Constituents of Roots of Rubia Lanceolata Hayata

A naphthohydroquinone and eight anthraquinones were isolated from the roots of Rubia lanceolata Hayata. Their structures were assigned as mollugin ( 1 ), l-hydroxy-2-methyl-9,10-anthraquinone ( 2 ), 2-methylquinizarin ( 3 ), 3-carbomethoxy-l-hydroxy-9,10-anthraquinone ( 4 ), lucidin ethyl ether ( 5 ), rubiadin ( 6 ), alizarin ( 7 ), ω-hydroxypachybasin ( 8 ) and digiferruginol ( 9 ) on the basis of spectral evidence. Among them, compounds 8 and 9 were isolated for the first time from Rubia species.     

Simultaneous Isolation and Purification of Mollugin and Two Anthraquinones from Rubia cordifolia by HSCCC

A preparative high-speed countercurrent chromatography (HSCCC) method for isolation and purification of three bioactive components, tectoquinone; 1-hydroxy-2-methylanthraquinone and mollugin from the Chinese medicinal plant Rubia cordifolia was successfully established. With a two-phase solvent system composed of light petroleum/ethanol/diethyl ether/water (5:4:3:1, v/v), 10 mg tectoquinone, 19 mg 1-hydroxy-2-methylanthraquinone and 16 mg mollugin were obtained from 100 mg of the crude petroleum extract in a one-step separation at a purity of 98.8, 95.8 and 98.3%, respectively. The structures of mollugin and anthraquinones were identified by ¹H NMR and ¹³C NMR.     

Anthraquinones from the Aerial Parts of Rubia cordifolia with Their NO Inhibitory and Antibacterial Activities

The present study aimed to identify the composition of the aerial parts of Rubia cordifolia L. A chemical investigation on the EtOAc extracts from the aerial parts of Rubia cordifolia resulted in the isolation of four new anthraquinones, namely Cordifoquinone A–D (1–4), along with 16 known anthraquinones. Their structures were elucidated on the basis of NMR and HR-ESIMS data. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1, 3 and 10 exhibited significant inhibitory activities with IC₅₀ values of 14.05, 23.48 and 29.23 μmol·L⁻¹, respectively. Their antibacterial activities of four bacteria, Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 29213), Salmonella enterica subsp. enterica (ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853), were also evaluated. Our results indicated that the antibacterial activity of these compounds is inactive.     

Four New Anthraquinones with Histone Deacetylase Inhibitory Activity from Ventilago denticulata Roots

Chromatographic separation of the crude extracts from the roots of Ventilago denticulata led to the isolation of four new anthraquinones, ventilanones L–O (1–4), together with eight known anthraquinones (5–12). Their structures were elucidated by spectroscopic methods (UV, IR, ¹H NMR, ¹³C NMR, and 2D NMR) and mass spectrometry (MS), as well as comparison of their spectroscopic data with those reported in the literature. HDACs inhibitory activity evaluation resulted that compound 2 exhibited moderate antiproliferative activity against HeLa and A549 cell lines but nontoxic to normal cell. Molecular docking indicated the phenolic functionality of 2 plays crucial interactions with class II HDAC4 enzyme.     

Anthraquinones tautomerism: VII. Hydroxy-substituted anthraquinones

Tautomerism of β-mono-, β,β′-dihydroxyanthraquinones, and their anions was studied for the first time by quantum-chemical and correlation methods. 2-Hydroxyanthraquinone exists exclusively in 9,10-quinoid form, and its ionization involves a tautomeric transformation into 10-oxido-2,9-anthraquinone. β,β′-Dihydroxyanthraquinones can exist as the corresponding 9,10-, 2,9-, 2,6-, and 2,3-quinoid tautomers, and the most characteristic forms of their anions are 2,9-quinoid structures. The considerable difference in the known spectra of the same compound is due to the shifts of the tautomeric equilibria.     

