Inhibitory Effect Of Baicalin Research Articles

Baicalin Ameliorates Cartilage Injury in Rats With Osteoarthritis via Modulating miR-766-3p/AIFM1 Axis

The study aims to elucidate the therapeutic mechanism of Baicalin (BAI) in alleviating cartilage injury in osteoarthritic (OA) rat models, concentrating on its regulation of the miR-766-3p/AIFM1 axis. An OA rat model was developed with unilateral anterior cruciate ligament transection (ACLT). Interventions comprised of BAI treatment and intra-articular administration of miR-766-3p inhibitor. For evaluation, histopathological staining was conducted to investigate the pathological severity of knee cartilage injury. The levels of oxidative stress (OS) indicators including MDA, SOD, and GSH-Px, were quantified using colorimetric assays. Inflammatory factors (IFs; TNF-α, IL-1β, and IL-6) in knee joint lavage fluids were assessed using ELISA, while RT-PCR was employed to quantify miR-766-3p expression. TUNEL apoptosis staining was utilized to detect chondrocyte apoptosis, and western blotting examined autophagy-related markers (LC3, Beclin, p62), extracellular matrix (ECM) synthesis-associated indices (COL2A, ACAN, MMP13), and apoptosis-inducing factor mitochondrion-associated 1 (AIFM1). Histological examination revealed a marked amelioration of cartilage injury in the BAI-treated OA rat models compared to controls. BAI treatment significantly reduced inflammation and OS of knee joint fluid, activated autophagy, and decreased chondrocyte apoptosis and ECM degradation. Interestingly, the inhibitory effects of BAI on these pathological markers were significantly decreased by the miR-766-3p inhibitor. Further assessment revealed that BAI efficiently promoted miR-766-3p expression while inhibiting AIFM1 protein expression. BAI potentially mitigates articular cartilage injury in OA rats, likely through modulation of miR-766-3p/AIFM1 axis.

Antifibrotic Effect of Baicalin on Arecoline Induced Human Oral Fibroblast: An In-Vitro Study.

Baicalin is a flavonoid obtained from the Chinese herb Scutellaria baicalensis, which has a wide varieties of health benefits and scope to be studied for its therapeutic potential in oral fibrosis. The aim of the study was to investigate the antifibrotic effect of a Baicalin in arecoline induced human oral fibroblast in vitro setting. Arecoline and ethanolic extracts of Baicalin were commercially purchased from Sigma-Aldrich. Human oral fibroblasts were cultured and characterized with specific fibroblast markers, and cells were stimulated with arecoline. An MTT assay (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) was executed to determine the half-maximal inhibitory concentration of arecoline and Baicalin. Arecoline-induced cells (25µg/ml) were treated with a non-toxic dose of Baicalin (proliferative dose of 25µg/ml). Cytokine (CCL2, CXCL-8, IL17, IL-beta, and IL-6) and fibrotic marker genes were studied by reverse transcription-polymerase chain reaction (RT-PCR). The inhibitory effect of Baicalin was studied to prove its antifibrotic properties. Arecoline significantly upregulated all inflammatory and fibrotic markers. On treatment with 25µg/ml of Baicalin, all inflammatory and fibrotic markers were inhibited. Arecoline affects fibroblast morphology, supporting the fact that arecoline is cytotoxic to cells. Baicalin can be used as an antifibrotic herb to treat OSMF.

Baicalin Antagonizes Prostate Cancer Stemness via Inhibiting Notch1/NF-κB Signaling Pathway.

