© 2006 Eitan Grunwald
Jessica Crable
© 2006 Eitan Grunwald |
Table of
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Few people know the nubmer of plants that contain toxins. We have planted many of them in our gardens or used them as decorations in our homes, unaware of how dangerous they can be. Here, the poison of the Mountain Laurel is examined.
Mountain Laurel is a flowering evergreen shrub, which can sometimes grow to the size of a tree. They can be found growing along the rocky sides of mountains and in the forests atop the mountains in the Eastern and Southern United States.[1] If the Mountain Laurel is unfamilar, you may also know it as one of these other common names, Ivybush, Calico Bush, Spoonwood, Sheep Laurel, Lambkill, or Calmoun.[2]
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The Mountain Laurel, scientific name Kalmia latifolia, belongs to the Ericaceae or Heath family.[1] Broad glossy leaves and clusters of white to pink star shaped flowers are characteristic of the laurel. |
 Grayanotoxin |
What make laurel toxic is the presence of grayanotoxin I and arbutin in all parts of the plant. Grayanotoxins are common among the plants of the Ericaceae family.[1] Also known as andromedotoxin, grayanotoxin is a polyhodroxylated cyclic diterpene. Diterpene are a class of terpenes that is composed of four isoprene units.[3] The structure of this toxin is fairly complex. When studies were first done on the toxin the chemical formula varied between studies. It was determined that several types of grayanotoxins existed with the same basic formula.[4] Grayanotoxin I, II, and IV are the most toxic. There are a total of thirty different related compounds.[5] |
 Arbutin  Drawn using ChemSketch  3D rendering using SDViewerLite |
Arbutin is hydroquinone glycoside.[6] The arbutin structure consits of a sugar, from which the name glycoside comes. The sugar is bonded to a phenolic sturcture, the hydroquinone, through the sugar's anomeric carbon. Hydroquinone is also known as benzene-1,4-diol, with two hydroxyl groups bonded para on an aromatic ring.[7] |
The complete synthesis of Grayanotoxin I has not yet been achieve. Grayanotoxin can be synthesized in a method that involves "stereoselective cyclization reactions induced by SmI2".[8] The toxin can be extracted using methanol. Analysis can be done through thin-layer chromatography and direct spectrophometric methods. Detection through the use of LC-MS/MS as been shown to be a rapid method of analysis to determine exposure.[5]
There are several different ways in which arbutin can be synthesized. Many of the reactions involve a glucoside and a phenylbenzene as reagents. One reaction involves a two step process which is more convenient than many of these classical methods. In this reaction arbutin is sythesized from glucose and an acetyl halide.[9] Arbutin is often analysized by spectrophotometry and capillary zone electrophoresis. Reversed-phase HPLC is the best method of quantitative analysis because it can be applied directly to crude extract.[10]
The typical symptoms of grayanotoxin poisoning are excesse salivation and perspiration, vomiting, and dizzy and weak spells. At high doses there may be symptoms such as disruption of myocardial activity, loss of coordination and severe muscle weakness.[3] The grayanotoxin acts on the sodium channels of the cell membrane. Action of the grayanotoxin is located where the protein is transmembrane. Because of the effects on the sodium channels grayanotoxin has become an important pharmalogical tool for the study of the channels, the location of action indicates the region in which activation and deactivation occurs.[11] The toxin binds to the region of the channel involved in the activation and deactivation of the channel, preventing if from inactivating. Nerve and muscle cells remain depolarized. Recovery from minor symptoms occurs within twenty-four hours. With more severe symptoms, vasopressor therapy is used to regain muscle strength and atropine therapy for braycardia, slowed heart rate.[12]
Arbutin is a hyroquinone, which are believed to be liver toxins, carcinogens, and irritants. Arbutin can cause vomiting, delirium, convulsions, and possible death.[13] This contributes to gatrointestinal irritation. Analysis has shown that there are higher levels of arbutin in the plant during the autumn season than at other times during the year. [10] Because arbutin is a tyrosinase inhibitor; tyrosinase is involved in the formation of melanin, it is used in cosmetics and and medicine to even skin tone.[6]Many glucosides have aslo been found to have antibacterial activity, but no such properity has been shown in arbutin.[14]
When searching on Scifinder Scholar I searched for each seperate toxin using the locate substance option. I then retrieved refrences related to spectral properties, preparation, and occurance. I performed each of these seperately to determine the refrences specific for each topic. The topics were refined to include only journals. For such a search the results were far fewer hits. For arbutin there were 1303 and when refined to spectral properties in journals the result was only 14. After reviewing the search results there were only a few that were relavent to by project and even fewer for articles with full text, from which to obtain information. When finding synthesis reactions reaction information was searched for arbutin as the products. There were a total of 16 such reactions.
"Bibliographic Information"