- An efficient total synthesis of chrysophanol and the sennoside C aglycon
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A rapid synthetic approach to the naturally occurring chrysophanol and the sennoside C aglycon is reported. The method involves a three-step protocol starting with commercially available aloin-A to give the two title compounds.
- Kuhnert, Nikolai,Molod, Hoshiar Y.
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Read Online
- An expedient and efficient synthesis of naturally occurring hydroxy substituted anthraquinones
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A general method for the synthesis of naturally occurring anthraquinones in high yield via Diels-Alder reaction is reported.
- Khan,Blessing,Schmidt
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Read Online
- A biocatalytic approach towards the preparation of natural deoxyanthraquinones and their impact on cellular viability
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Herein, a two-step chemoenzymatic process for the synthesis of medicinally important 3-deoxygenated anthra-9,10-quinones is developed. It involves a regio- and stereoselective reduction of hydroanthraquinones to (R)-configured dihydroanthracenones using an anthrol reductase of T. islandicus, followed by oxidation and dehydration to obtain deoxyanthraquinones in 65-80% yield. Comparison of the cell viability of normal human kidney HEK293 cells between anthraquinones and their deoxy derivatives revealed less toxicity for the latter.
- Das, Kiran,De, Arijit,Husain, Syed Masood,Maity, Biswanath,Mondal, Amit,Rajput, Anshul
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supporting information
p. 3087 - 3090
(2022/02/21)
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- Synthesis of (-)-Flavoskyrins by Catalyst-Free Oxidation of (R)-Configured Dihydroanthracenones in Aqueous Media and Its (Bio)synthetic Implications
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A catalyst-free method for the synthesis of dimeric (-)-flavoskyrins has been developed. It involves the autoxidation of chemoenzymatically synthesized (R)-configured dihydroanthracenones in the presence of molecular oxygen in buffer of pH 6.0 followed by spontaneous [4 + 2] cycloaddition in stereocontrolled exo-anti fashion to form (-)-flavoskyrins. The method is applied to obtain several homo- A s well as heterodimerized flavoskyrins (nine examples) in 27-72% yield and implies the involvement of a similar pathway in the (bio)synthesis of modified bisanthraquinones and their analogues.
- Mondal, Amit,De, Arijit,Husain, Syed Masood
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p. 8511 - 8515
(2020/11/12)
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- An efficient approach for the synthesis of novel methyl sulfones in acetic acid medium and evaluation of antimicrobial activity
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A series of nine methyl sulphones (3a-3i) starting from the aldehydes (1a-1i) were synthesized in two consecutive steps. In the first step, preparation of allyl alcohols (2a-2i) from their corresponding aldehydes by the reaction of sodium borohydride in methanol at room temperature is reported. Finally, methyl sulphones are synthesized by condensing sodium methyl sulfinates with allyl alcohols in the presence of BF3.Et2O in acetic acid medium at room temperature for about 2-3 h. The reaction conditions are simple, yields are high (85%-95%), and the products were obtained with good purity. All the synthesized compounds were characterized by their 1H, 13C NMR, and mass spectral analysis. All the title compounds were screened for antimicrobial activity. Among the compounds tested, the compound 3f has inhibited both Gram positive and Gram negative bacteria effectively and compound 3i has shown potent antifungal activity. These promising components may help to develop more potent drugs in the near future for the treatment of bacterial and fungal infections.
- Bollikolla, Hari Babu,Dasireddy, Chandra Rao,Kotra, Vijay,Ravi Kumar, Gollapudi,Varala, Ravi
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p. 1386 - 1394
(2020/11/20)
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- Inducing apoptosis through upregulation of p53: structure–activity exploration of anthraquinone analogs
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We previously reported a series of p53-elevating anthraquinone compounds with considerable cytotoxicity for acute lymphoblastic leukemia (ALL) cells. To further develop this class of compounds, we examined the effect of a few key structural features on the anticancer structure–activity relationship (SAR) in ALL cells. The active analogs showed comparable cytotoxicity and upregulation of p53 but did not induce significant downregulation of MDM2 as seen with the lead compound AQ-101, indicating the importance of the anthraquinone core scaffold for MDM2 regulation. The result from the current study not only contributes to the SAR framework of these anthraquinone derivatives but also opens up new chemical space for further optimization work.
