Haoyu Ye

Intermittent counter-current extraction as an alternative approach to purification of Chinese herbal medicine

This paper describes intermittent counter-current extraction, a novel method of using a conventional twin column counter-current chromatograph to either split a sample into two groups of compounds or extract and enrich a target compound from a crude extract. The first method is demonstrated by splitting a model mixture of four compounds into two groups. The second method is demonstrated by the extraction and enrichment of a high value target compound, triptolide, from a Chinese herbal medicine crude extract of Tripterygium wilfordii Hook. f., where it is found at low concentration (2%). This was achieved by retaining and enriching the target compound within the column while washing away all other components of the crude material. The success of the first method allowed the second method to be carried out without the need for costly preliminary experiments with the high value sample. 188mg of triptolide at greater than 98% purity was separated from 9.2g of crude extract, using 10l of solvent in a 3-h separation.

Millepachine, a novel chalcone, induces G2/M arrest by inhibiting CDK1 activity and causing apoptosis via ROS-mitochondrial apoptotic pathway in human hepatocarcinoma cells in vitro and in vivo

In this study, we reported millepachine (MIL), a novel chalcone compound for the first time isolated from Millettia pachycarpa Benth (Leguminosae), induced cell cycle arrest and apoptosis in human hepatocarcinoma cells in vitro and in vivo. In in vitro screening experiments, MIL showed strong antiproliferation activity in several human cancer cell lines, especially in HepG2 cells with an IC50 of 1.51 µM. Therefore, we chose HepG2 and SK-HEP-1 cells to study MILs antitumor mechanism. Flow cytometry showed that MIL induced a G2/M arrest and apoptosis in a dose-dependent manner. Western blot demonstrated that MIL-induced G2/M arrest was correlated with the inhibition of cyclin-dependent kinase 1 activity, including a remarkable decrease in cell division cycle (cdc) 2 synthesis, the accumulation of phosphorylated-Thr14 and decrease of phosphorylation at Thr161 of cdc2. This effect was associated with the downregulation of cdc25C and upmodulation of checkpoint kinase 2 in response to DNA damage. MIL also activated caspase 9 and caspase 3, and significantly increased the ratio of Bax/Bcl-2 and stimulated the release of cytochrome c into cytosol, suggesting MIL induced apoptosis via mitochondrial apoptotic pathway. Associated with those effects, MIL also induced the generation of reactive oxygen species. In HepG2 tumor-bearing mice models, MIL remarkably and dose dependently inhibited tumor growth. Treatment of mice with MIL (20mg/kg intravenous [i.v.]) caused more than 65% tumor inhibition without cardiac damage compared with 47.57% tumor reduction by 5mg/kg i.v. doxorubicin with significant cardiac damage. These effects suggested that MIL and its easily modified structural derivative might be a potential lead compound for antitumor drug.

Flow rate gradient high-speed counter-current chromatography separation of five diterpenoids from Triperygium wilfordii and scale-up.

In this paper, high-speed counter-current chromatography (HSCCC) instruments with different gravitational forces were applied for the separation of bioactive compounds from Triperygium wilfordii Hook.f. The critical parameters including sample concentration, sample volume and flow rate were first optimized on an analytical Mini-DE HSCCC system, and then scaled up to a preparative TBE 300A HSCCC system. Although this scale-up process was performed using different CCC instruments with different centrifuges and gravitational forces, the same resolutions were obtained and the elution time could be predictable. Five diterpenoid compounds and one unknown compound were separated from Triperygium wilfordii Hook.f. by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (HEMW) (3:2:3:2, v/v/v/v). This one-step flow gradient separation produced triptonide (25 mg), isoneotriptophenolide (77 mg), hypolide (83 mg), unknown compound (1 mg), triptophenolide (42 mg), triptonoterpene methyl ether VI (37 mg) from 320 mg crude extract with purities of 98.2%, 96.6%, 98.1%, 95.3%, 95.1%, and 96.5%, respectively. Their purities and structures were identified by high-performance liquid chromatography, mass spectrometry and NMR. This paper demonstrates that analytical CCC plays an important role in optimizing parameters and scale-up process when analytical CCC and preparative CCC are supplied by different manufacturers with different gravitational forces, and the scale-up process from analytical CCC to preparative CCC is still predictable.

