Amaryllidaceae alkaloids from Crinum latifolium with cytotoxic, antimicrobial, antioxidant, and anti-inflammatory activities

Four novel and potently bioactive Amaryllidaceae alkaloids, 4,8-dimethoxy-cripowellin C (1), 4,8-dimethoxy-cripowellin D (2), 9-methoxy-cripowellin B (3), and 4-methoxy-8-hydroxy-cripowellin B (4), together with one known alkaloid, cripowellin C (5) were isolated from the 95% EtOH extract of the bulbs of Crinum latifolium. Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (H-1.H-1 COSY, HMQC, and HMBC) NMR as well as spectroscopy high resolution mass spectrometry. All isolates were in vitro evaluated for their cytotoxic activity against seven lung cancer cell lines, in addition to antimicrobial activity for eight bacteria, scavenging potential using ABTS(.+) and DPPH test, and anti-inflammatory activity for Cox-1 and Cox-2 which had not previously been tested for crinane-type alkaloids with the cleavage between C-1 and C-13. Consequently, alkaloids 1-5 exhibited potent cytotoxicity against all of seven tested tumor cell lines with (IC50 < 30 nM). Alkaloids 3 and 4 displayed the significant antimicrobial activity with IC50 values < 0.50 mM and antioxidant activity in the ABTS(.+) and DPPH test. Additionally, Alkaloids 1-5 exhibited comparable inhibition of Cox-1 ( > 64%) and Cox-2 ( > 90%) with positive control.