To investigate the molecular mechanisms underlying the effect of baicalin on prostate cancer (PCa) progression both in vivo and in vitro. The in situ PCa stem cells (PCSCs)-injected xenograft tumor models were established in BALB/c nude mice. Tumor volume and weight were respectively checked after baicalin (100 mg/kg) treatment. Hematoxylin-eosin (HE) staining was used to observe the growth arrest and cell necrosis. mRNA expression levels of acetaldehyde dehydrogenase 1 (ALDH1), CD44, CD133 and Notch1 were determined by reverse transcription-polymerase chain reaction. Protein expression levels of ALDH1, CD44, CD133, Notch1, nuclear factor κB (NF-κB) P65 and NF-κB p-P65 were detected by Western blot. Expression and subcellular location of ALDH1, CD44, CD133, Notch1 and NF-κB p65 were detected by immunofluorescence analysis. In vitro, cell cycle distribution and cell apoptosis of PC3 PCSCs was assessed by flow cytometry after baicalin (125 µmol/L) treatment. The migration and invasion abilities of PCSCs were assessed using Transwell assays. Transmission electron microscopy scanning was utilized to observe the structure and autophagosome formation of baicalin-treated PCSCs. In addition, PCSCs were infected with lentiviruses expressing human Notch1. Compared with the control group, the tumor volume and weight were notably reduced in mice treated with 100 mg/kg baicalin (P<0.05 or P<0.01). Histopathological analysis showed that baicalin treatment significantly inhibited cell proliferation and promoted cell apoptosis. Furthermore, baicalin treatment reduced mRNA and protein expression levels of CD44, CD133, ALDH1, and Notch1 as well as the protein expression of NF-κB p-P65 in the xenograft tumor (P<0.01). In vitro, the cell proliferation of PCSCs was significantly attenuated after treatment with 125 µmol/L baicalin for 72 h (P<0.01). The cell migration and invasion rates were decreased following treatment with baicalin for 48 and 72 h (P<0.01). Baicalin notably induced cell apoptosis and seriously damaged the structure of PCSCs. The mRNA and protein expressions of CD133, CD44, ALDH1 and Notch1 in PCSCs were significantly downregulated following baicalin treatment (P<0.01). Importantly, the inhibitory effects of baicalin on PCa progression and stemness were reversed by Notch1 overexpression (P<0.05 or P<0.01). Mechanistically, baicalin exhibited a potential therapeutic effect on PCa via inhibiting the Notch1/NF-κB signaling pathway and its mediated cancer stemness.

Baicalin inhibits necroptosis by decreasing oligomerization of phosphorylated MLKL and mitigates caerulein-induced acute pancreatitis in mice

Necroptosis is a form of regulated necrosis mainly controlled by receptor-interacting protein kinases 3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL). Necroptosis has important roles in defensing against pathogenic infections, but it is also implicated in various inflammatory diseases including pancreatitis. Baicalin, a flavonoid from Scutellaria baicalensis Georgi, has been shown to possess anti-inflammatory and anti-pyroptosis properties, yet it is unclear whether baicalin can inhibit necroptosis and confer protection against necroptosis-related diseases. Here we reported that baicalin significantly inhibited necroptosis in macrophages induced by lipopolysaccharide plus pan-caspase inhibitor (IDN-6556), or by tumor-necrosis factor-α in combination with LCL-161 (Smac mimetic) and IDN-6556 (TSI). Mechanistically, baicalin did not inhibit the phosphorylation of RIPK1, RIPK3 and MLKL, nor membrane translocation of p-MLKL, during necroptotic induction, but instead inhibited p-MLKL oligomerization that is required for executing necroptosis. As intracellular reactive oxygen species (ROS) has been reported to be involved in p-MLKL oligomerization, we assessed the effects of N-acetyl-L-cysteine (NAC), an ROS scavenger, on necroptosis and found that NAC significantly attenuated TSI-induced necroptosis and intracellular ROS production concomitantly with reduced levels of oligomerized p-MLKL, mirroring the effect of baicalin. Indeed, inhibitory effect of baicalin was associated with reduced TSI-induced superoxide (indicating mitochondrial ROS) production and increased mitochondrial membrane potential within cells during necroptosis. Besides, oral administration of baicalin significantly reduced the severity of caerulein-induced acute pancreatitis in mice, an animal model of necroptosis-related disease. Collectively, baicalin can inhibit necroptosis through attenuating p-MLKL oligomerization and confers protection against caerulein-induced pancreatitis in mice.

Baicalin attenuates Streptococcus agalactiae virulence and protects tilapia (Oreochromis niloticus) from group B streptococcal infection