Separation of honokiol and magnolol by intermittent counter-current extraction

Recently, intermittent counter-current extraction (ICcE) has been developed and shown its advantage in improving resolution between targeted compounds. However, how to choose suitable parameters to increase the throughput has not been systematically studied yet. In present work, we first calculated theoretically the conditions to carry out ICcE elution mode. Then, honokiol and magnolol were separated as model compounds using ICcE elution mode to confirm our conclusion. After parameters like sample concentration and sample feed were optimized in analytical high-performance counter-current chromatography (HPCCC), the separation process was scaled up to preparative HPCCC successfully. 12.8 g honokiol and 16.1g magnolol were separated from 30 g mixture with purities of 98.6% and 93.7%. And the throughput of target isolation of ICcE elution mode was at least 3.75 x higher than isocratic elution mode with the same HPCCC instruments. Our results confirmed our theory calculation and demonstrated the enormous potential of ICcE on preparative separation of binary mixture.

Preparative separation of a terpenoid and alkaloids from Tripterygium wilfordii Hook. f. using high-performance counter-current chromatography: Comparison of various elution and operating strategies

This paper describes how high-performance counter-current chromatography (HPCCC) was used strategically for the separation of Tripterygium wilfordii Hook. f. Due to the complexity of Chinese herbal medicines, the initial ethanol crude extract was fractionated into seven fractions using medium-pressure liquid chromatography (MPLC). One terpenoid (triptolide) and three alkaloids (peritassine A, wilforgine and wilforine) were further separated from one of the MPLC fractions. This fraction (1.25 g) yielded 8 mg of triptolide and 28 mg of peritassines A after one HPCCC column pass and 30 mg of wilforgine and 120 mg of wilforine after a second column pass with respective purities of 97%, 93.6%, 95.0% and 94.4%, which were determined by high-performance liquid chromatography (HPLC). This was a one-step HPCCC separation, using an n-hexane-ethyl acetate-methanol-water (4:5:4:5, v/v) solvent system, where increases in theoretical plates have been sacrificed in favour of increasing throughput. Structures were identified by electrospray ionization mass spectrometry (ESI-MS), (1)H nuclear magnetic resonance ((1)H NMR) and (13)C nuclear magnetic resonance ((13)C NMR). Comparison of three different modes of eluting compounds retained in the liquid stationary phase: elution extrusion; dual mode and simple pump-out showed that simply pumping out the column contents at high flow gave better resolution and was eight times faster than the other two well-utilised methods. Triptolide and peritassines A were isolated for the first time from Tripterygium wilfordii Hook. f.

Synthesis and biological evaluation of novel pyranochalcone derivatives as a new class of microtubule stabilizing agents

Twenty-five novel pyranochalcone derivatives were synthesized and evaluated for their in vitro and in vivo antiproliferative activities. Among them, compound 10i exhibited superior potent activity against 21 tumor cell lines including multidrug resistant phenotype with the IC50 values ranged from 0.09 to 1.30 μM. In addition, 10i significantly induced cell cycle arrest in G2/M phase, promoted tubulin polymerization into microtubules and caused microtubule stabilization. Further studies confirmed that 10i significantly suppressed the growth of tumor volume in HepG2 xenograft tumor model. Our study demonstrated that 10i could have beneficial antitumor activity as a novel microtubule stabilizing agent.

Cytotoxic and apoptotic effects of constituents from Millettia pachycarpa Benth.

The aim of this study is to investigate the cytotoxic and apoptotic effects of constituents from the seeds of Millettia pachycarpa Benth. Fourteen compounds (1-14) including one novel chalcone (10) were isolated as active principles from Chinese herbal medicine M. pachycarpa Benth. Their structures were identified by using spectroscopic methods. All isolates were then evaluated for their cytotoxic effects against several cancer cell lines (HepG2, C26, LL2 and B16) with cisplatin as a positive control. And their apoptosis-inducing effects were tested against HeLa-C3 cells with taxol as a positive control. Both studies showed that compounds 1, 2, 7 and 10 demonstrated significant cytotoxic and apoptotic effects against cancer cells. Moreover, in the apoptosis assay the novel chalcone (10) showed strong apoptosis inducing effects at a concentration of 2μM within 36h. It was found to be the most potent apoptotic inducer of the compounds isolated from M. pachycarpa Benth.

