Anxiolytic effect of wogonin, a benzodiazepine receptor ligand isolated from Scutellaria baicalensis Georgi

The search for novel anxiolytics devoid of undesirable side-effects typical of classical benzodiazepines (BDZs) has been intense, and flavonoids, as a relative new class of ligands, have been shown to possess anxiolytic effects in vivo. The present study evaluated the pharmacological properties of a naturally occurring monoflavonoid, 5,7-dihydroxy-8-methoxyflavone or wogonin. The affinity (K(i)) of wogonin for the benzodiazepine site (BZD-S) on the gamma-aminobutyric acid(A) (GABA(A)) receptor complex was 0.92 microM. Using electrophysiological techniques, we showed that wogonin enhanced the GABA-activated current in rat dorsal root ganglion neurons, and in Xenopus laevis oocytes expressing recombinant rat GABA(A) receptors, the enhancement was partially reversed by the co-application of a 1 microM concentration of the BZD-S antagonist anexate (Ro15-1788). Acute toxicity and behavioral effects were examined in mice. Acute lethal activity was low, with an LD(50) of 3.9 g/kg. Oral administration of wogonin (7.5 to 30 mg/kg) elicited an anxiolytic response that was similar to that elicited by diazepam in the elevated plus-maze; a dose-dependent increase in open arm entries and time spent in open arms was observed. More importantly, its anxiolytic effect was blocked by the co-administration of Ro15-1788. In the holeboard test, not only did wogonin-treated mice experience an increased number of head-dips but they also spent more time at it, showing no signs of sedation. Furthermore, wogonin did not cause myorelaxant effects in the horizontal wire test. Taken together, these data suggest that wogonin exerts its anxiolytic effect through positive allosteric modulation of the GABA(A) receptor complex via interaction at the BZD-S. Its anxiolytic effect was not accompanied by sedative and myorelaxant side-effects typical of BDZs.

Antioxidative and anti-inflammatory activities of polyhydroxyflavonoids of Scutellaria baicalensis GEORGI

The active ingredients of 'golden root' of Scutellaria baicalensis GEORGI (Huang-Qin), a valuable traditional Chinese medicine, are polyhydroxyflavonoids, namely baicalein, oroxylin A and wogonin. With the objective of overcoming their poor solubility and to investigate their structure and activity relationships, baicaleinyl 7-O-sulfate was prepared, and extensive comparative antioxidative and anti-inflammatory tests were conducted. All the polyhydroxyflavonoids exhibited significant antioxidative and free-radical scavenging activities. In respect of their nitric oxide (NO) inhibition, wogonin was superior to all the other flavonoids, while oroxylin A was most potent in the inhibition of lipid peroxidation. Wogonin proved to be the most potent (82.9% inhibition, p<0.05) in its anti-inflammatory activity against carrageenan-induced rat hind paw edema. There was a correlation between the in-vivo anti-inflammatory activity and the in-vitro antioxidative activities.

Effects of wogonin, a plant flavone from Scutellaria radix, on skin inflammation: in vivo regulation of inflammation-associated gene expression

Flavonoids from plant origin show anti-inflammatory activity in vitro and in vivo. In addition to inhibition of inflammation-associated enzymes, such as cyclooxygenases (COX) and lipoxygenases, they have been found to regulate the expression of inflammation-associated proteins from in vitro experiments. In order to prove in vivo behavior and the potential for beneficial use against inflammatory skin disorders, the effect of wogonin (5,7-dihydroxy-8-methoxyflavone) on in vivo expression of several inflammation-associated genes was examined in the intact as well as in the inflamed mouse skin by reverse transcriptase-polymerase chain reaction analysis. When applied topically on the intact skin, only a high dose treatment of wogonin (1000 microg/ear/3 days) slightly increased COX-1 and fibronectin mRNA. On the other hand, wogonin at the doses of 250-1000 microg/ear/3 days potently lowered mRNA levels of COX-2 and tumor necrosis factor-alpha with less effect on intercellular adhesion molecule-1 and interleukin-1beta in a sub-chronic skin inflammation model of tetradecanoylphorbol-13-acetate-induced ear edema (multiple treatment). The decrease of prostaglandin E(2) concentration (27.3-34.3%) was concomitantly observed in the wogonin-treated groups. A similar effect was also observed in an acute inflammation model of arachidonic acid-induced ear edema. From the present study, wogonin was proved to differentially regulate the expression of inflammation-associated genes in vivo and to become a useful therapeutic agent for skin inflammatory diseases mainly due to its modulation of the expression of proinflammatory molecules.

