Loureirin B inhibits Cervical Cancer Development by Blocking PI3K/AKT Signaling Pathway: Network Pharmacology Analysis and Experimental Validation.

Loureirin B (LB) is an iconic component of Chinese dragon's blood that presents anti-cancer effects in gastric cancer and liver cancer. Although LB has shown benefits in treating several disorders such as cardiac fibrosis, cerebral ischemia/reperfusion, and osteoporosis, its effect on cervical cancer remains unknown. This study aimed to investigate the effects and mechanisms of LB on treating cervical cancer. A CCK-8 assay was conducted to determine the influence of LB on the viability of HeLa cells. Colony formation assay was performed to verify the impact of LB on HeLa cell proliferation. Cell cycle and apoptosis were detected by flow cytometry and western blot. The scratch assay, Transwell assay and western blot were used to examine the migration and invasion capacity of HeLa cells. The potential targets and signaling pathways of LB treating cervical cancer were predicted by network pharmacology analysis and subsequently validated in vitro. The results showed that the HeLa cell viability gradually declined to 64.83% for 12 h, 53.17% for 24 h, and 42.38% for 48 h after treatment with 5-80 µg/mL LB. Treatment with 20 µg/mL LB decreased cell colonies from 156.7 ± 11.7 to 102.7 ± 5.7. LB arrested cell cycle by reducing the expressions of Ki-67 and PCNA. Compared to the cell apoptosis rate of 2.63% in control group, LB increased it to 6.59% via upregulating Bax and suppressing Bcl-2 expressions. Additionally, LB reduced the invasion and migration capacity of HeLa cells by decreasing MMP-2 and MMP-9 levels. Network pharmacology analysis revealed that LB might suppress the PI3K/AKT signaling pathway to exert the aforementioned effects, as evidenced by a PI3K agonist attenuating the effects of LB on HeLa cells. In conclusion, this study demonstrated that LB inhibited the proliferation of cervical cancer cells, induced its apoptosis, and reduced its invasion and migration via targeting the PI3K/AKT signaling pathway.

Loureirin B ameliorates cholestatic liver fibrosis via AKT/mTOR/ATG7-mediated autophagy of hepatic stellate cells.

AIM OF THE STUDY: Chronic cholestasis leads to liver fibrosis, which lacks effective treatment. In this study, we investigated the role and mechanisms of action of loureirin B (LB) in cholestatic liver fibrosis. MATERIALS AND METHODS: Bile duct ligation (BDL)-induced hepatic fibrosis mice were used as in vivo models. Transforming growth factor-ß1 (TGF-ß1)-pretreated HSC-T6 cells were used to explore the mechanism by which LB attenuates liver fibrosis in vitro. RNA sequencing, quantitative PCR (qPCR), western blotting, immunohistochemistry and immunofluorescence were performed to detect the fibrosis markers and measure autophagy levels. Flow cytometry, cell counting kit-8 (CCK-8) assay, and 5'-ethynyl-2'-deoxyuridine (EdU) assay were conducted to detect cell proliferation and viability. GFP-RFP-LC3 adenovirus, autophagy-related protein 7 (ATG7) siRNA, and bafilomycin A1 (BafA1) were used to verify autophagic flux. RESULTS: Our results showed that LB ameliorates liver injury, inhibits collagen deposition, and decreases the expressions of fibrosis-related markers in BDL-induced mouse livers. In vitro, we found that LB inhibited proliferation and migration, promoted apoptosis, and inhibited the activation of HSC-T6 cells pretreated with TGF-ß1. RNA sequencing analysis of HSC-T6 cells showed that LB treatment predominantly targeted autophagy-related pathways. Further protein analysis indicated that LB downregulated the expression of phosphorylated AKT (p-AKT) and phosphorylated mTOR (p-mTOR), and upregulated LC3-II, p62, and ATG7 both in vivo and in vitro. Intriguingly, ATG7 inactivation reversed the antifibrotic effects of LB on HSC-T6 cells. CONCLUSIONS: LB can improve BDL-induced liver fibrosis by inhibiting the activation and proliferation of HSCs and is expected to be a promising antifibrotic drug.

Loureirin B improves H/R-induced hepatic ischemia-reperfusion injury by downregulating ALOX5 to regulate mitochondrial homeostasis.