Streptococcus agalactiae (S. agalactiae) is a major piscine pathogen that causes significant morbidity and mortality among numerous fish species, especially tilapia; these deaths have resulted in huge economic losses for aquaculture. Beta-hemolysin/cytolysin and hyaluronidase are critical virulence factors of S. agalactiae, thereby suggesting that they are important targets for the development of potential treatment strategies. Hence the effects of 40 phytochemicals on β-hemolytic/cytolytic activity and hyaluronidase production were evaluated in this paper. The results showed that only bacalin simultaneously possesses significant inhibitory effects on the β-hemolytic/cytolytic activity of five S. agalactiae strains and the hyaluronidase production of S. agalactiae PBSA0901. The β-hemolytic/cytolytic activity-inhibition ratios of 4 μg/mL baicalin ranged from 22.11% to 84.54%, and the half maximum inhibitory concentrations (IC50) of baicalin to the β-hemolytic/cytolytic activity of S. agalactiae PBSA0901 was 5.39 ± 0.55 μg/mL. Additionally, the inhibitory effects of baicalin on the β-hemolytic/cytolytic activity cannot be removed by passage. Baicalin at the concentration of 4 μg/mL completely inhibited S. agalactiae PBSA0901 from producing hyaluronidase. Furthermore, baicalin significantly increased the sensitivity of S. agalactiae PBSA0901 to H2O2. However, it had a nonsignificant effect on the sensitivity of S. agalactiae PBSA0901 to lysozyme. Moreover, studies in vivo demonstrated that baicalin had a significant inhibitory effect on the lethality of S. agalactiae PBSA0901. Furthermore, baicalin exerted a significant therapeutic effect on tilapia challenged by S. agalactiae PBSA0901, and the median effect concentration (EC50) was 525.8 mg/kg. These results indicated that baicalin would be an interesting therapeutic compound against S. agalactiae infection in tilapia.

Baicalin Inhibits NOD-Like Receptor Family, Pyrin Containing Domain 3 Inflammasome Activation in Murine Macrophages by Augmenting Protein Kinase A Signaling.

The flavonoid baicalin has been reported to possess potent anti-inflammatory activities by suppressing inflammatory signaling pathways. However, whether baicalin can suppress the activation of NOD-like receptor (NLR) family, pyrin containing domain 3 (NLRP3) inflammasome in macrophages is largely unknown. Here, we showed that baicalin treatment dose-dependently inhibited adenosine triphosphate (ATP) or nigericin-induced NLRP3 inflammasome activation, as revealed by the decreased release of mature interleukin (IL)-1β, active caspase-1p10, and high-mobility group box-1 protein from lipopolysaccharide (LPS)-primed bone marrow-derived macrophages. The formation of ASC specks, a critical marker of NLRP3 inflammasome assembly, was robustly inhibited by baicalin in the macrophages upon ATP or nigericin stimulation. All these inhibitory effects of baicalin could be partly reversed by MDL12330A or H89, both of which are inhibitors of the protein kinase A (PKA) signaling pathway. Consistent with this, baicalin strongly enhanced PKA-mediated phosphorylation of NLRP3, which has been suggested to prevent ASC recruitment into the inflammasome. Of note, the PKA inhibitor H89 could block baicalin-induced NLRP3 phosphorylation on PKA-specific sites, further supporting PKA’s role in this process. In addition, we showed that when administered pre and post exposure to Escherichia coli infection baicalin treatment significantly improved mouse survival in bacterial sepsis. Baicalin administration also significantly reduced IL-1β levels in the sera of bacterial infected mice. Altogether, our results revealed that baicalin inhibited NLRP3 inflammasome activation at least partly through augmenting PKA signaling, highlighting its therapeutic potential for the treatment of NLRP3-related inflammatory diseases.

Inhibitory effect of baicalin on allergic response in ovalbumin-induced allergic rhinitis guinea pigs and lipopolysaccharide-stimulated human mast cells.

Baicalin, a flavonoid compound purified from the dry roots of Scutellaria baicalensis Georgi, has generally been used for the treatment of various allergic diseases. However, there is little information about the anti-inflammatory effects of baicalin for allergic rhinitis. This study aims to investigate the anti-allergic effect of baicalin on allergic response in ovalbumin (OVA)-induced allergic rhinitis guinea pigs and lipopolysaccharide (LPS)-stimulated human mast cells. Using in vivo models, we evaluated the effect of baicalin on allergic rhinitis symptoms via recording the number of nasal rubs and sneezes. The levels of histamine, OVA-specific immunoglobulin E(IgE), eosinophil cationic protein (ECP) and inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The histological changes of nasal mucosa were observed by light microscope after HE staining. In vitro, the release of histamine and β-hexosaminidase of compound 48/80-induced human mast cells were measured by ELISA and PNP-NAG colorimetry, respectively. The productions of inflammatory cytokines of LPS-stimulated human mast cells were determined using ELISA. Western blot was used to test the protein expression of JAK2, p-JAK2, STAT5, p-STAT5, IKKβ, p-IKKβ, IκBα, p-IκBα and NF-κB (p65) of LPS-stimulated human mast cells. The oral administration of baicalin at doses of 50 and 200mg/kg improved allergic rhinitis symptoms and the histological changes of nasal mucosa and decreased the serum levels of histamine, ECP, interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α and OVA-specific IgE in OVA-induced allergic rhinitis guinea pigs. In vitro, baicalin suppressed the release of histamine and β-hexosaminidase in compound 48/80-induced human mast cells. In addition, baicalin also inhibited the productions of inflammatory cytokines such as IL-1β, IL-6, IL-8 and TNF-α and suppressed the phosphorylation of JAK2, STAT5, IKKβ, IκBα and the nuclear translocation of NF-κB (p65) subunit in LPS-stimulated human mast cells. These results suggest that baicalin can effectively prevent allergic response in OVA-induced allergic rhinitis guinea pigs and inhibit inflammatory response via blocking JAK2-STAT5 and NF-κB signaling pathways in LPS-stimulated human mast cells. Considered together,the results show that baicalin may be a useful drug in the treatment of allergic rhinitis.

