Isolation and identification of antialgal compounds from Potamogeton maackianus by activity-guided fractionation.

ZHANG, S. H.; CHENG, S. P.; SUN, P. S.; WANG', H. Q.; WU, Z. B.

Potamogeton maackianus is major submerged species in China. Its antialgal allelopathic activities have been demonstrated, but its antialgal compounds are not fully known. To investigate the antialgal chemicals of P. maackianus, EtOH extracts of this macrophyte were further isolated by activity-guided fractionations. The antialgal bioassays of fractions were tested on algal specie, Selenastrum capricornutum. Through column chromatography (silica gel chromatography, ODS C18 P-HPLC, Sephadex LH-20) and preparative thin layer chromatography (P-TLC), six antialgal compounds (PK1-6) were isolated and their structures were determined by mass spectrum (EI-MS) and nuclear magnetic resonance (NMR) spectroscopy (¹H, 13C, 13C-DEPT, H-H COSY, HSQC and HMBC). PK1-PK6 were identified as stigmasterol (PK1), 4-hydroxybenzoic acid (PK2), 6-hydroxy-α-ionone (PK3), (E)-4-(4-hydroxy-3,3,8-trimethyl-9- -oxa-bicycle[6.1.0]nonan-4-yl) but-3-en-2-one (PK4), 1H-indole-3-carbaldehyde (PK5) and lignan (+)-pinoresinol (PK6), respectively. All six compounds were isolated for the first time from P. maackianus, while, PK3 was isolated from natural plants for first time and PK4 is a new compound. The results of bioassay showed that algal growth were obviously inhibited by the six isolated compounds at 20 mg L-1, and antialgal activities followed the order: PK3, PK4 > PK6 > PK5 > PK2 > PK1. The PK3 and PK4 completely inhibited the growth of S. capricornutum but stigmasterol was less inhibitory (30.4%) to PK1.

POTAMOGETON; ALLELOPATHY; BIOLOGICAL assay; CHROMATOGRAPHIC analysis; NUCLEAR magnetic resonance; BOTANY

Allelopathy Journal, 2011, Vol 28, Issue 1, p95

0971-4693

Academic Journal