This study was conceived to explore the role and the mechanism of Loureirin B (LB) in hepatic IRI. The viability of LB-treated AML-12 cells was assessed using CCK-8 assay and inflammatory cytokines were detected using ELISA. The activities of ROS and oxidative stress markers MDA, SOD, and GSH-Px were detected using DCFH-DA and corresponding assay kits. The cell apoptosis and caspase3 activity were estimated with flow cytometry and caspase3 assay kits. The expressions of arachidonate 5-lipoxygenase (ALOX5) and apoptosis- and mitochondrial dynamics-related proteins were detected using western blot. The interaction between LB and ALOX5 was analyzed with molecular docking. The transfection efficacy of oe-ALOX5 was examined with RT-qPCR and western blot. Mitochondrial membrane potential was detected with JC-1 staining and immunofluorescence (IF) assay was employed to estimate mitochondrial fusion and fission. The present work found that LB revived the viability, inhibited inflammatory response, suppressed oxidative stress, repressed the apoptosis, and maintained mitochondrial homeostasis in H/R-induced AML-12 cells, which were all reversed by ALOX5 overexpression. Collectively, LB regulated mitochondrial homeostasis by downregulating ALOX5, thereby improving hepatic IRI.

Loureirin B protects against cerebral ischemia/reperfusion injury through modulating M1/M2 microglial polarization via STAT6 / NF-kappaB signaling pathway.

The latest research indicates that modulating microglial polarization from M1 to M2 phenotype may be a coping therapy for ischemic stroke. The present study thereby evaluated the effects of loureirin B (LB), a monomer compound extracted from Sanguis Draconis flavones (SDF), on cerebral ischemic injury and the potential mechanisms. The middle cerebral artery occlusion (MCAO) model was established in male Sprague-Dawley rats to induce cerebral ischemia/reperfusion (I/R) injury in vivo, and BV2 cells were exposed to oxygen-glucose deprivation and reintroduction (OGD/R) to mimic cerebral I/R injury in vitro. The results showed that LB significantly reduced infarct volume, neurological deficits and neurobehavioral deficits, apparently improved histopathological changes and neuronal loss in cortex and hippocampus of MCAO/R rats, markedly decreased the proportion of M1 microglia cells and the level of pro-inflammatory cytokines, and increased the proportion of M2 microglia and the level of anti-inflammatory cytokines both in vivo and in vitro. In addition, LB evidently improved the p-STAT6 expression and reduced the NF-κB (p-p65) expression after cerebral I/R injury in vivo and in vitro. IL-4 (a STAT6 agonist) exhibited a similar impact to that of LB, while AS1517499 (a STAT6 inhibitor) significantly reversed the effect of LB on BV-2 cells after OGD/R. These findings point to the protection of LB against cerebral I/R injury by modulating M1/M2 polarization of microglia via the STAT6/NF-κB signaling pathway, hence LB may be a viable treatment option for ischemic stroke.

The immunosuppressive effects and mechanisms of loureirin B on collagen-induced arthritis in rats.

