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.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 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.Download high-res image (254KB)Download full-size image

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.A pair of unusual new diphenyl glycerol ether enantiomers (−)-(S)-1 and (+)-(R)-1 and two new methyl benzamidobenzoates 2 and 3 were isolated from Chinese traditional herbal medicine “ban lan gen” (Isatis indigotica roots). The enantiomers were separated by HPLC on a chiral column. Compound 2 showed activities against replication of HSV-1 and Coxsackie virus B3 and against the LPS-induced NO production in mouse peritoneal macrophage. Compound 3 was active against HSV-1. These results, together with previous studies, demonstrate that the diverse chemical constituents with varied activities contribute to pharmacological efficacy that supports the traditional application of this herbal medicine.Download high-res image (122KB)Download full-size image

Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A−F (1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of ΔδC8-C7 values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones (1a–6a) are discussed.Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A–F (1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of ΔδC8-C7 values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones (1a–6a) are discussed.Download high-res image (319KB)Download full-size image

Four structurally unprecedented aconitane-type C19-diterpenoid alkaloid glycosides with isomeric arabinosyls, named aconicarmichosides A–D (1–4), were isolated from an aqueous extract of “fu zi”, the lateral roots of Aconitum carmichaelii. Their structures were determined as neoline 14-O-α- and 14-O-β-l-arabinopyranosides (1 and 2) and 14-O-α- and 14-O-β-l-arabinofuranosides (3 and 4), by spectroscopic and chemical methods including 2D NMR experiments and acid hydrolysis. Compounds 1–4 represent the first examples of glycosidic diterpenoid alkaloids.Four structurally unprecedented aconitane-type C19-diterpenoid alkaloid glycosides with isomeric arabinosyls, named aconicarmichosides A–D (1–4), were isolated from an aqueous extract of “fu zi”, the lateral roots of Aconitum carmichaelii. Their structures were elucidated by spectroscopic and chemical methods, including 2D NMR experiments and acid hydrolysis. Compounds 1–4 represent the first examples of glycosidic aconitane diterpenoid alkaloids.Download high-res image (142KB)Download full-size image

Gastradefurphenol (1), a minor 9,9′-neolignan with a novel carbon skeleton substituted by two p-hydroxybenzyls was isolated from an aqueous extract of the Gastrodia elata rhizomes (tian ma). Its structure was determined by extensive spectroscopic data analysis. Solvent-dependent free rotational restriction of bonds and equilibrium of two molecular states are discussed by comparison of the NMR spectroscopic data of 1 in acetone-d6 with those in CD3OD. A biogenetic pathway of 1 is postulated to be associated with metabolic processes of l-tyrosine.Download high-res image (130KB)Download full-size imageA minor 9,9′-neolignan with a novel carbon skeleton substituted by two p-hydroxybenzyls, named gastradefurphenol, was isolated from an aqueous extract of the Gastrodia elata rhizomes (tian ma). Solvent-dependent free rotational restriction of bonds and equilibrium of two molecular states are discussed by comparison of the NMR spectroscopic data of 1 in acetone-d6 with those in CD3OD. A plausible biosynthetic pathway of 1 is postulated to be associated with metabolic processes of l-tyrosine.

A rare arcutine-type C20-diterpenoid alkaloid, named aconicarmicharcutinium A and obtained as hydroxide (1) and trifluoroacetate (1a), was characterized as a minor constituent of “fu zi” (the lateral roots of Aconitum carmichaelii). The structures of 1 and 1a were elucidated by comprehensive analysis of spectroscopic data including 19F and 2D NMR experiments. Compounds 1 and 1a represent the first examples of the arcutine-type C20-diterpenoid alkaloid iminium.Download high-res image (92KB)Download full-size imageA rare arcutine-type C20-diterpenoid alkaloid was characterized as a minor constituent of “fu zi” (the lateral roots of Aconitum carmichaelii). The C20-diterpenoid alkaloid is an iminium named aconicarmicharcutinium A and obtained as hydroxide (1) and trifluoroacetate (1a) forms. Structures of 1 and 1a were elucidated by comprehensive analysis of spectroscopic data including 19F and 2D NMR experiments. Compounds 1 and 1a represent the first examples of the arcutine-type C20-diterpenoid alkaloid iminium.

