(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...
In the past few decades, the (1+1)-dimensional nonlinear Schrödinger (NLS) equation had been derived for envelope Rossby solitary waves in a line by employing the perturbation expansion method. But, with the development of theory, we note that the (1+1)-dimensional model cannot reflect the evolution of envelope Rossby solitary waves in a plane. In this paper, by constructing a new (2+1)-dimensional multiscale transform, we derive the (2+1)-dimensional dissipation nonlinear Schrödinger equation (DNLS) to describe envelope Rossby solitary waves under the influence of dissipation which propagate in a plane. Especially, the previous researches about envelope Rossby solitary waves were established in the zonal area and could not be applied directly to the spherical earth, while we adopt the plane polar coordinate and overcome the problem. By theoretical analyses, the conservation laws of (2+1)-dimensional envelope Rossby solitary waves as well as their variation under the influence of dissipation are studied. Finally, the one-soliton and two-soliton solutions of the (2+1)-dimensional NLS equation are obtained with the Hirota method. Based on these solutions, by virtue of the chirp concept from fiber soliton communication, the chirp effect of envelope Rossby solitary waves is discussed, and the related impact factors of the chirp effect are given.
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