Allium Sativum, Research Paper Example

Create a detailed phytochemistry table for your selected herb:  Allium sativum, garlic.  

Summarize one only analytical study, in which one or more constituents from your herb are identified.  While you are expected to focus on the analytical methods(s) used, a brief summary listing the main procedures (eg form of chromatography, detectors used, solvents) is required rather than in depth technical detail.

In order to identify the constituents of garlic a pytochemical analysis is conducted on the sample extract. In pytochemical analysis 500g of air dried bulbs of the Allium sativum, garlic is cut into small pieces and pulverized. The now powder bulbs are soaked in water and heated to 100 degrees centigrade.  It is left to cool and subsequently filtered into a clean container. The filtrate obtained is then dried in the oven for concentration and the resultant yellowish crystalline crude extract is used for toxicity studies. For further analytical study of the constituents of the herb phytochemical screening is done on the powdered plant material.

One of the constituents of garlic is allicin which is responsible for the usual odor of freshly cut garlic.  This component is produced from crushed garlic cloves or wet garlic powder by the rapid lysis of alliin by alliinase enzyme. Its solubility in water is only 2%, moderately soluble in hexane and is very soluble in organic solvents which are more polar than hexane. About its stability, it is most stable in water with a half life of 30 days at room temperature.  This is due to the fact that hydrogen bonding in water reduces the rate of self –reaction.

In summary allicin is isolated from an aqueous extract of garlic powder by the use of solid phase extraction chromatography method. Its concentration in the isolated fraction is made standard by spectrophotometry and HPLC analysis. The analysis of the sample is carried out by extracting garlic powder with water and quantifying it against the isolated allicin external standard. The HPLC is comprised of Phenomenex Prodigy™ ODS (3) C18, 5µm, 100Å, 4.6 x 250 mm; the mobile phase is methanol/water (50/50) at 0.9 mL/min and detection is at 240 nm (Han, Lawson, Hand, & Han, 1995).

Alternatively, the recently discovered  extracts of garlic which include typheramide and alfrutamide that have been tested in labs and discovered to have positive effects on COXs(COX 1 AND 2). Can be extracted from garlic cloves by the use of methanol (MeOH), the extract is partitioned using ethyl acetate (EtOAc) and n-butanol(n-BuOH) . ethyl acetate sample is fractionated using silica gel column. Typheramide and alfrutamide are then purified from the silica gel fractions by the use of high performance liquid chromatography (HPLC). The chemical structures of the constituents are verified using nuclear magnetic resonance (NMR) spectroscopic method (Park, 2011).

Summarize one only in vitro or in vivo study using the whole plant or plant extract that: a. demonstrate a therapeutic or pharmacological action       

In in-vitro studies garlic has been found to have antibacterial, antiviral and antifungal actions. Also it is claimed that garlic has the potential of preventing some diseases like atherosclerosis, hyperlipidemia, hypertension and cancer. In addition, garlic can prevent some specific types of cancer including stomach and colon cancers.

Studies in countries where garlic is used mostly as food record small incidences of cancer.  Also studies on both humans and animals have proven cardiovascular benefits. Garlic actually reduces the accumulation of cholesterol on the vascular walls of both humans and animals. This helps in the prevention of hypertension. Further, garlic supplements,( typheramide and alfrutamide) when taken in humans with high blood cholesterol, inhibit vascular calcification (Park, 2011).

Most studies with garlic over the last 15 years have focused particularly on the fields of cardiovascular and cancer research. Garlic has also been found to produce good anti-thrombotic actions.

In which one or more specific constituents are demonstrated or hypothesized to be partially or totally responsible for the actions in a.

Garlic extracts and constituents have demonstrated significant antithrombotic actions in both in vitro and in vivo systems. Constituents like allicin and adenosine are the most important anti platelet inhibitors due to their in vitro effects (Lawson & Hughes, 1991).

Constituents are metabolized rapidly in the body tissues and ajoene, which is found in small quantities in garlic is used in the treatment of thromboembolic disorders.

