Synthesis, Biological Evaluation, and Docking Studies of a Novel Sulfonamido-Based Gallate as Pro-Chondrogenic Agent for the Treatment of Cartilage.

Gallic acid (GA) and its derivatives are anti-inflammatory agents and are reported to have potent effects on Osteoarthritis (OA) treatment. Nonetheless, it is generally accepted that the therapeutic effect and biocompatibility of GA is much weaker than its esters due to the high hydrophilicity. The therapeutic effect of GA on OA could be improved if certain structural modifications were made to increase its hydrophobicity. In this study, a novel sulfonamido-based gallate was synthesized by bonding sulfonamide with GA, and its biological evaluations on OA were investigated. Results show that 5-[4-(Pyrimidin-2-ylsulfamoylphenyl)]-carbamoyl-benzene-1,2,3-triyl triacetate (HAMDC) was able to reverse the effects induced by Interleukin-1 (IL-1) stimulation, and it also had a great effect on chondro-protection via promoting cell proliferation and maintaining the phenotype of articular chondrocytes, as well as enhancing synthesis of cartilage specific markers such as aggrecan, collagen II and Sox9. Furthermore, a docking study showed that HAMDC fits into the core of the active site of a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), which provides an explanation for its activity and selectivity.

Effect of Longan polysaccharides on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro.

For autologous chondrocyte implantation (ACI) to restore cartilage defect, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but the high cost and potential tumorigenesis are the major obstacles. To ensure successful ACI therapy, it is of significance to find effective substituted pro-chondrogenic agent. Polysaccharides from plant extract have low toxicity and few undesirable side effects, which were reported to facilitate cartilage regeneration. In this study, we investigated the effect of Longan polysaccharides (LP) on rabbit articular chondrocytes through examination of the cell proliferation, morphology, viability, glycosaminoglycan synthesis and cartilage-specific gene expression. Results showed that close to the positive group which used the growth factor of TGF-ß, LP could effectively promote chondrocytes growth and enhance secretion and synthesis of cartilage extracellular matrix by up-regulating expression levels of aggrecan, collagen II and sox9 compared to the negative control. Expression of collagen I gene was effectively down-regulated, demonstrating the inhibition of chondrocytes dedifferentiation by LP. Hypertrophy that might lead to chondrocyte ossification was also undetectable in LP groups. Range of 4.69-18.76 µg/ml was recommended dose of LP, among which the most profound response was observed with 9.38 µg/ml. All the evidences revealed that LP may replace the growth factors to be applied in ACI therapy. This study might provide a basis for development of a novel agent in the treatment of articular cartilage defect.

Effect of epigallocatechin-3-gallate on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro.

In autologous chondrocyte implantation (ACI) to restore defective cartilage, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but their high cost and potential for tumorigenesis are major obstacles. To ensure successful ACI therapy, it is important to find an effective substitute pro-chondrogenic agent. Epigallocatechin-3-gallate (EGCG), one of the green tea catechins, has been widely investigated in studies of interleukin-1ß-induced chondrocytes. In the present study, the effects of EGCG on rabbit articular chondrocytes were investigated through the examination of cell proliferation, morphology, glycosaminoglycan synthesis and cartilage-specific gene expression. The results showed that EGCG could effectively promote chondrocyte growth and enhance the secretion and synthesis of the cartilage extracellular matrix by upregulating expression levels of aggrecan, collagen II and Sox9 genes. Expression of the collagen I gene was downregulated, which showed that EGCG effectively inhibited the dedifferentiation of chondrocytes. Hypertrophy, which may lead to chondrocyte ossification, was also undetectable in the EGCG groups. In conclusion, the recommended dose of EGCG was found to be in the range of 5 to 20 µM, with the most marked response observed with 10 µM. The present study may provide a basis for the development of a novel agent as a substitute for growth factors in the treatment of articular cartilage defects.

Effect of JJYMD-C, a novel synthetic derivative of gallic acid, on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro

Tissue engineering encapsulated cells such as chondrocytes in the carrier matrix have been widely used to repair cartilage defects. However, chondrocyte phenotype is easily lost when chondrocytes are expanded in vitro by a process defined as “dedifferentiation”. To ensure successful therapy, an effective pro-chondrogenic agent is necessary to overcome the obstacle of limited cell numbers in the restoration process, and dedifferentiation is a prerequisite. Gallic acid (GA) has been used in the treatment of arthritis, but its biocompatibility is inferior to that of other compounds. In this study, we modified GA by incorporating sulfamonomethoxine sodium and synthesized a sulfonamido-based gallate, JJYMD-C, and evaluated its effect on chondrocyte metabolism. Our results showed that JJYMD-C could effectively increase the levels of the collagen II, Sox9, and aggrecan genes, promote chondrocyte growth, and enhance secretion and synthesis of cartilage extracellular matrix. On the other hand, expression of the collagen I gene was effectively down-regulated, demonstrating inhibition of chondrocyte dedifferentiation by JJYMD-C. Hypertrophy, as a characteristic of chondrocyte ossification, was undetectable in the JJYMD-C groups. We used JJYMD-C at doses of 0.125, 0.25, and 0.5 µg/mL, and the strongest response was observed with 0.25 µg/mL. This study provides a basis for further studies on a novel agent in the treatment of articular cartilage defects.

In vitro effect of a synthesized sulfonamido-based gallate on articular chondrocyte metabolism.

Autologous chondrocyte implantation (ACI) is a promising strategy for cartilage repair and reconstitution. However, limited cell numbers and the dedifferentiation of chondrocytes present major difficulties to the success of ACI therapy. Therefore, it is important to find effective pro-chondrogenic agents that restore these defects to ensure a successful therapy. In this study, we synthesized a sulfonamido-based gallate, namely N-[4-(4,6-dimethyl-pyrimidin-2-ylsulfamoyl)-phenyl]-3,4,5-trihydroxy-benzamide (EJTC), and investigated its effects on rabbit articular chondrocytes through an examination of its specific effects on cell proliferation, morphology, viability, GAG synthesis, and cartilage-specific gene expression. The results show that EJTC can effectively promote chondrocyte growth and enhance the secretion and synthesis of cartilage ECM by upregulating the expression levels of the aggrecan, collagen II, and Sox9 genes. The expression of the collagen I gene was effectively downregulated, which indicates that EJTC inhibits chondrocytes dedifferentiation. Chondrocyte hypertrophy, which may lead to chondrocyte ossification, was also undetectable in the EJTC-treated groups. The recommended dose of EJTC ranges from 3.125 µg/mL to 7.8125 µg/mL, and the most profound response was observed with 7.8125 µg/mL. This study may provide a basis for the development of a novel agent for the treatment of articular cartilage defects.