Introduction: Rheumatoid arthritis (RA) is a common disease mainly affecting joints of the hands and wrists. The discovery of autoantibodies in the serum of patients revealed that RA belonged to the autoimmune diseases and laid a theoretical basis for its immunosuppressive therapy. The pathogenesis of autoimmune diseases mainly involves abnormal activation and proliferation of effector memory T cells, which is closely related to the elevated expression of Kv1.3, a voltage-gated potassium (Kv) channel on the effector memory T cell membrane. Drugs blocking the Kv1.3 channel showed a strong protective effect in RA model animals, suggesting that Kv1.3 is a target for the discovery of specific RA immunosuppressive drugs. Methods: In the present study, we synthesized LrB and studied the effects of LrB on collagen- induced arthritis (CIA) in rats. The clinical score, paw volume and joint morphology of CIA model rats were compared. The percentage of CD3+, CD4+ and CD8+ T cells in rat peripheral blood mononuclear and spleen were analyzed with flow cytometry. The concentrations of inflammatory cytokines interleukin (IL)-1b, IL-2, IL-4, IL-6, IL-10 and IL-17 in the serum of CIA rats were analyzed with enzyme-linked immunosorbent assay. The IL-1b and IL-6 expression in joints and the Kv1.3 expression in peripheral blood mononuclear cells (PBMCs) were quantified by qPCR. To further study the mechanisms of immunosuppressive effects of LrB, western blot and immunofluorescence were utilized to study the expression of Kv1.3 and Nuclear Factor of Activated T Cells 1 (NFAT1) in two cell models - Jurkat T cell line and extracted PBMCs. Results: LrB effectively reduced the clinical score and relieved joint swelling. LrB could also decrease the percentage of CD4+ T cells, while increase the percentage of CD8+ T cells in peripheral blood mononuclear and spleen of rats with CIA. The concentrations of inflammatory cytokines interleukin (IL)-1b, IL-2, IL-6, IL-10 and IL-17 in the serum of CIA rats were significantly reduced by LrB. The results of qPCR showed that Kv1.3 mRNA in the PBMCs of CIA rats was significantly higher than that of the control and significantly decreased in the LrB treatment groups. In addition, we confirmed in cell models that LrB significantly decreased Kv1.3 protein on the cell membrane and inhibited the activation of Nuclear Factor of Activated T Cells 1 (NFAT1) with immune stimulus. Conclusion: In summary, this study revealed that LrB could block NFAT1 activation and reduce Kv1.3 expression in activated T cells, thus inhibiting the proliferation of lymphocytes and the release of inflammatory cytokines, thereby effectively weakening the autoimmune responses in CIA rats. The effects of immunosuppression due to LrB revealed its potential medicinal value in the treatment of RA.

Loureirin B protects against obesity via activation of adipose tissue ω3 PUFA-GPR120-UCP1 axis in mice.

Obesity and related metabolic disorders are worldwide epidemics. Current lifestyle interventions and drug treatment for obesity seem insufficient. Here, we show that Loureirin B (LB), a major flavonoid molecule extracted from Sanguis Draxonis, prevents diet-induced obesity and ameliorates concomitant metabolic abnormalities including fatty liver, insulin resistance and systemic inflammation in mice. Mechanistically, LB treatment increases the proportion of ω3 polyunsaturated fatty acids (PUFAs) in brown adipose tissue (BAT) and white adipose tissue (WAT), which subsequently activates the key lipid sensor GPR120. In line with this, LB treatment promotes browning of WAT and activates BAT thermogenesis through upregulation of UCP1, a downstream effector of GPR120. Conversely, inhibition of GPR120 abolishes the thermogenic effect of LB in primary cultured brown adipocytes. Together, these results suggest that LB possesses anti-obesity property by enhancing adipose tissue thermogenesis via activation of ω3 PUFA-GPR120-UCP1 axis and holds promises for combating obesity and its related metabolic syndrome.

Loureirin B alleviates cardiac fibrosis by suppressing Pin1/TGF-ß1 signaling.

It is well-established that cardiac fibrosis contributes to cardiac dysfunction and adverse outcomes. However, the underlying mechanisms remain elusive, warranting further studies to develop new therapeutic strategies. It has been suggested that loureirin B can ameliorate the progression of fibrotic diseases. This study investigated the effects of loureirin B on cardiac fibrosis and explored the underlying mechanisms. Transverse aortic constriction (TAC) was performed to induce cardiac fibrosis in mice. Loureirin B (10 mg/kg/day) or saline was continuously delivered via subcutaneous osmotic mini-pumps. Cardiac fibroblasts (CFs) were treated with angiotensin II (Ang II, 100 nM, 24 h) to simulate fibrosis in vitro. Immunochemistry, echocardiography, and Sircol collagen assays were conducted to evaluate the cardioprotective effects. Quantitative real-time polymerase chain reaction, Western blot, and transfection techniques were performed to elucidate the mechanisms. Results showed that loureirin B prevented cardiac fibrosis and improved cardiac function in mice subjected to TAC. Treatment with loureirin B inhibited the elevation of inflammatory factors (interleukin-1ß, interleukin-6, and tumor necrosis factor-α), transforming growth factor-ß1 (TGF-ß1), and Pin1 induced by TAC. Furthermore, loureirin B treatment inhibited the increased fibroblast activation and collagen synthesis induced by Ang II in CFs. In addition, loureirin B inhibited increased expression of TGF-ß1 and Pin1 induced by Ang II or TAC. Mechanistically, overexpression of Pin1 induced increased TGF-ß1 expression and blocked the anti-fibrotic effects in Ang II-induced CFs treated with loureirin B. Loureirin B ameliorated cardiac fibrosis and dysfunction both in vitro and in vivo probably through the Pin1/TGF-ß1 signaling pathway.