Further research on garlic found an enzyme that can inhibit the activities of adenosine deaminase and cyclic AMP phosphodiesterase in the human body. Such enzyme inhibitors  typheramide and alfrutamide in garlic help in explaining several clinical effects in the body which include antithrombotic, vasodilation and anticancer actions (Lawson & Hughes,1991).  Finally garlic helps in preventing and reducing the aggregation of platelets, hypercholesterolemia  and hyperlipidaemia. This has led investigators to critically examine the constituents of garlic for antitumor and other actions like cytotoxins in both in vitro and lab animals (Lawson & Hughes, 1991).

Prepare a discussion based on your reading of at least four (4) primary research reports (including those selected for parts 2 and 3 above) as well as relevant secondary references, on the relationship between the action and clinical use of you’re herb and its known active constituents.  Speculation is permissible as long as there is some underlying rationale based on literature.  Where possible make reference to key pharmacological principles that are also covered in this course e.g. pharmacokinetics, receptor binding, synergy, hormesis.  You may also consider doses used experimentally and mode of administration and how this carries over to clinical applicability. (Allium sativum)

BBC reported in 2007 that garlic has properties of preventing and fighting the common cold. This assumption is based on the fact that traditionally garlic was used to reduce hoarseness and coughs. Also some people used it as an expectorant for coughs and croup. Garlic is also said to help in regulation of blood sugar levels. This is due to the fact that prolonged use of garlic extracts lower blood homocysteine levels preventing complications arising from diabetes mellitus. Garlic cloves can also be used to remedy infections related to chest, digestive disorders and fungal infections like thrush. Additionally it can be used as a dis-infectant due to its unique bacteriocidal and bacteriostatic properties. In nutcell information from different sources like epidemiology, clinical, and laboratory have proven that garlic has both biological and pharmacological compounds which are of benefit to the overall body. Many studies and research are still in progress to get more constituents from garlic that will be therapeutically useful (Lawson, Wood & Hughes, (1991).

Garlic has both internal and external actions in human. It can act internally as an antibacterial, antifungal, anti-inflammatory, antimicrobial, antihelmintic, antiseptic, antiviral, hypotensive-vasodilator, cholagogue, antispasmodic, antihyperlipidemic, increases HDL, anti-atheromatic, PAF antagonist, increases fibrinolytic activity, hypoglycemic, expectorant, diaphoretic, antioxidant, antitumour, antineoplastic, antimutagenic, diuretic, carminative and Emmenagogue.  Externally garlic can act as an antimicrobial, antifungal and  expectorant (Lawson & Hughes, 1991).

Garlic has long been known to be safe when consumed in reasonable quantities and it has not produced any toxic complications. However, in the consumption of unprocessed garlic caution should be taken in children, breast feeding mothers and pregnant women although there are no clinical evidence of adverse effects on lactation and pregnancy.

Investigators argue that garlic can change the nutritional quality and flavor of milk in lactating mothers; also it can cause irritation by forming burns, blisters and ulcers with very poor healing trends.   Garlic can also cause gastrointestinal irritation when the clove is consumed raw and finally gastrointestinal flora may be altered by garlic consumption.

Clinical relationship of the herb.
Prescription and dosage.
• When Fresh 2 to 5 garlic cloves can be used per day which are equivalent to approximately 5000 mg fresh daily.

Up to 30 gm may be consumed daily in acute conditions. Obtaining a consistent and therapeutic dosage of garlic is challenging due to the many forms of garlic that can be found commercially.

Standardized: 1000mg fresh is equivalent to 1000 mcg allicin potential or 10 mg. alliin. Five thousand (5000 mcg) allicin is a good general therapeutic dose (Lawson & Hughes, B ,1991).