The Effect of Baicalin as A PPAR Activator on Erythroid Differentiation of CD133(+)Hematopoietic Stem Cells in Umbilical Cord Blood.

The peroxisome proliferator-activated receptors (PPARs) are a group of nu- clear receptor proteins whose functions as transcription factors regulate gene expres- sions. PPARs play essential roles in the regulation of cellular differentiation, development, and metabolism (carbohydrate, lipid, protein), and tumorigenesis of higher organisms. This study attempts to determine the effect of baicalin, a PPARγ activator, on erythroid differentiation of cluster of differentiation 133(+)(CD133(+)) cord blood hematopoietic stem cells (HSCs). In this experimental study, in order to investigate the effects of the PPARγ agonists baicalin and troglitazone on erythropoiesis, we isolated CD133(+) cells from human umbilical cord blood using the MACS method. Isolated cells were cultured in erythroid-inducing medium with or without various amounts of the two PPARγ activa- tors (baicalin and troglitazone). Erythroid differentiation of CD133(+)cord blood HSCs were assessed using microscopic morphology analysis, flow cytometric analysis of erythroid surface markers transferrin receptor (TfR) and glycophorin A (GPA) and bycolony forming assay. Microscopic and flow cytometric analysis revealed the erythroid differentiation of CD133(+)cord blood HSCs under applied erythroid inducing conditions. Our flow cytometric data showed that the TfR and GPA positive cell population diminished significantly in the presence of either troglitazone or baicalin. The suppression of erythroid differentiation in response to PPARγ agonists was dose-dependent. Erythroid colony-forming ability of HSC decreased significantly after treatment with both PPARγ agonists but troglitazone had a markedly greater effect. Our results have demonstrated that PPARγ agonists modulate erythroid dif- ferentiation of CD133(+)HSCs, and therefore play an important role in regulation of normal erythropoiesis under physiologic conditions. Thus, considering the availability and applica- tion of this herbal remedy for treatment of a wide range of diseases, the inhibitory effect of baicalin on erythropoiesis should be noted.

Effects and Mechanism of Baicalin on Apoptosis of Cervical Cancer HeLa Cells I n -v itro.

The objective of this study was to observe the apoptosis-inducing effect and mechanism of baicalin on human cervical cancer HeLa cells. The inhibitory effect of baicalin on the growth of HeLa cells was measured by MTT assay, and cell proliferation and migration was analyzed by cell scratch assay. Morphological changes of apoptotic cells were viewed by the light microscope and electron microscope, and cell growth arrest was confirmed by flow cytometry. Moreover, Western blot was used for investigating the expression of apoptosis related proteins; spectrophotometry was used to examine Caspase-3 activation. Our results showed that baicalin could inhibit the proliferation of HeLa Cells via induction of apoptosis in a time and dose-dependent manner (P<0.01). Apoptotic signaling induced by baicalin was characterized by up-regulating Bax, Fas, FasL and Caspase-8 protein expression, and down-regulating of Bcl-2 protein expression. These results indicated that baicalin-induced apoptosis involved activation Caspase-3 in HeLa cells through the intracellular mitochondrial pathway and the surface death receptor pathway.