Loureirin B attenuates insulin resistance in HepG2 cells by regulating gluconeogenesis signaling pathway.

Insulin resistance (IR) is the main cause of type 2 diabetes. The liver is the organ where insulin is secreted from the pancreas, and it regulates the storage and release of glucose according to the body's demand. Althouth Loureirin B (LB) has been reported to promote insulin secretion and decrease blood glucose, the effects of LB on glucose metabolism in the liver and the mechanism is still unclear. Different concentrations of LB were applied to treat on insulin resistance model (IR-HepG2) cells. The research results showed that LB inhibited the production of ROS (Reactive oxygen species) in IR-HepG2 cells, promoted the phosphorylation of AKT, down-regulated the expression of FoxO1, and up-regulated the expression of IRS1 and GLUT4. In addition, LB also down regulated the glucose metabolism related genes PEPCK and GSK3ß. The glucose uptake, consumption and glycogen content were increased. Moreover, LB-treated diabetic mice also showed hypoglycaemic effects. In summary, LB may ameliorate type 2 diabetes by preventing the inactivation of IRS1/AKT pathway in IR-HepG2 cells, increasing insulin sensitivity, and regulating glucose uptake and production.

Modulation on tetrodotoxin-resistant sodium current of loureirin B in rat dorsal root ganglion neurons via cyclic AMP-dependent protein kinase A.

To search the modulation mechanism of loureirin B, a flavonoid is extracted from Dracaena cochinchinensis, on tetrodotoxin-resistant (TTX-R) sodium channel in dorsal root ganglion (DRG) neurons of rats. Experiments were carried out based on patch-clamp technique and molecular biological methods. We observed the time-dependent inhibition of loureirin B on TTX-R sodium currents in DRG neurons and found that neither occupancy theory nor rate theory could well explain the time-dependent inhibitory effect of loureirin B on TTX-R sodium currents. It suggested that a second messenger-mediated signaling pathway may be involved in the modulation mechanism. So the cyclin AMP (cAMP) level of the DRG neurons before and after incubation with loureirin B was tested by ELISA Kit. Results showed that loureirin B could increase the cAMP level and the increased cAMP was caused by the enhancement of adenylate cyclase (AC) induced by loureirin B. Immunolabelling experiments further confirmed that loureirin B can promote the production of PKA in DRG neurons. In the presence of the PKA inhibitor H-89, the inhibitory effect of loureirin B on TTX-R sodium currents was reversed. Forskolin, a tool in biochemistry to raise the levels of cAMP, also could reduce TTX-R sodium currents similar to that of loureirin B. These studies demonstrated that loureirin B can modulate the TTX-R sodium channel in DRG neurons via an AC/cAMP/PKA pathway involving the activation of AC and PKA, which also can be used to explain the other pharmacological effects of loureirin B.

Loureirin B suppresses RANKL-induced osteoclastogenesis and ovariectomized osteoporosis via attenuating NFATc1 and ROS activities.

Rationale: Osteoporosis is a severe bone disorder that is a threat to our aging population. Excessive osteoclast formation and bone resorption lead to changes in trabecular bone volume and architecture, leaving the bones vulnerable to fracture. Therapeutic approaches of inhibiting osteoclastogenesis and bone resorption have been proven to be an efficient approach to prevent osteoporosis. In our study, we have demonstrated for the first time that Loureirin B (LrB) inhibits ovariectomized osteoporosis and explored its underlying mechanisms of action in vitro. Methods: We examined the effects of LrB on RANKL-induced osteoclast differentiation and bone resorption, and its impacts on RANKL-induced NFATc1 activation, calcium oscillations and reactive oxygen species (ROS) production in osteoclasts in vitro. We assessed the in vivo efficacy of LrB using an ovariectomy (OVX)-induced osteoporosis model, which was analyzed using micro-computed tomography (micro-CT) and bone histomorphometry. Results: We found that LrB represses osteoclastogenesis, bone resorption, F-actin belts formation, osteoclast specific gene expressions, ROS activity and calcium oscillations through preventing NFATc1 translocation and expression as well as affecting MAPK-NFAT signaling pathways in vitro. Our in vivo study indicated that LrB prevents OVX-induced osteoporosis and preserves bone volume by repressing osteoclast activity and function. Conclusions: Our findings confirm that LrB can attenuate osteoclast formation and OVX-induced osteoporosis. This novel and exciting discovery could pave the way for the development of LrB as a potential therapeutic treatment for osteoporosis.