Scutellariae Radix and Coptidis Rhizoma Improve Glucose and Lipid Metabolism in T2DM Rats via Regulation of the Metabolic Profiling and MAPK/PI3K/Akt Signaling Pathway

Aim Scutellariae Radix (SR) and Coptidis Rhizoma (CR) have often been combined to cure type 2 diabetes mellitus (T2DM) in the clinical practice for over thousands of years, but their compatibility mechanism is not clear. Mitogen-activated protein kinase (MAPK) signaling pathway has been suggested to play a critical role during the process of inflammation, insulin resistance, and T2DM. This study was designed to investigate their compatibility effects on T2DM rats and explore the underlying mechanisms by analyzing the metabolic profiling and MAPK/PI3K/Akt signaling pathway. Methods The compatibility effects of SR and CR were evaluated with T2DM rats induced by a high-fat diet (HFD) along with a low dose of streptozocin (STZ). Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to discover potential biomarkers. The levels of pro-inflammatory cytokines; biochemical indexes in serum, and the activities of key enzymes related to glycometabolism in liver were assessed by ELISA kits. qPCR was applied to examine mRNA levels of key targets in MAPK and insulin signaling pathways. Protein expressions of p65; p-p65; phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K); phosphorylated-PI3K (p-PI3K); protein kinase B (Akt); phosphorylated Akt (p-Akt) and glucose transporter 2 (Glut2) in liver were investigated by Western blot analysis. Results Remarkably, hyperglycaemia, dyslipidemia, inflammation, and insulin resistance in T2DM were ameliorated after oral administration of SR and CR, particularly their combined extracts. The effects of SR, CR, low dose of combined extracts (LSC) and high dose of combined extracts (HSC) on pro-inflammatory cytokine transcription in T2DM rats showed that the MAPK pathway might account for the phenomenon with down-regulation of MAPK (P38 mitogen-activated protein kinases (P38), extracellular regulated protein kinases (ERK), and c-Jun N-terminal kinase (JNK)) mRNA, and protein reduction in p-P65. While mRNA levels of key targets such as insulin receptor substrate 1 (IRS1), PI3K, Akt2, and Glut2 in the insulin signaling pathway were notably up-modulated, phosphorylations of PI3K, Akt, and expression of Glut2 were markedly enhanced. Moreover, the increased activities of phosphoenolpyruvate carboxykinase (PEPCK), fructose-1,6-bisphosphatase (FBPase), glucose 6-phosphatase (G6Pase), and glycogen phosphorylase (GP) were highly reduced and the decreased activities of glucokinase (GK), phosphofructokinase (PFK), pyruvate kinase (PK), and glycogen synthase (GS) in liver were notably increased after treatment. Further investigation indicated that the metabolic profiles of plasma and urine were clearly improved in T2DM rats. Fourteen potential biomarkers (nine in plasma and five in urine) were identified. After intervention, these biomarkers returned to normal level to some extent. Conclusion The results showed that SR, CR, and combined extract groups were normalized. The effects of combined extracts were more remarkable than single herb treatment. Additionally, this study also showed that the metabonomics method is a promising tool to unravel how traditional Chinese medicines work.

A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis

Wogonin and baicalein are bioactive flavones in the popular Chinese herbal remedy Huang-Qin (Scutellaria baicalensis Georgi). These specialized flavones lack a 4'-hydroxyl group on the B ring (4'-deoxyflavones) and induce apoptosis in a wide spectrum of human tumor cells in vitro and inhibit tumor growth in vivo in different mouse tumor models. Root-specific flavones (RSFs) from Scutellaria have a variety of reported additional beneficial effects including antioxidant and antiviral properties. We describe the characterization of a new pathway for the synthesis of these compounds, in which pinocembrin (a 4'-deoxyflavanone) serves as a key intermediate. Although two genes encoding flavone synthase II (FNSII) are expressed in the roots of S. baicalensis, FNSII-1 has broad specificity for flavanones as substrates, whereas FNSII-2 is specific for pinocembrin. FNSII-2 is responsible for the synthesis of 4'-deoxyRSFs, such as chrysin and wogonin, wogonoside, baicalein, and baicalin, which are synthesized from chrysin. A gene encoding a cinnamic acid-specific coenzyme A ligase (SbCLL-7), which is highly expressed in roots, is required for the synthesis of RSFs by FNSII-2, as demonstrated by gene silencing. A specific isoform of chalcone synthase (SbCHS-2) that is highly expressed in roots producing RSFs is also required for the synthesis of chrysin. Our studies reveal a recently evolved pathway for biosynthesis of specific, bioactive 4'-deoxyflavones in the roots of S. baicalensis.

Isolation and purification of baicalein, wogonin and oroxylin A from the medicinal plant Scutellaria baicalensis by high-speed counter-current chromatography

The medicinal plant Scutellaria baicalensis Georgi has been used widely in traditional Chinese medicine for anti-inflammation, anticancer, antiviral and antibacterial infections, reducing the total cholesterol level and decreasing blood pressures. A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of three bioactive flavonoids, namely, baicalein, wogonin and oroxylin A, from S. baicalensis Georgi. Preparative HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-n-butanol-water (1:1:8:10, v/v/v/v) was successfully performed by increasing the flow-rate of the mobile phase stepwise from 1.0 to 2.0 ml min(-1) after 4 h. The components purified and collected were analyzed by high-performance liquid chromatography. The method yielded 144.8 mg of baicalein at 95.7% purity, 50.2 mg of wogonin at 98.5% purity, and 12.4 mg of oroxylin A at 93.2% purity from 500 mg of the crude extract in a one-step separation. The recoveries of baicalein, wogonin and oroxylin A were 92.7%, 91.6% and 92.5%, respectively.