Pharmacology of garlic

Pharmacological studies have proved that garlic constituents show a wide range of antimicrobial actions. These actions are active against several genera of bacterial infections like Staphylococcus, Streptococcus, Brucella, and Vibrio spp. They are also active against Viruses like Herpes simplex type 1 and type 2, Parainfluenza virus type 3, Vaccinia virus, Vesicular stomatitis virus and Human rhinovirus type 3. There is also activity against fungi like Candida albicans, Cryptococcus neoformans and worms (Ascaris lumbricoides)
Epidemiological studies have shown that the consumption of garlic reduces the incidence of cancer. In vitro studies of garlic extract in human and animal cell lines have proven that garlic has potent chemopreventative and anticancer effects (Lawson, Wood & Hughes, 1991) the constituents which act against cancer include various organo-sulphur compounds like the diallyl sulfides ajoene and selenium. Organo-sulfur compounds actually induces apoptosis in human promyelolekemic cells which in turn increase reduced glutathione hence reducing formation of polyamine in human prostate cancer lines. Selenium constituents protect the body against tumourogenesis and high selenium extracts  inihibit casinogenessis in humans and animals. Experiments on garlic have shown that the extracts of garlic have anti- inflamatory action and anti-oxidant activities related to reduce glutathione enhancement. The extracts can bring about immune modulation, macrophage oxidation burst increase and T-lymphocyte blastogenesis in vitro stimulation (Park, 2011).

Other activities of garlic extracts include the possession of diuretic, diaphoretic, emmenagogue and expectorant actions together with carminative and anti-spasmodic actions on the alimentary system (Heinrich, Koch,  Larry, Lawson,Williams & Wilkins,2005).
Garlic extracts doses of about 10mg alliin or a total of allicinequal to 4000mcg reduces the total serum cholesterol to a lower percentage of 10-12%. In particular garlic rises HDL but lowers LDL cholesterol making the ratio of LDL/HDL which is most significant than the overall reduction of total cholesterol (Han, Lawson,Hand,& Han1995).
Garlic also acts   against Atherosclerosis and LDL oxidation. Prescriptions of 600mg/day of garlic extracts reduce significant susceptibility of apolipoprotein B to oxidize. Doses of 600 mg/day considerably reduce the level of susceptibilty in apolipoprotein B to oxidative damage in only two weeks in a double blind placebo controlled trial. A longer span study (10months) for  hypercholesterolemic men also found diminishing susceptibility of lipoproteins to oxidation compared to placebo.
Clinical trials show that garlic has hypotensive effect in vitro and in human studies. Actually garlic lowers the systolic pressure by approximately 11mm Hg and diastolic by 5.0 mm Hg when taken in doses of 600-900 mg daily at standard alliin dose of 1.3%. The hypotensive effects include the ability of garlic extracts to hinder PAF and reduce the rheological viscosity of blood.
Garlic extracts inhibit the aggregation of the blood platelates and the formation of platelet thromboxane as well as increase the activity of fibrinolysis (Park, 2011).  More clinical trials reveal that garlic reduces blood viscosity though a mechanism of rheoregulation by vasodilation of precapillary arterioles which allow the inflow of interstitial fluid ( Lawson & Hughes, 1991).
Garlic has been alleged to be contradictory during pregnancy but herbalists and mid wives have revealed that garlic is safe and is useful for the treatment of upper respiratory infections during pregnancy (Lawson & Hughes, 1991).

Garlic constituents of typhermide and alfrutamide are have been proved to likely modulate the metabolism of arachidonic acid via inhibiting COX enzymes rather than LOX enzymes which may support traditional uses of the herb in preventing or treating diseases conditions related to in-flammation and cardiovascular diseases rather than asthma and immune diseases (Park, 2011).

Reference

Garty B, (1993). “Garlic burns”. Pediatrics 91 (3): 658–9.

Lawson, L., Wood, S. &  Hughes, B (1991).  “Analysis of Allicin and Other Thiosulfinates in Garlic Clove Homogenates,”. Planta Medica, 57, pp 263-270

Lawson & Hughes, B, (1991). “Characterization of Formation of Allicin and Other Thiosulfinates from Garlic,” Planta Medica, 58, pp. 345-350

Han, Lawson, Hand, & Han,(1995). “A Spectrophotometric Method for Quantitative determination of Allicin and Total Garlic Thiosulfinates.”. Biochem. 225, pp 157-160.

Park JB, 2011, Journal Of Medical Food: effects of typheramide and alfrutamide found in allium sativum on cyclooxygenases and lipoxygenases.226-231