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From an aqueous extract of “tian ma” (the steamed and dried rhizomes of Gastrodia elata), ten new compounds gastrodibenzins A−D (1−4) and gastrotribenzins A−F (5−10), along with known analogues (11−20), having structure features coupling between two and three p-hydroxybenzyl-derived units via carbon- and/or ether-bonds, were isolated and characterized by spectroscopic data analysis. Meanwhile, the new compounds 5a, 6a, 8a, 22, and 23, as well as the known derivatives 13a, 14a, 15, 17−21, 24, 25, and p-hydroxybenzyl aldehyde were isolated and identified from a refluxed aqueous solution of p-hydroxybenzyl alcohol. Methylation of 5a and 6a in methanol and ethylation of 6a, 8a, 13a, and 14a in ethanol produced 5 and 6 and 7, 8, 13, and 14, respectively. using ultra-performance liquid chromatography high-resolution electrospray ionization mass spectrometry (UPLC-HRESIMS) analysis of the refluxed solutions of p-hydroxybenzyl alcohol and the refluxed extracts of the fresh G. elata rhizome and “tian ma” extracts indicated consistent production and variation of the dimeric and trimeric derivatives of p-hydroxybenzyl alcohol upon extracting solvents and refluxing time. In various assays, the dimeric and trimeric derivatives showed more potent activities than p-hydroxybenzyl alcohol itself and gastrodin, which are the main known active constituents of “tian ma”. These results revealed for the first time that the more effective dimers and trimers can be produced through condensation of the co-occurring p-hydroxybenzyl alcohol during processing and decocting of the G. elata rhizomes, demonstrating insights into medicinal chemistry behind application protocols of traditional Chinese medicines. Graphic Abstract

Abstract Nine new gastrodin derivatives, including seven p-hydroxybenzyl-modified gastrodin ethers (1–7), 6′-O-acetylgastrodin (8), and 4-[α-d-glucopyranosyl-(1 →6)-β-d-glucopyranosyloxy]benzyl alcohol (9), together with seven known derivatives, were isolated from an aqueous extract of Gastrodia elata (“tian ma”) rhizomes. Their structures were determined by spectroscopic and chemical methods as well as single crystal X-ray diffraction. Compounds 1–4, 7, 10, and 11 were also isolated from a reaction mixture by refluxing gastrodin and p-hydroxybenzyl alcohol in H2O. As both gastrodin and p-hydroxybenzyl alcohol exist in the plant, the reaction results provide evidence for the production and increase/decrease of potential effective/toxic components when “tian ma” is decocted solely or together with ingredients in Chinese traditional medicine formulations, though the isolates were inactive in the preliminarily cell-based assays at concentrations of 10 μM. Moreover, using ultra-performance liquid chromatography high-resolution electrospray ionization mass spectrometry (UPLC-HRESIMS), 4, 7, 10, and 11, as well as component variations, were detectable in the freshly prepared extracts of different types of samples, including the freeze-dried fresh G. elata rhizomes. Graphic Abstract

Five new denudatine-type diterpenoid alkaloids (1–5), along with the known analogue aconicarmine (6), were isolated from an aqueous decoction of the lateral roots of Aconitum carmichaelii (fu-zi). Their structures were determined by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Compound 5 is the first denudatine-type diterpenoid alcohol iminium alkaloid, which could be partially transformed into the aza acetal form in pyridine-d5. Compound 5 inhibited mice writhing in an acetic acid-induced writhing assay.

Seven new monoterpene alkaloids (1−7), along with 18 known analogues, were isolated from an aqueous decoction of the hook-bearing stems of Uncaria rhynchophylla (Gou-teng). Their structures were determined by spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Compound 1 is the first monoterpene 22-norindoloquinolizidine alkaloid with a ketene unit, while 2 and 3 are unusual indoloquinolizidine alkaloids having an oxazinane ring.

Six new triterpenes, uncarinic acids K—P (1–6), along with 24 known analogues, were isolated as minor constituents of an aqueous decoction of the hook-bearing stems of Uncaria rhynchophylla (Gou-teng). By comprehensive spectroscopic data analysis, their structures were elucidated as derivatives of olean-12-en-28-oic acid and urs-12-en-28-oic acid with different oxidized forms at C-3, C-6, and/or C-23, respectively. Cell-based preliminary bioassay showed that the (E)-/(Z)-coumaroyloxy and (E)-/(Z)-feruloyloxy units at C-27 of olean-12-en-28-oic acid and urs-12-en-28-oic acid played roles in their bioactivities.

Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinson's disease. A cell model of Parkinson's disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining. Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01–1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells. The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway.

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 (1)H NMR data of the glucose with an authentic sugar sample and application of modified Mosher's method based on the MPA determination rule of Δδ(RS) values for 1a and 4a, and Δδ(S) values for 6a. The configuration of 7 was assigned by electronic circular dichroism calculations based on the quantum-mechanical time-dependent density functional theory.

Seven new 4-hydroxybenzyl-substituted glutathione derivatives (2-8), together with a known analogue (1), were isolated from the aqueous extract of Gastrodia elata Blume rhizomes. Their structures were determined by using spectroscopic and chemical methods. The absolute configurations of 1-8 were assigned by using Marfey's method, combined with comparing the NMR and CD spectroscopic data of sulfoxide moieties in 3-6 with those of S-(4-hydroxybenzyl)cysteine sulfoxide stereoisomers (9-12) synthesized as authentic samples. The configurations of 9-12 were confirmed by electronic CD calculations based on the quantum-mechanical time-dependent density functional theory. Furthermore, the structures of 1, 3, 5, 7, and 8 were verified by synthesis. Compound 3 was active against serum deprivation-induced PC12 cell damage and synthetic 9-14 exhibited activity against Fe(2+)-cysteine induced rat liver microsomal lipid peroxidation.

Seven new aromatic acid derivatives (1-7), together with five known analogs, were isolated from the lateral roots of Aconitum carmichaelii. Structures of the new compounds were determined by spectroscopic and chemical methods as 4-methyl ( - )-(R)-hydroxyeucomate (1), 4-butyl ( - )-(R)-hydroxyeucomate (2), 4-butyl-1-methyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (3), 1-butyl-4-methyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (4), dimethyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (5), dimethyl (+)-(R)-2-O-(4'-hydroxybenzoyl)malate (6), and methyl ( ± )-3-(4'-hydroxy-3'-methoxyphenyl)-3-sulfopropionate (7), respectively. Compounds 1 and 2 are 2-benzylmalates (eucomate derivatives), 3-6 belong to 2-O-benzoylmalates, and 7 is a rare phenylpropionate containing a sulfonic acid group. The absolute configurations of eucomate derivatives were confirmed by X-ray crystallographic analysis of 4-methyl eucomate (11).

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.

Six new glycosides (1-6) have been isolated from the flower buds of Lonicera japonica. Their structures including the absolute configurations were determined by spectroscopic and chemical methods as ( - )-2-hydroxy-5-methoxybenzoic acid 2-O-β-d-(6-O-benzoyl)-glucopyranoside (1), ( - )-4-hydroxy-3,5-dimethoxybenzoic acid 4-O-β-d-(6-O-benzoyl)-glucopyranoside (2), ( - )-(E)-3,5-dimethoxyphenylpropenoic acid 4-O-β-d-(6-O-benzoyl)-glucopyranoside (3), ( - )-(7S,8R)-(4-hydroxyphenylglycerol 9-O-β-d-[6-O-(E)-4-hydroxy-3,5-dimethoxyphenylpropenoyl]-glucopyranoside (4), ( - )-(7S,8R)-(4-hydroxy-3-methoxyphenylglycerol 9-O-β-d-[6-O-(E)-4-hydroxy-3,5-dimethoxyphenylpropenoyl]-glucopyranoside (5), and ( - )-4-hydroxy-3-methoxyphenol β-d-{6-O-[4-O-(7S,8R)-(4-hydroxy-3-methoxyphenylglycerol-8-yl)-3-methoxybenzoyl]}-glucopyranoside (6), respectively.

