Quinolizidines alkaloids: Petrosin and xestospongins from the sponge

Oceanapia sp.

KEISHAM SARJIT SINGH^a,*, BABULAL DAS^b and CHANDRAKANT G NAIK^a

^aBioorganic Chemistry Laboratory, National Institute of Oceanography (CSIR), Goa 403 004, India

^bDepartment of Chemistry, Indian Institute of Technology (IIT), Guwahati 781 039, India

e-mail: keisham@nio.org

MS received 10 May 2010; revised 27 April 2011; accepted 13 June 2011

Abstract. A bisquinolizidine alkaloid, petrosin (1) and a series of bis-1-oxaquinolizidine, xestospongins

(2–9), were obtained from the ethyl acetate extract of the sponge Oceanapia sp. Petrosin was obtained along

with xestospongin- C, D, E, F, G, H, I and J having di-hetroatom rings, from the ethyl acetate extract of the

sponge. The compounds exhibited moderate to high activities against some microorganisms and clinical isolates.

The structures of the alkaloids were elucidated by NMR and ESIMS spectroscopic data. The structure of

petrosin was confirmed by an X-ray diffraction study.

Graphical Abstract. Bisquinolizidine alkaloids, petrosin (1) and a series of bis-1-oxaquinolizidine

alkaloids, xestospongins (2–9), have been obtained from the ethyl acetate

extract of the marine sponge Oceanapia sp. collected from the southern coast

of India. The structures of the compounds were determined by NMR and

mass spectroscopic data. The structure of petrosin was confirmed by X-ray

crystallography.

Keywords. Alkaloid; bisquinolizidine; Oceanapia; sponge; crystallography.