Three new napelline-type C20-diterpenoid alkaloids, named aconicarmichinium A and B trifluoroacetates (1 and 2) and aconicarmichinium C chloride (3), were isolated from an aqueous extract of “fu zi”, the lateral roots of Aconitum carmichaelii. Their structures were elucidated by extensive spectroscopic data analysis. Compounds 1–3 represent the first examples of napelline-type C20-diterpenoid alkaloid alcohol iminiums, of which the structures were fully characterized. In addition, transformation and equilibration between the alcohol iminiums (1–3) and the aza acetals 1a–3a were investigated by measurements of the NMR spectra in protic and aprotic deuterium solvents including alkali pyridine-d5, along with evaporation under reduced pressure and gradual additions of TFA, AcOH, and HCl. The results demonstrated that the transformation and equilibration were solvent-, base-, and acid-dependent. Especially, in aqueous biological fluid, these C20-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions. The absolute configurations of 1–3 were confirmed by X-ray crystallographic analysis of 2a.Three napelline-type C20-diterpenoid alkaloid alcohol iminiums, named aconicarmichinium A and B trifluoroacetates (1 and 2) and aconicarmichinium C chloride (3), were isolated from an aqueous extract of “fu zi”, the lateral roots of Aconitum carmichaelii. Their structures were elucidated by extensive spectroscopic analysis. Solvent-, base-, and acid-dependent transformation and equilibration between the alcohol iminiums (1–3) and corresponding aza acetals 1a–3a were found. The absolute configurations of 1–3 were confirmed by X-ray crystallographic analysis of 2a.Download full-size image

A neolignan codonopiloneolignanin A (1) with a novel 2,9:2ʹ,9:7,7ʹ-tricyclo-8,9ʹ-neolignane skeleton was isolated from an aqueous extract of the Codonopsis pilosula roots. Its structure including the absolute configuration was elucidated by extensive spectroscopic analysis, including 2D NMR and electronic circular dichroism calculation. The proposed biosynthetic pathway of compound 1 is also discussed.Codonopiloneolignanin A (1), a neolignan with a novel 2,9:2ʹ,9:7,7ʹ-tricyclo-8,9ʹ-neolignane skeleton was isolated from an aqueous extract of the Codonopsis pilosula roots. Its structure including the absolute configuration was elucidated by extensive spectroscopic analysis, including 2D NMR and electronic circular dichroism calculation. The biosynthetic pathway of compound 1 is proposed.

Gastrolatathioneine (1), an unusual natural product derived from ergothioneine, a fungal amino acid containing an imidazole-2-thione moiety, was isolated from an aqueous extract of “tian ma” (the Gastrodia elata rhizomes). The structure of 1 including the absolute configuration was determined by extensive spectroscopic data analysis, combined with comparison of an experimental circular dichroism spectrum and calculated electronic circular dichroism spectra of stereoisomers, and confirmed by X-ray crystallography. The natural origin of 1 was proved by HPLC-ESIMS analysis of the crude extract. A biogenetic pathway of 1 is proposed on the basis of metabolic post-modification of ergothioneine that is biosynthesized by a symbiotic fungus. The plant and symbiotic fungus are co-producers of 1.An unusual natural product N,N-bis(4-hydroxybenzyl)ergothioneine, named gastrolatathioneine (1), was isolated from an aqueous extract of “tian ma”, the Gastrodia elata rhizomes. Its structure was elucidated by extensive spectroscopic data analysis and confirmed by X-ray crystallography. The natural origin of 1 was proved by HPLC-ESIMS analysis of the crude extract. A biosynthetic pathway of 1 is discussed on the basis of metabolic post-modification of ergothioneine from the symbiotic fungus.