Biological evaluation and molecular docking of baicalin and scutellarin as Helicobacter pylori urease inhibitors

Ethnopharmacological relevanceBaicalin and scutellarin are the principal bioactive components of Scutellaria baicalensis Georgi which has extensively been incorporated into heat-clearing and detoxification formulas for the treatment of Helicobacter pylori-related gastrointestinal disorders in traditional Chinese medicine. However, the mechanism of action remained to be defined. Aim of the studyTo explore the inhibitory effect, kinetics and mechanism of Helicobacter pylori urease (the vital pathogenetic factor for Helicobacter pylori infection) inhibition by baicalin and scutellarin, for their therapeutic potential. Materials and methodsThe ammonia formations, indicator of urease activity, were examined using modified spectrophotometric Berthelot (phenol–hypochlorite) method. The inhibitory effect of baicalin and scutellarin was characterized with IC50 values, compared to acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor. Lineweaver–Burk and Dixon plots for the Helicobacter pylori urease inhibition of baicalin and scutellarin was constructed from the kinetic data. SH-blocking reagents and competitive active site Ni2+ binding inhibitors were employed for mechanism study. Molecular docking technique was used to provide some information on binding conformations as well as confirm the inhibition mode. Moreover, cytotoxicity experiment using Gastric Epithelial Cells (GES-1) was evaluated. ResultsBaicalin and scutellarin effectively suppressed Helicobacter pylori urease in dose-dependent and time-independent manner with IC50 of 0.82±0.07mM and 0.47±0.04mM, respectively, compared to AHA (IC50=0.14±0.05mM). Structure-activity relationship disclosed 4′-hydroxyl gave flavones an advantage to binding with Helicobacter pylori urease. Kinetic analysis revealed that the types of inhibition were non-competitive and reversible with inhibition constant Ki of 0.14±0.01mM and 0.18±0.02mM for baicalin and scutellarin, respectively. The mechanism of urease inhibition was considered to be blockage of the SH groups of Helicobacter pylori urease, since thiol reagents (l,d-dithiothreitol, l-cysteine and glutathione) abolished the inhibitory action and competitive active site Ni2+ binding inhibitors (boric acid and sodium fluoride) carried invalid effect. Molecular docking study further supported the structure-activity analysis and indicated that baicalin and scutellarin interacted with the key residues Cys321 located on the mobile flap through SH·π interaction, but did not interact with active site Ni2+. Moreover, Baicalin (at 0.59–1.05mM concentrations) and scutellarin (at 0.23–0.71mM concentrations) did not exhibit significant cytotoxicity to GES-1. ConclusionsBaicalin and scutellarin were non-competitive inhibitors targeting sulfhydryl groups especially Cys321 around the active site of Helicobacter pylori urease, representing potential to be good candidate for future research as urease inhibitor for treatment of Helicobacter pylori infection. Furthermore, our work gave additional scientific support to the use of Scutellaria baicalensis in traditional Chinese medicine (TCM) to treat gastrointestinal disorders.

Inhibitory effect of baicalin on collagen-induced arthritis in rats through the nuclear factor-κB pathway.

This study focused on the potential therapeutic effect of baicalin on collagen-induced arthritis (CIA) in rats and the underlying mechanisms. The CIA rats were injected with baicalin (50, 100, or 200 mg/kg) once daily for 30 days. The rats were monitored for clinical severity of arthritis, and joint tissues were used for radiographic assessment and histologic examination. We quantified tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in experimental animals and used Western blots to assess levels of protein abundance, phosphorylation, and acetylation of nuclear factor (NF)-κB p65 and sirtuin 1 (sirt1) protein expression in joint tissues. Human fibroblast-like synoviocytes from rheumatoid arthritis (HFLS-RA) were adopted in further mechanistic investigations. Baicalin intraperitoneal injection for 30 days dose-dependently blocked clinical manifestations of CIA, such as functional impairment and swollen red paws. Meanwhile, it alleviated collagen-induced joint inflammation injury and inhibited the secretion of TNF-α and IL-1β in both rat synovium and HFLS-RA. Further mechanistic investigations revealed that baicalin suppresses NF-κB p65 protein expression and phosphorylation in synovial tissue and human-derived synoviocytes. Moreover, the acetylation of NF-κB p65 was downregulated by baicalin, which negatively correlates with the baicalin-induced upregulation of sirt1 expression in the same conditions. The data indicate that CIA in rats can be alleviated by baicalin treatment via relieving joint inflammation, which is related to the suppression of synovial NF-κB p65 protein expression and the elevation of its deacetylation by sirt1.

Contribution of baicalin on the plasma protein binding displacement and CYP3A activity inhibition to the pharmacokinetic changes of nifedipine in rats in vivo and in vitro.

