Abstract
Mosquitoes are exceptionally efficient in detecting their hosts for blood meal using odorant binding proteins, viz. 3N7H and 3Q8I and spread several dreadful diseases. DEET is a synthetic mosquito repellent widely used all over world for protection against mosquito bite. Reports reveal that, synthetic mosquito repellents may pose health problems in considerably large population. In view of the above fact, we made an attempt to discover efficient and novel natural mosquito repellent compounds with least impact on human health. Methanolic leaf extracts of Ocimum basilicum Linn. var. pilosum (willd.)-Benth and Ocimum tenuiflorum var. CIM-AYU were subjected to GC–MS analysis and obtained 35 phytochemical constituents. Repellent potentiality of the Ocimum compounds was assessed against 3Q8I and 3N7H of Anopheles gambiae. PDB structures of mosquito odorant binding proteins were downloaded, processed and docking studies were performed along with reference ligand DEET using Schrodinger MAESTRO 9.2 software. Molecular docking results reveal that phenol, 2-methoxy-3-(2-propenyl)-, licopersin, gamma sitosterol and benzene, 1,2-dimethoxy-4-(2-propenyl)- from O. tenuiflorum var. CIM-AYU are strongly bound with 3N7H. Whereas, 4h-1-benzopyran-4-one, 5-hydroxy-6,7-dimethoxy-2-(4-methoxyphenyl)-, catechol and monoacetin from O. basilicum Linn. var. pilosum (willd.)-Benth. show high binding affinity with odorant binding protein 3Q8I. All natural compounds tested in the present study display better docking scores than DEET. The results further substantiate that the 12 out of 35 compounds of the two Ocimum species found to be ideal candidates for design and development of potential mosquito repellents. ADME properties of the tested compounds further confirm that bioactive compounds of Ocimum species were found to be in acceptable range. Synchronized application of at least two different natural compounds (with best docking scores) which target 3N7H and 3Q8I (Odorant Binding Proteins of mosquito) proteins may provide enhanced protection against mosquitoes bite. Based on the ADME properties, natural compounds of Ocimum species can be considered for design and development of safe mosquito repellents.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-015-0346-x) contains supplementary material, which is available to authorized users.
Highlights
Mosquitoes act as vector for many protozoans, bacterial and viral diseases (Service 1996)
Of the 35 compounds tested for their binding affinity with odorant binding proteins of Anopheles mosquito, 2-hexadecen-1-ol, phytol, DL-alpha-tocopherol, phenol-2-methoxy-3-(2-propenyl), lycopersin, gamma-sitosterol, benzene, 1,2-dimethoxy-4-(2-propenyl)- of O. tenuiflorum exhibit strong binding affinity with odorant binding protein 3N7H
Active sites of the receptor 3Q8I and 3N7H were determined and docked with the compounds obtained from GC–MS analysis from two Ocimum
Summary
Mosquitoes act as vector for many protozoans, bacterial and viral diseases (Service 1996). To protect humans against mosquito born diseases, mosquito repellents’ in different forms (herbs, aromatic oils and synthetic compounds) were widely used all over world. The prime objective of the present investigation is to explore the possibility of repellent activity of potential natural compounds from Ocimum species against odorant binding proteins of Anopheles gambiae. Attempts were made to understand molecular mechanisms underlying possible interactions of natural mosquito repellent compounds against odorant binding proteins (3Q8I and 3N7H) of A. gambiae. Further these studies will widen the scope to choose the most suitable compounds for design and development of effective and safe mosquito repellents
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