Dan-Qi Li

Two new alkaloids from Portulaca oleracea and their cytotoxic activities

Two new alkaloids named (3R)-3,5-bis(3-methoxy-4-hydroxyphenyl)-2,3-dihydro-2(1H)-pyridinone (1) and 1,5-dimethyl-6-phenyl-1,2-dihydro-1,2,4-triazin-3(2H)-one (2), together with two known compounds (7′R)-N-feruloyl normetanephrine (3) and N-trans-feruloyl tyramine (4) were isolated from the air-dried aerial parts of Portulaca oleracea L. Their structures and configurations were elucidated by spectroscopic methods including 1D NMR, 2D NMR, and HR-MS techniques. In addition, compounds 1–4 were tested for in vitro cytotoxic activities against human lung (K562 and A549) and breast (MCF-7 and MDA-MB-435) cancer cell lines.

Cytotoxic triterpenoid glycosides (saikosaponins) from the roots of Bupleurum chinense.

As a part of our ongoing studies on cytotoxic triterpenoid saponins from herbal medicines, phytochemical investigation of the roots of Bupleurum chinense DC. afforded four new saikosaponins (1-4), along with 16 known ones (5-20). Their structures were established by direct interpretation of their spectral data, mainly HR-ESI-MS, 1D NMR and 2D NMR, and by comparison with literature data. Among them, compound 20 was isolated from the natural product for the first time. The cytotoxicities of all compounds against five selected human cancer cell lines (A549, HepG2, Hep3B, Bcap-37 and MCF-7) were assayed. In general, a number of the isolated compounds exhibited potent cytotoxic activities against the five selected human cancer cell lines. In particular, compounds 3, 8-9, 11-13, 16 and 20 showed more potent cytotoxic activities against the HepG2 and A549 cell lines than the positive control 5-fluorouracil. Based on the primary screening results, the preliminary structure-activity relationship (SAR) studies were also discussed. The SAR results suggest that the 13,28-epoxy bridge, the orientation of the hydroxyl group and the type of the sugar units are important requirements for cytotoxicity and selectivity.

Triterpenoid prosapogenols and prosapogenins from the husks of Xanthoceras sorbifolia.

Two new prosapogenins, 16-O-acetyl-21-O-(4-angeloyl)-α-l-rhamnopyranosyl barringtogenol C (1), 28-O-β-d-glucopyranosyl 16-deoxybarringtogenol C (2), were isolated from the acid hydrolyzate of the crude saponin obtained from the husks of Xanthoceras sorbifolia Bunge, along with six known triterpenoids. These structures were established on the basis of chemical and detailed spectral evidences. Compounds 1 and 2 showed cytotoxic activity against human cell lines (A375-S2, HeLa).

Neogenkwanines A–H: daphnane-type diterpenes containing 4,7 or 4,6-ether groups from the flower bud of Daphne genkwa

Neogenkwanines A–H (1–8), eight daphnane-type diterpenes possessing new skeletons with 4,7- or 4,6-ether groups, along with seven known ones (10–16), were isolated from Daphne genkwa. Their structures and absolute configurations were established by analysis of their NMR, X-ray crystallography, CD exciton chirality data and hydrolysis experiments. In addition, an MTT assay was used to examine the growth-inhibitory effects of all the new isolates on HL-60, Hep3B, and U87 cells; compounds 3, 4 and 5 exhibited significant inhibitory effects against Hep3B cell lines with IC50 values of 7.61, 8.16 and 8.35 μM, respectively.

Neuroprotective oleanane triterpenes from the roots of Bupleurum chinense

The discovery of new natural compounds with pharmacological properties is an increasingly important field, and a continuous phytochemical investigation of the roots of Bupleurum chinense D.C. has led to the isolation of 17 triterpenoids, including three new oleanane triterpenes (1-3) together with 14 known ones. Their structures were determined on the basis of 1D and 2D NMR spectra as well as HR-ESI-MS data. The cytotoxicities of all compounds against five selected human cancer cell lines were assayed. Only compounds 9 and 14 exhibited moderate activities. Recently, a number of investigations have focused on the neuroprotective properties of triterpenoids in B. chinense. In order to expand our knowledge about this herb, the neuroprotective effects of compounds 1-17 against hydrogen peroxide (H2O2)-induced neuronal cell damage in human neuroblastoma SH-SY5Y cells were evaluated. Compounds 1-3, 6-7 showed significant neuroprotective effects against H2O2-induced SH-SY5Y cell death. Preliminary structure-activity relationships (SARs) between neuroprotective effects and the isolates were also discussed.

A rapid extraction and analysis method for the simultaneous determination of 26 bioflavonoids in Portulaca oleracea L.

