Hydroxylated Metabolites of - and -Hexachlorocycl
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- 作者：Vishakha Raina ; Andrea Hauser ; Hans Rudolf Buser ; Daniel Rentsch ; Poonam Sharma ; Rup Lal ; Christof Holliger ; Thomas Poiger ; Markus D. Mü ; ller ; Hans-Peter E. Kohler
- 刊名：Environmental Science & Technology
- 出版年：2007
- 出版时间：June 15, 2007
- 年：2007
- 卷：41
- 期：12
- 页码：4292 - 4298
- 全文大小：164K
- 年卷期：v.41,no.12(June 15, 2007)
- ISSN：1520-5851
文摘
Although the use of hexachlorocyclohexane (HCH), one ofthe most popular insecticides after the Second WorldWar, has been discontinued in many countries, problemsremain from former production and waste sites. Despite thewidespread occurrence of HCHs, the environmental fateof these compounds is not fully understood. In particular,environmental metabolites of the more persistent 
-HCHand 
-HCH have not been fully identified. Such knowledge,however, is important to follow degradation and environmental fate of the HCHs. In the present study, several hydroxymetabolites that formed during incubation of - and-HCH with the common soil microorganism Sphingobiumindicum B90A were isolated, characterized, and stereochemically identified by gas chromatography-massspectrometry (GC-MS) and nuclear magnetic resonancespectroscopy (NMR). The metabolites were identifiedas isomeric pentachlorocyclohexanols (B1, D1) andtetrachlorocyclohexane-1,4-diols (B2, D2); -HCH additionallyformed a tetrachloro-2-cyclohexen-1-ol (D3) and a trichloro-2-cyclohexene-1,4-diol (D4), most likely by hydroxylationof -pentachlorocyclohexene (-PCCH), initially formed bydehydrochlorination. The dehydrochlorinase LinA wasresponsible for conversion of -HCH into -PCCH, and thehaloalkane dehalogenase LinB was responsible for thetransformation of -HCH and -HCH into B1 and D1,respectively, and subsequently into B2 and D2, respectively.LinB was also responsible for transforming -PCCH intoD3 and subsequently into D4. These hydroxylations proceededin accordance with SN2 type reactions with initialsubstitution of equatorial Cls and formation of axiallyhydroxylated stereoisomers. The apparently high reactivityof equatorial Cls in - and -HCH toward initial hydroxylationby LinB of Sphingobium indicum B90A is remarkable whenconsidering the otherwise usually higher reactivity ofaxial Cls. Several of these metabolites were detected ingroundwater from a former HCH production site in Switzerland.Their presence indicates that these reactions proceedunder natural environmental conditions and that themetabolites are of environmental relevance.
-HCHand -HCH have not been fully identified. Such knowledge,however, is important to follow degradation and environmental fate of the HCHs. In the present study, several hydroxymetabolites that formed during incubation of - and-HCH with the common soil microorganism Sphingobiumindicum B90A were isolated, characterized, and stereochemically identified by gas chromatography-massspectrometry (GC-MS) and nuclear magnetic resonancespectroscopy (NMR). The metabolites were identifiedas isomeric pentachlorocyclohexanols (B1, D1) andtetrachlorocyclohexane-1,4-diols (B2, D2); -HCH additionallyformed a tetrachloro-2-cyclohexen-1-ol (D3) and a trichloro-2-cyclohexene-1,4-diol (D4), most likely by hydroxylationof -pentachlorocyclohexene (-PCCH), initially formed bydehydrochlorination. The dehydrochlorinase LinA wasresponsible for conversion of -HCH into -PCCH, and thehaloalkane dehalogenase LinB was responsible for thetransformation of -HCH and -HCH into B1 and D1,respectively, and subsequently into B2 and D2, respectively.LinB was also responsible for transforming -PCCH intoD3 and subsequently into D4. These hydroxylations proceededin accordance with SN2 type reactions with initialsubstitution of equatorial Cls and formation of axiallyhydroxylated stereoisomers. The apparently high reactivityof equatorial Cls in - and -HCH toward initial hydroxylationby LinB of Sphingobium indicum B90A is remarkable whenconsidering the otherwise usually higher reactivity ofaxial Cls. Several of these metabolites were detected ingroundwater from a former HCH production site in Switzerland.Their presence indicates that these reactions proceedunder natural environmental conditions and that themetabolites are of environmental relevance.