THE TAMARIND SEED POLYSACCHARIDE
The Tamarind Seed Polysaccharide (TSP) is a natural molecule extracted from the Tamarind tree, which has long been used in the food industry. Due to its extraordinary similarity with Mucins, molecules of the ocular surface, it is effective in the treatment of dry eye syndrome.
TS-Polysaccharide is a natural substance extracted by seeds of plant Tamarindus indica . Chemically it is a water soluble galacto-xilo-glucan polysaccharide, with a medium molecular weight of 470 kDa.
The primary structure of Tamarind Seed Polysaccharide consists of a (1→4)-b-D-glucan spine with (1→6)-a-branched xylose, which is partially substituted by (1→2)-b-galactoxylose.
It possesses properties like high viscosity, broad pH tolerance and adhesivity, so this led to its application as stabilizer, thickener, gelling agent and binder in food and pharmaceutical industries. In addition to these, it has characteristics of non-carcinogenicity, mucoadhesivity, biocompatibility and high drug holding capacity.
The characteristic mucin-like structure of TS-Polysaccharide
It is thought that the increased retention time observed with Tamarind Seed Polysaccharide on the ocular surface can be explained by similarity of the structure of it to transmembrane mucins.
Mucins are a heterogeneous group of glycoproteins exceptionally voluminous that can be found, as main components, in all mucus secretion of wet epithelial surfaces. On the ocular surface, epithelial mucins serve as pre-ocular tear film stabilizer to prevent dehydration of the underlying epithelium, remarkable barrier against pathogens penetration and wetting and lubricant agent of the epithelial surface of cornea and conjunctiva when blinking.
The molecular structure of Tamarind Seed Polysaccharide, type "mucin-like", is very similar to the mucus glycoproteins and in particular to a MUC 1, a mucin present in the cornea and conjunctiva, in its extracellular projection in the glycocalyx.
The branched structure of the Tamarind Seed Polysaccharide, typical of tear film glycoproteins, allows the polysaccharide to adhere directly to the mucins of the glycocalyx. This interaction confers to the molecule a higher residence time on the ocular surface than Hyaluronic acid, previously the most efficacy product available. In addition, since the polymer has high capacity to hold water, the Tamarind Seed Polysaccharide-based solutions maintain properly humidified the ocular surface and increase the stability of the pre-corneal tear film that protects it from environmental hazards by creating a microenvironment favourable to the corneal surface repairing processes.
The patent for TSP-based eye drops
In 1990, the collaboration of Farmigea, the University of Pisa and Polytech in the study and characterization of Tamarind Seed Polysaccharide, led to the product currently marketed.
On Feb 5th, 1996 the Italian patent nº 1.283.911 was applied for and subsequently granted for “Opththalmic solutions viscosified with Tamarind Seed Polysaccharide”. In the period 1998-2001 the challenge for Farmigea has been to establish if Tamarind Seed Polysaccharide was a medication suitable for clinical development. In the period 2002-2005 the challenge for Farmigea has been to prove that Tamarind Seed Polysaccharide is an effective compound for the treatment of dry eye syndrome.
The properties of TSP in the treatment of dry eye syndrome
The rheological behaviour of the Tamarind Seed Polysaccharide solution, non-Newtonian, correctly mimics the tear fluid, very viscous when the eyelids are open and more fluid during the blink due to the stress produced by the eyelids closure. Consequently, the Tamarind Seed Polysaccharide ophthalmic solutions ensure proper protection of the ocular surface avoiding discomfort to blink.
For the properties of the polymer described above, the ophthalmic solutions containing Tamarind Seed Polysaccharide are efficient in maintaining proper hydration of the ocular surface, by associating with the tear film and reducing the evaporation. Adhering directly to the superficial layer of the corneal epithelium, the Tamarind Seed Polysaccharide is able to create an efficacy barrier that protects the eye from all the aggressions caused by external agents such as wind, prolonged exposure to sunlight, dry air, chlorinated or salted water, intense sunlight and air conditioning, preventing the phenomena of irritation, burning, redness and foreign body sensation that may ensue. The Tamarind Seed Polysaccharide in ophthalmic solution preservative free is also able to decrease the discomfort caused by prolonged wearing of contact lenses.
Bibliography:
• Ophthalmic solutions viscosified with tamarind seed polysaccharide, Saettone MF, Burgalassi S, Giannaccini B, Boldrini E, Bianchini P, Luciani G, European Patent EP0892636.
• Use of a new lachrymal substitute (TS Polysaccharide) in Contactology, Mannucci LL, Fregona I, Di Gennaro A, J Med Contactology and Low Vision 2000, 1(1): 6–9
• A scintigraphic investigation of the precorneal residence time of TS polysaccharide formulations in mild to moderate KCS patients, B. Lindsay, T. Jones, B. Brown, S. Osborne, C.G. Wilson, E.
• Development of a Simple Dry Eye Model in the Albino Rabbit and Evaluation of Some Tear Substitute, S. Burgalassi, L. Panichi, P. Chetoni, M. F. Saettone, E. Boldrini, Opthalmic Research 1999;31:229-35.
• Effect of Xyloglucan (TSP) on conjunctival cell adhesion to laminin and on corneal epithelium wound healing, S. Burgalassi, L. Raimondi, R. Pirisino, G. Banchelli, E. Boldrini, M. F. Saettone, Eu. J. of Ophthalmology 2000 Jan-Mar;10:71-6.
• Assessment of spontaneous contamination and evolution over tiem of pathogens introduced into ophthalmic formulations with a new lacrimal substitute (TAMARIND SEED POLYSACCHARIDE) after first opening, E. A. Debbia, E. Boldrini, I.Gualco, A.M. Schito, A. Marchese, Italian Journal of Dental and Clinical Microbiology
• Interaction between contact lenses and artificial tears: a Nuclear Magnetic Resonance Study, N. Pescosolido, L. Casciani, C. Castro, C. Manetti, ATO, 2004.
• Comparison between two tear substitutes in contact lens wearers, A,V, Bux, S.Z. Scalinci, L. Scorolli, M.C. Morara, R. Meduri, ATO, 2003.
• Establishing the tolerability and performance of tamarind seed polysaccharide (TSP) in treating dry eye syndrome: results of a clinical study, M. Rolando & C. Valente; BMC Ophthalmology volume 7, Article number: 5, 2007