been reported in several previous studies.
Neuroprotective functions:
Alzimers and parkinsons are leading neurodegenerative disorders in which former is associated with accumulation of amyloid beta peptides in motor neurons. The involvement of oxidative stress in formation of amyloid proteins were well understood, and it induces cell death when incubated with neuronal cell lines. Aged garlic extracts atlist for 10months have improved neuro protection with improved impaired learning and memory, neurotrophic and antioxidant activities.
S-allyl L-cystine, a active component of aged garlic extract have neuro protective effect in cultured cell lines. SAC protects against Ab-induced cell death and invivo studies were required to support the hypothesis strongly.
Prevention of advanced glycation end product formation and anti cardiovascular disorders properties:
Diabetes mellitus is a metabolic disorder characterized by chronic hyperglycaemia and hyperlipidaemia that predisposes affected individuals to long-term micro- and macrovascular complications of which cardiovascular disease is the most serious consequence. During hyperglycaemia, body proteins undergo increased glycation where glucose reacts non- enzymatically with protein amino groups to form a labile Shiff base that rearranges to a stable Amadori product. Accumulation of crosslinked advanced glycation endproducts in body tissues are believed to be responsible for the longterm complications of diabetes and ageing. Aged garlic extract contains potent antioxidant activity having rich in S-allyl cysteine which is a potent antioxidant and free radical scavenger S-allyl cysteine has Amadorin activity and inhibited formation of crosslinked advanced glycation endproducts. Many animal and humans studies showed that allyl-s-compounds have protective impact on CVD by decreasing Low density lipoprotein cholesterol and triglyceride levels in plasma lipids. Two meta-analyses of randomized, placebo-controlled human studies confirmed the hypocholesterolemic effects of garlic Animal studies, however, have shown that garlic supplementation in the diet depressed the
hepatic activities of lipogenic and cholesterogenic enzymes such as malic enzyme, fatty acid synthase, glucose-6 phosphate dehydrogenaseand 3-hydroxy-3-methylglutaryl- CoA (HMG- CoA) reductase
It is, therefore, reasonable that the hypocholesterolemic effect of garlic may stem in part from impaired cholesterol synthesis. In fact, we observed recently that garlic extracts that contained various sulfur compounds effectively decreased the plasma concentration of cholesterol, resulting possibly from an inhibition of hepatic cholesterol synthesis.
Anti Microbial activity:
Anti protozoal properties:
Allicin, ajoene and organosulfides from garlic are also effective antiprotozoals. It has been suggested that microbial cells are more affected than human cells because they do not have an
intracellular thiol content adequate to counterbalance the thiol oxidation by allicin and allicin- derived products. Ajoene has been shown to inhibit phosphatidyl choline synthesis in trypanosomes. Early work establishing garlic as a possible treatment for giardiasis used for gastrointestinal complaints specially with Entamoeba histolytica. Inhibitory activity was noted with crude extract at 25 μg ml–1and the lethal dosage was established as approximately 50 μg ml–1. Encouraged by these results, a clinical trial was carried out on patients that had giardiasis.
Garlic was established as an antigiardial, removing the symptoms from all patients within 24 h and completely
Transformation of principal thiosulfinates in garlic
Antibacterial properties
Garlic has been used for centuries in various societies to combat infectious disease. In India, garlic has been used to prevent wound infection and food spoilage In Ireland, at the turn of the twentieth century garlic was used to combat pulmonary infection. More recently garlic has been proven to be effective against a plethora of gram-positive, gram-negative and acid-fast bacteria.
These include Pseudomonas, Proteus, Staphylococcus aureus, Escherichia coli, Salmonella , Klebsiella Micrococcus, Bacillus subtulis, clostridium Mycobacterium and Helicobacter.
Interestingly, that garlic exerts a differential inhibition between beneficial intestinal microflora and potentially harmful enterobacteria Inhibition observed in E. coli was more than 10 times greater than that seen in Lactobacillus casei for the same garlic dose. The antibacterial activity of garlic is widely attributed to allicin. It is known that allicin has sulfydryl modifying activity and as such is capable of inhibiting sulfydryl enzymes. Garlic extract and allicin have been shown to exert bacteriostatic effects on some vancomycin- resistant enterococci.
