Osthole or imperatorin-mediated facilitation of glutamate release is associated with a synaptic vesicle mobilization in rat hippocampal glutamatergic nerve endings

Effects of imperatorin in the cardiovascular system and cancer

Patients with cancer survivors are at increased risk of cardiovascular disease(CVD). Cardio-oncology has developed as a new discipline with the advances in cancer treatment. There are many new challenges for the clinician and a new frontier for research and investigation. There is an urgent need for further study on the prevention of cardiovascular toxicity. Imperatorin (IMP) is a natural form of coumarin and extract from several plants with diver's pharmacokinetic effects, including antioxidant and anti-inflammatory properties. This review focus on the molecular mechanisms and pharmacological effects of Imperatorin maybe provide potential cancer and cardiovascular protection that targets IMP. Further studies are required to elucidate the entire spectrum of cytotoxic activities of these compounds to validate and expand their preclinical and clinical applications and to clarify the potential role of IMP.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

Docosahexaenoic acid reduces sterol regulatory element binding protein-1 and fatty acid synthase expression and inhibits cell proliferation by inhibiting pAkt signaling in a human breast cancer MCF-7 cell line

Background

Fatty acid synthase (FASN), the major enzyme in de novo fatty acid synthesis, is highly expressed in breast cancer and its expression is reduced by polyunsaturated fatty acids (PUFAs) in liver. We previously found a positive association between rat mammary tumor levels of the n-6 PUFA arachidonic acid (AA) and tumor weight. We examined the roles of the major n-3 PUFA, docosahexaenoic acid (DHA, 22:6n-3), and the major n-6 PUFA, AA, in FASN expression in, and proliferation of, human breast cancer MCF-7 cells.

Methods

The cells were treated for 48 h with BSA or 60 μM BSA-bound DHA, AA, or oleic acid (OA, 18:1n-9), then were incubated with or without estradiol or insulin. Western blot and ³H–thymidine incorporation assay were used to determine the role of DHA on FASN regulation and MCF-7 cell proliferation.

Results

DHA, but neither AA nor OA, inhibits estradiol-induced and insulin-induced expression of the precursor of sterol regulatory element binding protein-1 (p-SREBP-1), its mature form (m-SREBP-1), and FASN. Estradiol or insulin stimulation increased the pAkt/Akt and pS6/S6 ratios, expression of p-SREBP-1, m-SREBP-1, and FASN, and cell proliferation, and these effects were decreased by DHA. The DHA-induced decrease in FASN expression resulted from reduced pAkt/Akt signaling and not pERK1/2/ERK1/2 signaling. In addition, DHA enhanced the inhibitory effect of LY294002 on pAkt signaling and expression of p-SREBP-1, m-SREBP-1, and FASN. However, addition of rapamycin, an inhibitor of the mTOR signaling pathways, 1 h before addition of estradiol or insulin increased the pAkt/Akt ratio and FASN expression, and this effect was inhibited by addition of DHA 48 h before rapamycin.

Conclusion

We conclude that, in MCF-7 cells, DHA inhibits pAKT signaling and thus expression of p-SREBP-1, m-SREBP-1, and FASN and cell proliferation.

Cnidium monnieri: A Review of Traditional Uses, Phytochemical and Ethnopharmacological Properties

Cnidium monnieri (L.) Cuss., an annual plant of the Umbelliferae species is one of the most widely used traditional herbal medicines and its fruits have been used to treat a variety of diseases in China, Vietnam, and Japan. The aim of this review is to provide an up-to-date and comprehensive analysis of the botany, traditional uses, phytochemistry, pharmacology, toxicity and contraindication of Cnidium monnieri (L.) Cuss. and to provide future directions of research on this plant. To date, 350 compounds have been isolated and identified from Cnidium monnieri (L.) Cuss., including the main active constituent, coumarins. In vitro and in vivo studies suggest that osthole and other coumarin compounds possess wide range of pharmacological properties for the treatment of female genitals, male impotence, frigidity, skin-related diseases, and exhibit strong antipruritic, anti-allergic, antidermatophytic, antibacterial, antifungal, anti-osteoporotic effects. Although coumarins have been identified as the main active constituents responsible for the observed pharmacological effects, the molecular mechanisms of their actions are still unknown. Therefore, further studies are still required to reveal the structure-activity relationship of these active constituents. In addition, toxicological and clinical studies are also required to provide further data for pharmaceutical use.