- Agbowuro, Ayodeji A.,Anifowose, Abiodun,Lu, Wen,Tan, Chalet,Tripathi, Ravi,Wang, Binghe,Yang, Xiaoxiao
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p. 1199 - 1210
(2020/06/17)
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- Chemoenzymatic, biomimetic total synthesis of (-)-rugulosin B, C and rugulin analogues and their biosynthetic implications
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Herein, we report the chemoenzymatic synthesis of a heterodimeric (-)-rugulosin B, homodimeric (-)-rugulosin C, and several rugulin analogues in three to four steps starting from anthraquinones. This work supports dimerization between variously substituted putative monomeric intermediates during the biosynthesis of naturally occurring (+)-rugulosin B and C.
- Mondal, Amit,Singh, Shailesh Kumar,Manna, Tanaya,Husain, Syed Masood
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supporting information
p. 3337 - 3340
(2020/04/02)
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- Chemoenzymatic reduction of citreorosein and its implications on aloe-emodin and rugulosin C (bio)synthesis
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A chemoenzymatic reduction of citreorosein by the NADPH-dependent polyhydroxyanthracene reductase from Cochliobolus lunatus or MdpC from Aspergillus nidulans in the presence of Na2S2O4 gave access to putative biosynthetic intermediates, (R)-3,8,9,10-tetrahydroxy-6-(hydroxymethyl)-3,4-dihydroanthracene-1(2H)-one and its oxidized form, (R)-3,4-dihydrocitreorosein. Herein, we discuss the implications of these results towards the (bio)synthesis of aloe-emodin and (+)-rugulosin C in fungi.
- Mondal, Amit,Saha, Nirmal,Rajput, Anshul,Singh, Shailesh Kumar,Roy, Brindaban,Husain, Syed Masood
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supporting information
p. 8711 - 8715
(2019/10/16)
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- PROCESS FOR THE PREPARATION OF ALOE-EMODIN
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Process for the preparation of aloe-emodin from aloin comprising oxidizing aloin by treatment with an oxygen containing gas, in an acid reaction medium, in the presence of a copper salt catalyst.
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Page/Page column 7-8
(2009/10/21)
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- PROCESS FOR PREPARING ALOE-EMODIN
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A process for preparing aloe-emodin from aloin by oxidizing aloin by treatment with an oxygen-containing gas in the presence of an acid. The aloe-emodin may be used for the production of rhein and diacerein by oxidizing aloe-emodin by treatment with a chromium-free oxidizing medium to obtain rhein and purifying the rhein obtained. The rhein may be acetylated to obtain diacerein.
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Page/Page column 16
(2008/06/13)
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- Atropo-enantioselective total synthesis of knipholone and related antiplasmodial phenylanthraquinones
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The "lactone concept" has been efficiently employed for the first atropo-enantioselective synthesis of knipholone and related natural phenylanthraquinones. Besides the regio- and stereoselective construction of the biaryl axis, another important step was the "synthetically late" introduction of the C-acetyl group, either by a Friedel-Crafts type acetylation or by an ortho-selective Fries rearrangement first tested on simplified model systems and subsequently applied to the highly atroposelective preparation of the natural products and of simplified analogs thereof for biotesting. The synthetic availability of these natural biaryls, their precursors, and their unnatural analogs permitted a broader investigation of the antiplasmodial activities of these interesting biaryls.
- Bringmann, Gerhard,Menche, Dirk,Kraus, Juergen,Muehlbacher, Joerg,Peters, Karl,Peters, Eva-Maria,Brun, Reto,Bezabih, Merhatibeb,Abegaz, Berhanu M.
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p. 5595 - 5610
(2007/10/03)
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- Intramolecular aldol-type condensation between side chains of naphthoquinones: Biomimetic synthesis of 1,6- and 1,8-dihydroxyanthraquinones
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Intramolecular condensation of 2-(acetonyl)-3-acyljuglone derivatives under basic conditions gave 1,6- and/or 1,8-dihydroxyanthraquinones depending on the conditions employed. Treatment of 6-[(3-acetyl-5-methoxy-1,4-dioxo-1,4-dihydro-2-naphthyl)methyl]-2,2- dimethyl-4H-1,3-dioxin-4-one with K2CO3 in alcohol brought about the intramolecular Knoevenagel-type reaction to give 3-hydroxy-8-methoxy-1-methyl-9,10-dioxo-9,10-dihydro-anthracene-2- carboxylates in good yields, while the same naphthoquinone gave 4-hydroxy-5-methoxy-9,10-dioxo-9,10-dihydroanthracene-2-acetic acid in good yield by treatment with potassium bis(trimethylsilyl)amide (KHMDS). Chrysophanol, aloe-emodin, aloesaponarin I, and K1115A were prepared in good yields.
