Antiproliferative polycyclic polyprenylated acylphloroglucinols from Garcinia paucinervis.

Bioassay-guided isolation of the stems of Garcinia paucinervis led to one new adamantane-type polycyclic polyprenylated acylphloroglucinols (PPAPs), (-)-garpauvinin A (1), and four known analogues (2-5). The structure and absolute configuration of 1 was established via spectroscopic techniques and ECD method. All the isolates displayed moderate antiproliferative activity against HL-60, PC-3 and Caco-2 human cancer cell lines with IC50 values ranging from 0.81 to 19.92 µM, and exhibited low toxicity on WPMY-1 normal human cells, showing selectivity between normal and malignant prostate cells. The biosynthetic pathways of the isolated PPAPs were proposed.

Stilbenes with potent cytotoxicity from the seedcases of Paeonia suffruticosa Andrews.

Stilbenes (based on the 1,2-diphenylethylene skeleton) are a class of plant polyphenols with rich structural and bioactive diversity. Twenty-six stilbenes, including five undescribed compounds (7,8-dioxy-4,3',5'-trihydroxystilbene, trans-13'-methoxygnetin H, suffruticosol E, paestibenetrimerols A and B), were isolated from the seedcases of Paeonia suffruticosa Andrews. Their structures were elucidated by spectroscopic analyses and comparison with previously reported data. The absolute configurations of trans-13'-methoxygnetin H, suffruticosol E, paestibenetrimerols A and B were assigned from their respective electronic circular dichroism (ECD) spectra. Additionally, the structures of known compounds suffruticosols A, B and rockiol B were revised and the absolute configurations of them, and along with (+)-davidiol A, were also further determined by ECD. The isolated compounds, trans-gnetin H, cis-gnetin H and suffruticosol E, were found to have potent cytotoxicity against the DU-145 and MDA-MB-231 cell lines with IC50 values of 4.89-8.61 µM. The preliminary antitumor structure-activity relationship of these stilbenes is discussed as well.

Two ambuic acid dimers derived from homo-endo Diels-Alder reaction from Pestalotiopsis versicolor.

Two new dimers of ambuic acid, pestaloversicoloric acids A (1) and B (2), and a known derivative, 13(S)-hydroxyambuic acid (3), were isolated from the static fermentation product of Pestalotiopsis versicolor. The structural identification was accomplished via analyses on the data of HR-MS, 1 D and 2 D NMR, and ECD. Different from the well-known exo-type dimer, torreyanic acid, compounds 1 and 2 represent the first example of endo-type product derived from the intermolecular Diels-Alder reaction of two molecules of ambuic acid derivative with the identical absolute stereochemistry.

[Isoquinoline alkaloids from two species of Thalictrum genus plants].

The chemical constituents from the roots of Thalictrum cultratum and T. baicalense were investigated. By various isolation methods, such as silica gel, aluminium oxide, ODS, and Sephadex LH-20 column chromatographies, and semi-preparative HPLC, 11 simple isoquinoline alkaloids were isolated from the ethanol extract of the roots of these two plants, including a new compound, named dehydrothalflavine(1), and ten known ones(2-11): N-methylcorydaline(2), N-methylthalidaldine(3), thaliflavine(4), oxyhydrastinine(5), noroxyhydrastinine(6), dimethoxyisoquinolone(7), thalactamine(8), dehydronoroxyhydrastinine(9), 6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline(10), and isopicnarrhine(11). Their structures were elucidated on the basis of HR-ESI-MS and 1 D and 2 D NMR techniques. Compound 1 was a new isoquinoline alkaloid. Compound 11 was obtained from Tha-lictrum plant for the first time. All compounds did not show cytotoxic activities against HL-60, U937, HCT116, Caco-2, and HepG2 cancer cell lines.

Anti-tumor alkaloids from Peganum harmala.