Antifungal properties:
Antifungal activity was first established in 1936 by Schmidt and Marquardt whilst working with epidermophyte cultures. Many fungi have proven susceptible, including Candida ,Torulopsis, Trichophyton, Cryptococcus Aspergillus, Trichosporon and Rhodotorula. Garlic extracts were
shown to decrease the oxygen uptake, reduce the growth of the organism, inhibit the synthesis of lipids, proteins and nucleic acids and damage membranes. A sample of pure allicin was shown to be antifungal. Removal of the allicin from the reaction by solvent extraction decreased the antifungal activity. Activity has also been observed with the garlic constituents, diallyl trisulfide, against cryptococcal meningitis and ajoene, against Aspergillus . Again thiol addition to the test reduced the activity,suggesting the blocking of thiol oxidation by allicin. Inhibition of respiratory activity is thought to be due to inhibition of succinate dehydrogenase. The adhesion of Candida is also greatly reduced in the presence of garlic extract. Again this effect is diminished by the addition of thiol compounds. The addition of ajoene to some fungal growth mixtures, including Aspergillus niger, C. albicans and Paracoccidiodes has resulted in inhibition at concentrations lower than that experienced with allicin. Studies with aged garlic extract (with no allicin or allicin-derived constituents) showed no in vitro activity.However, when given to infected mice the number of organisms that were seen was reduced by up to 80%.
Antiviral properties
In comparison with the antibacterial action of garlic very little work has been done to investigate antiviral properties. The few studies have reported that garlic extract shows in vitro activity against influenza A and B, cytomegalovirus, rhinovirus, HIV, herpes simplex virus 1 and 2 , viral
pneumonia and rotavirus. Allicin, diallyl trisulfide and ajoene have all been shown to be active In the case of HIV, it is thought that ajoene acts by inhibiting the integrin- dependent processes.
Allyl alcohol and diallyl disulfide have also proven effective against HIV-infected cells. No activity has been observed with alliin or S-allyl cysteine; it appears that only allicin and allicin- derived substances are active.
Capsaicinoids
Capsaicinoids are the chemicals which give rise to the heat of chilies. They are present in almost every pepper. Capsaicinoids are the name given to the class of compounds found present in members of the capsicum family of plants. The most common of these compounds is N-Vanillyl- 8-methyl-6-(E)-noneamide or capsicin and dihydrocapsaicin which occurs in either 1:1 to 2:1 between plant to plant and represents more than 80% of total capsicinoids concentration. Nearly as common is Dihydrocapsaicin These occur in varying ratios from plant to plant, from a 1:1 ratio to 2:1. Between them they typically make up 80-90% of the total capsaicinoid concentration. The capsicin present in chilli is secondary metabolite it is an irritant for mammals including humans, and produces sensation of burning in any tissues with which it comes in contact. Pure capsaicin is a volatile, hydrophobic, colorless, odorless, and crystalline to waxy compound.
Capsaicin Dihydrocapsaicin
Capsacinoids were found to be defense in mechanism and their effects were less-than-lethal self- defense weapons, have been associated with respiratory failure and death in exposed animals and people. The studies described herein provide evidence for acute respiratory inflammation and damage to epithelial cells in experimental animals, and provide precise molecular mechanisms that mediate these effects using human bronchiolar and alveolar epithelial cells. Inhalation exposure of rats to pepper sprays (capsaicinoids) produced acute inflammation and damage to nasal, tracheal, bronchiolar, and alveolar cells in a dose-related manner. In vitro cytotoxicity assays demonstrated that cultured human lung cells (BEAS-2B and A549) were more susceptible to necrotic cell death than liver (HepG2) cells.
Capsaicin Biosynthesis in Plants
Capsaicin biosynthesis in plants is defined by two pathways: phenylpropanoid, which determines phenolic structure; and fatty acid metabolism, which determines the molecule’s fatty acids.