INTRODUCTION Portulaca oleracea L. (P. oleracea, purslane) is an edible plant that is widely distributed around the world, and flavonoids are its main bioactive constituents. Therefore, the detection of flavonoids is very important for a better understanding of its pharmacological actions and to monitor the product quality control of P. oleracea. OBJECTIVE To develop a rapid method to extract and determine 26 bioflavonoids in P. oleracea, based on microwave extraction (MWE) and triple quadrupole-linear ion trap mass spectrometry. METHODS The optimal conditions of MWE for the extraction of flavonoids from P. oleracea involved the use of methanol as the extraction solvent, a microwave power of 300 W, an extraction time of 450 s, and a solvent-to-solid ratio of 30 mL/g. The samples were analysed using an ultra-performance liquid chromatograph coupled with a triple quadrupole-linear ion trap mass spectrometer (UPLC-MS/MS) system. RESULTS The calibration curves of all 26 analytes showed good linearity (r ≥ 0.999) and the intra- and interday precisions and repeatability were all within required limits. The mean recoveries measured at three concentrations were higher than 94.2%, with RSDs lower than 2.94% for the targets. CONCLUSION The established MWE/UPLC-MS/MS method is a rapid and effective method for quality evaluation of P. oleracea from different production regions and different harvest periods.

Separation and identification of multiple constituents in Xiao Chai Hu Decoction (Sho-saiko-to) by bioactivity-guided fractionation combined with LC-ESI-QTOFMS/MS

Xiao Chai Hu Decoction (XCHD), named Sho-saiko-to in Japanese, is a well-known traditional Chinese medicine formula used in Asia. However, the characterization methods used in the past have lacked sensitivity and the nature of the active constituents of XCHD remains unclear. This study was carried out to establish the hyphenated method of bioactivity-guided fractionation and liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOFMS/MS) in order to identify the major bioactive constituents of XCHD. D101 macroporous resin was used to separate and enrich the material base into four fractions, XCHD-1, XCHD-2, XCHD-3 and XCHD-4. Each fraction was then evaluated for its antidepressant effect using depression-related parameters. An LC-ESI-QTOFMS/MS method in both positive and negative ion mode was also applied for separation and identification of the biological active fractions of XCHD. As a result, 79 compounds including polysaccharides, flavonoids, saikosaponins, ginsenosides, licoricesaponins and gingerols were detected, 69 of them were identified or tentatively characterized. Based on our preliminary characterization investigations, polysaccharides, gingerols and flavonoids in XCHD may contribute to the antidepressant effect of XCHD. In conclusion, the hyphenated method of bioactivity-guided fractionation and LC-ESI-QTOFMS/MS was meaningful for the isolation and preliminary identification of the biological active components in complex matrices of traditional Chinese medicine.

3, 3′-Neolignans from Pithecellobium clypearia Benth and their anti-inflammatory activity

Abstract The twigs and leaves of Pithecellobium clypearia Benth have been used as a folk medicine for the treatment of diseases related to inflammation in southern China for many years. To search for novel bioactive constituents as lead structures for anti-inflammatory drug development, seven new 3, 3′-neolignans ( 1 – 7 ), together with four known ones ( 8 – 11 ) were isolated from the 70% EtOH extract of the twigs and leaves of P. clypearia . Their structures were determined by spectroscopic analyses, especially the 1D, 2D NMR and CD spectra. The antioxidant and anti-inflammatory activities of all the isolated compounds were investigated. Among them, compound 11 showed promising activity against nitric oxide (NO) and considerable antioxidant activity. These findings will help in the effective use of P. clypearia as a valuable source of novel compounds for the prevention and treatment of inflammation-related disorders.

A new cyclolignan glycoside from the tubers of Pinellia ternata

A new 2,7′-type cyclolignan glycoside, cyclolignanyingoside A (1), together with six known compounds (2–7) were isolated from the tubers of Pinellia ternata (Thunb.) Breit. The structure of 1 was elucidated on the basis of chemical and spectral analysis, including 1D, 2D NMR analyses, HR-ESI-MS, and CD spectrometry. The cytotoxic, antioxidant and tyrosinase-inhibiting activities of all the isolates were determined. However, all the isolates exhibited no activity on the selected cell lines (Hep-3B, Bcap-37, and MCF-7). In addition, compounds 1–3 and 7 exhibited strong 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) free radical scavenging activity, and compounds 2 and 4 showed a moderate mushroom tyrsinase inhibitory activity.

Antioxidant and cytotoxic lignans from the roots of Bupleurum chinense

Abstract In the search for biologically active compounds from the roots of Bupleurum chinense D C., phytochemical investigation of its ethanol extract led to the isolation and identification of a new 8-O-4′ neolignan glucoside, saikolignanoside A (1), along with eight known lignans (2–9). Their structures were determined on the basis of IR, UV, HRESIMS, and NMR spectroscopic analyses. The antioxidant and cytotoxic effects of isolated compounds were evaluated in vitro. The isolated compounds (IC50 > 200 μM) did not display 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Whereas compounds 1–2, 5, 7, and 9 exhibited potent 2, 2′-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging properties with IC50 values ranging from 8.34 to 15.24 μM, while compounds 3–4, 6, 8 showed moderate properties. In addition, all compounds were evaluated for cytotoxicities against A549, HepG2, U251, Bcap-37, and MCF-7 cell lines. Compounds 5 and 9 (IC50 < 51.62 μM) possessed stronger cytotoxic activities against all the tested tumor cell lines, compared with the positive control 5-Fluorouracil.