Alkaloids from an aqueous extract of Uncaria rhynchophylla / 药学学报

Five alkaloids were isolated from a decoction of Uncaria rhynchophylla by a combination of various chromatographic techniques, including macroporous adsorbent resin, MCI resin, silica gel, Sephadex LH-20, and reversed phase HPLC. Their structures were characterized by comprehensive analyses of spectroscopic data as monoterpene indole alkaloids (+)-(7R)-3-oxo-7-hydroxy-3,7-seco-dihydrorhynchohylline (1), (+)-(7S)-3-oxo-7-hydroxy-3,7-seco-dihydrorhyncho-hylline (2), (+)-(7R)-3-oxo-7-hydroxy-3,7-seco-rhynchohylline (3) and (+)-(7S)-3-oxo-7-hydroxy-3,7-seco-rhynchohylline (4), and a β-carboline alkaloid 1,2,3,4-tetrahydro-1-oxo-β-carboline (5). Among them, 1 and 2 are new compounds, 3 and 4 are new natural products that were semi-synthesized from isorhynchohylline with incorrect specific rotations, and 5 is isolated for the first time from the genus Uncaria.

Chemical constituents from stems of Uncaria lancifolia / 中草药

Objective To study the chemical constituents from the stems of Uncaria lancifolia. Methods The isolation and purification were carried out by silica gel column chromatography, RP18, Sephadex LH-20, and preparative HPLC. The structures of the isolated compounds were elucidated by physical and chemical properties, and spectroscopic methods. Results Eighteen compounds were isolated and identified from 95% ethanol extract from the stems of U. lancifolia and characterized as uncarine A (1), uncarine E (2), isomitraphylline (3), tetrahydroalstonine (4), strictosidine (5), cadambine (6), glabratine (7), strictosamide (8), (13R)-hydroxy- octodeca-(9Z,11E,15Z)-trien-oic acid (9), (6S,9R)-roseoside (10), periplanetin (11), integracin A (12), integracin B (13), 6β,19α- dihydroxyurs-3-oxours-12-en-28-oic aicd (14), ursolic acid (15), oleanic acid (16), β-sitosterol (17), and β-daucosterol (18). Conclusion This is the first report for the chemical constituents from U. lancifolia. All compounds are obtained from this plant for the first time, and compounds 9-13 are isolated from Uncaria genus for the first time. Compounds 1-8 are monoterpene indole alkaloids, which are characteristic constituents in Uncaria genus.

Structural characterization of monoterpene indole alkaloids in ethanolic extracts of Rauwolfia species by liquid chromatography with quadrupole time-of-flight mass spectrometry / 药物分析学报

Rauwolfia species (Apocynaceae) are medicinal plants well known worldwide due to its potent bioactive monoterpene indole alkaloids (MIAs) such as reserpine, ajmalicine, ajmaline, serpentine and yohimbine. Reserpine, ajmalicine and ajmaline are powerful antihypertensive, tranquilizing agents used in hypertension. Yohimbine is an aphrodisiac used in dietary supplements. As there is no report on the comparative and comprehensive phytochemical investigation of the roots of Rauwolfia species, we have developed an efficient and reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for ethanolic root extract of Rauwolfia species to elucidate the fragmentation pathways for dereplication of bioactive MIAs using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC–ESI–QTOF–MS/MS) in positive ion mode. We identified and established diagnostic fragment ions and fragmentation pathways using reserpine, ajmalicine, ajmaline, serpentine and yohimbine. The MS/MS spectra of reserpine, ajmalicine, and ajmaline showed C-ring-cleavage whereas E-ring cleavage was observed in serpentine via Retro Diels Alder (RDA). A total of 47 bioactive MIAs were identified and characterized on the basis of their molecular formula, exact mass measurements and MS/MS analysis. Reserpine, ajmalicine, ajmaline, serpentine and yohimbine were unambiguously identified by comparison with their authentic standards and other 42 MIAs were tentatively identified and characterized from the roots of Rauwolfia hookeri, Rauwolfia micrantha, Rauwolfia serpentina, Rauwolfia verticillata, Rauwolfia tetraphylla and Rauwolfia vomitoria. Application of LC–MS followed by principal component analysis (PCA) has been successfully used to discriminate among six Rauwolfia species.

The catechol-O-methyltransferase inhibitory potential of Z-vallesiachotamine by in silicoand in vitro approaches

AbstractZ-Vallesiachotamine is a monoterpene indole alkaloid that has a β-N-acrylate group in its structure. This class of compounds has already been described in different Psychotriaspecies. Our research group observed that E/Z-vallesiachotamine exhibits a multifunctional feature, being able to inhibit targets related to neurodegeneration, such as monoamine oxidase A, sirtuins 1 and 2, and butyrylcholinesterase enzymes. Aiming at better characterizing the multifunctional profile of this compound, its effect on cathecol-O-methyltransferase activity was investigated. The cathecol-O-methyltransferase activity was evaluated in vitro by a fluorescence-based method, using S-(5′-adenosyl)-l-methionine as methyl donor and aesculetin as substrate. The assay optimization was performed varying the concentrations of methyl donor (S-(5′-adenosyl)-l-methionine) and enzyme. It was observed that the highest concentrations of both factors (2.25 U of the enzyme and 100 µM of S-(5′-adenosyl)-l-methionine) afforded the more reproducible results. The in vitro assay demonstrated that Z-vallesiachotamine was able to inhibit the cathecol-O-methyltransferase activity with an IC50 close to 200 µM. Molecular docking studies indicated that Z-vallesiachotamine can bind the catechol pocket of catechol-O-methyltransferase enzyme. The present work demonstrated for the first time the inhibitory properties of Z-vallesiachotamine on cathecol-O-methyltransferase enzyme, affording additional evidence regarding its multifunctional effects in targets related to neurodegenerative diseases.