Six alkaloids peharmalines F-K, along with 14 known ones, were isolated from the aerial part of Peganum harmala L.. The structures of the isolated compounds were determined based on their HR-ESI-MS data, extensive NMR spectroscopic analyses, and ECD calculations. 3-(4-Hydroxyphenyl)quinoline exhibited potent antiproliferative activity against the HepG-2 cell lines with an IC50 value of 3.05 µM. Norharmane displayed a moderate inhibition against A549 and HepG-2 cells with IC50 values of 16.45 µM and 17.27 µM, respectively.

New tirucallane-type triterpenoids from the resin of Boswellia carteriiand their NO inhibitory activities.

Six new tirucallane-type triterpenoids (1-6), along with ten known triterpenoids, were isolated from methylene chloride extract of the resin of Boswellia carterii Birdw. By the application of the comprehensive spectroscopic data, the structures of the compounds were clarified. The experimental electronic circular dichroism spectra were compared with those calculated, which allowed to assign the absolute configurations. Compounds 5 and 6 possesed a 2, 3-seco tirucallane-type triterpenoid skeleton, which were first reported. Their inhibitory activity against NO formation in LPS-activated BV-2 cells were evaluated. Compound 9 showed appreciable inhibitory effect, with an IC50 value of 7.58 ± 0.87 µmol·L-1.

Baicalensines A and B, Two Isoquinoline Alkaloids from the Roots of Thalictrum baicalense.

Baicalensines A (1) and B (2) were isolated from the roots of Thalictrum baicalense and structurally characterized using spectroscopic data, 13C NMR calculations, and the CASE algorithm. Compound 1, representing a new class of alkaloid dimers, contains berberine conjugated to a ring-opened isoquinoline. Compound 2 is the first reported natural benzylisoquinoline bearing a formyl group at C-3. Plausible biosynthetic pathways are proposed. Compound 1 exerted moderate cytotoxicity against the Caco-2 and HL-60 cell lines.

Polyprenylated xanthones from the twigs and leaves of Garcinia nujiangensis and their cytotoxic evaluation.

Inspired by the intriguing structures and bioactivities of polyprenylated xanthones, ten previously undescribed polyprenylated xanthones, nujiangxanthones G-P (1-10), and fifteen known ones (11-25) were isolated from the twigs and leaves of Garcinia nujiangensis. The structures of these compounds were established on the basis of spectroscopic data as well as comparison with the literature. Most of the isolates showed potent cytotoxicity against selected cancer cells. Compound 8 showed the highest effects against MDA-MB-231 and A549 cell lines with IC50 values of 4.12 and 2.67 µM and 16 demonstrated the most potent activity against MCF-7 cell line with an IC50 value of 3.36 µM.

New lignanamides and alkaloids from Chelidonium majus and their anti-inflammation activity.

Two new lignanamides, majusamides A and B (1 and 2), and two new alkaloids, chelidoniumine (3) and tetrahydrocoptisine N-oxide (4), together with six known hydroxycinnamic acid amides (HCCA) were isolated from the 75% ethanol extract of Chelidonium majus through the silica gel, Sephadex LH-20, MCI, ODS column chromatography, and semi-HPLC. Their structures were determined on the basis of spectroscopic data and physico-chemical methods. The absolute configurations of 1-3 were determined by electronic circular dichroism (ECD) calculations. The anti-inflammatory activities of all the isolates on the NO production in lipopolysaccharide (LPS)-induced macrophages were evaluated. Compounds 7 and 9 exhibited moderate inhibitory activity with IC50 values of 25.3 ±â€¯0.5 and 23.5 ±â€¯1.7 µM, respectively.

Polyketides from Pestalotiopsis zonata and structure revision of pestalrones A and B.

The structures of pestalrones A-B were revised via reinterpretation of the NMR data and a brief chemical transformation from the co-occurring polyketides, in our investigation on the secondary metabolites of Pestalotiopsis zonata, which also afforded a new α-pyrone derivative, pestazonatic acid, and four known analogs.

Three new polyketides from Ascotricha sp. ZJ-M-5 by the OSMAC strategy.