Iron-binding and anti-Fenton properties of baicalein and baicalin

Baicalein and baicalin, the major bioactive compounds found in the Chinese herb Scutellaria baicalensis, have been shown to be effective against cancer, bacterial infections and oxidative stress diseases. However, little is known about their mechanisms of action. To probe whether iron homeostasis modulation may play a role in their bioactivity, we have investigated their iron binding characteristics under physiologically relevant conditions. A 2:1 baicalein-ferrous complex was readily formed in 20mM phosphate buffer, pH 7.2, with a binding constant approximately 2-9 x 10(11)M(-2), whereas a 1:1 baicalein-ferric complex was formed, under the same conditions, with an apparent binding constant approximately 1-3 x 10(6)M(-1). Baicalein appears to bind the ferrous ion more strongly than ferrozine, a well known iron(II) chelator. Using (1) H NMR and Zn(2+) and Ga(3+) as probes, the iron-binding site on baicalein was elucidated to be at the O6/O7 oxygen atoms of the A-ring. No binding was observed for baicalin under the same NMR conditions. Furthermore, baicalein strongly inhibits the Fe-promoted Fenton chemistry via a combination of chelation and radical scavenging mechanism while baicalin can provide only partial protection against radical damage. These results indicate that baicalein is a strong iron chelator under physiological conditions and hence may play a vital role in modulating the body's iron homeostasis. Modulation of metal homeostasis and the inhibition of Fenton chemistry may be one of the possible mechanisms for herbal medicine.

A medicinal extract of Scutellaria baicalensis and Acacia catechu acts as a dual inhibitor of cyclooxygenase and 5-lipoxygenase to reduce inflammation

A mixed extract containing two naturally occurring flavonoids, baicalin from Scutellaria baicalensis and catechin from Acacia catechu, was tested for cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) inhibition via enzyme, cellular, and in vivo models. The 50% inhibitory concentration for inhibition of both ovine COX-1 and COX-2 peroxidase enzyme activities was 15 microg/mL, while the mixed extract showed a value for potato 5-LOX enzyme activity of 25 microg/mL. Prostaglandin E2 generation was inhibited by the mixed extract in human osteosarcoma cells expressing COX-2, while leukotriene production was inhibited in both human cell lines, immortalized THP-1 monocyte and HT-29 colorectal adenocarcinoma. In an arachidonic acid-induced mouse ear swelling model, the extract decreased edema in a dose-dependent manner. When arachidonic acid was injected directly into the intra-articular space of mouse ankle joints, the mixed extract abated the swelling and restored function in a rotary drum walking model. These results suggest that this natural, flavonoid mixture acts via "dual inhibition" of COX and LOX enzymes to reduce production of pro-inflammatory eicosanoids and attenuate edema in an in vivo model of inflammation.

Safety, tolerability, and pharmacokinetics of a single ascending dose of baicalein chewable tablets in healthy subjects

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Scutellaria baicalensis Georgi has been used extensively in traditional Chinese medicine for the treatment of inflammation, fever, cough, dysentery, and hypertension. Baicalein is a flavonoid isolated from the root of Scutellaria baicalensis Georgi and is a novel neuroprotective agent under development for the treatment of Parkinson׳s disease. We aimed to investigate the pharmacokinetic (PK) properties of baicalein and its main metabolite, bacalin, after single-dose administration in healthy Chinese subjects. The safety and tolerability of baicalein were also assessed.

MATERIALS AND METHODS

This was a Phase I, randomized, double-blind, single-dose trial of baicalein (100-2800 mg) in 72 healthy adults. Samples of blood, urine and feces were collected at regular intervals up to 48 h after administration of the study drug. Baicalein and baicalin were then analyzed using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The maximum concentration that the drug achieved after dosing (Cmax), time to Cmax (Tmax), terminal half-life (t₁/₂), area under the curve from time zero to time of last quantifiable concentration (AUC(0, t)), area under the curve from time zero to infinity (AUC(0, ∞)), apparent total plasma clearance (CL/F), and apparent total volume of distribution (V/F) were determined using non-compartmental models. Dose proportion was tested using a method combining the equivalence criterion and power model. Physical examinations, vital signs, ECG findings, hematology, and urinalysis were monitored before and at regular intervals after administration of the study drug.

RESULTS

The PK profile of baicelein and baicelin was characterized by a median Tmax of 0.75-3.5 h and 0.5-3 h, respectively, followed by a multiphasic profile with a t₁/₂ of 1.90-15.01 h and 4.22-10.80 h, respectively. The estimates of the proportionality coefficient (90% CI) for Cmax, AUC₀-t and AUC₀-∞ were 0.83 (0.70-0.96), 0.91 (0.81-1.00) and 0.92 (0.82-1.02), respectively. All values overlapped within the pre-specified range of (0.89-1.11), (0.93-1.07), and (0.93-1.07), respectively. Dose proportionality was inconclusive for a baicalein dose range of 100-2800 mg. The total urinary clearance of baicalein and baicalin was <1%. Approximately 27% of baicalein was eliminated as unchanged drug in feces. Baicalein was well tolerated. Eleven treatment-related adverse events were observed, and all were rated as "mild" and resolved without further treatment. No serious adverse events occurred.