Four stereoisomers of 3,5-bis(2-hydroxybut-3-en-1-yl)-1,2,4-thiadiazole, named insatindigothiadiazoles A–D (1a–1d), were isolated from the roots of Isatis indigotica. Their structures were determined by spectroscopic analysis; specifically, the absolute configurations were assigned by using the MPA determination rule based on ΔδRS values of MPA esters, and supported by electronic CD (ECD) calculations. Proposed biosynthetic pathways and preliminary investigations of the biological activities of 1a–1d against influenza virus A (H3N2), Coxsackie virus B3, and/or HSV-1 are also discussed.Four stereoisomers of 3,5-bis(2-hydroxybut-3-en-1-yl)-1,2,4-thiadiazole (1a–1d) were isolated from the roots of Isatis indigotica. Their structures including absolute configurations were determined by spectroscopic analysis combined with application of the MPA determination rule based on ΔδRS values of MPA esters. Postulated biosynthetic pathways of 1a–1d were discussed. The four stereoisomers exhibited selective antiviral activities against influenza virus A (H3N2), Coxsackie virus B3, and/or HSV-1, while selectivity was highly dependent upon the configurations.

Elucidation of the mechanism of action for drug candidates is fundamental to drug development, and it is strongly facilitated by metabolomics. Herein, we developed an imaging metabolomics method based on air-flow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) under ambient conditions. This method was subsequently applied to simultaneously profile a novel anti-insomnia drug candidate, N6-(4-hydroxybenzyl)-adenosine (NHBA), and various endogenous metabolites in rat whole-body tissue sections after the administration of NHBA. The principal component analysis (PCA) represented by an intuitive color-coding scheme based on hyperspectral imaging revealed in situ molecular profiling alterations in response to stimulation of NHBA, which are in a very low intensity and hidden in massive interferential peaks. We found that the abundance of six endogenous metabolites changed after drug administration. The spatiotemporal distribution indicated that five altered molecules—including neurotransmitter γ-aminobutyric acid, neurotransmitter precursors choline and glycerophosphocholine, energy metabolism-related molecules adenosine (an endogenous sleep factor), and creatine—are closely associated with insomnia or other neurological disorders. These findings not only provide insights into a deep understanding on the mechanism of action of NHBA, but also demonstrate that the AFADESI-MSI-based imaging metabolomics is a powerful technique to investigate the molecular mechanism of drug action, especially for drug candidates with multitarget or undefined target in the preclinical study stage.

Two new 1-(6′-O-acyl-β-d-glucopyranosyl)pyridinium-3-carboxylates, lonijaponinicotinosides A (1) and B (2), were isolated from an aqueous extract of the flower buds of Lonicera japonica. Their structures were determined by spectroscopic data analysis, and confirmed by comparison with synthetic 1-β-d-glucopyranosylpyridinium-3-carboxylate.Two new 1-(6′-O-acyl-β-d-glucopyranosyl)pyridinium-3-carboxylates, named lonijaponicotinosides A (1) and B (2), were isolated and characterized from an aqueous extract of the flower buds of Lonicera japonica.

A pair of indole alkaloid enantiomers with a novel bisindolylacetamide skeleton, insatindibisindolamides A and B (1a and 1b), was isolated from an aqueous extract of Isatis indigotica roots. The enantiomers were separated by chiral HPLC. Their structures and absolute configurations were elucidated by extensive spectroscopic analysis, including 2D NMR, X-ray crystallography, and electronic CD (ECD) calculation. The proposed biosynthetic pathway and preliminary investigations of the biological activity of compounds 1a and 1b are also discussed.A pair of indole alkaloid enantiomers having a novel bisindolylacetamide skeleton, insatindibisindolamides A and B (1a and 1b), was isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by extensive spectroscopic analysis, especially 2D NMR, X-ray crystallography, and electronic CD (ECD) calculation. The proposed biosynthetic pathway and preliminary investigations of the biological activity of compounds 1a and 1b are also discussed.

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.

Two new β-hydroxy amino acid-coupled secoiridoids, named serinosecologanin (1) and threoninosecologanin (2), were isolated from an aqueous extract of the flower buds of Lonicera japonica. Their uncommon structures including absolute configurations were determined by spectroscopic data analysis, and confirmed by semisynthesis from the co-occurring secologanin (3) and secologanic acid (4). Compounds 1 and 2 exhibited resistant activity against β-glucosidase from almonds and hesperidinase from Aspergillus niger, they also showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by the platelet-activating factor with inhibition rates of (34.9 ± 3.1)% and (53.6 ± 2.6)%, respectively.