Six new glycosidic constituents (1-6), together with 10 known analogs, have been isolated from the bark of Machilus robusta. Structures of the new compounds, including the absolute configurations, were determined by spectroscopic and chemical methods as ( - )-nectandrin B-β-d-glucopyranoside (1), ( - )-(7R,7'R,8S,8'R)-4,4'-dihydroxy-3,3'-dimethoxy-7,7'-epoxylignan-4-O-β-d-glucopyranoside (2), ( - )-(7R,7'R,8S,8'R)-4,4'-dihydroxy-3,3'-dimethoxy-7,7'-epoxylignan-4'-O-β-d-glucopyranoside (3), ( - )-(8S,8'R)-4,4'-dihydroxy-3,3',5'-trimethoxylignan-4'-O-β-d-glucopyranoside (4), ( - )-(7R,8R)-syringylglycerol-8-O-β-d-glucopyranoside (5), and ( - )-3-hydroxy-2-methyl-4-pyrone-3-O-β-d-xylopyranosyl-(1 → 6)-O-β-d-glucopyranoside (6), respectively.

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.

Accumulation of α-synuclein (α-syn) in the brain is a characteristic of Parkinson's disease (PD). In this study, we investigated whether treatment with tunicamycin, an endoplasmic reticulum (ER) stress inducer, led to the accumulation of α-syn in PC12 cells, and where α-syn protein was accumulated, and finally, whether bibenzyl compound 20c, a novel compound isolated from Gastrodia elata (Tian ma), could alleviate the accumulation of α-syn and ER stress activation in tunicamycin-treated PC12 cells.PC12 cells were treated with tunicamycin for different time (6 h, 12 h, 24 h, 48 h). Cell viability was determined by a MTT assay. Subcellular fractions of ER and mitochondria were extracted with the Tissue Endoplasmic reticulum Isolation Kit. The levels of α-syn protein and ER-stress-associated downstream chaperones were detected using Western blots and immunofluorescence.Treatment of PC12 cells with tunicamycin (0.5-10 μg/mL) dose-dependently increased the accumulation of α-syn monomer (19 kDa) and oligomer (55 kDa), and decreased the cell viability. Accumulation of the two forms of α-syn was observed in both the ER and mitochondria with increasing treatment time. Co-treatment with 20c (10Tunicamycin treatment caused accumulation of α-syn monomer and oligomer in PC12 cells. Bibenzyl compound 20c reduces the accumulation of α-syn and inhibits the activation of ER stress, which protected PC12 cells against the toxicity induced by tunicamycin.

Five new phenylpropene diglycosides (1-5), together with three known analogs, have been isolated from an ethanol extract of the bark of Machilus wangchiana. Their structures were determined by spectroscopic and chemical methods. In the preliminary assay, compounds 2 and 5-8 reduced dl-galactosamine (GalN)-induced hepatocyte (WB-F344 cells) damage with 37-41% inhibitions at 10 μM.

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 IC(50) values of 3.70-12.35 μM, and 17 inhibits Coxsackie virus B3 replication with an IC(50) of 6.87 μM.

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.

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 3beta-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.

Four new minor constituents including two cyclodipeptides (1 and 2) and two cyclopentene derivatives (3 and 4), together with four known cyclodipeptides, have been isolated from an ethanolic extract of the tubers of Gymnadenia conopsea. Their structures including absolute configurations were determined by spectroscopic data interpretation combined with chemical methods. Among them, compound 1 contains an abnormal S-(4''-hydroxybenzyl)cysteine residue, 3 and 4 possess [(4-methylcyclopentyl)methyl]benzene and (4-hydroxymethylcyclopentyl)benzene carbon skeletons, respectively, both of which are first found from the natural source.

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 IC(50) value of 6.1 microM and inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with an IC(50) value of 15.3 microM. Jolkinol B (11) showed a potent activity against HIV-1 replication with an IC(50) value of 12.6 muM. However, compounds 1-9 and the other known compounds were inactive in the three assays used.

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.

Twenty-six new diterpenoid alkaloids, 1-26 (1-4: hetisan-type C(20)-diterpenoid alkaloids; 5-26: aconitane C(19)-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 C(19)-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.

Five new 9,10-anthraquinones (1-5) were isolated from an ethanol extract of the roots of Knoxia valerianoides. Their structures including absolute configuration of 1 were determined by spectroscopic analysis. Compounds 4 and 5 showed moderate activity against nitrogen oxide production in macrophages induced by lipopolysaccharide, at 10(- 5) M, with inhibition ratios of 50.4 ± 3.6 and 41.7 ± 2.1%, 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 IC(50) 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.

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.

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 beta-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 IC(50) values of 0.13 and 2.66 muM, respectively.