CONCLUSIONS

Single oral doses of 100-2800 mg of baicalein were safe and well tolerated by healthy subjects. Clinical laboratory assessments showed no signs of toxicity in the liver or kidney. The favorable safety profile and PK properties warrant further clinical studies for baicalein.

Comparative pharmacokinetics of baicalin after oral administration of pure baicalin, Radix scutellariae extract and Huang-Lian-Jie-Du-Tang to rats

Huang-Lian-Jie-Du-Tang (HLJDT) is an important "heat-clearing" multiherb remedy of traditional Chinese medicine, and Radix scutellariae (Scutellaria baicalensis Georgi, Labiatae) is a key ingredient herb in it. Baicalin and wogonoside are two main effective ingredients enriched in Radix scutellariae. In the present study, pharmacokinetic differences of baicalin following oral administration of pure baicalin, Radix scutellariae extract, baicalin co-administrated with extract of the other three herbs of HLJDT and HLJDT were investigated in male S.D. rats with approximately the same dose of 200 mg/kg baicalin. The pharmacokinetic comparison of wogonoside was conducted only in Radix scutellariae extract and HLJDT. Plasma concentrations of baicalin and wogonoside were determined using HPLC method. Unpaired Student's t-test was used for statistical comparison. The results indicated that baicalin and wogonoside demonstrated bimodal phenomenon in the plasma profile. Some ingredients in the other three herbs of HLJDT, not in Radix scutellariae itself, had pharmacokinetic interaction with baicalin and wogonoside and hence decreased their systematic exposure level (p<0.01). The absorption site of baicalin was preliminary evaluated in rat using in situ absorption in stomach and different intestinal segments and results revealed the existence of double-site absorption of baicalin. The first absorption site was in upper intestinal, probably via directly absorption of baicalin; while the second absorption site was in colon in the form of aglygon.

Baicalein, an active component of Scutellaria baicalensis, protects against lipopolysaccharide-induced acute lung injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalein (BE), a phenolic flavonoid extracted mainly from the root of Scutellaria baicalensis Georgi, a Chinese herb, is traditionally used in oriental medicine. Several studies have demonstrated that BE exerts many beneficial effects including anti-inflammatory and antioxidant activities. However, its effect on acute lung injury (ALI) and the molecular mechanisms involved remain unclear and warrant further investigation. The aim of the study is to investigate whether BE improves lipopolysaccharide (LPS, intratracheally, i.t.)-induced ALI in rats, and further study the underlying mechanisms of its activity.

MATERIAL AND METHODS

Rats were administrated with LPS (5mg/kg/body weight, i.t.) through a 24-gauge catheter to establish the ALI model. The effects of BE on the levels of pro-inflammatory cytokines, nitrite/nitrate in bronchoalveolar lavage fluid, and the expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and nuclear factor-kappa B (NF-κB) activation as well as the histopathological changes were evaluated.

RESULTS

Results showed that BE (20mg/kg, i.p.) treatment markedly attenuated LPS-induced lung edema, elevation of the levels of IL-1β, TNF-α, IL-6, CINC-3, and nitrite/nitrate in bronchoalveolar lavage fluid accompanied by a remarkable improvement of lung histopathological symptoms. The LPS-enhanced inflammatory cell infiltration and myeloperoxidase activity, O2(-) formation and the expression of inducible nitric oxide synthase and nitrotyrosin in lungs were all attenuated by BE. Notably, BE could augment Nrf2/HO-1 cascade, but inhibited NF-κB activation in LPS-instilled lungs that was strongly reversed by blocking HO-1 activity.

CONCLUSION

This study is the first to demonstrate that BE protects against LPS-induced ALI in rats. The underlying mechanisms may include inhibition of NF-κB-mediated inflammatory responses and upregulation of Nrf2/HO-1 pathway, which ultimately alleviates the pathological symptoms of ALI.

Identification and quantification of eight flavones in root and shoot tissues of the medicinal plant huang-qin (Scutellaria baicalensis Georgi) using high-performance liquid chromatography with diode array and mass spectrometric detection

A method of analysis of eight flavones using high-performance liquid chromatography (HPLC)-diode array detection (DAD)-mass spectrometry (MS) in root and aerial tissues of the medicinal plant Scutellaria baicalensis was developed. The identity of the analytes was confirmed using retention time, UV-vis and mass spectral comparisons to commercial standards. Both UV-vis and mass spectral patterns were characterized for glycosylated flavones. Two additional flavone glycosides were tentatively identified as chrysin-7-glucuronide and wogonoside, but not quantified. Greenhouse and in vitro-grown tissues were analyzed with flavone concentrations ranges of 0.14-150 and 0.030-1.7 microg/mg for greenhouse root and shoot tissue, respectively, and 0.0068-6.4 and 0.082-1.5 microg/mg for in vitro-grown roots and shoots, respectively.

