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Structure–Activity Relationship Studies on the Mosquito Toxicity and Biting Deterrency of Callicarpenal Derivatives
Author(s) -
Cantrell Charles L.,
Klun Jerome A.,
Pridgeon Julia,
Becnel James,
Green Solomon,
Fronczek Frank R.
Publication year - 2009
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200800291
Subject(s) - aedes aegypti , anopheles stephensi , biting , ixodes scapularis , toxicology , chemistry , insect bites and stings , toxicity , biology , tick , virology , botany , ecology , larva , immunology , organic chemistry , ixodidae
Callicarpenal (=13,14,15,16‐tetranorclerod‐3‐en‐12‐al=[(1 S ,2 R ,4a R ,8a R )‐1,2,3,4,4a,7,8,8a‐octahydro‐1,2,4a,5‐tetramethylnaphthalen‐1‐yl]acetaldehyde; 1 ) has previously demonstrated significant mosquito bite‐deterring activity against Aedes aegypti and Anopheles stephensi in addition to repellent activity against host‐seeking nymphs of the blacklegged tick, Ixodes scapularis. In the present study, structural modifications were performed on callicarpenal ( 1 ) in an effort to understand the functional groups necessary for maintaining and/or increasing its activity and to possibly lead to more effective insect control agents. All modifications in this study targeted the C(12) aldehyde or the C(3) alkene functionalities or combinations thereof. Mosquito biting deterrency appeared to be influenced most by C(3) alkene modification as evidenced by catalytic hydrogenation that resulted in a compound having significantly less effectiveness than 1 at a test amount of 25 nmol/cm 2 . Oxidation and/or reduction of the C(12) aldehyde did not diminish mosquito biting deterrency, but, at the same time, none of the modifications were more effective than 1 in deterring mosquito biting. Toxicities of synthesized compounds towards Ae. aegypti ranged from an LD 50 value of 2.36 to 40.11 μg per mosquito. Similarly, LD 95 values ranged from a low of 5.59 to a high of 104.9 μg.