Osthole: A Review on Its Bioactivities, Pharmacological Properties, and Potential as Alternative Medicine

This paper reviews the latest understanding of biological and pharmacological properties of osthole (7-methoxy-8-(3-methyl-2-butenyl)-2H-1-benzopyran-2-one), a natural product found in several medicinal plants such as Cnidium monnieri and Angelica pubescens. In vitro and in vivo experimental results have revealed that osthole demonstrates multiple pharmacological actions including neuroprotective, osteogenic, immunomodulatory, anticancer, hepatoprotective, cardiovascular protective, and antimicrobial activities. In addition, pharmacokinetic studies showed osthole uptake and utilization are fast and efficient in body. Moreover, the mechanisms of multiple pharmacological activities of osthole are very likely related to the modulatory effect on cyclic adenosine monophosphate (cAMP) and cyclic adenosine monophosphate (cGMP) level, though some mechanisms remain unclear. This review aims to summarize the pharmacological properties of osthole and give an overview of the underlying mechanisms, which showcase its potential as a multitarget alternative medicine.

Bioavailability enhancement of osthole after oral administration of Bushen Yizhi prescription extract to rats followed by Cnidium monnieri (L.) Cusson fruits extract in comparison to pure osthole at different doses

ETHNOPHARMACOLOGICAL RELEVANCE

Bushen Yizhi prescription (BSYZ) is a traditional Chinese compound prescription, which is commonly used in China for treating ShenXu and hypophrenia based on traditional Chinese medicine and Alzheimer's Disease according to modern Chinese medicine. Cnidium monnieri (L.) Cusson fruits (CM) is treated as the main herb of BSYZ, and its main active ingredient Osthole (OST) is considered as one of the major active ingredients of BSYZ. Even though OST plays an important role in the BSYZ its bioavailability is poor. In order to investigate whether the bioavailability of OST was influenced by BSYZ and CM extract, the comparative evaluations on pharmacokinetics of OST after oral administration of pure OST at different doses, CM and BSYZ extract were studied.

MATERIALS AND METHODS

30 rats were randomly assigned to five groups and orally administered with pure OST at different doses (15, 75 and 150 mg/kg), CM (15 mg/kg OST) and BSYZ (15 mg/kg OST) extract. At different predetermined time points after administration, the concentrations of OST in rat plasma were determined by using the HPLC-UV method, and main pharmacokinetic parameters were investigated.

RESULTS

The results showed that the pharmacokinetic parameters of OST were significantly different (p<0.05) among the groups. The AUC(0→t), AUC(0→∞) and Cmax of OST were significantly increased after oral administration of BSYZ extract, followed by CM extract, in comparison to pure osthole at different doses.

CONCLUSIONS

This present study indicated that the bioavailability of pure OST after oral administration was extremely low and it was dramatically enhanced because of the synergistic effect of the traditional Chinese Bushen Yizhi prescription.

Effect of oral imperatorin on memory in mice

The aim of this study was to explore the effect of the acetylcholinesterase inhibiting mixture of extracts of Angelica archangelica fruit and Geranium sylvaticum on memory. Furthermore the effect of the main compound, the furanocoumarin imperatorin, which has been shown to affect several neurotransmitters, was studied. Passive avoidance was measured by step-down latency and step-through latency of 10 months old mice receiving 0.79 mg/kg of imperatorin daily, pure or as part of the extracts, for 14 days or longer. Step-down latency was significantly higher in both groups receiving imperatorin than in the control group. In contrast, no difference was found between treatment groups regarding step-through latency. The results indicate that the imperatorin is the main active component of the extract mixture.

Suppression of voltage-gated Na(+) channels and neuronal excitability by imperatorin

Imperatorin is a naturally occurring furocoumarin compound isolated from plants such as Angelica archangelica and Cnidium monnieri. It has multiple pharmacological effects including anticonvulsant effects. Here we determined the effects of imperatorin on voltage-gated Na(+) channels (VGSC) using whole-cell patch clamp techniques in differentiated neuronal NG108-15 cells. We showed that imperatorin inhibited VGSC; such inhibition did not show state-dependence. Imperatorin caused a left shift in the steady-state inactivation curve without affecting activation gating. The inhibition of VGSC by imperatorin displayed a mild frequency-dependence. Imperatorin was also shown to inhibit VGSC and action potential amplitude without affecting voltage-gated K(+) channels in rat hippocampal CA1 neurons. In conclusion, our results suggest that imperatorin dampens neuronal excitability by inhibiting VGSC.