Characterization of Chemical Constituents in Scutellaria baicalensis with Antiandrogenic and Growth-Inhibitory Activities toward Prostate Carcinoma

PURPOSE

Botanical preparations are widely used by patients with prostate cancer. Scutellaria baicalensis, a botanical with a long history of medicinal use in China, was a constituent of the herbal mixture PC-SPES, a product that inhibited prostate cancer growth in both laboratory and clinical studies. Due to the difficulties encountered when evaluating the efficacy of complex natural products, we sought to identify active chemical constituents within Scutellaria and determine their mechanisms of action.

EXPERIMENTAL DESIGN AND RESULTS

We used high-performance liquid chromatography to fractionate S. baicalensis and identified four compounds capable of inhibiting prostate cancer cell proliferation; baicalein, wogonin, neobaicalein, and skullcapflavone. Comparisons of the cellular effects induced by the entire extract versus the four-compound combination produced comparable cell cycle changes, levels of growth inhibition, and global gene expression profiles (r(2) = 0.79). Individual compounds exhibited antiandrogenic activities with reduced expression of the androgen receptor and androgen-regulated genes. In vivo, baicalein (20 mg/kg/d p.o.) reduced the growth of prostate cancer xenografts in nude mice by 55% at 2 weeks compared with placebo and delayed the average time for tumors to achieve a volume of approximately 1,000 mm(3) from 16 to 47 days (P < 0.001).

CONCLUSIONS

Most of the anticancer activities of S. baicalensis can be recapitulated with four purified constituents that function in part through inhibition of the androgen receptor signaling pathway. We conclude that clinical studies evaluating the efficacy of these agents in the context of chemoprevention or the treatment of prostate cancer are warranted.

Scutellaria baicalensis, a herbal medicine: anti-proliferative and apoptotic activity against acute lymphocytic leukemia, lymphoma and myeloma cell lines

Scutellaria baicalensis (S.B.) is a widely used Chinese herbal medicine. We initially investigated its in vitro anti-tumor activities. S.B inhibited the growth of ALL, lymphoma and myeloma cell lines by inducing apoptosis and cell cycle arrest at clinically achievable concentrations. The anti-proliferative effect was associated with mitochondrial damage, modulation of the Bcl family of genes, increased level of the CDK inhibitor p27(KIP1) and decreased level of c-myc oncogene. HPLC analysis of S.B. showed it contains 21% baicalin and further studies confirmed it was the major anti-cancer component of S.B. Thus, Scutellaria baicalensis should be tested in clinical trials for these hematopoietic malignancies.

Gegen Qinlian decoction alleviates experimental colitis via suppressing TLR4/NF-κB signaling and enhancing antioxidant effect

BACKGROUND

Gegen Qinlian decoction (GQ), a Chinese medicinal herb decoction, has been widely used as efficient medicine for the treatment of acute colitis in clinics, but underlying molecular mechanisms have not been fully clarified.

HYPOTHESIS/PURPOSE

Inflammation and oxidative stress have been reported to constitute a crucial part in the pathogenesis of ulcerative colitis (UC). Hence, this study was designed to investigate the antiinflammatory activity and antioxidative effect of GQ.

STUDY DESIGN

Mice induced by 5% dextran sulfate sodium (DSS) and macrophage RAW264.7 cells stimulated by lipopolysaccharide (LPS) were used in this study.

METHODS

Ethanol extracts of GQ were orally administered for 1 week on the dosage of 0.3, 1.5, or 7.5g/kg/day and berberine (BBR, 100mg/kg/d) was selected as a positive group in the animal experiments. In vitro, GQ (25, 50, 100µg/ml) or BBR (20µM) co-cultured with RAW264.7 for 2h prior to LPS stimulation.

RESULTS

The results showed that GQ oral administration alleviated the severity of colitis notably. It reduced toll-like receptor 4 (TLR4) expression and NF-κB activation in mucosa, which was accompanied with down regulation of several inflammatory cytokines in the colon, including tumor necrosis factor (TNF-α), interleukin (IL)-6, IL-1β and IL-4. Furthermore, GQ oral administration attenuated the oxidative stress in the colon of UC mice, evidenced by the decrease of myeloperoxidase (MPO) activity and malondialdehyde (MDA) level, and the elevation of glutathione (GSH) content. In parallel with the vivo experiment results, cell research indicated GQ dramatically reduced the production of TNF-α, IL-6, IL-1β and nitric oxide (NO), as well as that of reactive oxygen species (ROS) upon stimulation of LPS.

CONCLUSION

Together, our present study indicates that inhibition of TLR4/NF-κB signaling and enhancement of antioxidant effect might be the potential mechanisms for the therapeutic effect of GQ against UC.

