Mosquito larvicidal constituents from Lantana viburnoides sp viburnoides var kisi (A. rich) Verdc (Verbenaceae).
OBJECTIVE
Lantana viburnoides sp viburnoides var kisi is used in Tanzania ethnobotanically to repel mosquitoes as well as in traditional medicine for stomach ache relief. Bioassay-guided fractionation and subtraction bioassays of the dichloromethane extract of the root barks were carried out in order to identify the bioactive components for controlling Anopheles gambiae s.s. mosquito larvae.


METHODS
Twenty late III or early IV instar larvae of An. gambiae s.s. were exposed to various concentrations of the plant extracts, fractions, blends and pure compounds, and were assayed in the laboratory by using the protocol of WHO 1996. Mean mortalities were compared using Dunnett's test (p < 0.05) and lethal concentration calculated by Lackfit Inversel of the SAS programme.


RESULTS
The crude extract (LC50 = 7.70 ppm in 72 h) and fractions exhibited different level of mosquito larvicidal activity with subtraction of some fractions resulting in activity enhancement. The active fractions contained furanonaphthaquinones regio-isomers (LC50 = 5.48-5.70 ppm in 72 h) and the lantadene triterpenoid camaric acid (LC50 = 6.19 ppm in 72 h) as active principles while the lupane triterpenoid betulinic acid (LC50 < 10 ppm in 72 h) was obtained from the least active fraction.


CONCLUSIONS
Crude extracts and some fractions had higher or comparable larvicidal activity to the pure compounds. These results demonstrate that L. viburnoides sp viburnoides var kisi extracts may serve as larvicides for managing various mosquito habitats even in their semi-purified form. The isolated compounds can be used as distinct markers in the active extracts or plant materials belonging to the genus Lantana.
Innocent
Ester
E
Institute of Traditional Medicine, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania. einnocent@muhas.ac.tz
Joseph
Cosam C
CC
Gikonyo
Nicholus K
NK
Moshi
Mainen J
MJ
Nkunya
Mayunga H H
MH
Hassanali
Ahmed
A
D000818:Animals; D000852:Anopheles; D007306:Insecticides / Q000494:pharmacology*; D032410:Lantana / Q000737:chemistry*; D007814:Larva / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*
D007306:Insecticides; D010936:Plant Extracts