Bianthrone -glycosides. 2. Three new compounds from tubers

Absolute configurations of biantraquinones from Eremurus spectabilis BIEB

This report covers extraction, isolation, and characterisation studies on Eremurus spectabilis BIEB (Liliaceae) species. Eremurus spectabilis BIEB was extracted with hexane, chloroform, ethyl acetate, and methanol, respectively. Using chromatographic methods, two known bianthraquinones (ES3, 7,10'-bichrysophanol and ES6, chrysalodin), three known anthraquinones (ES1, chrysophanol; ES2, chrysophanol-8-methyl ether; ES4, aloe emodin) and one known steroidal compound (ES5, daucosterol) were isolated from the chloroform extract. Structures of these isolated compounds were revealed by 1D and 2D NMR and HRMS spectroscopies. Absolute configurations of ES3 and ES6 were determined by single crystal X-Ray diffraction analysis.

Bioguided Identification of Active Antimicrobial Compounds from Asphodelus bento-rainhae and Asphodelus macrocarpus Root Tubers

Root tubers of Asphodelus bento-rainhae subsp. bento-rainhae (AbR), a vulnerable endemic species, and Asphodelus macrocarpus subsp. macrocarpus (AmR) have traditionally been used in Portugal to treat inflammatory and infectious skin disorders. The present study aims to evaluate the in vitro antimicrobial activity of crude 70% and 96% hydroethanolic extracts of both medicinal plants, specifically against multidrug-resistant skin-related pathogens, to identify the involved marker secondary metabolites and also to assess the pre-clinical toxicity of these medicinal plant extracts. Bioguided fractionation of the 70% hydroethanolic extracts of both species using solvents of increasing polarity, namely diethyl ether (DEE: AbR-1, AmR-1), ethyl acetate (AbR-2, AmR-2) and aqueous (AbR-3, AmR-3) fractions, enabled the identification of the DEE fractions as the most active against all the tested Gram-positive microorganisms (MIC: 16 to 1000 µg/mL). Furthermore, phytochemical analyses using TLC and LC-UV/DAD-ESI/MS techniques revealed the presence of anthracene derivatives as the main constituents of DEE fractions, and five known compounds, namely 7'-(chrysophanol-4-yl)-chrysophanol-10'-C-beta-D-xylopyranosyl-anthrone (p), 10,7'-bichrysophanol (q), chrysophanol (r), 10-(chrysophanol-7'-yl)-10-hydroxychrysophanol-9-anthrone (s) and asphodelin (t), were identified as the main marker compounds. All these compounds showed high antimicrobial activity, particularly against Staphylococcus epidermidis (MIC: 3.2 to 100 µg/mL). Importantly, no cytotoxicity against HepG2 and HaCaT cells (up to 125 µg/mL) for crude extracts of both species and genotoxicity (up to 5000 µg/mL, with and without metabolic activation) for AbR 96% hydroethanolic extract was detected using the MTT and Ames tests, respectively. Overall, the obtained results contribute to the concrete validation of the use of these medicinal plants as potential sources of antimicrobial agents in the treatment of skin diseases.

Arylations with Nitroarenes for One-Pot Syntheses of Triaryl-methanols and Tetraarylmethanes

Triarylmethanols are well-known core structures in natural products and pharmacologically relevant compounds. In general, transition metal-based catalysts or highly reactive organometallics are employed for the synthesis of these compounds. Herein,...

Analytical Characterization of an Inulin-Type Fructooligosaccharide from Root-Tubers of Asphodelusramosus L

Plant-based systems continue to play a pivotal role in healthcare, and their use has been extensively documented. Asphodelus L. is a genus comprising various herbaceous species, known by the trivial name Asphodelus. These plants have been known since antiquity for both food and therapeutic uses, especially for treating several diseases associated with inflammatory and infectious skin disorders. Phytochemical studies revealed the presence of different constituents, mainly anthraquinones, triterpenoids, phenolic acids, and flavonoids. Although extensive literature has been published on these constituents, a paucity of information has been reported regarding the carbohydrate composition, such as fructans and fructan-like derivatives. The extraction of water-soluble neutral polysaccharides is commonly performed using water extraction, at times assisted by microwaves and ultrasounds. Herein, we reported the investigation of the alkaline extraction of root-tubers of Asphodelus ramosus L., analyzing the water-soluble polysaccharides obtained by precipitation from the alkaline extract and its subsequent purification by chromatography. A polysaccharide was isolated by alkaline extraction; the HPTLC study to determine its composition showed fructose as the main monosaccharide. FT-IR analysis showed the presence of an inulin-type structure, and NMR analyses allowed us to conclude that A. ramosus roots contain polysaccharide with an inulin-type fructooligosaccharide with a degree of polymerization of 7–8.