Difference of growth-inhibitory effect of Scutellaria baicalensis-producing flavonoid wogonin among human cancer cells and normal diploid cell

Methanol extract from cultured Scutellaria baicalensis cells inhibited the proliferation of human monocytic leukemia cell line THP-1 and human osteogenic sarcoma cell line HOS. The inhibitory effects of baicalin, baicalein and wogonin, the three major flavonoids contained in the extract, were studied. It should be noted that wogonin did not show the inhibitory effect on human fetal lung normal diploid cell line TIG-1, as compared to the inhibition observed in cancer cells. Physiological analyses in THP-1 cells showed that wogonin induced cell cycle arrest at G(2)/M phase and apoptosis. This is the first report discovering a cancer-specific apoptosis-inducing activity of wogonin.

Simultaneous determination of baicalin, wogonoside, baicalein, wogonin, oroxylin A and chrysin of Radix scutellariae extract in rat plasma by liquid chromatography tandem mass spectrometry

A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of baicalin, wogonoside, baicalein, wogonin, oroxylin A and chrysin in rat plasma, using naringin as an internal standard. After acidifying with HCl, plasma samples were pretreated by liquid-liquid extraction with acetone. Chromatographic separation was accomplished on a Hypersil Gold-C(18) analytical column (2.1×150 mm, 5 μm) utilizing a gradient elution profile and a mobile phase consisting of (A) 0.1% formic acid in water and (B) acetonitrile. Detection was performed by multiple reaction monitoring (MRM) mode using electrospray ionization in the positive ion mode. All analytes showed good linearity over the investigated concentration range (r>0.9900). The lower limit of quantification was 0.5 ng/ml for baicalin, wogonoside, wogonin and oroxylin A, and 1.0 ng/ml for baicalein and chrysin. Intra-day and inter-day precisions (RSD%) were less than 15% and accuracy (RE%) ranged from -6.7% to 5.8%. The validated method was successfully applied to investigate the pharmacokinetics of the major flavonoids of Radix scutellariae extract after oral administration to rats.

Differential effects of natural polyphenols on neuronal survival in primary cultured central neurons against glutamate- and glucose deprivation-induced neuronal death

Neuronal injury in the central nervous system following ischemic insult is believed to result from glutamate toxicity and glucose deprivation. In this study, polyphenols isolated from Scutellaria baicalensis Georgi, including baicalin, baicalein, and wogonin, were investigated for their neuroprotective effects against glutamate/NMDA (Glu/NMDA) stimulation and glucose deprivation in primary cultured rat brain neurons. Cell death was accessed by lactate dehydrogenase (LDH) release assay for necrosis, and mitochondrial activity was accessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction activity assay. It was found that both baicalin and baicalein decreased LDH release of the cultured neurons after 24 h treatment, whereas wogonin profoundly increased LDH release after 2 h treatment and resulted in neuronal death after 24 h. Glu/NMDA treatment profoundly increased LDH release and moderately decreased MTT reduction activity in an NMDA receptor-dependent manner. Both baicalin and baicalein significantly reduced Glu/NMDA-increased LDH release, in which baicalein is much more potent than baicalin. Glu/NMDA-increased intracellular calcium was also significantly attenuated by baicalin and baicalein. Baicalin and baicalein did not affect glutamate receptor binding activity, but baicalein did moderately decrease Glu/NMDA-induced nitric oxide (NO) production. In the glucose deprivation (GD) study, baicalein but not baicalin showed significant protective effects on the GD-increased LDH release, without affecting the GD-induced NO production, in cultured rat brain neurons. These results suggest that baicalein is the most effective compound among three polyphenols tested in preventing neurotoxicity induced by both glutamate and GD, whereas baicalin was only effective in preventing glutamate toxicity. Wogonin might have a neurotoxic effect on the brain.

Anticonvulsant effect of wogonin isolated from Scutellaria baicalensis

In previous studies, we identified sedative effects of Scutellaria baicalensis extracts and found that these extracts or their constituents may also have anticonvulsive effects. Wogonin is a natural product isolated from S. baicalensis, which possesses central nervous system effects such as anxiolytic and neuroprotective activities. In this study, we investigated the effects of wogonin on convulsion related behaviors, such as myorelaxation, motor coordination, and anticonvulsant effects of wogonin on chemical induced seizure and electroshock seizure in mice or rats. The effect of wogonin on membrane potential was also observed. Wogonin was intraperitoneally injected into mice or rats 30 min prior to testing. Animals treated with wogonin did not change locomotor activities as well as endurance times on the rota-rod, which indicates that wogonin did not cause a sedative and myorelaxation effect. Wogonin significantly blocked convulsion induced by pentylenetetrazole and electroshock but not convulsion induced by strychnine. Wogonin also significantly reduced the electrogenic response score, but flumazenil treatment reversed this decrease to the level of the control group. The wogonin treatment increased Cl(-)influx into the intracellular area as dose increased. Flumazenil and bicuculline treatment, however, inhibited the Cl(-) influx induced by wogonin. These results indicate that the anticonvulsive effects produced by wogonin were mediated by the GABAergic neuron.

Anti-H1N1 virus, cytotoxic and Nrf2 activation activities of chemical constituents from Scutellaria baicalensis

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Qin, derived from the roots of Scutellaria baicalensis Georgi, is a popular Chinese herbal medicine mainly used to treat influenza and cancer. This study aims to elucidate the anti-influenza, anti-cancer and anti-oxidation effective components of S. baicalensis.

