PROJECT BACKGROUND

1. Bridgman anvil Solid-state synthesis of boron-containing hyaluronic acid:preparation, structural and biologicalevaluationSergey Uspenskiy, Vladimir Khabarov, Alexander Zelenetskii, Mikhail SelyaninInternational Research Centre “Martinex”, Russia PROJECT BACKGROUND We designed a new family of the products for Boron Neutron Capture Therapy (BNCT). Instead of the molecules with covalently bonded boron atoms (urea or thiourea type spacers, boron-peptides, boron-nucleic acids, etc) we proposed the new complex molecules – supramolecular structures based on hyaluronic acid. The approach suggests a creation of polycomplexes with hyaluronic acid and polyborate chains. Such complexes are as stable as covalently bonded boron-contained organic compounds, because they consists of the polychelate fragments, distributed inside hyaluronic acid matrix. General Principle of Boron-Neutron Capture Therapy The method BNCT is a binary method of the cancer treatment, in which an interaction of two non-harmful components leads to creation of the highly toxic products which affect only cancer cells. Such mechanism is assured by providing the cancer tissue with a sufficient amount of the isotope 10B, following by an exposure with neutrons. As a result of the “capture” of the neutron by the atoms of 10B, such highly active particles as 4Не (а-particle) and 7Li are created. Both particles are known to be deadly for the cancer cells. Since both 4Не and 7Li have the life span comparable with the size of the single cell (≤ 14 мcм), the kill the cells only within the tumor tissue surrounding the location of 10B. С-О region(normalized by employing as internal standard the СН band) Boron – HA manufacturing method Initially the complexes HA-sodium tetraborate were prepared on the Bridgman anvil. The solid phase method was transferred to twin-screw extruder, which is designed for solid phase chemical reactions. Model compounds - possible complexes of borates with saccharides Complex of boronic acid witha-diols Borax (sodium tetraborate hexahydrate) Borax (sodium tetraborate hexahydrate) Borate complex with sucrose B:HA 4:1 Molar ratio B: HA 1:1 (Molar ratio) Complex of polyborates with HA Twin screw extruder HA B:HA 4:1 Molar ratio B: HA 1:1 (Molar ratio HA Equilibrium of borate-borate complex which leads to ligand exchange at the boron atom The absorption peak at 1481 сm-1 indicated the interaction of borax with HA due to carboxyl and carbinol groups as proton donors with oxygen atoms of B-O-B groups and boron-contained anions [В-О(-) : О-Н···О, О-Н···(-)О] and simultaneously due to free electron pairs of the hetero atoms as electron donors [-О(:)···В, -N(:)···B]. The band at 1461 сm-1(shoulder), shows a formation of the boronic acid esters R-O-B. Twin screw extruder operation with screws rotation in the same direction IR spectra of Na2B4O7 *10H2O and HA with the spectra of their reaction products RESULTS: Based on the IR data of the characteristic absorption bands, all functional groups of HA are involved by the chelate bonds with boron-oxide chains. The most important is the bond B-O-C. In that structures HA serves as polydentate ligand of boron-oxides. The complexes are very stable both as aqueous solutions and when injected in vivo. The kinetic studies of the complex distribution in tumor tissue showed that the product selectively accumulates in tumor and provides boron content 55 mкg/g tissue, which corresponds to necessary conditions for efficient application of BNCT. B-HA complex accumulationin vivo B:HA 4:1 Molar ratio B: HA 1:1 (Molar ratio Carbonylandamide region (normalized by employing as internal standard the СН band) • CONCLUSIONS: • The existence of the supramolecular complex Boron-HA has been confirmed by IR spectroscopy. • The product satisfied the requirements for BNCT regarding boron accumulation in tumor tissue. • The toxicological studies confirmed product safety. • The product can be produced in an industrial scale. The strong interaction of all ether and hydroxyl groups of polysaccharide with oxygen atoms of B-O-B groups and the anions B-O(-) simultaneously due to free electron pairs and hydrogen atoms of -О(:)···В, О-Н···О, О-Н···(-)О groups. In the cyclic variants it leads to creation of the chelate complexes. The possibility of the creation of the bonds C-O-B is due to reaction В-О-В + НО-С- → В-ОН + В-О-С. . Product accumulation in tissue Boron content in tumor depending on the method of administration (intra-tumor or “under bed”) Boron content sharply decreases within one day.It creates opportunity for product multiple applications. In 1 h after administration “under bed” the boron content is only 1.5 times lower than after intra-tumor administration. It suggests that the product migration into tumor is quite efficient. It allows to consider such administration mode as multiple injections into several points surrounding the tumor.