A Comprehensive Review on the Medicinal Plants from the Genus Asphodelus

Abstract: Plant-based systems continue to play an essential role in healthcare, and their use by different cultures has been extensively documented. Asphodelus L. (Asphodelaceae) is a genus of 18 species and of a total of 27 species, sub-species and varieties, distributed along the Mediterranean basin, and has been traditionally used for treating several diseases particularly associated with inflammatory and infectious skin disorders. The present study aimed to provide a general review of the available literature on ethnomedical, phytochemical, and biological data related to the genus Asphodelus as a potential source of new compounds with biological activity. Considering phytochemical studies, 1,8-dihydroxyanthracene derivatives, flavonoids, phenolic acids and triterpenoids were the main classes of compounds identified in roots, leaf and seeds which were correlated with their biological activities as anti-microbial, anti-fungal, anti-parasitic, cytotoxic, anti-inflammatory or antioxidant agents.

Palladium-catalysed stereoselective synthesis of 4-(diarylmethylidene)-3,4-dihydroisoquinolin-1(2H)-ones: expedient access to 4-substituted isoquinolin-1(2H)-ones and isoquinolines

Palladium-catalysed stereoselective synthesis of 4-(diarylmethylidene)-3,4-dihydroisoquinolin-1(2H)-ones and their straightforward transformations to 4-substituted isoquinolin-1(2H)-ones and isoquinolines are described.

Synthesis of triarylmethanols via tandem arylation/oxidation of diarylmethanes

A tandem arylation/oxidation of diarylmethanes for the convenient synthesis of unsymmetrical triarylmethanols bearing different aryl and heteroaryl groups is described. A Pd(OAc)2-NiXantphos catalyst system efficiently catalyzed arylation of weakly acidic sp3-hybridized C-H bonds of diarylmethanes with aryl bromides, and the arylation products were then oxidized in situ to carbinols by simply opening the reaction flasks to air. The triarylmethanol products were obtained in 35-98% yield.

Alterporriol-type dimers from the mangrove endophytic fungus, Alternaria sp. (SK11), and their MptpB inhibitions

A new alterporriol-type anthranoid dimer, alterporriol S (1), along with seven known anthraquinone derivatives, (+)-aS-alterporriol C (2), hydroxybostrycin (3), halorosellinia A (4), tetrahydrobostrycin (5), 9α-hydroxydihydrodesoxybostrycin (6), austrocortinin (7) and 6-methylquinizarin (8), were isolated from the culture broth of the mangrove fungus, Alternaria sp. (SK11), from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra. The absolute configurations of 1 and the axial configuration of 2 were defined by experimental and theoretical ECD spectroscopy. 1 was identified as the first member of alterporriols consisting of a unique C-10−C-2′ linkage. Atropisomer 2 exhibited strong inhibitory activity against Mycobacteriumtuberculosis protein tyrosine phosphatase B (MptpB) with an IC₅₀ value 8.70 μM.

Biologically Active Secondary Metabolites from Asphodelus Microcarpus

Bioassay guided fractionation of the ethanolic extract of Asphodelus microcarpus Salzm.et Vivi (Asphodelaceae) resulted in the isolation of one new metabolite, 1,6-dimethoxy-3-methyl-2-naphthoic acid (1) as well as nine known compounds: asphodelin (2), chrysophanol (3), 8-methoxychrysophanol (4), emodin (5), 2-acetyl-1,8-dimethoxy-3-methylnaphthalene (6), 10-(chrysophanol-7’-yl)-10-hydroxychrysophanol-9-anthrone (7), aloesaponol-III-8-methyl ether (8), ramosin (9) and aestivin (10). The compounds were identified by 1D and 2D NMR and HRESIMS. Compounds 3, 6 and 10 were isolated for the first time from this species. Compounds 3 and 4 showed moderate to weak antileishmanial activity with IC50 values of 14.3 and 35.1 μg/mL, respectively. Compound 4 exhibited moderate antifungal activity against Cryptococcus neoformans with an IC50 value of 15.0 μg/mL, while compounds 5, 7 and 10 showed good to potent activity against methicillin resistant Staphylococcus aureus (MRSA) with IC50 values of 6.6, 9.4 μg/mL and 1.4 μg/mL respectively. Compounds 5, 8 and 9 displayed good activity against S. aureus with IC50 values of 3.2, 7.3 and 8.5 μg/mL, respectively. Compounds 7 and 9 exhibited a potent cytotoxic activity against leukemia LH60 and K562 cell lines. Compound 10 showed potent antimalarial activities against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum with IC50 values in the range of 0.8-0.7 μg/mL without showing any cytotoxicity to mammalian cells.

