Ramosissimin, a new flavonol from Tararix ramosissima, induces apoptosis in rheumatoid arthritis fibroblast-like synoviocytes.

Tamarix ramosissima is a traditional Chinese herbal medicine used for rheumatoid arthritis (RA) treatment in Northwest China. Chemical investigation of EtOH/H2O extracts of T. ramosissima led to the discovery of a new flavonol, ramosissimin (1), together with the known flavonoids compounds quercetin (2), quercetin-3'4'-dimethylether (3) and kaempferol (4). By means of high resolution electrospray ionization mass spectroscopy (HRESIMS) and 1D and 2D-NMR experiments, and after comparison with literature data, the structures of the compounds were determined. The effect of compound 1 on the viability of RA fibroblast-like synoviocytes (RA-FLS) was evaluated by MTT assay. Apoptosis-inducing effect of compound 1 in RA-FLS was further investigated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay and activated caspase-3/7 level assessment using luminescent assay. The results revealed that ramosissimin displayed remarkable proliferation inhibitory effect in RA-FLS. Furthermore, compound 1 could significantly induce cellular apoptosis of RA-FLS and increase activated caspase-3/7 levels. It is suggested that ramosissimin may inhibit the proliferation of RA-FLS by inducing apoptosis.

Tamaractam, a New Bioactive Lactam from Tamarix ramosissima, Induces Apoptosis in Rheumatoid Arthritis Fibroblast-Like Synoviocytes.

Chemical investigation of Tamarix ramosissima Ledeb, a traditional herbal medicine used for rheumatoid arthritis (RA) treatment in northwest China, led to the discovery of a new phenolic aromatic rings substituted lactam, tamaractam (1), together with the previously reported compounds cis-N-feruloyl-3-O-methyldopamine (2) and trans-N-feruloyl-3-O-methyldopamine (3). The structures of the compounds were determined by high resolution electrospray ionization mass spectroscopy (HRESIMS) and 1D and 2D-NMR experiments, as well as comparison with the literature data. The effects of the three compounds on the viability of RA fibroblast-like synoviocytes (RA-FLS) were assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Pro-apoptosis effect of compound 1 in RA-FLS was further investigated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, activated caspase-3/7 level assessment using luminescence assay, and sub-G1 fraction measurement using flow cytometry. It was found that these three compounds displayed variable proliferation inhibitory activity in RA-FLS, and compound 1 exhibited the strongest effect. Compound 1 could remarkably induce cellular apoptosis of RA-FLS, increase activated caspase-3/7 levels, and significantly increase sub-G1 fraction in the cell cycle. The results suggested that compound 1 may inhibit the proliferation of RA-FLS through apoptosis-inducing effect, and these compounds may contribute to the anti-RA effect of T. ramosissima.