Caracterização química do caracol africano (Achatina (Lissachatina) fulica (Bowdich, 1822) e avaliação dos efeitos do muco cutâneo em úlceras de córnea em coelhos (Oryctolagus cuniculus)

Abstract

Since it had been introduced in Brazil dating back to the 80s, the Great African Snail Achatina fulica has spread all over the country. Some researchers associate its incredibly good adaptation success to the dermal mucous of this species. With the objective and the aim of better knowing and understanding the dermal mucous of the Great African Snail and also suggesting new forms of taking advantage of it with a view to controlling this invading and exotic snail, this work carried out the chemical characterization of the shell, of the snail without the shell and of the dermal mucous of the Great African Snail, collected in the State of Alagoas, Brazil, and also evaluated and assessed the scarring/healing action of a solution from the mucous, already confirmed for skin tissue, in corneal ulcers surgically produced in rabbits. The wild snails were kept in a laboratory utilizing a new methodology specially developed for keeping arboreal snails in laboratory, with sensibly improved hygienic conditions, reduction of the time spent for the daily treatment and reduction of animal stress. The following determinations were carried out: the mineral composition of the snail without its shell, of the shell and of the mucous; the centesimal composition of the lyophilized mucous and the anti oxidizing capacity evaluated through the seizing activity of the free radical 2,2- diphenyl-1-picryl-hydrazyl (DPPH). With regards to the results, the macro and micro minerals composition present in the snail without a shell, in the shell and in the dermal mucous of the A. fulica was determined for 23 nutrients, 5 macro-nutrients (Ca, P, Na, K and Mg) and 18 micro-nutrients (Al, As, Ba, Cd, Cr, Cu, Fe, Li, Mn, Mo, Ni, Si, Sr, V, Zn, Co, Sb and Se). With regards to the centesimal composition, the following data was obtained: dried matter (91.72 ± 1.85), humidity (8.28 ± 0.97), ashes (31.1 ± 0.35), crude protein (49.97 ± 3.21), carbohydrates (8.15 ± 1.43), total calories (242.48 ± 53.23 kcal), lipids in 100 g (2.5 ± 0.44), cholesterol (50.2 ± 0.3). The mucous did not show anti oxidizing capacity in any of the analysed samples. For the experiment in vivo, the evolution of the corneal lesions on the 18 rabbits, divided in three groups of 6 animals: the control group, the mucous group and the group treated with the ophthalmic solution Epitegel, was accompanied and monitored by the percentage measurement of scarring/healing of the 36 areas of scarring through 144 macro photographs taken along the experiment at 0, 24, 48 and 72 hours. To carry out the experiment, duly approved by the Ethical Committee of UFAL (The Federal University of Alagoas), process no. 010190/2011-85, a scalpel blade to remove the corneal epithelium previously circumscribed by a circular scalpel (punch no. 5) and the anaesthetic protocol utilized comprised 3 steps: tranquilizing with acepromazine (0.05 mg/kgPV/IM), anaesthetizing with cetamine chlorydrate (12 mg/IM/kgPV) and local anesthetizing with proxymethacaine chlorydrate 0,5%. For the orientation regarding the ideal choice for mucous concentration for the treatment of the lesions on the experiment in vivo, solutions were tested in the following concentrations: 0.01 mg mL-¹, 0.03 mg mL-¹, 0.06 mg mL-¹ and 0.125 mg mL-¹. The cellular viability was verified through the MTT and Trypan Blue methods. No statistical differences were observed between the tested concentrations; therefore, the chosen concentration to be the base for the preparation of the ophthalmic solution was the one that better stimulated the cellular proliferation (0.125 mg mL-1). With regards to the results, there were no statistical differences between the mucous group and the Epitegel; the ophthalmic solution based on the mucous (0.125 mg 25 μL-1) had a similar performance to the ophthalmic solution Epitegel 10 g (Ophthalmological Gel Dexpantenol 50 mg g-1, positive control), one of the best available medicines in the market for the treatment of corneal ulcers/lesions. Nevertheless, both presented some significance, regarding the result of the control group, which presented a longer scarring/healing time. With 72 hours, of the 12 lesions of the control group, only 2 (16.66%) were scarred/healed; of the Epitegel group, only 8 (66.66%) were scarred/healed and of the mucous groups, all (100%) were scarred/healed. It has been thus demonstrated the scarring/healing capacity of the A. fulica’s mucous also for the treatment of corneal ulcers and its specific action, besides accelerating the recovery of lesions in animals, it did not produce, in any of them, a single visible scar.