Antimalarial compounds fromKniphofia foliosa roots

During the course of screening Ethiopian medicinal plants for their antimalarial properties, it was found that the dichloromethane extract of the roots of Kniphofia foliosa Hochst. (Asphodelaceae), which have long been used in the traditional medicine of Ethiopia for the treatment of abdominal cramps and wound healing, displayed strong in vitro antiplasmodial activity against the chloroquine-sensitive 3D7 strain of Plasmodium falciparum with an ED50 value of 3.8 microg/mL and weak cytotoxic activity against KB cells with an ED50 value of 35.2 microg/mL. Five compounds were isolated from the roots and evaluated for their in vitro antimalarial activity. Among the compounds tested, 10-(chrysophanol-7'-yl)-10-(xi)-hydroxychrysopanol-9-anthrone and chryslandicin, showed a high inhibition of the growth of the malaria parasite, P. falciparum with ED50 values of 0.260 and 0.537 microg/mL, respectively, while the naphthalene derivative, 2-acetyl-1-hydroxy-8-methoxy-3-methylnaphthalene, exhibited a less significant antimalarial activity with an ED50 value of 15.4 microg/mL. To compare the effect on the parasite with toxicity to mammalian cells, the cytotoxic activities of the isolated compounds against the KB cell line were evaluated and 10-(chrysophanol-7'-yl)-10-(xi)-hydroxychrysopanol-9-anthrone and chryslandicin displayed very low toxicity with ED50 values of 104 and 90 microg/mL, respectively. This is the first report of the inhibition of the growth of P. falciparum by anthraquinone-anthrone dimers and establishes them as a new class of potential antimalarial compounds with very little host cell toxicity.

Constituents of Eremurus chinensis

A novel bianthraquinone glycoside, 8-O-beta-D-glucopyranosyl-1,1', 8'-trihydroxy-3,3'-dimethyl-2,7'-bianthraquinone (1); two naphthalene derivatives, 2-acetyl-1-hydroxy-8-methoxy-3-methylnaphthalene (2) and 2-acetyl-1, 8-dimethoxy-3-methylnaphthalene (3); and a novel pre-anthraquinone, 1-oxo-4(S),9-dihydroxy-8-methoxy-6-hydroxymethyl-1,2,3, 4-tetrahydroanthracene (4), were isolated from Eremurus chinensis. Their structures were established by spectroscopic and chemical methods. In addition, the known compounds chrysophanol, chrysophanol 8-methyl ether, aloesaponol III 8-methyl ether (5), and 10-(chrysophanol-7'-yl)-10-hydroxychrysophanol-9-anthrone were also isolated and identified from this plant.

Fusapyrone and deoxyfusapyrone, two antifungal alpha-pyrones from Fusarium semitectum

A strain of Fusarium semitectum Berk. & Rav. from maize stalk rot in southern Italy produced bioactive metabolites when cultured on autoclaved rice kernels at room temperature for 4 weeks. The organic extracts of fungal culture showed a strong antibiotic activity towards Geotrichum candidum in disk diffusion assays, but they were not toxic to Artemia salina larvae. Two antifungal metabolites were isolated and characterized by chemical and spectroscopic methods as two 3-substituted-4-hydroxy-6-alkyl-2-pyrones, in particular, the 3-(4-deoxy-beta-xylo-hexopyranosyl)-4-hydroxy-6-[2-hydroxy-7-hydroxymeth yl- 1,1,5,9,11-pentamethyl-3,5,8-heptadecatrienyl]-2H-pyran-2-one and its 6-[2-hydroxy-1,1,5,7,9,11-hexamethyl] analog, which were named fusapyrone and deoxyfusapyrone, respectively.