GAS in Brazil (MSc. thesis)

The Giant African Snail (Lissachatina fulica) is around in Brazil for more than 30 years. Aquino (2013) has made his Master thesis on this subject within the framework of biology and health policy. Since this kind of theses is often difficult to grasp (no formal publication, unless the author takes the effort to write also a paper summarising the data), it is mentioned here. As an exception, the full text (in Portuguese) is added after the reference.


The abstract reads: “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 study 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 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. This methodology has been described in details at the XXII EBRAM in 2011, in Fortaleza, State of Ceará, Brazil, and published in the form of a scientific article under the name “new breeding management for snails (molusca: gastropoda: pulmonata) in plastic boxes (recipients/containers)”. The following analyses 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), 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 (12mg/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 Tripan 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 gratifyingly 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) had a similar performance to the ophthalmic solution Epitegel 10g (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, furthermore than merely accelerating the recovery of lesions in animals and it also did not produce, in any of them, a single visible scar. It is yet to be exactly known its action mechanism in conjunction with the set of steps of the corneal scarring/healing, especially if it detains a stimulating action over the reproduction of trunk cells, which are responsible for the regeneration of this epithelium”.

Aquino, M. C. (2013): Caracterizaçao química do caracol africano (Achatina (Lissachatina) fulica (Bowdich, 1822) e avaliação dos efeitos do muco cutâneo em úlceras de córnea em coelhos (Oryctolagus cuniculus). MSc. thesis, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas, 94 pp.

Aquino 2013


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