Three new compounds, ascotrichols A-B (1-2) and ascotrichrone A (3), along with two known isocoumarin derivatives (4-5), were isolated from the solid culture of a sea mud-derived fungus, Ascotricha sp. ZJ-M-5 on rice media. The structures were elucidated by extensive spectroscopic analyses, including 1D and 2D NMR data, and the absolute configurations were determined by electronic circular dichroism and biogenetic correlation.

Hybrid of dehydroergosterol and nitrogenous alternariol derivative from the fungus Pestalotiopsis uvicola.

A new hybrid of dehydroergosterol and nitrogenous alternariol derivative, pestauvicomorpholine A (1), and three alternariol analogues (2-4) including a new aminated one, pestauvicolactone A (2), were isolated from the fermentation product of the fungus Pestalotiopsis uvicola on rice media. Compounds 1 and 2 represent the first example of aza-alternariol and aza-alternariol-steroid derived from transamination followed by intermolecular hetero-Diels-Alder reaction.

Bioassay- and Chemistry-Guided Isolation of Scalemic Caged Prenylxanthones from the Leaves of Garcinia bracteata.

With bioassay- and chemistry-guided fractionation, seven new caged prenylxanthones including two scalemic mixtures, epiisobractatin (1), 13-hydroxyisobractatin (2), 13-hydroxyepiisobractatin (3), 8-methoxy-8,8a-dihydrobractatin (4), 8-ethoxy-8,8a-dihydrobractatin (5), garcibracteatone (6), and 8-methoxy-8,8a-dihydroneobractiatin (7), and the eight known compounds 8-15 were isolated from the leaves of Garcinia bracteata. The structures were unambiguously elucidated through analysis of spectroscopic data. The 2D structures and relative configurations of 1 and 5 were confirmed by X-ray crystallographic analysis. The separation of the enantiomers of 1-5 was accomplished by chiral-phase HPLC. The absolute configurations of the enantiomers of 1 and 5 were assigned by comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. The absolute configurations of the related compounds were determined via comparisons of their ECD data with those of the enantiomers of 1 and 5, respectively. Notably, compound 7, with a neo caged skeleton, is the first representative of a novel type of caged xanthone lacking a Δ8(8a) double bond. The isolated compounds exhibited significant cell growth inhibitory activities in vitro against human leukemic HL-60 and K562 cell lines, with GI50 values ranging from 0.2 to 8.8 µM. A preliminary structure-activity relationship is discussed.

Chiral resolution and anticancer effect of xanthones from Garcinia paucinervis.

Bioassay-guided fractionation of the dichloromethane-soluble portion of the stems of Garcinia paucinervis led to the isolation of eight new xanthones, including three pairs of enantiomers, (+) and (-) paucinervins L-N (1a-3a, and 1b-3b), one optically pure compound, (-) paucinervin O (4), and one new analogue, paucinervin P (5), as well as thirteen known xanthones (6-18). Their structures were established by detailed analysis of extensive spectroscopic data. The absolute configurations of 1-4 were confirmed by ECD calculations. All the isolates 1-18 displayed antiproliferative effect against HL-60 with IC50 values ranging from 0.87 to 29.14 µM, of which compound 5 was the most active. Compounds 6, and 14 exhibited potential inhibitory activity against PC-3 cells, while compounds 5-7, 14, and 16-17 displayed cytotoxic potency against Caco-2 cells. A preliminary structure-activity relationship was also discussed.

Racemic indole alkaloids from the seeds of Peganum harmala.

Five pairs of new 2-oxoindole alkaloids, (±)-peganumalines A-E (1-5), and a new indole alkaloid, peganumaline F (6), along with two known analogues, were isolated from the seeds of Peganum harmala. Their structures and absolute configurations were elucidated through spectroscopic analyses and quantum chemistry calculations. Notably, (±)-peganumalines A (1) represent a pair of rare 2-oxoindole dimeric alkaloid enantiomer with the hitherto unknown carbon skeleton. All isolates were tested for antiproliferative and antibacterial activities.

Four new compounds from the roots of Euphorbia ebracteolata and their inhibitory effect on LPS-induced NO production.

