The Grayanotoxins

The Grayanotoxins.—Although the grayanotoxins have been known for many years, their structures have been clarified only during the last decade. Several papers in this field have been published during the past year. On the basis of 

In this work the C-3 and C-5 hydroxy-groups were also linked by acetal formation. These ethers require a trans a/b ring junction for their formation. 

Mishima, T. Kozima, H. Kakisawa, and K. Nakanishi, Ghent, and Pharm. Bull. Japan), 1969, 17, 2036. 

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A group of tetracyclic diterpenoids, the grayanotoxins, extracted from the leaves of plants of the family Ericaceae have similar actions to BTX. The general structure is given in Figure 1.11 [129—132]. Again, these toxins act when applied to the inner or the outer surface of excitable membranes, are antagonised by low sodium or TTX, but differ from BTX in that they are reversible and can be washed out of the tissue [133]. 

The kaurane and atisane diterpenes, in a variety of forms, serve as substrates for the elaboration of an array of complex, highly functionalized natural products including the gibberellins, the grayanotoxins, and the aconite alkaloids e.g., talatizidine, 286). The biogenesis of each of these... 

The lipid-soluble toxins (veratridine, batrachotoxin, aconitine, grayanotoxins). These toxins cause persistent activation of Na channels, i.e., their permanent opening and hence membrane depolarization 56-58). 

On the side, this causes me to wonder if the diterpenoid toxins of Rhododendrons, known as grayanotoxins, which mimic the physiologic effects of ciguatoxins, also chelate metal cations. 

Grayanotoxins.—Pieris japonica (Ericaceae) contains a number of diterpenoid toxins. An X-ray analysis of pieristoxin G (100) has been published and the structures (101)—(103) have been assigned to asebotoxins VI, VIII, and IX respectively. 

The Williams approach to bicyclo[5.4.0]undecane containing molecules such as the cyathins, striatins, dolastanes, clavularanes, grayanotoxins, tiglianes, and daphnanes also utilizes an oxidopyrylium cycloaddition to generate the ether constrained bicyclic (Scheme 4.81) (164). The object of the Williams study was to prepare the bicyclo[5.4.0]undecanes and investigate the regio- and stereocon-trolled oxidation of the substrate. 

Chapter 3), where novel skeletons and complex functionality make pre-Z-ray methods quite unsuitable. But the relatively ready access to Z-ray facilities is underlined by analyses (e.g. grayanotoxin-l, and taxinine ) undertaken to establish doubtful points of stereochemistry. 

Andromedotoxin (Grayanotoxin I) is a diterpene found in all parts of the plant. It opens sodium channels in the myocardium and increases permeability. 

The entire plant is potentially toxic to humans. Onset of action typically occurs within 2 h of ingestion with complete resolution by 24 h. Most exposures result in no toxicity. Grayanotoxin poisoning may result from consumption of honey acquired from a hive where... 

The conversion of the relay (128) into grayanotoxin II has been described earlier. The synthesis of this relay has been achieved utilizing the photochemical rearrangement of the dienone (126) to the cyclopentanone (127). The conversion of... 

PbTX-3, PbTX-9). ervatamlne, grayanotoxin. ciguatoxin, pumiliotoxins (pumiliotoxin A B), veratridine, and the pyrethroids have essentially similar actions. See sodium-CHANNEL activators SODIUM-CHANNEL BLOCKERS. 

Grayanotoxins.—The X-ray crystal structures for grayanotoxins XVI—XIX have been reported.123-125 Routes to 1,5-secograyanotoxins (grayanol) derivatives have been described.126 127... 

Horeau and Kagan5 applied the method to a large number of steroids and found that it led to the correct configurations. It has been applied successfully to terpencs, -2 to caryophyllene derivatives,6 to grayanotoxin-I (1) and related toxins,7 and to sesquiterpene lactones,8 for example (2). 

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