COX-2 inhibitors(NitroMed, Inc.)

In this work, a series of novel Pterostilbene-oxime ether-carboxylic acid (POC) derivatives (d1-d10, e1-e10 and 1-13) were designed, synthesized, and characterized by spectroscopic techniques. In order to further determine the absolute configuration of these compounds, one of them, compound d3, was investigated by X-ray single crystal diffraction method. d3 had a triclinic crystal with P-1 space group, and its CHCH and CHN was confirmed as E configuration. A strong hydrogen bond was formed between the hydrogen atom in CHCH moiety and the nitrogen atom in CHN moiety, which was a vital factor in the formation and stability of E configuration in the CHCH and CHN. The safety and anti-inflammatory activities of compounds (d1-d10, e1-e10 and 1-13) in vitro were evaluated. At 20 μM, compounds (d1-d10, e1-e10 and 1-13 were non-toxic and exhibited weak to strong inhibitory effects on the LPS-induced NO release. Among them, five compounds (1, 2, 7, 8 and 9) showed excellent anti-inflammatory effects with IC₅₀ (NO) values ranging from 9.87 to 19.78 μM, as well as strong COX-2 inhibitory abilities with IC₅₀ (COX-2) values ranging from 85.44 to 140.88 nM. Moreover, there was a rough positive correlation between their anti-inflammatory properties and the COX-2 inhibitory abilities. Compounds (1, 2, 7, 8 and 9) smoothly docked with COX-2 protein (PDB ID: 5KIR) to form stable complexes with strong hydrogen bonds, with an affinity range of -8.3 to -9.9 kcal/mol. SAR indicated that the amidation of POC at R₂ position was more favorable for enhancing the compound's biological actives than esterification. In addition, the 4-fluobenzyl substitution at R₂ position of the oxime ether moiety can obviously enhance the activity of above amide derivates. Introducing acyl groups (CO(CH₂)_nCH₃, n = 2, 4 and 6) into NH(CH₂)₃OH group to form ester chain is disadvantageous for activity enhancing, moreover, the longer the carbon chain, the poorer the activity. The strongest COX-2 inhibitor (IC₅₀ (COX-2) = 85.44 ± 3.88 nM), compound 7, exerted as anti-inflammatory activities (IC₅₀ (NO) = 9.87 ± 1.38 μM) by down-regulating the expression of COX-2 and iNOS, and modulating NF-κB/MAPK signaling pathways.

Retrograde intramedullary nailing is commonly performed to stabilize distal femoral shaft fractures which may lead to iatrogenic injuries of the knee articular cartilage. The limited regenerative capability of cartilage may further be hindered by intake of non-steroidal anti-inflammatory drugs (NSAIDs) which are usually advised for injuries of the musculoskeletal system. The current study was designed to evaluate the histological changes in the femoral articular cartilage of knee joint after retrograde femoral nailing of rats.

Retrograde intramedullary nailing was performed in 36 adult male Wistar rats, divided into three groups of 12 each. Groups 1 and 2 were given nonselective and selective COX 2 inhibitors, respectively, while the third group was taken as control. Half of the animals from each group were sacrificed at the second week, and remainder on the seventh week, and samples of the femoral articular cartilage were assessed for cartilage regeneration according to the modified Mankin scoring on histology while BMP-2 expression was evaluated on immunohistochemistry.

Mean modified Mankin scores for cartilage degradation were increased in animals taking NSAIDs at the second and seventh weeks of healing (P = 0.02, P < 0.001 respectively). There was a significant decrease in chondrocytes at the second week (P = 0.001), along with the loss of proteoglycan content in these animals at both time points (P = 0.001). The BMP-2 expression was significantly enhanced in the control group at the second (P = 0.001) and seventh weeks (P = 0.001).

The results reveal that intake of NSAIDs hinders the process of cartilage healing by reducing the number of chondrocytes and loss of proteoglycan content and decreased expression of BMP-2.