Three new diterpenoids, ebractenoids O~Q (1-3), and a new phenolic glucoside, γ-pyrone-3-O-ß-d-(6-galloyl)-glucopyranoside (4), together with 6 known compounds, were isolated from the 95% ethanol extract of the roots of Euphorbia ebracteolata, and their structures were elucidated on the basis of spectroscopic data. The absolute configurations of 1-3 were determined by electronic circular dichroism (ECD) calculations. The inhibitory effects of all the isolates with exception of compounds 8 and 10 on the NO production in lipopolysaccharide (LPS)-induced macrophages were evaluated. All of them exhibited significant inhibitory activity.

Cytotoxic quinazoline alkaloids from the seeds of Peganum harmala.

Seventeen quinazoline alkaloids and derivatives, containing two pairs of new epimers, named as (S)- and (R)-1-(2-aminobenzyl)-3-hydroxypyrrolidin-2-one ß-d-glucopyranosyl-(1 → 6)-ß-d-glucopyranoside (1, 2), (S)- and (R)-vasicinone ß-d-glucopyranosyl-(1 → 6)-ß-d-glucopyranoside (3, 4), and a new enantiomer (12b), together with six known ones (5-8, 10, and 12a), and three pairs of known enantiomers (9, 11, and 13), were isolated from the ethanol extracts of the seeds of Peganum harmala L.. Their structures including the absolute configuration were elucidated by using 1D and 2D NMR, and ECD calculation approaches. The cytotoxic activities of all isolated compounds were evaluated. 11 showed moderate cytotoxicity against PC-3 cells with an IC50 value of 15.41 µM.

Antiproliferative Dimeric Aporphinoid Alkaloids from the Roots of Thalictrum cultratum.

Inspired by the intriguing structures and bioactivities of dimeric alkaloids, 11 new thalifaberine-type aporphine-benzylisoquinoline alkaloids, thalicultratines A-K, a tetrahydroprotoberberine-aporphine alkaloid, thalicultratine L, and five known ones were isolated from the roots of Thalictrum cultratum. Their structures were defined on the basis of NMR and HRESIMS data. The antiproliferative activities of compounds 1-17 were evaluated against human leukemia HL-60 and prostate cancer PC-3 cells. Most alkaloids showed potent cytotoxicity against selected cancer cells. Preliminary SARs are discussed. The most active new compound (3), with an IC50 value of 1.06 µM against HL-60 cells, was selected for mechanism of action studies. The results revealed that compound 3 induced apoptosis and arrested the HL-60 cell cycle at the S phase with the loss of mitochondria membrane potential. The nuclear morphological Hoechst 33258 staining assay was also carried out, and the results confirmed apoptosis.

Neobraclactones A-C, three unprecedented chaise longue-shaped xanthones from Garcinia bracteata.

Neobraclactones A-C (1-3), featuring an unprecedented further rearranged prenylxanthone skeleton with a unique octahydro-2H-1,3-dioxacyclopenta[c,d]inden-2-one scaffold, along with their biosynthesis-related known compound neobractatin (4), were isolated from the leaves of Garcinia bracteata. Their structures with absolute configurations were determined by extensive analyses of spectroscopic data and ECD calculations. Compounds 1 and 2 showed significant growth inhibition activities against the human leukaemia HL-60 and K562 cell lines with GI50 values from 0.40 to 0.86 µM.

Bioactive terpenoids from Silybum marianum and their suppression on NO release in LPS-induced BV-2 cells and interaction with iNOS.

Three new (1-3) and one known (4) bioactive terpenoids were isolated from the seeds of Silybum marianum based on the investigation to get new NO inhibitors. Their structures were determined by extensive NMR (1D and 2D NMR) and MS spectroscopic data, and the absolute configurations were identified by experimental and calculated ECD spectra. The NO inhibitory activities in murine microglial BV-2 cells and interactions with iNOS protein by molecular docking were evaluated for all compounds. The results showed that these compounds had potent NO inhibitory effects.