New Phenylphenalene Derivatives from Water Hyacinth (Eichhornia crassipes)

Abstract

Water hyacinth (Eichhornia crassipes) is a cause of great concern in terms of environmental and agricultural impacts in many parts of the world. Phytochemical investigation of water hyacinth led to the isolation of six new phenylphenalenes, 2,3-dihydro-3,9-dihydroxy-5-methoxy-4-phenyl-1H-phenalen-1-one (1), 2,3-dihydro-8-methoxy-9-phenyl-1H-phenalene-1,4-diol (2), 2,3-dihydro-4,8-dimethoxy-9-phenyl-1H-phenalen-1-ol (3), 2,3-dihydro-9-(4-hydroxyphenyl)-8-methoxy-1H-phenalene-1,4-diol (4), 2,6-dimethoxy-9-phenyl-1H-phenalen-1-one (5), and 7-(4-hydroxyphenyl)-5,6-dimethoxy-1H-phenalen-1-one (6), together with the four known compounds 7 -10. Their structures were elucidated by spectrometric methods including 1D-and 2D-NMR, and MS analysis. These compounds may be involved in allelopathic interactions of water hyacinth with neighboring plants.Introduction. -Water hyacinth (Eichhornia crassipes (Mart. ) Solms), a plant of the family Pontederiaceae, causes globally annual losses of more than $100 million to hydroelectricity generation, irrigation schemes, fisheries, riparian communities, and water transport [1]. The free-floating aquatic weed originating from the Amazon basin in South America has been introduced by man in China in the early 20th century [2]. However, water hyacinth possesses the ability to absorb heavy metals which accumulate in the root, making this plant of little use. Previous studies reported the isolation of some phenylphenalenes from water hyacinth [3 -5]. We collected the material of water hyacinth in Dianchi Lake at Kunming where the lake is severely polluted. Six new compounds, 2,3-dihydro-3,9-dihydroxy-5-methoxy-4-phenyl-1H-phenalen-1-one (1), 2,3-dihydro-8-methoxy-9-phenyl-1H-phenalene-1,4-diol (2), 2,3-dihydro-4,8-dimethoxy-9-phenyl-1H-phenalen-1-ol (3), 2,3-dihydro-9-(4-hydroxyphenyl)-8-methoxy-1H-phenalene-1,4-diol (4), 2,6-dimethoxy-9-phenyl-1H-phenalen-1-one (5), and 7-(4-hydroxyphenyl)-5,6-dimethoxy-1H-phenalen-1-one (6), together with four known ones, hydroxyanigorufone (¼ 2-hydroxy-9-(4-hydroxyphenyl)-1H-phenalen-1-one; 7) [3], 5,6-dimethoxy-7-phenyl-1H-phenalen-1-one (8) [4], 2-hydroxy-8-(4-hydroxyphenyl)-1H-phenalen-1-one (9) [5], and methyl ferulate (¼ methyl 3-(4-hydroxy-3-methoxyphenyl)prop-2-enoate; 10), were isolated from the whole plant of E. crassipes (Fig. 1). The known compounds have already been reported in this species.

Synthesis of 2,6-dimethoxy-9-phenyl-1H-phenalen-1-one and structural revision of the benzoindenone from Eichhornia crassipes

“…Finally, treatment of 8 with potassium carbonate and iodomethane in DMF gave 3 in 90% yield through a nucleophilic substitution reaction (Scheme 3). The physical and spectroscopic data of the synthetic compound 3 were identical to those reported in the literature [11] (Supplementary material).…”

“…1) was isolated and its structure determined [11]. Recently, we found that the NMR data of 2 highly matched with those of 3 [11]. The originally assigned structure of 2 was found to be incorrect.…”

“…In search of potential allelochemical compounds from E. crassipes, compound 3 ( Fig. 1) was isolated and its structure determined [11]. Recently, we found that the NMR data of 2 highly matched with those of 3 [11].…”

Eichhornia crassipes: a Powerful Bio-indicator for Water Pollution by Emerging Pollutants

“…DellaGreca et al . 18 were among the first to describe the existence of new “phenylphenalene” structures extracted from water hyacinths. They identified two interesting compounds, phenyl naphthalenedicarboxylic acid and a dimeric oxidized phenylphenalene skeleton, that might play a role as phytoalexins and phytoanticipins.…”

Bioactivity and biochemical analysis of water hyacinth (Eichhornia crassipes)

“…The plant is known for its well ability to grow in severe polluted water (So et al 2003). A large number of biologically active compounds have been extracted from this weed (Greca et al 1991(Greca et al , 1992Wang et al 2011). Recently, considerable attention has been given at harvesting the aquatic plant for practical uses to partially defray the cost of removing plants from water ways and use it as economical sources in many parts of the world (Widjajanto et al 2003;Sharshar and Haroon 2009).…”