Qing-Lan Guo

A minor diterpenoid with a new 6/5/7/3 fused-ring skeleton from Euphorbia micractina.

A novel diterpenoid with an unprecedented 6/5/7/3 fused-ring skeleton, euphorbactin (1), was isolated from an ethanol extract of the roots of Euphorbia micractina. The structure was determined by extensive spectroscopic studies, especially by 2D NMR and CD data analysis. A proposed biosynthetic pathway and preliminary investigations of the biological activity of compound 1 are also discussed.

C14-Polyacetylene glucosides from Codonopsis pilosula

Seven new C14-polyacetylene glucosides codonopilodiynosides A–G (1–7) were isolated from an aqueous extract of the Codonopsis pilosula roots. Their structures were determined by spectroscopic and chemical methods as (–)-(5S,6E,12E)-tetradeca-6,12-dien-8,10-diyn-1,5,14-triol 5-O-β-d-glucopyranoside (1), (–)-(5S,6E,12E)-tetradeca-6,12-dien-8,10-diyn-1,5,14-triol 5-O-β-d-glucopyranosyl-(1″ → 2′)-β-d-glucopyranoside (2), (–)-(5S,6E,12E)-tetradeca-6,12-dien-8,10-diyn-1,5,14-triol 5,14-di-O-β-d-glucopyranoside (3), (–)-(5S,6E)-tetradeca-6-en-8,10-diyn-1,5,14-triol 5-O-β-d-glucopyranoside (4), (–)-(5S,6E,12E)-tetradeca-6,12-dien-8,10-diyn-1,5-diol 5-O-β-d-glucopyranosyl-(1″ → 2′)-β-d-glucopyranoside (5), (–)-(6S,4E,12E)-tetradeca-4,12-dien-8,10-diyn-1,6-diol 6-O-β-d-glucopyranosyl-(1″ → 2′)-β-d-glucopyranoside (6), and (–)-(5S,6E)-tetradeca-6-en-1,5-epoxy-8,10-diyn-14-ol 14-O-β-d-glucopyranosyl-(1″ → 2′)-β-d-glucopyranoside (7), respectively. The absolute configurations of 1–7 were assigned by enzymatic hydrolysis followed by isolation of glucose and aglycones (1a and 4a–7a), and subsequent comparison of specific rotation, TLC, and 1H NMR data of the glucose with an authentic sugar sample and application of modified Moshers method based on the MPA determination rule of ΔδRS values for 1a and 4a, and ΔδS values for 6a. The configuration of 7 was assigned by electronic circular dichroism calculations based on the quantum-mechanical time-dependent density functional theory.

4-Hydroxybenzyl-substituted amino acid derivatives from Gastrodia elata

Seven new 4-hydroxybenzyl-substituted amino acid derivatives (1−7), together with 11 known compounds, were isolated from an aqueous extract of the rhizomes of Gastrodia elata Blume. Their structures were determined by spectroscopic and chemical methods. Compounds 1−3 are pyroglutamate derivatives containing 4-hydroxybenzyl units at the N atom and 4−7 are the first examples of natural products with the 4-hydroxybenzyl unit linked via a thioether bond to 2-hydroxy-3-mercaptopropanoic acid (4−6) and 2-hydroxy-4-mercaptobutanoic acid (7), which would be biogenetically derived from cysteine and homocysteine, respectively. The structures of 1 and 2 were verified by synthesis, while the absolute configurations of 4, 5 and 7 were assigned using Mosher’s method based on the MPA determination rule of ΔδRS values. The known compound 4-(hydroxymethyl)-5-nitrobenzene-1,2-diol (8) exhibited activity against Fe2+-cysteine induced rat liver microsomal lipid peroxidation with IC50 values of 9.99×10−6 mol/L.

Acetylenes and fatty acids from Codonopsis pilosula

Four new acetylenes (1–4) and one new unsaturated ω-hydroxy fatty acid (5), together with 5 known analogues, were isolated from an aqueous extract of Codonopsis pilosula roots. Their structures were determined by spectroscopic and chemical methods. The new acetylenes are categorized as an unusual cyclotetradecatrienynone (1), tetradecenynetriol (2), and rare octenynoic acids (3 and 4), respectively, and 3 and 4 are possibly derived from oxidative metabolic degradation of 1 and/or 2. The absolute configuration of 1 was assigned by comparison of the experimental circular dichroism (CD) spectrum with the calculated electronic circular dichroism (ECD) spectra of stereoisomers based on the quantum-mechanical time-dependent density functional theory, while the configuration of 2 was assigned by using modified Mosher׳s method based on the MPA determination rule of ΔδRS values for diols.