Rapid identification of dragon blood samples from Daemonorops draco, Dracaena cinnabari and Dracaena cochinchinensis by MALDI-TOF mass spectrometry.

INTRODUCTION: Dragon blood is a deep-red plant resin which has been used as folk medicine for more than a thousand years. It can be produced from at least four entirely different plant families: Asparagaceae, Arecaceae, Chamaesyce, and Fabaceae. Current pharmacopeia states that the only "authentic" source of dragon blood is the palm tree, Daemonorops draco. OBJECTIVE: The present study aims to find a high-throughput method to screen and identify the plant sources of commercial dragon blood products. METHODOLOGY: A matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) based method for rapid screening of dracorhodin in commercial dragon blood samples was established in this study. RESULTS: Well-resolved peaks of dracorhodin in spectra were observed in the crude extracts of samples. Dragon blood samples from two other plant species, Dracaena cinnabari and Dracaena cochinchinensis, were also examined. Their indicator compounds, loureirin A and B, were detected in these plants. CONCLUSION: A MALDI-TOF based method for preliminarily examination of commercial dragon blood samples is reported here. In contrast to MALDI-TOF, liquid chromatography mass spectrometry (LC-MS) is a time-consuming and costly method, not ideal for routine and large-scale screening of commercial samples.

Loureirin B Promotes Axon Regeneration by Inhibiting Endoplasmic Reticulum Stress: Induced Mitochondrial Dysfunction and Regulating the Akt/GSK-3ß Pathway after Spinal Cord Injury.

Axon retraction greatly limits functional recovery after spinal cord injury (SCI) and neuron polarization, which affects processes including axon formation and development, is a promising target for promoting axon regeneration. Increasing microtubule stability has been demonstrated to improve intrinsic axon regeneration processes and is critically related to endoplasmic reticulum (ER)-mitochondria interactions. We used real-time polymerase chain reaction, Western blotting, and immunofluorescence to screen a variety of natural compounds, and found that Loureirin B (LrB) effectively promoted neuron polarization and axon regeneration in vitro and in vivo. LrB significantly inhibited ER stress and thereby promoted mitochondrial functions by regulating mitochondrial fusion. Further, LrB reactivated the Akt/GSK-3ß pathway, which plays critical roles in cell survival and microtubule stabilization. Taken together, our results suggest that the effects of LrB on neuron regeneration involve the inhibition of ER stress-induced mitochondrial dysfunction and activation of the Akt/GSK-3ß pathway, which further promotes microtubule stabilization. LrB may therefore be a promising candidate for facilitating recovery following SCI.

New Quality Problems and Control Methods for Imported Draconis Sanguis / 中国药学杂志

OBJECTIVE: To explore the new quality problems of Draconis Sanguis imported from Indonesia. METHODS: According to the quality standard of imported medicinal materials and Ch.P method, exploratory analysis was carried out on 10 batches of imported Draconis Sanguis and three batches of Draconis Sanguis fruits. RESULTS: The dracohodin content in three batches of Draconis Sanguis fruits was 1.2%-2.4%. Three batches of imported Draconis Sanguis were obtained by directly pulverization of Draconis Sanguis fruits, and loureirin A and loureirin B were detected in one batch of Draconis Sanguis, suggesting that dracaena cochinchinensis was added. CONCLUSION: Among the 10 batches of imported Draconis Sanguis, three batches are determined to be unqualified due to character inconformity, and the other batch is judged to be unqualified due to the addition of dracaena cochinchinensis.

Simulated Microgravity Altered the Metabolism of Loureirin B and the Expression of Major Cytochrome P450 in Liver of Rats.

