By

 Akpa, U. A. Ph.D., FWHO, FRSTMH

Professor of Pharmaceutical Microbiology and Biotechnology,

Director, Medical Biotechnology, National Biotechnology Development Agency, Federal Ministry of Science and Technology, Abuja. Nigeria. akpaalexu@yahoo.com

Introduction

Snails belong to the phylum known as Mollusca. They are invertebrates with soft bodies that are covered with hard calcareous shells. They can be found on land, in saltwater and in freshwater. The number of snail species runs into thousands (Adedotun and Fikayo, 2014). Snails secrete visco-elastic slime or mucus which acts both as an adhesive and lubricant and enables the creature to adhere to and glide over all types of surfaces including rough or potentially hostile terrain (Thomas, 2013). The mucus are produced in the cells located in the epithelium of the skin, both on the foot and upper surface of the body.

The precursor of slime produced by the snail is in form of highly hygroscopic grains, which are stored within the cells in the form of granules coated with a protective water resistant membrane which keeps them dry. These packets only break open after they have been released from the cell, a process which is thought to be mediated by contact with extracellular ATP (Deyrup-Olsen, 1992). These released granules rapidly absorb up to 100 times their initial volume of water to form the familiar mucus or slime.

Mucus helps to prevent snails from drying out, renders them fairly unattractive as food for predators and is also thought to help prevent infection and facilitate healing. Most snails have the ability of withdrawing into their shell especially when danger is perceived. This is a form of defense mechanism due to their inability to escape from the site of danger.

Snail Production and Techniques

Snail supply as meat and other economic benefits are usually affected by seasonality and other human activities such as use of pesticides, deforestation, burning of bush etc. If these factors are not controlled, the snails (giant land snail) will sooner or later get extinct.

Snail farming is the rearing of snails in captivity. These snails are confined in an enclosure where most of their needs like feed, water and lime are supplied on a daily basis by the farmer.

Snail Nutrient Contents and Minerals

Internationally, snail meat commands good market in Europe and North America. The French snail requirement is about 5million Kg/annum, out of this; more than 60% is imported. Italy is said to consume about 306 million snails annually. In West Africa, Cote d’Ivoire has estimated annual snail consumption of 7.9 million kg (NAERLS).

Presently in Nigeria, mollusks serve as a significant and essential part of the daily diet of kalabaris, Itsekiris, Yorubas and many other coastal tribes. Molluscs constitute the major and cheapest source of protein in Nigeria (Yoloye, 1984; Ademolu et al., 2004). In West Africa, snail meat has traditionally been a major source of protein in the diet of people living in the forest belt (Cobbinah, 1993).

It is believed that the nutritional quality of snail meat depends on the nutritional quality of feed they consume in the wild or in captivity, which in turn determines their preference and palatability (Kalio and Etela, 2011). Meat of snail is palatable, nutritious and rich in essential amino acids such as lysine, leucine, isoleucine and phenylalanine as well as high iron content (Imevbore, 1990).

Jummai and Okoli (2013), evaluated the compositional nutrient content of Achatina fulica (giant east African snail) and the result indicated wide variety of minerals that are essential nutrients, it includes; moisture (80/100g), protein (13/100g), cholesterol (1.4/100g), carbohydrate (2.5/100g) and ash (1.3/100g). The most desirable factor in Achatina fulica meat is the low cholesterol content of the meat (Table 1). The result also shows that Achatina fulica meat contains the following minerals; potassium (382mg) is the predominant element; the high amount can play an important role in electrolyte balance of the body. Phosphorus (272mg), calcium (10.00mg) and sodium (70.00mg) are the next elements reasonably present in Achatina fulica meat. The following minerals are also present but at small quantity- iron, magnesium, zinc and copper.

Fagbuaro et al. (2006) studied mineral composition of four species of giant land snails meat and the result demonstrated that these four species of snail meat have high concentrations of the following minerals; zinc, iron, magnesium, calcium, phosphorus, potassium and sodium. The result, therefore, shows that the four species of snails are good sources of magnesium, sodium and potassium. All these traceable elements play important roles in the healthy body. Thus, the consumption of snails will definitely increase the level of these major elements in the body.

Table 1: Nutritional values of snail compared with other animal protein sources.

