Phytochemical examination of the lichen, Lecanora gangaleoides Nyl

Abstract

The natural products isolated from Lecanora gangaleoides include two depsides, atranorin (1 ) and chloroatranorin (2), two depsidones, gangaleoidin (4) and leoidin ( 5 ) , and the bisanthraquinone, skyrin (6). The constitution (5) for leoidin has been established by its transformation into the diphenyl ether (15) which was also obtained from gangaleoidin (4).Six compounds, which were all believed to be natural products, were isolated when the lichen, Lecanora gangaleoides, was first investigated by Nolan during the period 1935-1943. 1-3 Three of these natural products were identified as the depsides, atranorin ( I ) and chloroatranorin (2) and the depsidone, gangaleoidin (3). In addition, three uncharacterised compounds were also isolated which included (i) a colourless compound, C,6H,1C13010, m.p:.. 231-233 "C, (ii) a red pigment, rhodophyscin, and (111) a yellow pigment, endococcin. The constitution (3) proposed by Nolan for gangaleoidin was based upon an extensive investigation l P 3 by the Dublin group. However, much later it became clear that their structural proposal (3) for gangaleoidin required careful re-examination. The studies by Sargent, Vogel, and Elix4 and our independent investigations 5.6 established that gangaleoidin had the constitution (4). Sargent, Vogel, and Elix reported the isolation from their sample of Lecanora gangaleoides of atranorin (l), chloroatranorin (2), gangaleoidin (4), and an orange metabolite, which was not characterised but was probably identical with rhodophyscin.' We were also simultaneously examining this problem 5.6 and we now report upon our phytochemical exam i na t i o n of Lecanora gangaleoides.The lichen, Lecanora gangaleoides, which was collected in North Wales, yielded six compounds which were obviously identical with the six substances previously described by Nolan.' Atranorin (I), chloroatranorin (2) and gangaleoidin (4) were easily identified. Leoidin, C, ,H 14C1207, m.p. 231-233' C , is obviously identical with the unnamed compound, m.p. 23 1-233 "C, previously isolated by Nolan 0 CHO Me Atranor in ( 1 ) X = H Chloroatranorin ( 2 ) x = c I Skyrin ( 6 ) * We thank Mr. N. Woodhead of the Department of Botany, University College of North Wales, Bangor, for his advice regarding the location of this lichen near Dyffryn Ardudwy, Merionethshire. * We thank Dr. C. A. Wachtmeister, Institutionen for organisk Kemi, Kungl. Universitet J. Stockholm, for his kind assistance in providing authentic samples of lichen metabolites. t We thank Professor S. Shibata, Meiji College of Pharmacy, Tokyo, for a sample of ( + )-skyrin.

Supramolecular isomerism in the hydrogen-bonded network of (5R,10R)-3,8-dihydroxy-5,10-diethoxy-5,10-dihydrochromeno[5,4,3-cde]chromene monohydrate

“…The reaction process might involve firstly the dimerization of the initial 3,4-dihydroxybenzaldehyde via coupling of the a-C atoms, which is known as radical coupling reaction for phenols during its oxidation with dioxygen catalyzed by some metal compounds [11]. Then the closure of two pyrone rings and the formation of the final product were formed by condensation between each pair of the hydroxyl group and the vicimal carbonyl of another benzene system, and followed by the attacking of ethanol (Scheme 1) which is similar to the reported formation of pseudoskyrin diethyl ether from skyrin [12] and the formation of 6,12-dioxaanthantrene from 1,1¢-bi-2-naphthol [13]. The molecular structure of 1 is shown in Fig.…”

Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products

“…1), binaphthalenes like (-)-gossypol (2) (2), bianthraquinones like skyrin (3) (3)(4)(5)(6)(7), and biaryls with annelated heterocyclic rings like bismurrayafoline-B (4) (8) and desertorin A (Sa) (9,10), which is-although built up from a single monomeric precursor -constitutionally unsymmetric. 1), binaphthalenes like (-)-gossypol (2) (2), bianthraquinones like skyrin (3) (3)(4)(5)(6)(7), and biaryls with annelated heterocyclic rings like bismurrayafoline-B (4) (8) and desertorin A (Sa) (9,10), which is-although built up from a single monomeric precursor -constitutionally unsymmetric.…”

“…As an example, NOE interactions of the methyl groups at C-1 and C-2' in dioncophylline A (25, see Fig. 5. 5.…”

“…15. From a whole series of Podocarpus species (Podocarpaceae), the two dimeric diterpenes podototarin (76) and macrophyllic acid (77) have 5 The compounds 74, 76. and 77 might also be considered as dimeric hydrogenated naphthalenes (sec Chapter 2.2.) What is known, though, is that only one of the possible atropo-diastereomers has been found.…”

A Novel Chlorinated Diphenyl Ether fromByrsonima microphylla(Malpighiaceae)

“…Dichlorine depsidone was obtained from the lichen, Lecanora gangaleoides, 7) and diphenyl ethers with similar structures to of that 1 had previoulsy been isolated from an Aspergillus species; 8) however, it was not possible to compare the spectroscopic data for this compound with 1 once the structure had been established by chemical transformation. Although chlorinecontaining compounds have been isolated from lichens and fungi, there are also reports on the isolation of chlorine-containing derivatives from Lilium maximowizii 9) and Sesamum indicum roots.…”