Dibenzyl Bromophenols with Diverse Dimerization Patterns from the Brown Alga Leathesia nana

Abstract

Six novel dibenzyl bromophenols (1-6) with different dimerization patterns and two propyl bromophenol derivatives (7 and 8), together with 11 known bromophenol derivatives, were isolated from the ethanolic extract of the brown alga Leathesia nana. On the basis of spectroscopic methods the structures of the new compounds were determined as 5,6'-diethyloxymethyl-3,4,2'-tribromo-2,3',4'-trihydroxydiphenyl ether (1), 2-(2,3-dibromo-4,5-dihydroxybenzyl)-3,5-dihydroxy-4-methoxybenzyl alcohol (2), 6-(2,3-dibromo-4,5-dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (3), 9,10-dihydro-9,10-dimethoxy-3,4,7,8-tetrabromo-1,2,5,6-tetrahydroxyanthracene (4), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (5), rel-(4aS,10aR)-(+/-)-6,7-dibromo-4a-hydroxy-3,8-dihydroxymethyl-10a-methoxy-1,4,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxin-1-one (6), (E)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propenal (7), and 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)-1-propanol (8). Some compounds including 3 showed in vitro selective cytotoxicity against several human cancer cell lines. This is the first brown alga to be reported containing bromophenols.

Synthesis and carbonic anhydrase inhibitory properties of novel bromophenols including natural products

“…Halis Türker Balaydın 1,2 , Hakan Soyut 1,3 , Deniz Ekinci 4 , Süleyman Göksu 1 , Şükrü Beydemir localization, catalytic activity and susceptibility to different classes of inhibitors. Some of these isozymes are cytosolic (CA I, CA II, CA III, CA VII and CA XIII), others are membrane-bound (CA IV, CA IX, CA XII and CA XIV), two are mitochondrial (CA VA and CA VB), and one is secreted in saliva (CA VI).…”

“…The organic phase was separated and the water phase was extracted with EtOAc (2 × 30 mL). The combined organic phases were dried over Na 2 SO 4 …”

“…Of these natural compounds, 5,5′-methylenebis(3,4-dibromobenzene-1,2-diol) (1) and 3,4-dibromo-5-(2-bromo-3,4-dihydroxy-6-(methoxymethyl)benzyl)benzene-1,2-diol (2) exhibit enzyme inhibition, e.g. isocitrate lyase 3 cytotoxicity 4 , feeding deterrent 5 , and microbial 6,7 activities, while 3,4,6-tribromo-5-(2,5-dibromo-3,4-dihydroxybenzyl) benzene-1,2-diol (3) and 5,5′-methylenebis(3,4,6-tribromo-benzene-1,2-diol) (4) exhibit significant aldose reductase inhibitory activity 8 . Additionally, it was reported that bromophenol 1 is an inhibitor of protein tyrosine phosphatase 9 .…”

Synthesis and paroxonase activities of novel bromophenols

“…These compounds have attracted much attention in the field of functional food and pharmaceutical agents 2 . It has been reported that naturally occurring bromophenol 1 shows enzyme inhibition 3 , cytotoxicity 4 , feeding deterrent 5 , anti-microbial 6 , anti-cancer 7 and anti-oxidant 8 activities. Aldose reductase 9 and carbonic anhydrase 10 inhibitory properties of natural products 2-3 have also been noted ( Figure 1).…”

Gold-Catalyzed Benzylic Azidation of Phthalans and Isochromans and Subsequent FeCl₃-Catalyzed Nucleophilic Substitutions

“…[9][10][11][12][13] We have continuously investigated the iron [14][15][16][17][18][19][20] -or gold [21][22][23] -catalyzed activation at the benzylic position of various skeletons accompanied by the benzylic C-O bond cleavage. During these investigations, the benzylic position of phthalan (1; n=1) as a benzene fused cyclic ether was found to be directly azidated in the presence of a gold catalyst and trimethylsilylazide (TMSN 3 ) without the C-O bond cleavage to give the 1-azido phthalan (2) (Chart 1). The direct azidations at the benzylic position of phthalan and isochroman (1; n=2) were previously accomplished using stoichiometric iodine reagents [9][10][11] in the presence of azido sources, such as TMSN 3 and NaN 3 .…”