A novel bromophenol from marine red alga Symphyocladia latiuscula

Abstract

(1), a new bromophenol, was isolated from the ethanol extract of marine red alga Symphyocladia latiuscula, with a known compound, 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (2). Their structures were elucidated by spectroscopic analysis, including high-resolution mass spectroscopy, and 1 and 2-dimensional NMR techniques. Compounds 1 and 2 showed inhibitory activity against Staphyloccocus aureus with IC 50 102 and 50 μg/mL, respectively. Symphyocladia latiuscula is a marine red algal species belonging to the family Rhodomelaceae, order Ceramiales, that is distributed mainly in Korea, Japan, and the north part of the Chinese coast. Some bromophenols have been isolated from this species that possess aldose reductase inhibitory activity [1], antibacterial activity [2], and free-radical-scavenging activity [3][4][5][6]. In the course of our search for biologically active constituents of marine algae from Chinese coast, we have shown that the ethanol extract and EtOAc fraction of Symphyocladia latiuscula possess anti-Staphyloccocus aureus activity. Therefore, the EtOAc fraction was subject to further chemical investigation, which resulted in the isolation and identification of two bromophenols: 2,3,6,-tribromo-4,5-dihydroxybenzyl ethyl ether (1) and the known compound 2,3,6,-tribromo-4,5-dihydroxybenzyl methyl ether (2). Herein, we report the isolation, structure elucidation, and antimicrobial activity of these bromophenols.Compound 1 was obtained as a brown gum. The IR spectrum showed absorptions at 3493, 1582, and 1548 cm -1 , suggesting the presence of phenolic hydroxyl and aromatic rings. The ESIMS of 1 exhibited a characteristic tribrominated pseudomolecular ion peak cluster at m/z 401/403/405/407 [M-H] -(1:3:3:1), and the HRESIMS at m/z 400.8018 [M-H] -established the molecular formula C 9 H 9 Br 3 O 3 . The 13 C NMR and DEPT spectrum showed six quaternary carbons [δ C 130.5 (s, C-1), 113.7 (s, C-2), 114.3 (s, C-3), 143.8 (s, C-4), 145.3 (s, C-5), 118.9 (s, C-6)], two oxymethylene [δ C 66.4 (t, C-8), δ C 74.2 (t, C-7)], and one methyl carbon signal [δ C 15.5 (q, C-9)]. Besides a pair of characteristic proton spin-coupling systems attributed to one ethoxyl unit at δ H 3.58 (2H, q, J = 7.0 Hz, H-8) and 1.17 (3H, t, J = 7.0 Hz), the 1 H NMR spectrum showed another singlet at δ H 4.82 (2H, s, H-7), which was assigned to the oxymethylene protons of the fully substituted benzene ring. The protonated carbons and their corresponding protons were unambiguously assigned by the HSQC experiment. The 1 H-1 H COSY showed a cross peak for H 2 -8 and H 3 -9, which confirmed the ethoxyl group. In the HMBC spectrum, the correlations from H-7 to C-1, C-8, and C-9 established the connections from C-7 to C-8 by an oxygen atom and the attachment of the ethyloxymethylene group to C-1. In combination with the chemical shift values of the carbons and biogenetic considerations in which the bromophenols from Symphyocladia latiuscula are characterized by a 2,3,6-tribromo-4,5-dehydroxy moiety. Compound 1 was established as 2,3,6-tribr...

Marine natural products

“…391 The bromophenol 371 was obtained from Polysiphonia urceolata (Yantai, China) and characterised by spectroscopic techniques and DFT theoretical analysis. 391 The bromophenol 371 was obtained from Polysiphonia urceolata (Yantai, China) and characterised by spectroscopic techniques and DFT theoretical analysis.…”

Two New Bromophenols with Radical Scavenging Activity from Marine Red Alga Symphyocladia latiuscula

“…The 1 H NMR spectrum of 1 showed three multiplets assignable to a 1,3-disubstituted propane unit at δ 2.99 (2H, quartet, J = 6.6 Hz, H 2 -4), 1.60 (2H, quintet, J = 6.6 Hz, H 2 -3), and 2.28 (2H, t, J = 6.6 Hz, H 2 -2), one doublet sp 3 methylene at δ 4.51 (2H, d, H-7′) and an ester methoxyl singlet at δ 3.58 (3H, s, O CH3), and two exchangeable broad triplets assigned to amino protons at δ 5.85 (1H, brt, J = 4.8 Hz, N′-H) and 5.84 (1H, brt, J = 6.6 Hz, N–H). The 13 C NMR data for 1 revealed the carbon signals associated with the above structural units (Table 1) as well as a set of resonances for the 2,3,6-tribromo-4,5-dihydroxybenzyl unit [2,3,4,5,6,7,8] and two additional signals associated to ester carbonyl carbon at δ 173.2 (C-1) and one sp 2 -hybridized quaternary carbon at δ 157.4 (C-5). The NMR signals of protons and corresponding carbons were assigned by the 1 H– 1 H COSY and HSQC experiments (Table 1).…”

“…This red alga is a rich source of bromophenols with high chemical diversity and various biological activities. Previous chemical studies on this species have resulted in the characterization of 25 monoaryl and diaryl bromophenols with a variety of bioactivities, such as antibacterial [2,3], antifungal [4,5], free-radical-scavenging [6,7], aldose reductase inhibitory [8], antiviral [9], anticancer [10] and Taq DNA polymerase inhibitory activities [11]. During the course of our continuing search for new biologically active bromophenols from this marine red alga, by mass spectrum guided fractionation, two new bromophenols ( 1 and 2 ) with radical scavenging activity were characterized (Figure 1).…”

Anti-inflammatory effect of polyphenol-rich extract from the red alga Callophyllis japonica in lipopolysaccharide-induced RAW 264.7 macrophages

“…These algae are a source of variable bioactive components, such as polyphenols, alkaloids, and terpenes, and particularly polyphenols, which considered one of the most numerous and widely distributed chemical groups. Based on their structures, red algae are classified into different families with different contents of phenolic acids, phenylpropanoids, flavonoids, and the less-common lignans and stilbenes and have been the object of intense interest due to their various pharmacological activities such as antioxidative, α-glucosidase inhibitory, antimicrobial, aldose reductase inhibitory, antitumor, and anti-inflammatory activities (Wang et al 2005, Ma et al 2006, Lee et al 2007a, Kim et al 2008b, Li et al 2009, Xu et al 2009.…”