Guanidine Alkaloids from Monanchora arbuscula: Chemistry and Antitumor Potential

• Published in: Chemistry & biodiversity Vol. 8; no. 8; pp. 1433 - 1445
• Main Authors: Ferreira, Elthon G., Wilke, Diego V., Jimenez, Paula C., de Oliveira, Julieta R., Pessoa, Otília Deusdênia L., Silveira, Edilberto R., Viana, Francisco A., Pessoa, Cláudia, de Moraes, Manoel Odorico, Hajdu, Eduardo, Costa-Lotufo, Letícia Veras
• Format: Journal Article
• Language: English
• Published: Zürich WILEY-VCH Verlag 01.08.2011; WILEY‐VCH Verlag
• Subjects: Alkaloids; Cytotoxic activity; Guanidine alkaloids; Monanchora arbuscula
• ISSN: 1612-1872; 1612-1880
• DOI: 10.1002/cbdv.201000161

Five guanidine alkaloids, mirabilin B (1), 8bβ‐hydroxyptilocaulin (2), ptilocaulin (3), and a mixture of the 8β‐ and 8α‐epimers, 4 and 5, of 8‐hydroxymirabilin (1,8a;8b,3a‐didehydro‐8‐hydroxyptilocaulin), were isolated from Monanchora arbuscula colonies collected off the northeastern Brazilian coast. All structures were elucidated by spectroscopic analysis, including 1D (1H‐, 13C‐ (BB), and 13C‐DEPT) and 2D (COSY, HSQC, and HMBC) NMR experiments, and comparison with the literature data. The cytotoxicity of the isolated compounds were evaluated against four tumor cell lines, showing that mirabilin B (1) and the two epimers were inactive, while 8bβ‐hydroxyptilocaulin (2) and ptilocaulin (3) presented IC50 values in the range of 7.9 to 61.5 μM, and 5.8 to 40.0 μM, respectively. Further studies on the mechanism of action of ptilocaulin, using HL‐60 leukemia cells, demonstrated that this guanidine compound induced apoptosis of the treated cells.