Yanhusanines A-F, Isoquinoline-Derived Alkaloid Enantiomers from Corydalis yanhusuo and Their Biological Activity.

Six new pairs of isoquinoline alkaloid enantiomers, designated as yanhusanines A-F (1-6), were isolated from an aqueous extract of Corydalis yanhusuo tubers. The structures of these enantiomers were elucidated via physicochemical analysis and a variety of spectroscopic methods. All compounds were resolved into their enantiomers via chiral-phase HPLC, and their configurations were determined by DP4+ NMR calculation methods, specific rotations, and comparison of experimental and calculated ECD spectra. Compounds 1-6 bear a rare 9-methyl moiety, and compound 1 possesses a rare 1-oxa-6-azaspiro[4.5]decane core containing an N-CHO group. Compounds (+)-2, (-)-2, (+)-4, (-)-4, (+)-5, (-)-5, (+)-6, and (-)-6 exhibited selective inhibitory activities against human carboxylesterase (hCE2), in the IC50 value range of 2.0-13.2 µM.

Structures and Biological Evaluation of Monoterpenoid Glycosides from the Roots of Paeonia lactiflora.

Fractionation of an aqueous extract of the air-dried roots of a traditional Chinese medicinal plant, Paeonia lactiflora, yielded the new monoterpenoid glycosides 1-10. Their structures were assigned via spectroscopic techniques, and the absolute configurations of 1, 4-6, and 8 were verified via chemical methods, specific rotation, and electronic circular dichroism data. Compounds 1-4 are rare compared to the reported cage-like paeoniflorin derivatives; that is, they comprised two monoterpenoidal moieties. In the in vitro assay, compounds 5, 8, and 9 showed weak inhibitions against lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophages, with IC50 values of 64.8, 60.1, and 97.5 µM, respectively.

[Chemical constituents from water-soluble extract of dry roots of Paeonia lactiflora].

Nineteen compounds were isolated from the water-soluble extract of the dry roots of Paeonia lactiflora by using various chromatographic techniques. Their structures were identified by MS， NMR and other spectroscopic analysis as paeoniflorin(1)， 4-O-ethylpaeoniflorin(2)， 2'-O-benzoylpaeoniflorin(3)， benzoylpaeoniflorin(4)， 4"-hydroxy-benzoyloxypaeoniflorin(5)， moudanpioside C(6)， 6'-O-benzoyl-4"-hydroxy-3"-methoxy-paeoniflorin(7)， paeoniflorin B(8)， 6-O-benzoylalbiflorin(9)， secoisolariciresinol (10)， (+)-lyoniresinol(11)， dihyrodehydrodiconiferyl alcohol(12)， (7S，8S)-threo-7，9，9'-trihydroxy-3，3'-dimethoxy-8-O-4'-neolignan(13)， (+)-neo-olivil (14)， [(3S)-5-methyl-2，3-dihydro-1-benzofuran-3-yl]methanol(15)， 5-hydroxy-3S-hydroxymethyl-6-methyl-2，3-dihydrobenzofuran(16)， (+)-(R)-2-hydroxy-1-(4-methoxyphenyl)-1-propan-1-one(17)， (+)-(2R)-1-(4-hydroxy-3-methoxyphenyl)-2-propanol(18)， (+)-(4S)-(2E)-4-hydroxy-2-nonenoic acid(19). Compounds 15 and 18 are new natural products， while compounds 10， 11， 13， 14， 17 and 19 are isolated from the genus Paeonia for the first time.

[Study on structural conversion of dihydrochelerythrine in different solvents].

Dihydrochelerythrine was isolated from the ethanol extract of Corydalis yanhusuo by chromatographic and recrystallization techniques. To our knowledge, this is the first report that dihydrochelerythrine was found to be unstable. The NMR, HPLC, and LC-MS were applied to monitor the structural conversion process of dihydrochelerythrine. The results showed that when dissolved in polar deuteration solvent (e.g., DMSO-d6 & MeOD), dihydrochelerythrine is directly converted to chelerythrine gradually. However, if used non-polar reagent (e.g.,CD2Cl2), the sample of dihydrochelerythrine undergoes the formation of pseudobase, chelerythrine, and bimolecular ether then followed by oxidation to oxychelerythrine as the major final product. Which leads to this phenomenon maybe is that the C-6 in dihydrochelerythrine is highly reactive to nucleophiles, and is easily converted to different derivatives in different solvents attributed to the solvent effect. This finding will contribute to the extraction and isolation, bioactivity screening, and quality evaluation of medicinal materials containing dihydrochelerythrine and other similar derivatives.

[A new styrene dimer derivative from Litsea greenmaniana].

A new styrene dimer derivative has been isolated from the branch of Litsea greenmaniana by column chromatography over silica gel and Sephadex LH-20, as well as semi-preparative HPLC. Its structure was identified by spectroscopic data analysis (MS, UV, IR, 1D and 2D NMR) as (E)-2,4-bis(p-hydroxyphenyl)-2-butenol, named as listeanol. At a concentration of 1×10-5 mol•L⁻¹, compound 1 was inactive in the assays, including cytotoxicity against human tumor cell lines (HCT-8, Bel-7402, BGC-823, A549 and A2780), antioxidant activity in Fe²âº-cystine-induced rat liver microsomal lipid peroxidation, neuroprotective activity against serum deprivation or glutamate induced neurotoxicity in cultures of PC12 cells, and the inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).

Bysspectin A, an unusual octaketide dimer and the precursor derivatives from the endophytic fungus Byssochlamys spectabilis IMM0002 and their biological activities.

Bysspectin A (1), a polyketide-derived octaketide dimer with a novel carbon skeleton, and two new precursor derivatives, bysspectins B and C (2 and 3), were obtained from an organic extract of the endophytic fungus Byssochlamys spectabilis that had been isolated from a leaf tissue of the traditional Chinese medicinal plant Edgeworthia chrysantha, together with a known octaketide, paecilocin A (4). Their structures were determined by HRMS, 1D and 2D NMR spectroscopic analysis. A plausible route for their biosynthetic pathway is proposed. Compounds 1-3 were tested for their antimicrobial activities. Only compound 3 was weakly active against Escherichia coli and Staphyloccocus aureus with MIC values of 32 and 64 µg/mL, respectively. Further, the inhibitory effects on human carboxylesterases (hCE1, hCE2) of compounds 1 and 4 were evaluated. The results demonstrated that bysspectin A (1) was a novel and highly selective inhibitor against hCE2 with the IC50 value of 2.01 µM. Docking simulation also demonstrated that active compound 1 created interaction with the Ser-288 (the catalytic amino-acid in the catalytic cavity) of hCE2 via hydrogen bonding, revealing its highly selective inhibition toward hCE2.