The endophytic fungus Chaetomium globosum was originally separated from marine red alga Polysiphonia urceolate Grev that was collected in the coast of Qingdao, China. The liquid medium was incubated at room temperature for 40 days. The mycelium and filtrate were extracted with methanol and EtOAc respectively. Crude extracts were evaporated from mycelium and filtrate respectively under reduced pressure at 40°C. The two extracts were assayed against P-338 and A-549 cell lines and each showed significant bioactivity. Since the HPLC profiles of the two extracts were nearly identical, they were combined before further separation. Initial chromatographic separation of the extracts was performed on silica gel (200-300 mesh, Qingdao Haiyang Chemical Inc., China) column chromatography (CC) with a gradient solvent system from 3% acetone/petroleum ether to 100% acetone. The fractions were monitored by inspection of thin layer chromatography (TLC). Fractions l2-l5 were combined and were further chromatographied on silica gel using an EtOAc/petroleum ether gradient system to give a subfraction containing 4 compounds shown below, which was further purified over Sephadex LH-20 (Merck, Darmstadt, Germany) using chloroform/MeOH (1:1) as solvent system. Four benzaldehyde derivatives were finally isolated and purified.

The chemical structures of the 4 secondary metabolites were spectroscopically analyzed with IR (Nicolet Impact 400 FT-IR Spectrophotometer), EIMS (Autospec 3000), and lD and 2D NMR (Bruker 500 MHZ spectrometer) spectral data. They were determined as:

(I) 2-(l -heptenyl)-3, 6-dihydroxy-5-(3-methyl-2-butenyl) benzaldehyde;

(II) 2-heptyl-3, 6-dihydroxy-5-(3-methyl-2-butenyl) benzaldehyde;

(III) 2-(3, 5-heptadienyl)-3, 6-dihydroxy-5-(3-methyl-2-butenyl) benzaldehyde;

(IV) 2-(l, 3, 5-heptatrienyl)-3, 6-dihydroxy-5-(3-methyl-2-butenyl) benzaldehyde.

Although a series of benzaldehyde derivatives have been isolated from terrestrial fungi such as from Aspergillus sp., these 4 compounds were isolated from marine-derived fungus for the first time.