- Uno, Hidemitsu,Masumoto, Akane,Honda, Erina,Nagamachi, Yumi,Yamaoka, Youtarou,Ono, Noboru
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p. 3189 - 3197
(2007/10/03)
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- First, atropo-enantioselective total synthesis of the axially chiral phenylanthraquinone natural products knipholone and 6′-O-methylknipholone
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The first stereoselective access to an axially chiral arylanthraquinone, the antimalarial natural product knipholone (3), was achieved by application of the "lactone concept". Key steps were the intramolecular coupling of the bromoester 1, to give the configurationally unstable biaryl lactone 2, and the enantioselective ring cleavage to form 3.
- Bringmann, Gerhard,Menche, Dirk
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p. 1687 - 1690
(2007/10/03)
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- Antioxidant constituents from rhubarb: Structural requirements of stilbenes for the activity and structures of two new anthraquinone glucosides
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The methanolic extracts from five kinds of rhubarb were found to show scavenging activity for DPPH radical and ·O2-. Two new anthraquinone glucosides were isolated from the rhizome of Rheum undulatum L. together with two anthraquinone glucosides, a naphthalene glucoside, and 10 stilbenes. In the screening test for radical scavenging activity of rhubarb constituents, stilbenes and a naphthalene glucoside showed activity, but anthraquinones and sennosides did not. In addition, most stilbenes inhibited lipid peroxidation of erythrocyte membrane by tert-butyl hydroperoxide. Detailed examination of the scavenging effect on various related compounds suggested the following structural requirements; 1) phenolic hydroxyl groups are essential to show the activity; 2) galloyl moiety enhances the activity; 3) glucoside moiety reduces the activity; 4) dihydrostilbene derivatives maintain the scavenging activity for the DPPH radical, but they show weak activity for ·O2-. In addition, several stilbenes with both the 3-hydroxyl and 4′-methoxyl groups inhibited xanthine oxidase.
- Matsuda, Hisashi,Morikawa, Toshio,Toguchida, Iwao,Park, Ji-Young,Harima, Shoichi,Yoshikawa, Masayuki
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- Inhibitors from rhubarb on lipopolysaccharide-induced nitric oxide production in macrophages: Structural requirements of stilbenes for the activity
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By bioassay-guided separation, three stilbenes (rhapontigenin, piceatannol, and resveratrol), two stilbene glucoside gallates (rhaponticin 2″-O-gallate and rhaponticin 6″-O-gallate), and a naphthalene glucoside (torachrysone 8-O-β-D-glucopyranoside) with inhibitory activity against nitric oxide (NO) production in lipopolysaccharide-activated macrophages were isolated (IC50=11-69μM). The oxygen functions (-OH, -OCH3) of stilbenes at the benzene ring were essential for the activity. The glucoside moiety reduced the activity, while the α,β-double bond had no effect. Furthermore, the active stilbenes (rhapontigenin, piceatannol, and resveratrol) did not inhibit inducible NO synthase activity, but they inhibited nuclear factor-κB activation following expression of iNOS. Copyright
- Kageura, Tadashi,Matsuda, Hisashi,Morikawa, Toshio,Toguchida, Iwao,Harima, Shoichi,Oda, Mamiko,Yoshikawa, Masayuki
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p. 1887 - 1893
(2007/10/03)
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- Process for the preparation of rhein and its diacyl derivatives
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The present invention regards a process for the preparation of rhein and corresponding diacyl derivatives, in particular diacerein, via oxidation of aloe-emodin and its triacyl derivatives with salts of nitrous acid, possibly followed by acylation of the rhein thus obtained.
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- Methylation and Hydroxylation Studies on Aloe-emodin
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The chemistry of aloe-emodin (3) has been explored with a view toward its use as a synthon for the regiospecific synthesis of adriamycin and analogues of it.Routes for satisfactory large-scale monomethyl ether formation at C8 (4) and regiospecific introduction of a phenolic oxygen function at C4 (21) are described.Interesting side reactions were encountered, including an apparent peri O to O acyl wandering reaction during methylation and a reductive debromination reaction during displacement of an aryl bromide by methanolic methoxide.
- Alexander, Jose,Bhatia, Ashok V.,Mitscher, Lester A.,Omoto, Shoji,Suzuki, Toshio
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