Baicalin purified from the root of Radix scutellariae is widely used in clinical practices. This study aimed to evaluate the effect of baicalin on the pharmacokinetics of nifedipine, a CYP3A probe substrate, in rats in vivo and in vitro. In a randomised, three-period crossover study, significant changes in the pharmacokinetics of nifedipine (2 mg/kg) were observed after treatment with a low (0.225 g/kg) or high (0.45 g/kg) dose of baicalin in rats. In the low- and high-dose groups of baicalin-treated rats, C max of total nifedipine decreased by 40%±14% (P<0.01) and 65%±14% (P<0.01), AUC0–∞ decreased by 41%±8% (P<0.01) and 63%±7% (P<0.01), Vd increased by 85%±43% (P<0.01) and 224%±231% (P<0.01), and CL increased by 97%±78% (P<0.01) and 242%±135% (P<0.01), respectively. Plasma protein binding experiments in vivo showed that C max of unbound nifedipine significantly increased by 25%±19% (P<0.01) and 44%±29% (P<0.01), respectively, and there was a good correlation between the unbound nifedipine (%) and baicalin concentrations (P<0.01). Furthermore, in vitro results revealed that baicalin was a competitive displacer of nifedipine from plasma proteins. In vitro incubation experiments demonstrated that baicalin could also competitively inhibit CYP3A activity in rat liver microsomes in a concentration-dependent manner. In conclusion, the pharmacokinetic changes of nifedipine may be modulated by the inhibitory effects of baicalin on plasma protein binding and CYP3A–mediated metabolism.

Inhibitory effects of baicalin in the early stage of 3T3-L1 preadipocytes differentiation by down-regulation of PDK1/Akt phosphorylation

Baicalin is a flavonoid derived from the root of Scutellaria baicalensis and exhibits a broad spectrum of biological activities including anti-adipogenesis. However, the inhibitory role of baicalin in the early stage of 3T3-L1 adipocyte differentiation relevant to the signaling up-stream of peroxisome proliferator-activated receptor-γ (PPAR-γ) and CCAAT/enhancer binding proteins (C/EBPs) expression is unclear, and is the subject of the present investigation. We used 3T3-L1 preadipocytes for adipocyte differentiation, Oil Red-O staining for the intracellular lipid accumulation assay, and real-time polymerase chain reaction (RT-PCR) for assaying the expression of major adipocyte transcription factors. We found that baicalin markedly suppressed the Akt phosphorylation in early stage of adipocytes differentiation. In addition, we observed that baicalin and LY294002 (as an inhibitor of Akt phosphorylation) significantly inhibited adipocyte differentiation by down-regulating several adipocyte-specific transcription factors, including PPAR-γ and C/EBPs in 3T3-L1 preadipocytes. Furthermore, we observed that baicalin significantly suppressed the Akt phosphorylation by inhibiting phosphoinositide-dependent kinase 1 (PDK1). These results indicate that the anti-adipogenesis effect of baicalin involves down-regulation of major transcription factors in 3T3-L1 adipocyte differentiation including PPAR-γ, C/EBP-β, and C/EBP-α through the down-regulation of PDK1/Akt phosphorylation.

Inhibitory Effect of Baicalin and Baicalein on Ovarian Cancer Cells

Ovarian cancer is one of the primary causes of death for women all through the Western world. Baicalin and baicalein are naturally occurring flavonoids that are found in the roots and leaves of some Chinese medicinal plants and are thought to have antioxidant activity and possible anti-angiogenic, anti-cancer, anxiolytic, anti-inflammatory and neuroprotective activities. Two kinds of ovarian cancer (OVCAR-3 and CP-70) cell lines and a normal ovarian cell line (IOSE-364) were selected to be investigated in the inhibitory effect of baicalin and baicalein on cancer cells. Largely, baicalin and baicalein inhibited ovarian cancer cell viability in both ovarian cancer cell lines with LD50 values in the range of 45–55 μM for baicalin and 25–40 μM for baicalein. On the other hand, both compounds had fewer inhibitory effects on normal ovarian cells viability with LD50 values of 177 μM for baicalin and 68 μM for baicalein. Baicalin decreased expression of VEGF (20 μM), cMyc (80 μM), and NFkB (20 μM); baicalein decreased expression of VEGF (10 μM), HIF-1α (20 μM), cMyc (20 μM), and NFkB (40 μM). Therefore baicalein is more effective in inhibiting cancer cell viability and expression of VEGF, HIF-1α, cMyc, and NFκB in both ovarian cancer cell lines. It seems that baicalein inhibited cancer cell viability through the inhibition of cancer promoting genes expression including VEGF, HIF-1α, cMyc, and NFκB. Overall, this study showed that baicalein and baicalin significantly inhibited the viability of ovarian cancer cells, while generally exerting less of an effect on normal cells. They have potential for chemoprevention and treatment of ovarian cancers.