A minor diterpenoid with a novel carbon skeleton, secoeuphoractin (1), was isolated from an ethanol extract of the roots of Euphorbia micractina. Its structure including the absolute configuration was determined by extensive spectroscopic studies, especially by 2D NMR and CD data analysis, in combination with a plausible biosynthetic pathway associated with co-occurring diverse diterpenoids. This compound showed activity against HIV-1 replication with an IC50 value of 1.76 ± 0.61 μmol/L.A minor diterpenoid with a novel carbon skeleton, named secoeuphoractin, was isolated from an ethanol extract of the roots of Euphorbia micractina.

Twelve new minor diterpenoids, possessing 5/6/8 (1 and 2), 5/6/7/3 (3–9), and 5/6/6/4 (10–12) fused-ring skeletons, as determined by spectroscopic analysis, were isolated from an ethanol extract of the roots of Euphorbia micractina, together with 25 known compounds. The structures of the diterpene skeletons are rare and have been found only in compounds isolated from Euphorbia micractina and Euphorbia villosa. On the basis of the octant rule for cyclohexanones, the absolute configurations of 1–12, as well as of the known euphactins A–D and euphoractins A–D (13–15), could be assigned by circular dichroism spectroscopy. In addition, the co-occurring jolkinol B (16) was chemically transformed to euphoractin E (17), supporting the absolute configuration assignment and the biogenetic relationship between the different types of diterpenes. Compound 9 showed activity against HIV-1 replication in vitro, with an IC50 value of 8.8 ± 0.6 μM.

Nine new homosecoiridoid alkaloids, named lonijaposides O–W (1–9), along with 19 known compounds, were isolated from an aqueous extract of the flower buds of Lonicera japonica. Their structures and absolute configurations were determined by spectroscopic data analysis and chemical methods. Lonijaposides O–W have structural features that involve amino acid units sharing the N atom with a pyridinium (1–5) or nicotinic acid (6–9) moiety. The absolute configurations of the amino acid units were determined by oxidation of each pyridinium ring moiety with potassium ferricyanide, hydrolysis of the oxidation product, and Marfey’s analysis of the hydrolysate. This procedure was validated by oxidizing and hydrolyzing synthetic model compounds. The phenylalanine units in compounds 4, 5, and 9 have the d-configuration, and the other amino acid units in 1–3 and 6–8 possess the l-configuration. Compounds 1, 4, 6, and 9 and the known compounds 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 5′-O-methyladenosine exhibited antiviral activity against the influenza virus A/Hanfang/359/95 (H3N2) with IC50 values of 3.4–11.6 μM, and 4 inhibited Coxsackie virus B3 replication with an IC50 value of 12.3 μM.

A pair of enantiomers (1a and 1b) of an indole alkaloid containing dihydrothiopyran and 1,2,4-thiadiazole rings was isolated from an aqueous extract of the root of Isatis indigotica. The structures and absolute configurations of the enantiomers were determined by extensive spectroscopic analysis, especially 2D NMR, modified Mosher’s method, and electronic CD (ECD). The proposed biosynthetic pathway and preliminary investigations of the biological activity of compounds 1a and 1b against influenza virus A/Hanfang/359/95 (H3N2) and HSV-1 are also discussed.

Two novel tricyclic spirolactones bearing long linear alkyl chains, yaoshanenolides A (1) and B (2), formed by Diels–Alder[4 + 2] cycloaddition of a molecule of each butenolide with β-phellandrene, were isolated from the bark of Machilus yaoshansis. Their structures and absolute configurations were determined by extensive spectroscopic methods, especially 2D NMR and ECD data analysis. The proposed biosynthetic pathway is discussed. Both compounds exhibited nonselective cytotoxic activities against several human cancer cell lines.

Nine new dammarane triterpene glycosides (1–3 and 8–13) and 12 known analogues have been isolated from an ethanol extract of the roots of Machilus yaoshansis. Compounds 1–7 have an uncommon 20,23-dihydroxydammar-24-en-21-oic acid-21,23-lactone moiety that was previously reported in compounds isolated from Gynostemma pentaphyllum. The configurations of the lactone moieties in 1–3 were determined by comparison of the experimental ECD spectra of 1–3 and the hydrolysates, 1a and 1b, with the corresponding calculated ECD spectra. On the basis of NMR and ECD data analysis of 1–7, the previously reported C-20 and C-23 configurations of 4–7 and related derivatives from Gynostemma pentaphyllum were revised. In addition, the application of NMR data and Cotton effects to the determination of the relative and absolute configurations of the γ-lactone moiety in 3β,20,23-trihydroxydammar-24-en-21-oic acid-21,23-lactone derivatives is discussed.