Involvement of the cGMP pathway in the osthole-facilitated glutamate release in rat hippocampal nerve endings

Osthole, an active constituent isolated from Cnidium monnieri (L.) Cusson, has previously been shown to have the capacity to increase depolarization-evoked glutamate release in rat hippocampal nerve terminals. As cGMP-dependent signaling cascade has been found to modulate glutamate release at the presynaptic level, the aim of this study was to further examine the role of cGMP signaling pathway in the regulation of osthole on glutamate release in hippocampal synaptosomes. Results showed that osthole dose-dependently increased intrasynaptosomal cGMP levels. The elevation of cGMP levels by osthole was prevented by the phosphodiesterase 5 inhibitor sildenafil but was insensitive to the guanylyl cyclase inhibitor ODQ. In addition, osthole-induced facilitation of 4-aminopyridine (4-AP)-evoked glutamate release was completely prevented by the cGMP-dependent protein kinase (PKG) inhibitors, KT5823, and Rp-8-Br-PET-cGMPS. Direct activation of PKG with 8-Br-cGMP or 8-pCPT-cGMP also occluded the osthole-mediated facilitation of 4-AP-evoked glutamate release. Furthermore, sildenafil exhibited a dose-dependent facilitation of 4-AP-evoked release of glutamate and occluded the effect of osthole on the 4-AP-evoked glutamate release. Collectively, our findings suggest that osthole-mediated facilitation of glutamate release involves the activation of cGMP/PKG-dependent pathway.

Distinct effects of imperatorin on allergic rhinitis: imperatorin inhibits caspase-1 activity in vivo and in vitro

Because imperatorin (IPT), the furanocoumarins exhibits anti-inflammatory activity, we reasoned that IPT might modulate the allergic rhinitis (AR). The aim of this study was to analyze the regulation of AR by IPT. Here, we show the effect and mechanism of IPT in an ovalbumin (OVA)-induced AR model. The number of rubs after the OVA challenge in the OVA-sensitized mice was significantly higher than that in the OVA-unsensitized mice. The increased number of rubs was inhibited by the oral administration of IPT. The increased levels of IgE and histamine in the OVA-sensitized mice were reduced by IPT administration. The levels of interferon-γ were enhanced, whereas the levels of interleukin (IL)-4 were reduced on the spleen tissue of the IPT-administered AR mice. Protein levels of IL-1β, macrophage inflammatory protein-2, intercellular adhesion molecule-1, and cyclooxygenase-2 were reduced by IPT administration in the nasal mucosa of the OVA-sensitized mice. In the IPT-administered mice, the number of eosinophils and mast cells infiltration increased by OVA-sensitization were also decreased. In addition, IPT inhibited caspase-1 activity in the same nasal mucosa tissue. In activated human mast cells, the receptor-interacting protein 2 (RIP2), IκB kinase (IKK)-β, nuclear factor-κB (NF-κB)/RelA, and caspase-1 activation were increased, but increased RIP2, IKK-β, NF-κB/RelA, and caspase-1 activation were inhibited by the treatment of IPT. In addition, IPT inhibited caspase-1 activity and IL-1β production in IgE-stimulated bone marrow-derived mast cells. We can conclude that IPT exerts significant effects by regulating of caspase-1 activation in AR animal and in vitro models.

HPLC-based activity profiling of Angelica pubescens roots for new positive GABAA receptor modulators in Xenopus oocytes

A petroleum ether extract of the traditional Chinese herbal drug Duhuo (roots of Angelica pubescens Maxim. f. biserrata Shan et Yuan), showed significant activity in a functional two-microelectrode voltage clamp assay with Xenopus oocytes which expressed recombinant γ-aminobutyric acid type A (GABA(A)) receptors of the subtype α(1)β(2)γ(2S). HPLC-based activity profiling of the active extract revealed six compounds responsible for the GABA(A) receptor modulating activity. They were identified by microprobe NMR and high resolution mass spectrometry as columbianetin acetate (1), imperatorin (3), cnidilin (4), osthol (5), and columbianedin (6). In concentration-dependent experiments, osthol and cnidilin showed the highest potentiation of the GABA induced chloride current (273.6%±39.4% and 204.5%±33.2%, respectively at 300 μM). Bisabolangelone (2) only showed minor activity at the GABA(A) receptor. The example demonstrates that HPLC-based activity profiling is a simple and efficient method to rapidly identify GABA(A) receptor modulators in a bioactive plant extract.