Adopted from Nwosu (2003)

Jatto et al. (2010) evaluated the proximate and mineral composition of different four species of snail shell to ascertain some of its constituents that may be useful in the treatment of water and waste water.  The analysis of the composition of metals or minerals of snail shell shows that all the species consist of manganese, zinc, copper and iron in different amounts. However the amount of iron is the highest in all the species. This is one possibility for the relevance of snail shell as a coagulant in the treatment of water and waste water (Ademoroti, 1996).

Application of snails in pharmaceuticals

Snails have been used in Medicine since antiquity and prepared according to several formulations. In 1738, universal pharmacopeia published a paper by Lemery (1738) on procedure of extracting liquid from crushed snail into fresh milk of female donkey for the treatment of tuberculosis related symptoms and urine ardour of nephritis. In 1817, snails were stringed into rosaries and were used as shop signs for pharmacies. At about that same time, the new Natural History Dictionary stated that one can pick up snail for use in medicine and are recommended as broth for the throat.

A pharmaceutical reference book in 1877 edition of Dorvault mentioned several products based on snails such as snail paste with donkey milk, quelquejeu snail paste, Figuier or de Mure snail pectoral syrup, as well as Baron-Barthelemy snail pectoral paste. Pharmaceutical formulations based on helicine was published by a pharmacist in Beziers (Herault, France) by name Baron-Barthelemy who discussed the therapeutic properties of helicine which include activities against most inflammations, and especially against cold and cough, bronchitis, catarrhs, asthma, various types of haemoptysis, tonsillitis, pharyngitis, hoarsenesss, sore throat, influenza, croup, whooping cough of children, lung diseases such as pneumonia and pulmonary phthisis, nervous stomach and intestinal cramps, gastritis, gastro-enteralgia, headaches coming from a pathological disorder of stomach, cough that follows or comes with inflammatory skin diseases such as: the measles, scarlet fever, small pox, erysipelas, and so on, prolonged diseases with irritation and weakening, and some skin diseases (Baron-Barthelemy, 1855a).

For the first time, the actual preparation of snail products were described by Quevauviller (1953) in which helicidine, pertussidine, pomaticine were made from snail mucus but with different production processes like most either being soaked with 1% ww of sodium chloride, processed at low temperature under vacuum evaporation, or freeze dried or spray dried.

Elicina is a Chilean snail slime-based product which came about by the observation of Chilean snail farmers in the French food market who found that skin lesions healed quickly, with no scars, when they handled snails.

For centuries snails have been used as treatment for a wide variety of medical conditions. In recent times, a series of investigations have been carried out on the active components of snails. Snail slime has been used sporadically as skin treatment since the time of the Ancient Greek; Hippocrates reportedly recommended the use of crushed snails to relieve inflamed skin (Thomas, 2013). Hippocrates, Celse, Pliny, Galien etc., prescribed snail extracts in crude form or in mixtures with wine or milk for the treatment of various ailments. Snail extract or slime have been used with success for the treatment of inflammations especially against cold and cough, bronchitis, catarrhs, asthma, various type of haemoptysis, tonsillitis, pharyngitis, hoarseness, sore throat, influenza, croup, whooping cough, lung diseases such as pneumonia and pulmonary phthisis, stomach and intestinal cramp, gastritis, gastro-enteralgia and headache coming from a pathological disorder of the stomach (Bonnemain, 2005). Snails also have curative properties against diseases associated with feminity and fertility (Cranga and Cranga, 1991).

Snail products may have a role in orthopaedics as researchers at Herriot-Watt University found that the slime of Giant African land snails contain unusual crystals of calcite. This is because under adverse conditions the snail will retract into its shell and produce significant quantities of this slime which dries and quickly hardens to form the animal’s epiphragm; a protective covering formed across the opening of the shell when the snails go into periods of deep rest (Thomas, 2013).

The composition of slime is thought to vary according to species, and it is believed that it is possible that each may also be able to vary in its formulation (Ewoldt and Hosoi, 2009). Mucus consists of a complex mix of proteoglycans, glycosaminoglycans, glycoprotein enzymes, hyaluronic acid, copper peptides, antimicrobial peptides and metal ions (Smith et al., 2009).

The principal benefits associated with the use of snails as topical treatments are therefore associated with the chemical and/or physical properties of the slime or mucus that they produce in abundance, particularly when threatened or irritated.