Loureirin B (LB) is the marker compound of dragon blood (DB), which exhibits great potentials in protecting astronauts' health against radiation and simulated microgravity (SM). Pharmacokinetics of LB is reported to be significantly altered by SM. Here, we investigated key metabolic features of LB in rat liver microsome (RLM) and the effects of SM on LB metabolism as well as on expression of major hepatic cytochrome P450 (CYP450) isoforms. Ten metabolites were tentatively identified based on fragmentation pathways using LC-MS/MS method and elimination kinetics of LB followed a typical Michaelis-Menten equation (V max was 1.32 µg/min/mg and K m was 13.33 µg/mL). CYP1A2, CYP2C11, CYP2D1, and CYP3A2 were involved in the metabolism of LB and the relative strength was: CYP3A2 > CYP2C11 > CYP2D1 > CYP1A2. Comparative studies suggested that elimination of LB in RLM was remarkably increased by 3-day and 14-day SM, and the generation of identified metabolites was affected as well. Additionally, 3-day and 14-day SM showed obvious regulatory effects on the expression of major CYP450 isoforms, which might contribute to the increased elimination of LB. The data provided supports for the application of DB as a protective agent and the reasonable use of current medications metabolized by hepatic CYP450 in space missions.

Loureirin B inhibits the proliferation of hepatic stellate cells and the Wnt/ß-catenin signaling pathway by regulating miR-148-3p.

BACKGROUND: We investigated the activity of loureirin B against liver fibrosis and the underlying molecular mechanisms. METHODS: Hepatic stellate cells (HSCs) from Sprague-Dawley rats were treated with different concentrations of loureirin B. We used the MTT assay to determine HSC proliferation, flow cytometry to analyze apoptosis, and western blot to determine the expressions of Bax, Bcl-2, Wnt1 and ß-catenin. Real-time PCR was used to determine the expressions of Wnt1 and miR-148-3p. RESULTS: The MTT assay showed that loureirin B treatment significantly inhibited the proliferation of HSCs in time- and dose-dependent manners. Loureirin B significantly promoted the apoptosis of HSCs, increased the expression of Bax and decreased the Bcl-2 level. Western blot analysis showed that the expressions of Wnt1 and ß-catenin were obviously lower in the loureirin B treatment group than in the control group. We also found that loureirin B could decrease the Wnt1 mRNA level and increase miR-148-3p expression. Knockdown of miR-148-3p using inhibitor could reverse the effects of loureirin B on the proliferation and apoptosis of HSCs and the expressions of Bax, Bcl-2, Wnt1 and ß-catenin. CONCLUSION: Our results suggest that loureirin B inhibited the proliferation and promoted the apoptosis of HSCs, and suppressed the Wnt/ß-catenin signaling pathway via regulation of miR-148-3p.

Loureirin B promotes insulin secretion through inhibition of KATP channel and influx of intracellular calcium.

The development of new diabetes drugs continues to be explored. Loureirin B, a flavonoid, extracted from Dracaena cochinchinensis, has been confirmed to increase insulin secretion and decrease blood glucose levels. For searching the promotion of insulin secretion with the treatment of loureirin B, experiments were employed based on cell experiments and computational methods. First, promotion of insulin secretion was dependent on extracellular glucose concentration. At the genetic level, loureirin B enhanced the relative mRNA level of Pdx-1 and MafA. Meanwhile the intracellular level of ATP increased due to the continuous absorption of glucose. Further experiments showed that the currents of KATP channel on Ins-1 cells were inhibited and the voltage-dependent calcium channels were subsequently activated. The increase of Cx43 protein expression might mediate the Ca2+ to the intracellular. Through computational simulation, we hypothesized that loureirin B might interact with KATP channels to promote insulin secretion. In conclusion, it could be concluded that loureirin B promoted insulin secretion mainly through increasing mRNA level of Pdx-1, MafA, intracellular ATP level, inhibiting the KATP current, influx of Ca2+ to the intracellular.

Inhibitive effect of loureirin B plus capsaicin on tetrodotoxin-resistant sodium channel.

