Chlorinated orcinols

Chlorinated orcinol derivatives have been isolated from diseased bulbs of the edible lily Lilium maximowiczii. The antifungal activity of these compounds was tested against Bipolaris leersiae. Inhibition of the conidial germination depends on the number of chlorine atoms in the compounds. The trichlorinated orcinol 156 shows the highest activity. Dichlorinated orcinols, e.g. 157, are next, and the monochlorinated ones, e.g. 158, are still less active. The nonchlorinated orcinol shows lowest activity [121]. 

Monde K, Satoh H, Nakamura M, Tamura M, Takasugi M (1998) Organochlorine Compounds from a Terrestrial Higher Plant Structures and Origin of Chlorinated Orcinol Derivatives from Diseased Bulbs of Lilium maximowiczii. J Nat Prod 61 913... 

Monde, K., H. Satoh, M. Nakamura, M. Tamura, and M. Takasugi. 1998. Organochlo-rine compounds from a terrestrial plant structures and origin of chlorinated orcinol derivatives from diseased bulbs of Lilium maximowiczii. ]. Nat. Prod. 61 913-921. 

Chlorinated orcinol p zra-depsides occur very rarely in lichens and until recently timidulin (207) was the sole known representative. Two further chlorodepsides have now been isolated, 3,5-dichloro-2 -0-methylanziaic acid (208) from Lecanora sulphurella 183) and 3-chlorodivaricatic acid (209) from Thelomma mammosum 197). 

For their detection, the papers may be sprayed with reagents commonly used for the detection of keto and aminodeoxy sugars. Those of particular value include the direct Ehrlich reaction, the orcinol-trichloroacetic acid reagent, the chlorine-benzidine reagent for the detection of —NH—CO— groupings, and the Bial reaction as modified by Bohm und Baumeister. The limit of detection with the orcinol-trichloroacetic acid reagent is reported to be 5 ixg. of V-acetylneuraminic acid. For the detection of methoxyneuraminic acid, ninhydrin may also be used. 

P-orcinol series The orcinol-type compounds discussed in the previous section form a closely related series of substances in which changes in the length and oxidation state of the 6-alkyl substituents are major sources of variation among phenolic units. The compounds synthesised by various combinations of these units show secondary modifications attributable to 0-methylation, chlorination, decarboxylation and lactonisation. The p-orcinol compounds may undergo all of the same secondary reactions, but the most common variation is in the oxidation state of the Cj substituents at the 3- and 6-positions of the phenolic acid units. 

The colored reaction products obtained in the C test are unstable and easily destroyed by an excess of the reagent. Hypothamnolic acid (albeit substituted at the position between the m-hydroxyls) gives a red color with C which disappears within seconds. The chemistry behind the Ctest has not been elucidated. Possibly a combination of chlorination and oxidation reactions leads to monomeric and/or dimeric quinonoid structures. Only one colored compound has been isolated from the reaction of orcinol with calcium hypochlorite the yellow tetrachlorodihydroorcinol (L. Gren and J. Santes-son, unpublished). 

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