Design, synthesis, and structure-activity relationship studies of novel millepachine derivatives as potent antiproliferative agents.

In this paper, 38 millepachine derivatives have been designed, synthesized and evaluated for their in vitro and in vivo antiproliferative activity. Among these novel derivatives, 15 displayed more potent antiproliferative activity than millepachine against HepG2, K562, SK-OV-3, HCT116, HT29, and SW620 tumor cells (mean IC(50) = 0.64 vs. 2.86 μM, respectively). Furthermore, 15 could effectively inhibit tubulin polymerization in HepG2 cells, and induce the HepG2 cell cycle arrest at the G2/M phase in a concentration-dependant manner. Further studies confirmed that 15 significantly suppressed the growth of tumor volume and exerted more potent anticancer potency than millepachine and anticancer drug cisplatin in A549 lung xenograft tumor model.

Deguelin—An inhibitor to tumor lymphangiogenesis and lymphatic metastasis by downregulation of vascular endothelial cell growth factor-D in lung tumor model

Deguelin, a rotenoid of the flavonoid family, has been reported to possess antiproliferative and anticarcinogenic activities in several cell lines and tumor models. However, it is still unclear whether deguelin effectively inhibits tumor‐associated lymphangiogenesis and lymphatic metastasis. Since tumor production of vascular endothelial cell growth factor (VEGF)‐D was associated with tumor lymphangiogenesis and lymphatic metastasis, we established the mouse lymphatic metastasis model by transfecting high expression VEGF‐D into LL/2 Lewis lung cells (VEGF‐D‐LL/2) and explored the effects of deguelin on lymphatic metastasis in the immunocompetent C57BL/6 mice. Our results indicated that deguelin inhibited proliferation, migration of VEGF‐D‐LL/2 cells via downregulating AKT and mitogen‐activated protein kinase pathway and interfered tube formation of lymphatic vascular endothelial cells on matrigel at nanomolar concentrations. Deguelin significantly downregulated the expression of VEGF‐D both at mRNA and protein levels in VEGF‐D‐LL/2 cells in a dose‐dependent manner. In the in vivo study, intraperitoneal administration of deguelin (4 mg/kg) remarkably inhibited the tumor‐associated lymphangiogenesis and lymphatic metastasis. The rates of lymph node and lung metastasis in deguelin‐treated mice were 0 and 16.7% compared with 58.3 and 83.3% in control group mice, respectively. Deguelin also resulted in a remarkable delay of tumor growth and prolongation of life span. Immunohistochemical staining with antibodies against VEGF‐D, LYVE‐1 and VEGFR‐3 revealed fewer positive vessel‐like structures in deguelin‐treated mice compared with control group mice. Taken together, we demonstrate for the first time that deguelin suppresses tumor‐associated lymphangiogenesis and lymphatic metastasis by downregulation of VEGF‐D both in vitro and in vivo.

Barbigerone, a natural isoflavone, induces apoptosis in murine lung-cancer cells via the mitochondrial apoptotic pathway.

Barbigerone is a naturally occurring isoflavone with antioxidant activity. In present study, we investigated the antitumor activity of barbigerone against murine lung cancer cells LL/2 and the possible mechanism in vitro. Our results showed that barbigerone inhibited LL/2 cells proliferation in a concentration- and time-dependent manner and caused apoptotic death of LL/2 cells. Barbigerone-induced apoptosis was characterized by enhanced mitochondrial cytochrome c release, activation of caspase-3,-9, but not caspase-8. Exposure of LL/2 cells to barbigerone resulted in upregulation of Bcl-2-associated protein (Bax) and down-regulation of Bcl-2. In addition, proliferation inhibitory effect of barbigerone was associated with decreased level of phosphorylated p42/44 mitogen-activated protein kinase (p42/44 MAPK) and phosphorylated Akt. Moreover, barbigerone exhibit less toxicity to non-cancer cells than tumor cells. In conclusion, our results indicated that barbigerone can inhibit murine lung cancer cell proliferation by inducing apoptosis via mitochondrial apoptotic pathway and by decreasing phosphorylated p42/44 MAPK and Akt. Its potential to be a candidate of anti-cancer agent is worth being further investigated.