Seventeen new alkaloids (1–17) and 14 known analogues have been isolated from an aqueous extract of the root of Isatis indigotica. The structures and absolute configurations of these compounds were determined by extensive spectroscopic data analysis, including 2D NMR, single-crystal X-ray crystallography using anomalous scattering of Cu Kα radiation, and electronic circular dichroism spectra calculations based on the quantum-mechanical time-dependent density functional theory. Compounds 1, 2, and 3 are the first examples of natural products with unique linkages between a molecule of 2-(4-methoxy-1H-indol-3-yl)acetonitrile and 2-(1H-indol-3-yl)acetonitrile, 2-(4-methoxy-1H-indol-3-yl)acetonitrile, and 4-hydroxyphenylethane, respectively. Compounds (−)-4 and (+)-4 represent the first natural products with the pyrrolo[2,3-b]indolo[5,5a,6-b,a]quinazoline skeleton. Some structural assignments for the new alkaloids suggest that the assignments made for certain previously reported alkaloids require revision. Compounds 1–3 and arvelexin (18) show antiviral activity against the influenza virus A/Hanfang/359/95 (H3N2), with IC50 values of 3.70–12.35 μM, and 17 inhibits Coxsackie virus B3 replication with an IC50 of 6.87 μM.

Five triterpenoids with a new 25-norfern carbon skeleton (1–5), a lupane triterpenoid (6), and four 20-hydroxyprogesterone acyl esters (7–10), together with 23 known compounds, were isolated from the stem (with skin removed) of Sinocalamus affinis. The absolute configuration of compound 1 was confirmed by single-crystal X-ray crystallographic analysis using anomalous scattering of Cu Kα radiation. Compounds 1–5 exhibited inhibitory activity against protein tyrosine phosphatase 1B.

Twenty-six new diterpenoid alkaloids, 1–26 (1–4: hetisan-type C20-diterpenoid alkaloids; 5–26: aconitane C19-diterpenoid alkaloids), and two known analogues, hypaconitine 27 and benzoylmesaconine 28, have been isolated from a water extract of the lateral root of Aconitum carmichaelii. Compounds 7 and 8 are rare examples of conformational isomers obtained from the same material. The conformation and conformational transformation of ring A in the C19-diterpenoid alkaloids are discussed on the basis of NMR data analysis in combination with single-crystal X-ray crystallography of 6 and 27 by anomalous scattering of Cu Kα radiation. In preliminary analgesic and toxicity assays, the isomer with ring A in the chair conformation (8 or 27) was found to be more active than that with ring A in the boat conformation (7 or 27a). In addition, 15, 16, and 19 showed neuroprotective activity.

Seventeen new lathyrane diterpenoids (1–17) and two known analogues have been isolated from an ethanolic extract of Euphorbia micractina roots. Their structures including absolute configurations were determined by spectroscopic data interpretation and single-crystal X-ray crystallography. Compound 10 showed activity against HIV-1 replication in vitro, with an IC50 value of 8.2 μM. Compounds 6, 7, 11, 14, 15, and 18, at 10–6 M, showed significant vascular-relaxing activities against phenylephrine-induced vasoconstriction with relaxation rates of 48%, 41%, 42%, 48%, 50%, and 53%, respectively.

Twenty-two new lignans and neolignans (1−22), together with 14 known analogues, have been isolated from an ethanolic extract of the stem (with skin removed) of Sinocalamus affinis. Their structures were elucidated by spectroscopic and chemical methods. On the basis of systematic NMR and circular dichroism (CD) data analysis, the validity of J7,8 and ΔδC8−C7 values to distinguish threo and erythro aryl glycerol units in different neolignans and the CD data [particularly the Rh2(OCOCF3)4-induced CD data (the E band)] to determine the absolute configurations at C-8 (C-7) of the aryl glycerol units are discussed. At a concentration of 10 μM, compounds 20 and 22 inhibited NO production in mouse peritoneal macrophages 84.2 ± 5.9% and 71.7 ± 1.0%, respectively. Compounds 19, 20, and 22 showed activity against serum deprivation induced PC12 cell damage by increasing the cell viability from 80.7 ± 2.8% to 91.6 ± 6.4%, 107.2 ± 8.0%, and 97.6 ± 8.5%, respectively.