Capsaicin concentration increases gradually during fruit development reaching maximum levels at 40 to 50 days, after which it tends to degrade into secondary compounds due to peroxidase action. Research aimed at increasing or improving pungent compound production has revealed that hydric stress increases capsaicinoid levels because water deficit affects the phenylpropanoid pathway.Hydric stress also increases capsaicin levels by raising activity of the enzymes phenylalanine
ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (C4H) and CS, all involved in capsaicin biosynthesis. Administration of the capsaicin precursors 8-methyl-noneic acid and vanillylamine had demonstrated that 8-methylnoneic acid occurs at lower levels than vanillylamine and is therefore the limiting substrate for capsaicin synthesis. These results suggest the possibility of controlling capsaicin synthesis in the plant by manipulating substrate concentrations and water availability, which would be a cost-effective, viable alternative for increasing capsaicin production.
Mechanism of Action
Capsaicin can bond to transient receptor potential vanilloid 1 (TRPV1), previously known as the vanilloid receptor, which is mainly expressed in the sensory neurons. TRPV1 is also broadly distributed intissues of the brain, bladder, kidneys, intestines, keratinocytes of epidermis, glial cells, liver, and polymorphonuclear granulocytes, mast cells, and macrophages. Contact between capsaicin and sensoryneurons produces pain, inflammation and a localized heat sensation. When applied locally to skin, it promotes an analgesic response due to desensitizing of the sensory neurons caused by substance P depletion. This mechanism has served as a base for studies of the structure-activity relationship which are aimed at development of new synthetic ligands for the TRPV1. Capsaicin’s effects in the nervous system are not exclusively analgesic. A number of studies include results showing that it participates in release of somatostatine, CGRP and endotheline.
Clinical Applications in Humans
Protection against ulcers:
Research into the possible protective role of capsaicin in the gastrointestinal tract have produced controversial results and clearly indicates the need for further clinical trials to better define effective dosages. At low concentrations (0.13–160 μM) in rats, capsaicin is reported to protect the gastric mucous against ulceration by ethanol, whereas when administered at high concentrations (1 or 2 mg/mL) in rat stomachs it is reported to worsen damage to the gastric mucous caused by ethanol or aspirin. In a study involving 84 healthy human subjects, capsaicin was found to have protective properties against ethanol- and indomethacine-associated gastropathy, with a dose dependent decrease in base gastric acid output (ED50 for 400 μg capsaicin) and increased gastric emptying. A possible explanation is that capsaicin mediates the antiulcerous effect by vasodilation and increasing gastric mucous blood flow (GMBF) and this is mediated by nitric oxide and CGRP release by these TRPV1 bearing cells.
Regulation over adipose tissue accumulation:
In rodents, capsaicinoids were found to be reduced adipose tissue accumulation by enhancing energy and lipid metabolism, possibly by increasing catecholamine secretion from the adrenal medulla in response to activation of the sympathetic nervous system.
Pain relief:
As mentioned above, capsaicin has been included in topical treatments aimed at relief of different neuropathic pain conditions, although it can produce skin irritation. Capsaicin and its analogues have been used in topical creams and patches to treat chronic pain syndromes such as
post-herpetic neuralgia, musculoskeletal pain, diabetic neuropathy, osteoarthritis and rheumatoid arthritis. It has also been applied to treat pain from rashes, psoriasis, mastectomy, and bladder disorders. Adverse effects (burning, stinging and erythema) are normally limited to the application site, although respiratory irritations from cream inhalation and occasional systemic effects have been reported.
Conclusion
Garlic is cultivated worldwide and its potential medical properties have been recognized for thousands of years. Garlic has acquired a reputation in many cultures as a formidable prophylactic and therapeutic medical agent. Many recent studies have demonstrated garlic’s pharmacologic effects, such as antibacterial, antifungal, hypolipidemic, hypoglycemic, antiothrombotic, antioxidant and anticancer properties. Although garlic is known for its many pharmaceutical effects, these abilities can be depressed by preparation or processing methods.
The negative influence of heating may be related to suppression of the activity of the enzyme alliinase. Studies showed evidence that 10 min “standing” time after crushing garlic is necessary for the biologically active generation of compounds to reduce the blunting effects of heating.
Capsicinoids from foods like chillies showed various biological properties such as anti microbial, oxidative and inflammatory properties. So garlic and chili has many nutraceuticals properties which have to be promoted in our population to obtain its beneficial effects.