Comparative study performed in seven different countries revealed 20 times fewer cadivascular disease related death in countries that consume more of snail meat (Bonnemain, 2005). This is due to α-linolenic acid content in snail meat. This α-linolenic acid has been reported to have protective effect against cardiovascular disease and also prevents ventricular fibrillation and reduces platelet aggregation (Lanzaman-Petitthory, 2001))

Helix pomatiagglutinin (HPA) which is a lectin has been extracted from common snail. This is used as a prognostic indicator for some cancers, such as those of the breast, stomach and colon (Dewk and Ross, 2001; Brooks and Leathem, 1991). Snail mucin which has cytoprotective and anti-spasmodic activities possess potent antiulcer properties without any toxic effect (Nwodo et al., 2009). Currently, several Antimicrobial peptides (AMP) have been identified from molluscs (Otero-Gonzalez et al., 2010; Tincu and Taylor (2004); Xu q, 2010). These AMP’s have been documented to have antimicrobial activity against Gram-negative and Gram-positive bacteria and the fungus Candida albicans (Zhong, 2013).

From all above, one can safely say that pharmaceutical industries now have drugs that can function as cardio-protective, hepatoprotective, anti-aging and anti-cancer; thanks to snails extract.

Application of Snails in Cosmetics and Cosmeceuticals

From antiquity, mollusc extracts have proven to be effective against dermatological conditions. Snail meat can serve as both macro and micro nutrients required for normal skin growth when used in the production of soap or body cream as indicated by the folk report in which it is used to sooths irritation and slight injuries to the skin caused by shaving, and has also shown to be effective in removing skin warts.

Quave et al. (2008) described how slugs are used in Italy to treat dermatitis, inflammations, calluses, and acne, and to promote wound healing. Thomas (20013) also published a monitored experiment in which slug slime cleared skin wart on four applications.

Common garden snail contains antioxidant superoxide dismutase (SOD) and Glutathione-S-Transferase (GST) activities (Brieva, 2008). Antioxidant are substances that may protect cells from damage caused by unstable molecules known as free radicals or reactive oxygen species. SODs found in common garden snail acts as antioxidant and protect cellular components from being oxidized by free radicals.

Snail slime stimulates fibroblast proliferation, extracellular matrix assembly and regulation of metalloproteinase activities. These properties together provides an array of molecular mechanisms underlying the secretion induced cellular regeneration (Brieva, 2008).

Several works have shown the importance of snail formulations in cosmetics industry and one of them is the work published in the International Journal of Cosmetics and Science by Cruz (2012), which demonstrated that snail slime increased migration and increased the expression of cell-cell-substrate adhesion molecules in mammalian fibroblast and keratinocyte cells. Snail extracts recently has been crystalized into powdered form.

Physical and chemical analysis carried out showed that snail extract powder contains the following elements: proteins and vitamins which enriches and softens the skin; natural collagen and elastin which are the main components of the human skin connective tissue; natural glycolic acid allows the skin to exfoliate, thereby eliminating dead cells that are on the surface of the skin, along with wrinkles and expression lines. Since the glycolic acid found on the snail is not synthetic, it does not irritate the skin; natural allantoin is what makes regeneration of skin possible. It helps in reducing the appearance of scars and stretch marks, and it helps in healing wounds faster; leaving almost no marks.

Due to these properties, snail slime is used to treat acne, acne scars, age spots, wrinkles, expression lines and many other skin conditions. The cosmetics industry over the years has been coming up with snail slime products such as hand and face creams and gels; body lotions, creams and gels; eye and lip serum; after sun moisturizers and sun tan lotions.

Cosmetics/ Hospitality

The use of snail and periwinkle shells in cosmetics, hospitality and decoration has been noted in our traditional societies from time `immemorial. In some traditional African societies, snail and periwinkle shells are used as necklaces, bracelets, pendants, and waist ornaments. Periwinkle and snail shells have also been used in traditional African societies to strengthen, beautify and decorate floors and walls of homes.

In recent times, snail and periwinkle shells have been used in the decoration of hotels, museums, art galleries, libraries, paintings and other art works. Also snail and periwinkle shells which are known to be rich in calcium and potassium have been ground into fine powder, bagged and sold to poultry and fish feed manufacturers.

The use of snail and periwinkle shells in cosmetics, hospitality industry, in the arts and art works, and in the decoration of homes and hospitals gives rise we think to a totally new industry “cosmetality industry”.

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