E. S. Lukina

Conjugation of Chondroitin Sulfates with Amines

Conjugation of chondroitin sulfates with pharmacologically important amines in a water medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide was studied. Conjugates with amide and isoureidocarbonyl groups were synthesized. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 5; see also http://www.maik.ru

Synthesis of glucosaminoglycans hydroxamic acids

The hydroxamic functional group –C(=O)NHOH is introduced into polysaccharides in order to prepare water-soluble antioxidants [1–3], matrix metalloproteinase inhibitors [2, 4], and iron chelators [5, 6] based on them. The reaction of natural and synthetic alkyl esters of polysaccharides and hydroxylamine base is usually used to synthesize the hydroxamic acids [2, 5, 7]. For this, the content of hydroxamic units is <25% [2]. We showed earlier that the reaction of glycosaminoglycans (GAG) with 1-ethyl-3-[3(dimethylamino)propyl]carbonyldiimide (CDI) formed readily O-(glycosaminoglycanoyl)isoureas that exhibited ester properties [8–10]. Therefore, we studied the reaction of the corresponding O-acylisoureas with alkaline NH2OH in aqueous and alcoholic solution in order to prepare hydroxamic acids of hyaluronic acid (1), dermatan sulfate (2), and heparin (3). The action of a five-molar excess of CDI on GAG 1, 2, and 3 synthesized the corresponding O-acylisoureas 4, 5, and 6. Treatment with an alkaline aqueous solution of NH2OH converted them into hydroxamic acids 7, 8, and 9, respectively (Scheme 1). The appearance in IR spectra of 7–9 of absorption bands at 1552–1559 cm–1 that were characteristic of N–H stretching vibrations in –C(=O)NHOH [7] and the formation of iron–hydroxamate complexes with an absorption maximum at 520 nm [11] were consistent with the formation of hydroxamic units in the GAG structures.

Conjugates of hyaluronic acid and chondroitin sulfates with 4-aminoantipyrine and their analgesic properties

Heteropolysaccharides of the glucosaminoglycan class, e.g. hyaluronic acid (HA) and chondroitin sulfates (CS), are known for their reparative and regenerative properties, on the basis of which several drugs for treating diseases of the musculoskeletal system were developed [1–3]. HA and CS stimulate regeneration of cartilage and bone tissue and exhibit antiinflammatory and analgesic activity. High-molecular-weight HA is the principal component in the sinovial fluid replacements Sinokrom, Sinvisk, etc. These are highly viscous hydrogels for intra-joint administration that act as a lubricant for painful joints [2]. The active substance CS in chondro-protector drugs (Chondroxide etc.) normalizes the exchange of cartilage tissue substances including phosphorus and calcium, decreases the pain level, and increases the flexibility of afflicted joints [3, 4]. In order to enhance the anti-inflammatory and analgesic activity of HA (1) and CS [2, a 3:2 mixture of CS-4 and CS-6], we incorporated into their structures 1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one (4-aminoantipyrine) (3). The corresponding conjugates 4 and 5 (Scheme 1) were synthesized by the reaction of glucosaminoglycans 1 and 2 with amine 3 through the action of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (CDI) [5].

Acid glycosaminoglycans and their chemical modification

The modern state of chemical modification of hyaluronic acid, chondroitin sulfates, and heparin is considered, and the possible application of modified glycosaminoglycans as potential drugs is discussed.

Chemical modification of heparin

Heparin was modified at carboxyl groups by reaction with several pharmacologically important amino-containing compounds in aqueous medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. In dependence on the nature of the amine and the ratio of reagents, conjugates containing 36–100% amide and 0–25% isoureidocarbonyl groups were synthesized. Isoureidoarylamide groups are present, along with amide moieties, in the products of heparin modification by hydroxyl-containing aromatic amines. The conjugate of heparin with p-aminobenzoic acid contained oligomeric arylamide.

Ozonides with the tetrahydroquinoline and dehydroabietic fragments

Acid-catalyzed three-component condensation of methyl 12-aminodehydroabietate, aromatic aldehydes, and cyclopentadiene gave methyl (4R)-4-aryl-6-isopropyl-10,13a-dimethyl-3a,4,5,8,9,9a,10,11,12,13,13a,13d-dodecahydro-3H-cyclopenta[c]naphtho[1,2-f]quinoline-10-carboxylates and their (4S)-diastereomers. Ozonolysis of the double bond in their N-trifluoroacetyl derivatives synthesized from the (4R)-diastereomers afforded the corresponding ozonides with the (1S,4R,5aS,6R,11aR,12R,15aS,15dR)-configuration.

Synthesis of conjugates of hyaluronic and nicotinic acids

Conjugates with nicotinic acid of hyaluronic acid carboxylic and hydroxyl groups were synthesized and exhibited polyampholyte properties.

Hyaluronic acid based hydroxamate and conjugates with biologically active amines: In vitro effect on matrix metalloproteinase-2.

In this study, water soluble hyaluronic acid (HA) based hydroxamate and conjugates with biologically active amines and hydrazides such as p- and o-aminophenols, anthranilic, 4- and 5-aminosalicylic acids, nicotinic, N-benzylnicotinic and isonicotinic hydrazides, p-aminobenzenesulfonamide (Streptocide), p-aminobenzoic acid diethylaminoethyl ester (Procaine), and 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one (4-aminoantipyrene) were examined as matrix metalloproteinase-2 inhibitors (MMPIs). In a dose of 0.27-270μM, the most efficient MMPIs were HA conjugates with o-aminophenol=4-aminoantipyrine>4-aminosalicylic acid>5-aminosalicylic acid. Conjugates with Streptocide, Procaine and HA hydroxamate showed 40-50% inhibitory effect at all used concentrations. Conjugates with anthranilic acid and isonicotinic hydrazide (Isoniazid) in a dose of 0.27μM inhibited enzyme activity by ∼70%, but with the concentration increase their inhibitory effect was decreased.

Cyclocondensation of methyl 12-aminodehydroabietate with aldehydes and cyclopentadiene. Synthesis of tricyclic diterpenoide fused to tetrahydroquinoline

Three-component cyclocondensation of methyl 12-aminodehydroabietate with cyclopentadiene and formaldehyde or acetaldehyde under acid catalysis afforded polysubstituted naphthoquinoline derivatives with fused oxetanocyclopentane and cyclopentene fragments. Ozonation of the double bond in the N-trifluoroacetyl cyclopentene derivatives gave the corresponding ozonide.

Synthesis of 6-aryl-6,6a,7,9a-tetrahydro-5H-cyclopenta[c] 1,7- and -1,8-phenanthrolines

A three-component acid-catalyzed cyclocondensation of 5-aminoquinoline and 5-aminoisoquinoline with aromatic aldehydes and cyclopentadiene leads to (6S*,6aR*,9aS*)-6-aryl-6,6a,7,9a-tetrahydro-5H-cyclopenta[c]-1,7-and (6S*,6aR*,9aS*)-6-aryl-6,6a,7,9a-tetrahydro-5H-cyclopenta[c]-1,8-phenanthrolines.