Structural characterization of a glycoprotein from white jade snails (Achatina Fulica) and its wound healing activity

Snail mucus is rich in proteins and polysaccharides, which has been proved to promote wound healing in mice in our previous research. The aim of this study was to investigate the effective component in snail mucus that can exert the wound healing potential and its structural characterization. Here, the glycoprotein from the snail mucus (SM1S) was obtained by DEAE-Sepharose Fast Flow and Sephacryl S-300 columns. The structural characteristics of SM1S were investigated via chromatographic techniques, periodic acid oxidation, FT-IR spectroscopy and NMR spectroscopy. Results showed that SM1S was a glycoprotein with a molecular weight of 3.8 kDa (83.23 %), consists of mannose, glucuronic acid, glucose, galactose, xylose, arabinose, fucose at a ratio of 13.180:4.875:1043.173:7.552:1:3.501:2.058. In addition, the periodic acid oxidation and NMR analysis showed that SM1S contained 1,6-glycosidic bonds, and might also contain 1 → 4 and 1 → 2 glycosidic or 1 → 3 glycosidic bonds. Furthermore, the migration experiment of human skin fibroblasts in vitro suggested that SM1S had a good effect to accelerate the scratch healing of cells. This study suggested that SM1S may be a prospective candidate as a natural wound dressing for the development of snail mucus products.

Extraction, structure, pharmacological activities and applications of polysaccharides and proteins isolated from snail mucus

Snail mucus had medical applications for wound healing as early as ancient Greece and the late Han Dynasty (China). A literature search found 165 modern research papers discussing the extraction methods, chemical compositions, pharmacological activities, and applications of snail mucus. Thus, this review summarized the research progress on the extraction, structure, pharmacological activities, and applications of polysaccharides and proteins isolated from snail mucus. The extraction methods of snail mucus include natural secretion and stimulation with blunt force, spray, electricity, un-shelling, ultrasonic-assisted, and ozone-assisted. As a natural product, snail mucus mainly comprises two polysaccharides (glycosaminoglycan, dextran), seven glycoproteins (mucin, lectin), various antibacterial peptides, allantoin, glycolic acid, etc. It has pharmacological activities that encourage cell migration and proliferation, and promote angiogenesis and have antibacterial, anti-oxidative and anticancer properties. The mechanism of snail mucus' chemicals performing antibacterial and wound-healing was proposed. Snail mucus is a promising bioactive product with multiple medical applications and has great potential in the pharmaceutical and healthcare industries. Therefore, this review provides a valuable reference for researching and developing snail mucus.

Biological properties of mucus from land snails (Lissachatina fulica) and freshwater snails (Pomacea canaliculata) and histochemical study of mucous cells in their foot

Background

Mucus derived from many land snails has been extensively utilised in medicine and cosmetics, but some biological activities of the mucus need to be well documented. Nevertheless, most mucus is obtained from land snails, while mucus from freshwater snails has yet to be attended.

Methods

This study aims to determine and compare mucus's antioxidant and anti-inflammatory activities from the land snail Lissachatina fulica and the freshwater snail Pomacea canaliculata. ABTS, DPPH, reducing power and total antioxidant activity assays were used to evaluate the antioxidant capacity. Inhibition of nitric oxide production in lipopolysaccharide-activated RAW 264.7 cells was performed to determine the anti-inflammatory activity. Additionally, the histochemical analysis of mucous cells in each snail foot was conducted to compare the distribution of mucous cells and types of mucins using periodic acid-Schiff and Alcian blue staining.

Results

Mucus from L. fulica and P. canaliculata exhibited antioxidant and anti-inflammatory activities in different parameters. L. fulica mucus has higher total antioxidant (44.71 ± 2.11 mg AAE/g) and nitric oxide inhibitory activities (IC50 = 9.67 ± 0.31 µg/ml), whereas P. canaliculata mucus has better-reducing power activity (43.63 ± 2.47 mg AAE/g) and protein denaturation inhibition (IC50 = 0.60 ± 0.03 mg/ml). Histochemically, both species' dorsal and ventral foot regions contained neutral and acid mucins in different quantities. In the dorsal region, the neutral mucins level in L. fulica (16.64 ± 3.46%) was significantly higher than that in P. canaliculata (11.19 ± 1.50%), while the acid mucins level showed no significant difference between species. Levels of both mucins in the ventral foot region of L. fulica (15.08 ± 3.97% and 10.76 ± 3.00%, respectively) were significantly higher than those of P. canaliculata (2.25 ± 0.48% and 2.71 ± 0.56%, respectively). This study revealed scientific evidence of the biological capacity of mucus from L. fulica and P. canaliculata as well as provided helpful information on the region of the foot which produces effective mucus.