Inhibitory Effects of Baicalin on the Expression and Activity of CYP3A Induce the Pharmacokinetic Changes of Midazolam in Rats

Baicalin, a flavonoid compound isolated from Scutellaria baicalensis, has been shown to possess antiinflammatory, antiviral, antitumour, and immune regulatory properties. The present study evaluated the potential herb-drug interaction between baicalin and midazolam in rats. Coadministration of a single dose of baicalin (0.225, 0.45, and 0.90 g/kg, i.v.) with midazolam (10 mg/kg, i.v.) in rats resulted in a dose-dependent decrease in clearance (CL) from 25% (P < 0.05) to 34% (P < 0.001) with an increase in AUC0−∞ from 47% (P < 0.05) to 53% (P < 0.01). Pretreatment of baicalin (0.90 g/kg, i.v., once daily for 7 days) also reduced midazolam CL by 43% (P < 0.001), with an increase in AUC0−∞ by 87% (P < 0.01). Multiple doses of baicalin decreased the expression of hepatic CYP3A2 by approximately 58% (P < 0.01) and reduced midazolam 1′-hydroxylation by 23% (P < 0.001) and 4′-hydroxylation by 21% (P < 0.01) in the liver. In addition, baicalin competitively inhibited midazolam metabolism in rat liver microsomes in a concentration-dependent manner. Our data demonstrated that baicalin induced changes in the pharmacokinetics of midazolam in rats, which might be due to its inhibition of the hydroxylation activity and expression of CYP3A in the liver.

Baicalin and baicalein, constituents of an important medicinal plant, inhibit intracellular Ca2+ elevation by reducing phospholipase C activity in C6 rat glioma cells.

Glial cells have a role in maintaining the function of neural cells. This study was undertaken to clarify the effects of baicalin and baicalein, flavonoids isolated from an important medicinal plant Scutellariae Radix (the root of Scutellaria baicalensis Georgi), on glial cell function using C6 rat glioma cells. Baicalin and baicalein caused concentration-dependent inhibition of a histamine-induced increase in intracellular Ca2+ concentrations ([Ca2+]i). The potency of baicalein was significantly greater than that of baicalin. The noradrenaline- and carbachol-induced increase in [Ca2+]i was also inhibited by baicalein and both drugs inhibited histamine-induced accumulation of total [3H]inositol phosphates, consistent with their inhibition of the increase in [Ca2+]i. These results suggest that baicalin and baicalein inhibit [Ca2+]i elevation by reducing phospholipase C activity. The inhibitory effects of baicalin and baicalein on [Ca2+]i elevation might be important in the interpretation of their pharmacological action on glial cells, such as inhibition of Ca2(+)-required enzyme phospholipase A2.

Inhibitory effect of baicalin on germ tube formation and adhesion of Candida albicans

To investigate the effects of baicalin against Candida albicans germ tube formation, and adherence to buccal epitherial and vaginal epitherial cells. Various concentrations of baicalin (100, 50, 10 mg x L(-1)) were incubated with C. albicans suspension, the mixed suspension of C. albicans and human buccal epitherial cells, the mixed suspension of C. albicans and vaginal epitherial cells, respectively. The effects of baicalin on C. albicans germ tube formation, and adherence to buccal epitherial and vaginal epitherial cells were then assessed microscopically. All concentrations of baicalin could inhibit C. albicans germ tube formation, and adherent to buccal epitherial and vaginal epitherial cells,while there was no significant difference between standard and clinical strains. Baicalin could inhibit C. albicans germ tube formation, and adherence to buccal epitherial and vaginal epitherial cells.