Sixteen new neolignans and lignans (1–16), together with 12 known analogues, have been isolated from an ethanol extract of the bark of Machilus robusta. Compounds 1 and 2 showed activity against HIV-1 replication in vitro, with IC50 values of 2.52 and 2.01 μM, respectively. At 10 μM, 6, 8, and 9 reduced dl-galactosamine-induced hepatocyte (WB-F344 cells) damage, and 9 could additionally attenuate rotenone-induced PC12 cell damage. The known compounds (−)-pinoresinol (17) and (+)-lyoniresinol (18) were active against serum deprivation induced PC12 cell damage.

Homosecoiridoids (1–15) were isolated from the flower buds of Lonicera japonica. Compounds 1–4, designated as loniphenyruviridosides A–D, possess unprecedented skeletons featuring phenylpyruvic acid derived moieties coupled with an iridoid or a secoiridoid nucleus. Compounds 5–15 (lonijaposides D–N) are additional examples of the unusual pyridinium alkaloid-coupled secoiridoids (lonijaposides A–C). The validity of the CD data to determine the configuration of the secoiridoid derivatives is discussed on the basis of detailed CD data analysis and semisynthesis of 2 and 3 with the co-occurring secologanic acid. The configuration of secologanic acid was determined by a single-crystal X-ray crystallographic analysis using anomalous scattering of Cu Kα radiation. Biosynthetic pathways of the homosecoiridoids were postulated. Compounds 1–4 inhibited STAT-3 activity of HELF cells, and lonijaposides F (7), H (9), I (10), and K (12) showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor.

Seven new cucurbitane triterpene glucosides (1–5, 8, and 9) and five known analogues (6, 7, 10, cucurbitacin I 2-O-β-d-glucopyranoside, and khekadaengoside K) have been isolated from an ethanol extract of roots of Machilus yaoshansis. Compounds 1 and 2 have an unusual 16,23:22,25-diepoxy unit, 4 is an uncommon cucurbitane 25-carbamate with the carbamoyl amino group attached at C-24 to form an oxazolidinone ring in the side chain, and 8 is the first example of a trinorcucurbitane derivative. The configurations in several pairs of C-24 epimeric cucurbitacins with 24,25-dihydroxy-22-one side chains were assigned, and the validity of J23a,24 and J23b,24 values to differentiate the configuration at C-24 in these cucurbitane derivatives is discussed. Compounds 2–4 showed in vitro activity against protein tyrosine phosphatase 1B with IC50 values of 8.63, 2.81, and 4.26 μM, respectively. Cucurbitacin E 2-O-β-d-glucopyranoside (10) showed selective cytotoxicity against BGC-823 and A549 cancer cells with IC50 values of 4.98 and 3.20 μM, respectively.

Four highly acylated diterpenoids with a new 3,4-secograyanane skeleton, secorhodomollolides A−D (1−4), have been isolated from the flower buds of Rhododendron molle. Their structures including absolute configurations were determined on the basis of spectroscopic data interpretation and single-crystal X-ray crystallography. Compound 4 exhibited significant analgesic and sedative effects at a dose of 5 mg/kg, and compound 2 showed selective cytotoxic activity against human hepatoma carcinoma cell line (Bel-7402) with IC50 0.97 μM.

Four steroids, a homopregnene (1) and three heptanorergosterane derivatives (2−4), nine tremulane sesquiterpenes (5−13), and 18 known compounds have been isolated from cultures of the fungus Phellinus igniarius. Their structures and absolute configurations were elucidated by spectroscopic data analysis. In preliminary in vitro assays, at 10−5 M, compounds 8, 9, 13, and 3β-hydroxy-11,12-O-isopropyldrimene (14) showed significant vascular-relaxing activities against phenylephrine-induced vasoconstriction with relaxing rates of 35.7%, 45.4%, 46.6%, and 32.1%, respectively, as compared with the blank control.