MATERIALS AND METHODS

Various column chromatography techniques and semi-preparative HPLC were used to isolate Scutellaria compounds, and their structures were identified by HRESIMS and NMR spectroscopic analysis. The pure compounds were evaluated for anti-influenza activities against A/WSN/33 (H1N1) virus in MDCK cells, cytotoxic activities against HepG2, SW480 and MCF7 human cancer cells by MTS assay, and antioxidant activities by Nrf2 luciferase reporter assay. In addition, the contents of 12 major compounds in 27 batches of S. baicalensis were simultaneously determined by a fully validated UPLC/UV method.

RESULTS

A total of thirty compounds (1-30), including four new ones (3, 7, 11 and 23), were isolated from S. baicalensis. Baicalin (15), baicalein (26), wogonin (27), chrysin (28) and oroxylin A (30) showed potent anti-H1N1 activities, with IC50 values of 7.4, 7.5, 2.1, 7.7 and 12.8 μM, respectively, which were remarkably more potent than the positive drug Osv-P (oseltamivir phosphate, IC50 45.6 μM). Most free flavones (26-28 and 30) showed significant cytotoxic activities at 10 μM (up to 61.2% inhibition rate). Furthermore, 30 could activate Nrf2 transcription by 3.8-fold of the control at 10 μM. UPLC analysis indicated the 12 major compounds (including the bioactive ones) accounted for 195.93 ± 43.9 mg g(-)(1) of the herbal materials.

CONCLUSION

This study demonstrated that free flavones showed potent anti-influenza, anti-cancer and anti-oxidative activities. They are important effective components of S. baicalensis, and can be used as chemical markers for quality control of this herbal medicine.

Anti-inflammatory effects of Scutellaria baicalensis extract via suppression of immune modulators and MAP kinase signaling molecules

AIM OF THE STUDY

A herbal preparation using Scutellaria baicalensis (S. baicalensis) Georgi (Huang Qin, SB) was formulated to effectively protect cancer patients from inflammatory reactions. Although SB, is one of the most widely used herbs in oriental medicine for anti-inflammation, anti-cancer, anti-viral, anti-bacterial and tonifying the immune response, the underlying mechanism(s) by which these effects are induced remains unclear.

RESULTS

Here, we report that SB displays anti-inflammatory effects in a zymosan-induced mouse air-pouch model by reducing the expression of nitric oxide (NO), inducible NOS (iNOS), Cyclooxygenase2 (COX-2), Prostaglandin E2 (PGE2), Nuclear Factor-kappaB (NF-kappaB) and IkappaBalpha as well as inflammatory cytokines, such as IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha. In a similar manner, SB also reduced the production of nitric oxide, PGE2, IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha, by decreasing the expression of iNOS, COX-2, IkappaB kinase alphabeta (IKKalphabeta) phosphorylation, IkappaBalpha and IkappaBalpha phosphorylation in LPS-treated Raw 264.7 cells. Additionally, SB interfered with the nuclear translocation of NF-kappaB p65 and p50, resulting in NF-kappaB-dependent transcriptional repression. We further demonstrate that SB attenuated the activity of c-Raf-1/MEK1/2, Erk1/2, p38 and JNK phosphorylation in LPS-treated Raw 264.7 cells.

CONCLUSIONS

Taken together, these results confirm the strong anti-inflammatory properties of SB by inhibition of iNOS, COX-2, PGE2, IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha expression. This was achieved through the down-regulation of IKKalphabeta, IkappaBalpha, NF-kappaB activation via suppression of c-Raf-1/MEK1/2 (Mitogen-activated protein kinase/ERK kinase) and MAP kinase phosphorylation in the zymosan-induced mice air-pouch and Raw 264.7 cells. These results support the use of SB herbs for its potent anti-inflammatory activity.

Study of the chemical composition and antimicrobial activities of ethanolic extracts from roots of Scutellaria baicalensis Georgi

Scutellaria baicalensis Georgi (SBG), commonly named Huangqin, showed strong in vitro antimicrobial effects. However, limited research is available to systematically evaluate the effects of extraction methods on the phytochemical composition of SBG and its associated antimicrobial effects. In addition, limited studies have tested SBG as a natural antimicrobial agent on fresh produce such as tomatoes. In the current study, powered roots of SBG were extracted with 60, 80, and 100% ethanol, and their antiviral and antibacterial activities were evaluated. SBG ethanol extracts (SBGEEs) at 6.25 mg/mL showed limited antiviral activities against coliphage MS2 and hepatitis A virus. The SBG 80% ethanol extract (SBG80%EE) exhibited the lowest minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) against six foodborne pathogens. SBG80%EE had the highest contents of flavonoids and phenolic acids determined by high-performance liquid chromatography (HPLC). Among these bioactive compounds, ferulic acid had the lowest MIC and MBC values, 0.4 and 1.0 mg/mL, respectively, followed by baicalein and baicalin. Washing with SBG80%EE (12.5 mg/mL) resulted in >1 log reduction of Salmonella enterica serovars Typhimurium, Kentucky, Senftenberg, and Enteritidis on surface-inoculated grape tomatoes. None of SBGEE solutions changed the total phenolic content, color, or pH values of grape tomatoes. The quantification of these antimicrobial flavonoids and phenolic acids is important to maintain the quality and antimicrobial efficacy of SBG extracts. In addition, the application of SBG on tomatoes has provided valuable insights on the potential usage of this antimicrobial extract.