Inhibitory effects of baicalin on IL-1β- induced MMP-1/TIMP-1 and its stimulated effect on Collagen-I production in human periodontal ligament cells

Our previous research has proved that baicalin can inhibit the expression of Matrix metalloproteinases (MMPs) in periodontal ligament cells (PDLC) by cell immunocytochemistry. Therefore, the purpose of this study was to address the effects of baicalin on the total protein amount and Collagen I mRNA expression in PDLC, and the regulatory effects on Matrix metalloproteinase-1/ tissue inhibitors of metalloproteinase-1( MMP-1/ TIMP-1 ) expression. PDLC were incubated with 0–1000 ng/ml baicalin for 1, 3 and 5 days. Coomasie brilliant blue staining was used to detect the synthesis of the total protein, and the collagen I mRNA expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR). PDLC were treated with phorbol 12-myristate 13-acetate (PMA) or interleukin-1β (IL-1β) with or without 100 ng/ml baicalin and then mRNA levels for MMP-1 and TIMP-1 were detected. Enzyme linked immunosorbent assay (ELISA) was used to assess the MMP-1 protein. The range of 1–1000 ng/ml baicalin can enhance the amount of the total protein of PDL cells and the response had a dose-dependent manner in the range of 1–100 ng/ml baicalin. And 0–1000 ng/ml baicalin also significantly increased the Collagen I mRNA expression of PDLC. 1–100 pmol/ml PMA and 0.01–1 ng/ml IL-1βsignificantly ( p < 0.05) stimulated the production of MMP-1 by PDLC at both the transcriptional and the translational level. Different concentration PMA enhanced TIMP-1 mRNA expression, but IL-1βdid not affect the TIMP-1 mRNA expression. Moreover, in the presence of 100 ng/ml baicalin, both the MMP-1 and TIMP-1 mRNA expression were down regulated. The present study suggests that baicalin inhibits IL-1βinduction of MMP-1 by altering the mRNA and protein levels. In addition, baicalin may increase Collagen I mRNA and total protein levels in PDLC.

Anti-pruritic effect of baicalin and its metabolites, baicalein and oroxylin A, in mice

To explore whether intestinal microflora plays a role in anti-pruritic activity of baicalin, a main constituent of the rhizome of Scutellaria baicalensis (SB). Baicalin was anaerobically incubated with human fecal microflora, and its metabolites, baicalein and oroxylin A, were isolated. The inhibitory effect of baicalin and its metabolites was accessed in histamine- or compound 48/80-induced scratching behavior in mice. Baicalin was metabolized to baicalein and oroxylin A, with metabolic activities of 40.2+/-26.2 and 1.2+/-1.1 nmol.h(-1).mg(-1) wet weight of human fecal microflora, respectively. Baicalin (20, 50 mg/kg) showed more potent inhibitory effect on histamine-induced scratching behavior when orally administered than intraperitoneally. In contrast, baicalein and oroxylin A had more potent inhibitory effect when the intraperitoneally administered. The anti-scratching behavior activity of oral baicalin and its metabolites was in proportion to their inhibition on histamine-induced increase of vascular permeability with oroxylin A more potent than baicalein and baicalin. In Magnus test using guinea pig ileum, oroxylin A is more potent than baicalein and baicalin in inhibition of histamine-induced contraction. The anti-scratching behavioral effect of oral baicalin was significantly reduced when oral antibiotics were simultaneously administered, whereas the effect of baicalein and oroxylin A were not affected. Oral baicalin may be metabolized by intestinal microflora into baicalein and oroxylin A, which ameliorate pruritic reactions through anti-histamine action.

Effects of Baicalin onChlamydia trachomatisInfectionin vitro

Baicalin has emerged as a promising agent for the therapy of infectious diseases due to the increasing number of pathogenic microbial strains resistant to several antibiotics. In this study, we investigated the inhibitory activity of baicalin on Chlamydia infection in vitro. We found that baicalin blocked the infection of HeLa cells in vitro when added to the infected cells. In order to shed light on the inhibitory effects of baicalin on the Chlamydia-infected cells, the expression of RFX5 and Chlamydia protease-like activity factor (CPAF) mRNAs and proteins in the Chlamydia-infected cells were examined using Western blot and real-time RT-PCR analysis. The results demonstrated that RFX5 and CPAF were upregulated and downregulated, respectively, by baicalin. Because CPAF is responsible for degrading RFX5, it is suggested that CPAF is a primary target of baicalin and plays an important role in downregulating RFX5. In conclusion, our findings demonstrated that baicalin can effectively inhibit Chlamydia Trachomatis in HeLa cells and therefore can be considered a potential agent for the therapy of infectious diseases caused by C. trachomatis.