Fourteen new abietane (1−14) and seven new C20-norabietane (15−21) diterpenes, together with five known analogues, have been isolated from the stem bark of Fraxinus sieboldiana. Their structures were elucidated by spectroscopic data analysis. In the in vitro assays, at 10−5 M, compounds 8, 16, and 22 showed inhibitory activity against the release of β-glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor, with 59.7 ± 4.8%, 56.1 ± 5.6%, and 65.9 ± 3.1% inhibition, respectively. Compound 23 was active against H5N1 avian influenza virus with an IC50 value of 4.8 μM. Compounds 3 and 5 exhibited selective cytotoxic activities against A2780 (IC50 1.7 μM) and A549 (IC50 6.0 μM), respectively.

Nine minor new tirucallane (1−7) and euphane (8 and 9) triterpenoids including five hydroperoxides, together with 18 known compounds, have been isolated from an ethanolic extract of the roots of Euphorbia micractina. Their structures including absolute configurations were elucidated by spectroscopic and chemical analysis. In the in vitro assays, betulin (10) showed a selective cytotoxic activity against A2780 ovarian cells with an IC50 value of 6.1 μM and inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with an IC50 value of 15.3 μM. Jolkinol B (11) showed a potent activity against HIV-1 replication with an IC50 value of 12.6 μM. However, compounds 1−9 and the other known compounds were inactive in the three assays used.

Eleven new metabolites, butanolides 1−6, lignan derivatives 7−9, sesquiterpene 10, and 3′,4′-seco-flavane derivative 11, have been isolated from an ethanol extract of Machilus wangchiana. Twenty known compounds, including ginkgolides A and B (16 and 17), were also isolated. Their structures and absolute configurations were determined by spectroscopic and chemical methods. Compounds 7, 8a, 8b, 9, 11, (+)-guaiacin (12), meso-dihydroguaiaretic acid (13), and hamabiwalactone A (15) showed potent in vitro activities against the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs) induced by platelet-activating factor (PAF), with 42.5−75.6% inhibition at 10−5 M. Compounds 8, 8a, 8b, 9, and 11 reduced dl-galactosamine (GalN)-induced hepatocyte (WB-F344 cells) damage with 39.4 ± 6.3% to 53.6 ± 3.5% inhibition at 10−4 M. Isomahubannolide-23 (14) was cytotoxic against human stomach cancer (BGC-823) and ovarian cancer (A2780) cell lines, with IC50 values of 0.13 and 2.66 μM, respectively.

Eleven new compounds including two sesquiterpenes with an unusual 2,2,5,9-tetramethylbicyclo[6.3.0]undecane carbon skeleton (1 and 2), five phytane-type diterpene dilactones (3−7), an ent-clerodane diterpene dilactone (8), and three phenylpropenol esters (9−11), together with a diacylphenol (12) and 38 known compounds, have been isolated from an ethanolic extract of Heteroplexis micocephala. Their structures including absolute configurations were elucidated by spectroscopic and chemical analyses. In the in vitro assays, compound 6 showed a selective cytotoxic activity against A2780 with an IC50 value of 4.37 μM, while sinapyl diangelate (13) showed a potent activity inhibiting HIV-1 replication with an IC50 value of 4.04 μM.

Seven new neolignan glycosides (1–7), two arylglycerol glycosides (8, 9), and 18 known glycosides have been isolated from an ethanolic extract of the root of Iodes cirrhosa. Their structures including absolute configurations were determined by spectroscopic and chemical methods. Based on analysis of the NMR data of threo and erythro 8–4′-oxyneolignans and arylglycerols in different solvents, the validity of J7,8 and ΔδC8−C7 values to distinguish threo and erythro derivatives was discussed. In the in vitro assays, compound 4 and liriodendrin (17) both showed activity against glutamate-induced PC12 cell damage at 10−5 M.

Four new dimeric phenolic glycosides (1−4), a new iridoid diglycoside (5), and 15 known glycosides have been isolated from an ethanolic extract of the bark of Adina polycephala. Their structures were determined by spectroscopic and chemical methods. Compounds 1, 3, and 5 showed in vitro inhibitory activity against the release of β-glucuronidase in rat polymorphonuclear leukocytes induced by platelet-activating factor.