Sesquiterpene glycosides from the roots of Codonopsis pilosula

Three new sesquiterpene glycosides, named codonopsesquilosides A−C (1−3), were isolated from an aqueous extract of the dried roots of Codonopsis pilosula. Their structures including absolute configurations were determined by spectroscopic and chemical methods. These glycosides are categorized as C15 carotenoid (1), gymnomitrane (2), and eudesmane (3) types of sesquiterpenoids, respectively. Compound 1 is the first diglycoside of C15 carotenoids to be reported. Compound 2 represents the second reported example of gymnomitrane-type sesquiterpenoids from higher plants. The absolute configurations were supported by comparison of the experimental circular dichroism (CD) spectra with the calculated electronic CD (ECD) spectra of 1−3, their aglycones, and model compounds based on quantum-mechanical time-dependent density functional theory. The influences of the glycosyls on the calculated ECD spectra of the glycosidic sesquiterpenoids, as well as some nomenclature and descriptive problems with gymnomitrane-type sesquiterpenoids are discussed.

C14-polyacetylenol glycosides from the roots of Codonopsis pilosula.

Abstract Eight new C14-polyacetylenol glycosides, containing ene-diyne and ene-yn-ene chromophores named codonopilodiynosides H-M (1–6) and codonopiloenynenosides A and B (7 and 8), respectively, together with three known analogs lobetyolinin, pratialin B, and lobetyolin (9–11), were isolated from an aqueous extract of the roots of Codonopsis pilosula. Their structures were determined by spectroscopic and chemical methods including 2D NMR data analysis and enzymatic hydrolysis. The absolute configurations of aglycones in 1–10 were assigned by application of the methoxyphenylacetic acid (MPA) determination rule of ΔδRS values and/or the empirical rule of Mo2(OAc)4-induced circular dichroism for the vicinal diols, or by comparison of specific rotation values with those of reported compounds. Compounds 4–6 are the first polyacetylenol glycosides possessing a cis-ene-diyne chromophore from the genus Codonopsis, while 8 has a rear trans-ene-yn-cis-ene chromophore and a (6S,7S)-6,7-diol unit against a (6R,7R)-6,7-diol unit in the others. The absolute configurations of lobetyolinin (9) and pratialin B (10) were determined for the first time.

Aromatic compounds from an aqueous extract of “ban lan gen” and their antiviral activities

A pair of new diphenyl glycerol ether enantiomers (−)-1 and (+)-1 and two new methyl benzamidobenzoates 2 and 3, named (−)-(R)- and (+)-(S)-isatindigotrioic acid [(−)-1 and (+)-1] and isatindigoticamides A (2) and B (3), respectively, were isolated from an aqueous decoction of the roots of Isatis indigotica (ban lan gen). Their structures were elucidated by spectroscopic data analysis including 2D NMR experiments. The absolute configurations of (−)-1 and (+)-1 were assigned based on the CD exciton chirality method. Compounds 2 and 3 exhibited antiviral activities against HSV-1 with IC50 values of 4.87 and 25.87 μmol/L, respectively. Compound 2 was also found active against Coxsackie virus B3 and LPS-induced NO production.

Indole alkaloid sulfonic acids from an aqueous extract of Isatis indigotica roots and their antiviral activity

Six new indole alkaloid sulfonic acids (1–6), together with two analogues (7 and 8) that were previously reported as synthetic products, were isolated from an aqueous extract of the Isatis indigotica root. Their structures including the absolute configurations were determined by spectroscopic data analysis, combined with enzyme hydrolysis and comparison of experimental circular dichroism and calculated electronic circular dichroism spectra. In the preliminary assay, compounds 2 and 4 showed antiviral activity against Coxsackie virus B3 and influenza virus A/Hanfang/359/95 (H3N2), respectively.

Aconicarmisulfonine A, a Sulfonated C20-Diterpenoid Alkaloid from the Lateral Roots of Aconitum carmichaelii

A novel sulfonated C20-diterpenoid alkaloid with an unprecedented carbon skeleton and significant analgesic activity (46.7% inhibition at 0.1 mg/kg, i.p.), named aconicarmisulfonine A (1), was isolated from an aqueous extract of the lateral roots of Aconitum carmichaelii. Its structure was determined by comprehensive analysis of spectroscopic data, especially by 2D NMR spectroscopic data combined with ECD calculation and single-crystal X-ray diffraction. The plausible biosynthetic pathways of compound 1 are also discussed.

Diglycosidic indole alkaloid derivatives from an aqueous extract of Isatis indigotica roots

Abstract Six new indole alkaloid diglycosides named isatigotindolediosides A-F (1–6), along with three known analogs (7–9), were isolated from an aqueous extract of the Isatis indigotica roots (ban lan gen). Their structures including the absolute configurations were determined by comprehensive spectroscopic data analysis, combined with enzyme or acid hydrolysis, and comparison of experimental circular dichroism (CD) and calculated electronic circular dichroism (ECD) spectra. In the preliminary assays, compounds 3, 5, and 8 showed antiviral activity against Coxsackie virus B3.