Purification and characterisation of heparin-like sulfated polysaccharides with potent anti-SARS-CoV-2 activity from snail mucus of Achatina fulica

Heparin-like sulfated polysaccharide, acharan sulfate, was purified from the mucus of an African giant snail with unique sulfated glycosaminoglycans (GAGs). This study reported on finding novel and safe heparin resources from Achatina fulica for further use as well as easy isolation and purification of the active fraction from the initial raw material. Its structure was characterised by a strong-anion exchange combined with high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) spectroscopy. The results indicated that the potential acharan sulfate fraction is a glycosaminoglycan composed of several repeating disaccharide units, namely, of →4)-α-IdoA(2S)(1→4)-α-GlcNAc/GlcNAc(6S)/GlcNSO₃(6S)(1→, and hence, presents heterogeneity regarding negative net charge density. Furthermore, the heparinase digests inhibit the binding of SARS-CoV-2 spike protein to the ACE2 receptor. In summary, the acharan sulfate presented in this work has shown its great potential for application in the preparation of sulfated polysaccharides as an alternative to heparin with important biological activity.

Snail mucus from the mantle and foot of two land snails, Lissachatina fulica and Hemiplecta distincta, exhibits different protein profile and biological activity

OBJECTIVE

Snails secrete different types of mucus that serve several functions, and are increasingly being exploited for medical and cosmetic applications. In this study, we explored the protein pattern and compared the biological properties of the mucus secreted from the mantle collar and foot of two snail species, Lissachatina fulica and Hemiplecta distincta.

RESULT

Protein profile showed a different pattern between the two species and between the two secretory parts. The mantle-specific protein bands were further characterized and among them was an antibacterial protein, achacin. Accordingly, the mucus from the mantle exhibited the higher antibacterial activity than that from the foot in both snail species. The mucus from H. distincta, first reported here, also showed antibacterial properties, but with a lower activity compared to that for L. fulica. Snail mucus also exhibited anti-tyrosinase activity and antioxidant activity but with no significant difference between the foot and mantle mucus. These results indicate some different protein compositions and biological activities of snail slime from the mantle and foot, which might be associated with their specific functions in the animal and are useful for medical applications.

Prediction of anticancer peptides against MCF-7 breast cancer cells from the peptidomes of Achatina fulica mucus fractions

Several reports have shown antimicrobial and anticancer activities of mucous glycoproteins extracted from the giant African snail Achatina fulica. Anticancer properties of the snail mucous peptides remain incompletely revealed. The aim of this study was to predict anticancer peptides from A. fulica mucus. Two of HPLC-separated mucous fractions (F2 and F5) showed in vitro cytotoxicity against the breast cancer cell line (MCF-7) and normal epithelium cell line (Vero). According to the mass spectrometric analysis, 404 and 424 peptides from the F2 and F5 fractions were identified. Our comprehensive bioinformatics workflow predicted 16 putative cationic and amphipathic anticancer peptides with diverse structures from these two peptidome data. These peptides would be promising molecules for new anti-breast cancer drug development.

Simultaneous determination of allantoin and glycolic acid in snail mucus and cosmetic creams with high performance liquid chromatography and ultraviolet detection

A new methodology for simultaneous quantitative analysis of allantoin and glycolic acid in snail mucus and cosmetic creams was developed. HPLC separation was achieved a Synergi-Hydro RP column within 7min using isocratic elution with potassium phosphate (pH 2.7; 10mM) at a flow rate of 0.7mL/min at 30°C. Sample pretreatment was performed by dilution of mucus or cosmetic cream in the elution buffer, heating at 60°C for 20min, adjusting the pH to 2.9 and purification with hexane extraction. Linearity was determined with spiked samples and the LLOQ values of 0.0125 and 0.2500mg/mL were determined for allantoin and glycolic acid, respectively. Accuracy and intra- and inter-day repeatability were studied at three levels of concentrations (0.04, 0.08 and 0.16mg/mL for allantoin and 0.1, 1.5 and 4.0mg/mL for glycolic acid) using spiked mucus and cream base samples; mean values of recovery were in the range of 96.81-102.42% in all matrices tested, whereas the respective RSDs (%Relative Standard Deviation) were less than 3.04% in all cases. Spiked mucus and cream samples were stable (RSD<4.16 and relative error<4.34%) at room temperature and at 4°C for 1 week and at -18°C for 6 months; samples were also stable after three freeze-thaw cycles. The method was applied to the analysis of different lots of snail mucus, and of three commercial creams containing snail mucus.