Three pairs of alkaloid enantiomers from the root of Isatis indigotica

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Five new sulfur-enriched alkaloids isatithioetherins A–E (1–5), and two pairs of scalemic enantiomers (+)- and (−)-isatithiopyrin B (6a and 6b) and isoepigoitrin and isogoitrin (7a and 7b), along with the known scalemic enantiomers epigoitrin and goitrin (8a and 8b), were isolated and characterized from an aqueous extract of the Isatis indigotica roots. Their structures were determined by extensive spectroscopic data analysis, including 2D NMR and theoretical calculations of electronic circular dichroism (ECD) spectra based on the quantum-mechanical time-dependent density functional theory (TDDFT). Compounds 1–5 represent a novel group of sulfur-enriched alkaloids, biogenetically originating from stereoselective assemblies of epigoitrin-derived units. Isolation and structure characterization of 6a and 6b support the postulated biosynthetic pathways for the diastereomers 9a and 9bvia a rare thio-Diels–Alder reaction. Compounds 2 and 4 showed antiviral activity against the influenza virus A/Hanfang/359/95 (H3N2, IC50 0.60 and 1.92 μmol/L) and the herpes simplex virus 1 (HSV-1, IC50 3.70 and 2.87 μmol/L), and 2 also inhibited Coxsackie virus B3 (IC50 0.71 μmol/L).

Section: Discussionsupporting

confidence: 59%

Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Sulfur-enriched alkaloids from the root of Isatis indigotica

Guo

Chen

et al. 2018

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“…The extraction procedures also differ from a classic protocol of utilization by decocting the medicines with water. Therefore, as part of our program to systematically study the chemical diversity of traditional Chinese medicines and their biological effects 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , an aqueous decoction of the raw lateral roots of A. carmichaelii was investigated. In previous papers, we reported four new hetisan-type, three new napeline-type, a new arcutine-type, and a novel type C 20 -diterpenoid alkaloids, twenty-six new aconitane-type C 19 -diterpenoid alkaloids including four unique glycosidic neoline derivatives with isomeric arabinosyls, two new 2-(quinonylcarboxamino)benzoates, and seven new aromatic acid derivatives, as well as solvent-/base-/acid-dependent transformation and equilibration between alcohol iminium and aza acetal forms of the napeline-type C 20 -diterpenoid alkaloids 43 , 44 , 45 , 46 , 47 , 48 , 49 .…”

Section: Introductionmentioning

confidence: 99%

C19-Diterpenoid alkaloid arabinosides from an aqueous extract of the lateral root of Aconitum carmichaelii and their analgesic activities

Guo

Xia

Meng

et al. 2018

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Eight new C19-diterpenoid alkaloid arabinosides, named aconicarmichosides E–L (1–8), were isolated from an aqueous extract of the lateral roots of Aconitum carmichaelii (Fu Zi). Their structures were determined by spectroscopic and chemical methods including 2D NMR experiments and acid hydrolysis. Compounds 1–8, together with the previously reported four neoline 14-O-arabinosides from the same plant, represent the only examples of glycosidic diterpenoid alkaloids so far. At a dose of 1.0 mg/kg (i.p.), as compared with the black control, compounds 1, 2, and 4–6 exhibited analgesic effects with >65.6% inhibitions against acetic acid-induced writhing of mice. Structure–activity relationship was also discussed.

“…Indole alkaloids are an important class of organic molecules that contain one or more indole or indoline motifs. They widely distribute as secondary metabolites in bacteria, fungi, plants and animals1., 2., 3.. Some indole alkaloids have been demonstrated to be cytotoxic ( e.g.…”

Section: Introductionmentioning

confidence: 99%

Cytotoxic and antibacterial polyketide-indole hybrids synthesized from indole-3-carbinol by Daldinia eschscholzii

Lin

Jiang

Mei

et al. 2019

Two skeletally undescribed polyketide-indole hybrids (PIHs), named indolchromins A and B, were generated from indole-3-carbinol (I3C) in the fungal culture ( Daldinia eschscholzii ). The indolchromin structures were elucidated mainly by their 1D and 2D NMR spectra with the former confirmed by the single-crystal X-ray crystallographic analysis. Each indolchromin alkaloid was chirally separated into four isomers, whose absolute configurations were assigned by comparing the recorded circular dichroism (CD) spectra with the electronic CD (ECD) curves computed for all optional stereoisomers. Furthermore, the indolchromin construction pathways in fungal culture were clarified through enzyme inhibition, precursor feeding experiment, and energy calculation. The cascade reactions, including decarboxylative Claisen condensation catalyzed by 8-amino-7-oxononanoate synthase (AONS), C( sp 3 )-H activation, double bond migration, and Michael addition, all undergone compatibly during the fungal cultivation. In an MIC range of 1.3–8.6 μmol/L, (2 S ,4 R )- and (2 R ,4 S )-indolchromin A and (2 R ,4 S )-indolchromin B are inhibitory against Clostridium perfringens , Clostridium difficile , Veillonella sp., Bacteroides fragilis , and Streptococcus pyogenes . (2 R ,4 S )-Indolchromin A and (2 S ,4 S )-indolchromin B were cytotoxic against the human breast cancer cell line MDA-MB-231 with IC 50 values of 27.9 and 131.2 nmol/L, respectively, with the former additionally active against another human breast cancer cell line MCF-7 (IC 50 94.4 nmol/L).