Novel, Meso-Substituted Cationic Porphyrin Molecule for Photo-Mediated Larval Control of the Dengue Vector Aedes aegypti

Abstract

BackgroundControl 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.MethodologyThe 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.Main FindingsThe 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/cm2, which is 50–100 times lower than that of natural sunlight, LC50 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.ConclusionsThe 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.

Potential applications of porphyrins in photodynamic inactivation beyond the medical scope

“…However, the use of porphyrins for this purpose was only mentioned from the late 1980s of the last century [118][119][120][121]. Since then, the use of natural or synthetic porphyrin derivatives has been increasingly exploited to control and eradicate various types of insects, including pest flies capable of inducing significant damage to agricultural crops, and mosquitoes vectors of pathogens responsible for malaria (Anopheles), yellow fever (Culex, Aedes) dengue fever (Aedes) and encephalitis (Aedes, Culex, Anopheles) [46][47][48]50,[66][67][68]. Nowadays, there is a global distribution of these organisms.…”

“…No [47] No [50,52,69] On filter paper [82] On cotton fabric [86,108] On polysilsesquioxane plastic films [61] On cotton fabric [87] On azide-modified cellulose nanocrystals [43,75] On chloroacetyl cellulose ester chlorides [78] On cellulose laurate esters plastic films [79] No [71] No [93] No [49,71,93,110] and Tri-Py + -Me-PF on silica coated Fe3O4 nanoparticles [70] and also on CoFe2O4 nanoparticles [111] No [81] No [105] No [36,37,71,74,81,105]; Tetra-Py + -Me was entrapped into microporous silica gels [88] and into three alkylene-bridged polysilsesquioxanes [89] On optically transparent indium tin oxide electrodes [63] On chitosan membranes [72] Pd(II) TetraTPPCO2H On a polyurethane matrix [83] No [105] In hydrophilic polycaprolactone and polyurethane (TecophilicH) nanofibers [60]; on electrospun polymeric nanofiber materials polyurethane Larithane TM , polystyrene, polycaprolactone, and polyamide 6 [76]; into three alkylene-bridged polysilsesquioxanes [89]; and in a silica-gel supported antimony porphyrin complex SbTPP [97,98] No [44,…”

“…Lucantoni et al [47] 12 -Py + -Me) with two distinct carriers: a model of a pharmaceutical oral vehicle (Eudragit ® S100, EU) and a model of foodstuff carrier (cat food pellet Friskies ® , CF). These phorphyrin-carrier formulates (50 M Tri-Py + -C 12 -Py + -Me dose) were tested against overnight fed Anopheles gambiae and Anopheles arabiensis larvae, exposed to sunlight (30-110 mW cm −2 ) for 0.5-3 h. These conditions led to high photoinactivation efficiency against laboratory reared A. gambiae and A. arabiensis larvae (almost complete mortality).…”

Efficacy of Photogem® (Hematoporphyrin Derivative) as a Photoactivatable Larvicide against Aedes aegypti (Diptera: Culicidae) Larvae

“…The same distribution dynamics was observed in Ae. aegypti larvae incubated in C14 porphyrin [14]. Due to their amphiphilic character, porphyrin molecules cross lipid barriers efficiently and act on different intracellular structures, as mitochondria and endoplasmic reticulum [13].…”

“…aegypti [14]. Larvae were irradiated with fluorescent lamps in a 400-800 nm spectral rangeat 4.0 mW/cm 2 …”