Chemical Constituents and Their Anti-inflammatory Activities from the Stems of Cryptolepis buchanani

The stems of Cryptolepis buchanani are traditionally used for the treatment of inflammation, including arthritis, muscle and joint pain. In the present study, 3 crude extracts (hexane, EtOAc and methanol) from the stems of C. buchanani were evaluated for anti-inflammatory effects using an in vitro model of RAW 264.7 macrophages. At a concentration of 50 μg/mL, the hexane and EtOAc crude extract have inhibited nitric oxide (NO) production by 84.33±2.01 and 82.49±0.92 %, respectively. 3,4-Dihydroxyl benzoic acid (1), vanillic acid (2), syringaldehyde (3), isoscopoletin (4) and stigmast-4-ene-3,6-dione (5) were isolated from hexane and EtOAc crude extracts. Their structures were identified on the basis of 1H and 13C NMR, as well as a comparison of the data from previous reports. Compounds 1-5 were evaluated for anti-inflammatory activity. Compound 3 showed activity of NO inhibition with IC50 values of 49.07 μM (Indomethacin IC50 values of 39.21 μM). In addition, compounds 1-3 and 5 were isolated for the first time from this plant.
HIGHLIGHTS

The crude hexane and ethyl acetate (EtOAc) (each, 50 mg/mL) inhibited nitric oxide (NO) production with inhibition percentage at 84.33 and 82.49, respectively
3,4-Dihydroxyl benzoic acid, vanillic acid, syringaldehyde and stigmast-4-ene-3,6-dione were isolated for the first time from this plant
Syringaldehyde showed activity of NO inhibition with IC50 values of 49.07 μM (Indomethacin IC50 values of 39.21 μM)         

GRAPHICAL ABSTRACT