Baicalin reduces the permeability of the blood-brain barrier during hypoxia in vitro by increasing the expression of tight junction proteins in brain microvascular endothelial cells

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalin is one of the principal flavonoids isolated from the dried root of Scutellariae Baicalensis Georgi and has been widely used as a traditional herbal medicine to suppress brain edema and reduce cerebral ischemic damage. However, the effects of baicalin on the blood-brain barrier (BBB) are poorly understood.

AIM OF THE STUDY

To explore the effects of baicalin on the permeability of the BBB under ischemic conditions in vitro with regard to changes in the tight junctions(TJ) proteins claudin-5 and zonula occludens-1 (ZO-1).

MATERIALS AND METHODS

Brain microvascular endothelial cells(BMVECs) from Bal b/c mice were cultured to establish an in vitro BBB model. Oxygen and glucose deprivation (OGD) was applied to simulate ischemia. The experiment consisted of a normal control group, a model group and baicalin-treated groups (high-dose group, moderate-dose group and low-dose group). Transendothelial electrical resistance (TEER) and permeability to HRP were used as indicators of changes in BBB permeability. A real-time fluorescent quantitative assay was utilized to monitor the transcriptional changes in claudin-5 and ZO-1, and western blotting was used to detect the changes in protein expression of claudin-5, ZO-1 and PKC.

RESULTS

OGD led to a significant increase of permeability in this in vitro BBB model. Baicalin effectively decreased the permeability of the BBB, promoted transcription and expression of TJ proteins (claudin-5 and ZO-1) and reduced the levels of PKC.

CONCLUSIONS

We propose that baicalin is capable of restoring the barrier function of the BBB under ischemic conditions and this beneficial effect may be linked to the decreased expression of TJ proteins.

Huangqin decoction ameliorates DSS-induced ulcerative colitis: Role of gut microbiota and amino acid metabolism, mTOR pathway and intestinal epithelial barrier

BACKGROUND

The clinical treatment of ulcerative colitis (UC) is limited. A traditional Chinese medicinal formula, Huangqin decoction (HQD), is chronicled in Shang Han Lun and is widely used to ameliorate gastrointestinal disorders, such as UC; however, its mechanism is yet to be clarified.

PURPOSE

The present study aimed to investigate the effect of HQD on 7-day colitis induced by 3% dextran sulfate sodium (DSS) in mice and further explore the inhibitory effect of metabolites on DSS-damaged FHC cells.

METHODS

The therapeutic efficacy of HQD was evaluated in a well-established DSS-induced colitis mice model. The clinical symptoms were analyzed, and biological samples were collected for microscopic examination, metabolomics, metagenomics, and the evaluation of the epithelial barrier function. The mechanism of metabolites regulated by HQD was evaluated in the DSS-induced FHC cell damage model. The samples were collected to detect the physiological functions of the cells.

RESULTS

HQD suppressed the inflammation of DSS-induced colitis in vivo, attenuated DSS-induced clinical manifestations, reversed colon length reduction, and reduced histological injury. After HQD treatment, the DSS-induced gut dysbiosis was modulated, and the gut microbiota achieved a new equilibrium state. In addition, HQD activated the mTOR signaling pathway by upregulating amino acid metabolism. Significant phosphorylation of S6 and 4E-BP1 ameliorated intestinal epithelial barrier dysfunction. Moreover, HQD-regulated metabolites protected the epithelial barrier integrity by inhibiting DSS-induced apoptosis of FHC cells and regulating the proteins affecting apoptosis and cell-cell junction.

CONCLUSIONS

These findings indicated that the mechanism of HQD was related to regulating the gut microbiota and amino acid metabolism, activating the mTOR signaling pathway, and protecting the intestinal mucosal barrier integrity.

Separation methods used for Scutellaria baicalensis active components

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. Its roots have been used for anti-inflammation, anticancer, antiviral and antibacterial infections of the respiratory and the gastrointestinal tract, cleaning away heat, moistening aridity, purging fire, detoxifying toxicosis, reducing the total cholesterol level and decreasing blood pressures. Baicalin, baicalein, wogonin and oroxylin A are its main active components. This review provides an overview of various separation, detection, and identification techniques employed for the quantitative and qualitative determination of these active components. Applications of high-performance liquid chromatography, high-speed counter-current chromatography, thin layer chromatography, capillary electrophoresis, and micellar electrokinetic capillary chromatography to the separation and determination of these active components are described. Examples of identification of these active components and their metabolites in complex matrices by high-performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry are also presented. The advantages and limitations of these separation and identification methods are assessed and discussed.