Ten minor new glycosidic constituents (1−10), together with 10 known compounds, have been isolated from a neuroprotective fraction of an ethanolic extract of the tubers of Gymnadenia conopsea. The structures of 1−10 were determined using spectroscopic and chemical methods. The compounds isolated were evaluated for activity in in vitro assays for acetylcholine esterase and monoamine oxidase inhibitory activities.

Four new cadinane sesquiterpenes (1−4), including a dimeric cadinane derivative (2) and a peroxide cadinane analogue (3), have been isolated from the leaves of Eupatorium adenophorum. Their structures including absolute configurations were determined on the basis of spectroscopic data interpretation and single-crystal X-ray crystallography. Compound 4 showed in vitro cytotoxicity against the HCT-8, Bel-7402, and A2780 cancer cell lines.

Three pyridinium inner salt alkaloids, lonijaposides A−C (1−3), based on an unprecedented skeleton of an N-substituted nicotinic acid nucleus coupled through C-5 with C-7 of a secoiridoid, together with seven known iridoids, have been isolated from the flower buds of Lonicera japonica. Their structures were elucidated by spectroscopic and chemical analyses. Lonijaposide C (3) showed activity against the release of glucuronidase in rat polymorphonuclear leukocytes induced by the platelet-activating factor.

Three pairs of enantiomerically pure alkaloids with diverse structure features, named isatindigoticoic acid A and epiisatindigoticoic acid A [(−)-1 and (+)-1], phaitanthrin A and epiphaitanthrin A [(−)-2 and (+)-2], and isatindopyrromizol A and epiisatindopyrromizol A [(−)-3 and (+)-3], respectively, were isolated from an aqueous extract of the roots of Isatis indigotica. Racemic and scalemic mixtures of these enantiomers were separated by HPLC on a chiral semi-preparative column. Their structures including absolute configurations were determined by extensive spectroscopic analysis in conjunction with the calculation of electronic circular dichroism (ECD) spectra. The enantiomer pairs possess parent structures of 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid, indolo[2,1-b]quinazolinone, and 3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazol-1-one, respectively. Except for phaitanthrin A [(−)-2] which the configuration was previously undetermined, these compounds are new enantiomeric natural products.Three pairs of alkaloid enantiomers (−)-/(+)-1−(−)-/(+)-3, having parent structures of 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid, indolo[2,1-b]quinazolinone, and 3-thioxohexahydro-1H-pyrrolo[1,2-c]imidazol-1-one, respectively, were isolated from a Chinese traditional herbal medicine “ban lan gen” (Isatis indigotica roots). Their absolute configurations were determined by comparison of experimental CD and calculated ECD spectra. Separation of these racemic and scalemic mixtures indicates that I. indigotica is an uncommon plant to produce diverse enantiomeric natural products, providing a fertile area for further inquiry for biogenetic mechanisms to create distinctive enantiomers, as well as for chemical synthesis and in-depth biological evaluation.Download full-size image

Two pairs of unusual scalemic enantiomers with a novel carbon skeleton of 2-[1′-(4″-hydroxy-3″,5″-dimethoxyphenyl)ethyl]-2-methoxyindolin-3-one, named isatidifoliumindolinones A–D (1–4), were isolated from an aqueous extract of Isatis indigotica leaves (da qing ye). Their structures including absolute configurations were determined by spectroscopic data analysis combined with comparison of their experimental CD and calculated ECD spectra. Validity of the ECD spectra calculation to assign the absolute configurations is discussed. Plausible biosynthetic pathways of 1–4 are proposed. Stereochemistry-dependent activity against LPS-induced NO production in BV2 cells was observed, and among the stereoisomers compound 4 is most active.Two pairs of scalemic enantiomers with a novel carbon skeleton of 2-[1′-(4″-hydroxy-3″,5″-dimethoxyphenyl)ethyl]-2-methoxyindolin-3-one, named isatidifoliumindolinones A–D (1–4), were isolated from an aqueous extract of Isatis indigotica leaves (da qing ye). Their structures including absolute configurations were determined by spectroscopic data analysis combined with comparison of their experimental CD and calculated ECD spectra. Postulated biosynthetic pathways of 1–4 were discussed. The four stereoisomers exhibited stereochemistry-dependent activity against LPS-induced NO production in BV2 cells.