OBJECTIVE: To investigate whether the effect of loureirin B plus capsaicin on tetrodotoxin-resistant (TTX-R) sodium channel. METHODS: By using whole-cell patch-clamp recordings, in acutely isolated dorsal root ganglion (DRG) neurons, the combined effects of loureirin B and capsaicin on TTX-R sodium channel were observed. Based on the data, the interaction between loureirin B and capsaicin in their modulation on TTX-R sodium channel was assessed. RESULTS: Loureirin B could not induce transient inward TRPV1 current. Capsazepine, a transient receptor potential vanilloid l (TRPV1) antagonist, could not attenuate the block of 0.64 mmol/L loureirin B on TTX-R sodium channel. There was no significant difference (P > 0.05) between IC50 of loureirin B (0.37 mmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that (0.38 mmol/L) in capsaicin-insensitive DRG neurons. However, there was a significant difference (P < 0.05) between the IC50 of capsaicin (0.28 ¦Ìmol/L) on TTX-R sodium channel in capsaicin-sensitive DRG neurons and that (52.24 ¦Ìmol/L) in capsaicin-insensitive DRG neurons. Four combinations composed of various concentrations of loureirin B and capsaicin could all inhibit TTX-R sodium currents but have different interactions between loureirin B and capsaicin. CONCLUSION: Loureirin B plus capsaicin could produce double blockage on TRPV1 and modulation on TTX-R sodium channel. The action of loureirin B on TTX-R sodium channel was independent of TRPV1 but similar with that of capsaicin on TTX-R sodium channel in capsaicin-insensitive DRG neurons.

Comparison of three methods for analyzing loureirin B and human serum albumin interaction using capillary electrophoresis.

Loureirin B (LB), a bioactive drug, is widely used in the treatment of biological diseases. However, due to its poor solution in water, it is important to find the approach which helps LB to specific biological targets. As the most abundant protein in plasma, HSA plays the role of a carrier of numerous drug ligand. Thus, the interaction between LB and HSA was explored by ACE, CE frontal analysis, and pressure-mediated ACE under simulated physiological conditions (pH 7.4). The binding constants were calculated as 13.14 × 104 L/mol, 7.00 × 104 L/mol, and 2.78 × 104 L/mol for each method, respectively. At the same time, the binding site number (n = 1.429) could be only calculated by the CE frontal analysis method. Furthermore, good experimental repeatability was obtained by pressure-mediated ACE with RSDs for retention times and peak areas within 2.149 and 1.228, respectively.

Determination of five active components in Draconis Resina by QAMS method / 中草药

Objective To establish a quantitative analysis of multi-components by single marker (QAMS) for determination of five active components in Draconis Resina and discuss application of QAMS in quality control of ethnic medicines. Methods Using the method of HPLC, the Fortis Xi C18 column (250 mm × 4.6 mm, 5 μm) was used. The mobile phase was composed of acetonitrile (A)-1.0% acetic acid (B) with gradient elution (0-10 min, A: 25%→30%; 10-60 min, A: 30%→50%) at the flow rate of 1.0 mL/min. The detection wavelength was 278 nm, the column temperature was 30 ℃ and the sample size was 10 μL. Pterostilbene was selected as an internal standard to establish the relative correction factors (RCFs) of 7, 4’-dihydroxyflavone, resveratrol, loureirin A, and loureirin B with reference to pterostilbene so as to achieve simultaneous determination of multi-indexed components. The contents of five active components were determined by both external standard method (ESM) and QAMS. Meanwhile, relative error (RE) between QAMS and ESM was analyzed to evaluate QAMS method. Results There were good linearities in the range of 10.23-102.27 μg/mL for 7,4’-dihydroxyflavone, 11.01-110.14 μg/mL for resveratrol, 9.47-94.72 μg/mL for loureirin A, 11.59-115.90 μg/mL for loureirin B and 24.35-243.52 μg/mL for pterostilbene, RCFs of 7,4’-dihydroxyflavone, resveratrol, loureirin A and loureirin B with reference to pterostilbene were 0.626, 1.064, 1.154, and 0.837 respectively, and repeatability was good in different experimental conditions (RSD < 3.0%).There were no significant difference between the quantitative results of the two methods. Conclusion QAMS method is feasible, credible, and can be used to determine multiple components in Draconis Resina. QAMS can be adopted as a novel strategy for quality control of ethnic medicines.

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF-ß/Smad pathway.

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars. To investigate the therapeutic effects of loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that loureirin B dose-dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α-SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, loureirin B effectively inhibited TGF-ß1-induced upregulation of ColI, ColIII and α-SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF-ß1-stimulated fibroblasts. Taken together, this study demonstrates that loureirin B could downregulate the expression of fibrosis-related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF-ß1-induced fibrosis, during which TGF-ß1/Smad2/3 pathway is likely involved. These findings suggest that loureirin B is a potential therapeutic compound for HS treatment.