Anthraquinones of the lichenAsahinea chrysantha

From a hexane extract of the dry lichen we have isolated six anthraquinones: chrysophanol (I), islandicin (II), cynodontin (III), emodin (IV), a tetrahydroxymethylanthraquinone (V), and a pentahydroxymethylanthraquinone (VI). The structures of (I) and (IV) were confirmed by direct comparison with authentic samples. The structures of (II) and (III) were established by the aid of UV, IR, PMR, and mass spectra. Pigments (V) and (VI) were isolated from a carbonate extract. Pigment (V): mp > 320°C; UV spectrum (nm) 258, 283, 310, 447, 500, 533; mass spectrum: 286 (M⁺ 100%), 270, 258, 257, 241, 229, 216, 213, 212, 211, 201, 161, 155, 137, 115, 105, 97. Pigment (VI): mp 315°C; UV spectrum (nm): 247, 261, 302, 500, 540, 565, 578; IR spectrum (cm^–1): 1587, 3492; mass spectrum: 302 (M⁺, 100%), 286, 274, 245, 228, and the metastable ions 248.6, 219.1, and 192.5. The positions of the -hydroxyls in the molecules of (V) and (VI) have not been definitively established.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 160–165, March–April, 1980.     

Anthraquinones tautomerism: VI. Substituted 1,4,5-trihydroxyanthraquinones

1,4,5-Trihydroxy-9,10-anthraquinone and its substituted derivatives exist in equilibrium of structures distinguished by quinoid tautomerism and rotational isomerism. Their electron absorption spectra contain π₁, π*-bands corresponding to 9,10-and 1,10-, more seldom to 1,5-and 1,4-anthraquinoid structures. Of three isomeric 1,10-anthraquinones only 4,8,9-trihydroxy-1,10-antraquinones were found. All tautomer may exist as conformers with contiguous CO and OH groups not bound by an intramolecular hydrogen bond. The considerable difference in color of structurally similar substituted compounds is due to tautomerism and conformer transformations.     

Tautomerism in Athraquinones: II. α-Hydroxy-substituted Anthraquinones

The fine structure of experimental π_l,π*-absorption bands of the α hydroxyanthraquinones originates from the prototropic anthraquinoid tautomerism. The tautomeric transformations occur both in the ground and excited states of the molecules; therewith the excited states are more sensitive to the tautomerization than the ground ones. The wavelength and intensity of the π_l,π*-bands, the values of all quantum-chemical characteristics studied for the tautomers of α hydroxyanthraquinones are linearly related to the number of hydroxy groups. The effect of the isomerism of di- and trihydroxyanthraquinones on this relationship was considered.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 722–729.Original Russian Text Copyright © 2005 by Fain, Zaitsev, Ryabov.     

The mutagenic constituents of Rubia tinctorum.

Twenty compounds were isolated from the roots of Rubia tinctorum which are used as a commercial source of madder color. Among these compounds, mollugin (1), 1-hydroxy-2-methylanthraquinone (2), 2-ethoxymethylanthraquinone(11), rubiadin (13), 1,3-dihydroxyanthraqunone (14), 7-hydroxy-2-methylanthraquinone (16), lucidin (17), 1-methoxymethylanthraquinone (18) and lucidin-3-O-primeveroside (19) showed mutagenicity with Salmonella typhimurium TA 100 and/or TA 98. Since the mutagenic compounds isolated are anthraquinone derivatives with the exception of compound 1, structure-mutagenicity relationships of the anthraquinones were also studied. The results suggested that the greatest activity is exhibited by 1,3-dihydroxyanthraquinones possessing methyl or hydroxylmethyl group on carbon 2.     

Constituents of the roots of Rubia yunnanensis

Four new naphthohydroquinones, rubinaphthins A (1), B (2), C (3), and D (4), together with 11 known compounds were isolated and characterized from the roots of Rubia yunnanensis. The structures of 1-4 were elucidated by spectral analysis and chemical transformation.