Novel, meso-substituted cationic porphyrin molecule for photo-mediated larval control of the dengue vector Aedes aegypti.
BACKGROUND
Control of the mosquito vector population is the most effective strategy currently available for the prevention of dengue fever and the containment of outbreaks. Photo-activated oxidants may represent promising tools for developing effective, safe and ecofriendly novel larvicides. The purpose of this study was to evaluate the potential of the synthetic meso-substituted porphyrin meso-tri(N-methylpyridyl), meso-mono(N-tetradecylpyridyl)porphine (C14) as a photoactivatable larvicide against the dengue vector Aedes (Stegomyia) aegypti.


METHODS
The photophysical and photochemical properties of the C14 molecule were assessed spectrophotometrically. Photomediated larvicidal efficacy, route of intake and site of action were determined on Ae. aegypti larvae by laboratory bioassays and fluorescence microscopy. Using powdered food pellet for laboratory rodents (a common larval food used in the laboratory) as a carrier for C14, loading-release dynamics, larvicidal efficacy and residual activity of the C14-carrier complex were investigated.


RESULTS
The C14 molecule was found to exert a potent photosensitizing activity on Ae. aegypti larvae. At irradiation intervals of 12 h and 1 h, at a light intensity of 4.0 mW/cm(2), which is 50-100 times lower than that of natural sunlight, LC(50) values of 0.1 µM (0.15 mg/l) and 0.5 µM (0.77 mg/l) were obtained, respectively. The molecule was active after ingestion by the larvae and caused irreversible, lethal damage to the midgut and caecal epithelia. The amphiphilic nature of C14 allowed a formulate to be produced that not only was as active against the larvae as C14 in solution, but also possessed a residual activity of at least two weeks, in laboratory conditions.


CONCLUSIONS
The meso-substituted synthetic porphyrin C14, thanks to its photo-sensitizing properties represents an attractive candidate for the development of novel photolarvicides for dengue vector control.
School of Pharmacy, University of Camerino, Camerino, Italy. Leonardo.lucantoni@unicam.it
Leonardo
L
Lucantoni
Michela
M
Magaraggia
Giulio
G
Lupidi
Robert Kossivi
RK
Ouedraogo
Olimpia
O
Coppellotti
Fulvio
F
Esposito
Clara
C
Fabris
Giulio
G
Jori
Annette
A
Habluetzel
D000330:Aedes / Q000187:drug effects*; D000818:Animals; D001681:Biological Assay; D003715:Dengue / Q000517:prevention & control; D004199:Disease Vectors; D007306:Insecticides / Q000008:administration & dosage* / Q000737:chemistry* / Q000302:isolation & purification / Q000493:pharmacokinetics; D007413:Intestinal Mucosa / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D008027:Light; D008856:Microscopy, Fluorescence; D017319:Photosensitizing Agents / Q000008:administration & dosage* / Q000737:chemistry* / Q000302:isolation & purification / Q000493:pharmacokinetics; D011166:Porphyrins / Q000008:administration & dosage* / Q000737:chemistry* / Q000302:isolation & purification / Q000493:pharmacokinetics; D013053:Spectrophotometry; D016019:Survival Analysis
D007306:Insecticides; D017319:Photosensitizing Agents; D011166:Porphyrins