Oroxylin a, but not vasopressin, ameliorates cardiac dysfunction of endotoxemic rats

Modulation of diverse oncogenic signaling pathways by oroxylin A: An important strategy for both cancer prevention and treatment

BACKGROUND

Regardless of major advances in diagnosis, prevention and treatment strategies, cancer is still a foreboding cause due to factors like chemoresistance, radioresistance, adverse side effects and cancer recurrence. Therefore, continuous development of unconventional approaches is a prerequisite to overcome foregoing glitches. Natural products have found their way into treatment of serious health conditions, including cancer since ancient times. The compound oroxylin A (OA) is one among those with enormous potential against different malignancies. It is a flavonoid obtained from the several plants such as Oroxylum indicum, Scutellaria baicalensis and S. lateriflora, Anchietea pyrifolia, and Aster himalaicus.

PURPOSE

The main purpose of this study is to comprehensively elucidate the anticancerous effects of OA against various malignancies and unravel their chemosensitization and radiosensitization potential. Pharmacokinetic and pharmacodynamic studies of OA have also been investigated.

METHOD

The literature on antineoplastic effects of OA was searched in PubMed and Scopus, including in vitro and in vivo studies and is summarized based on a systematic review protocol prepared according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The term "oroxylin A" was used in combination with "cancer" and all the title, abstracts and keywords appeared were considered.

RESULTS

In Scopus, a total of 157 articles appeared out of which 103 articles that did not meet the eligibility criteria were eliminated and 54 were critically evaluated. In PubMed, from the 85 results obtained, 26 articles were eliminated and 59 were included in the preparation of this review. Mounting number of studies have illustrated the anticancer effects of OA, and its mechanism of action.

CONCLUSION

OA is a promising natural flavonoid possessing wide range of pleiotropic properties and is a potential anticancer agent. It has a great potential in the treatment of multiple cancers including brain, breast, cervical, colon, esophageal, gall bladder, gastric, hematological, liver, lung, oral, ovarian, pancreatic and skin. However, lack of pharmacokinetic studies, toxicity assessments, and dose standardization studies and adverse effects limit the optimization of this compound as a therapeutic agent.

Oroxylin A: A Promising Flavonoid for Prevention and Treatment of Chronic Diseases

There have been magnificent advancements in the understanding of molecular mechanisms of chronic diseases over the past several years, but these diseases continue to be a considerable cause of death worldwide. Most of the approved medications available for the prevention and treatment of these diseases target only a single gene/protein/pathway and are known to cause severe side effects and are less effective than they are anticipated. Consequently, the development of finer therapeutics that outshine the existing ones is far-reaching. Natural compounds have enormous applications in curbing several disastrous and fatal diseases. Oroxylin A (OA) is a flavonoid obtained from the plants Oroxylum indicum, Scutellaria baicalensis, and S. lateriflora, which have distinctive pharmacological properties. OA modulates the important signaling pathways, including NF-κB, MAPK, ERK1/2, Wnt/β-catenin, PTEN/PI3K/Akt, and signaling molecules, such as TNF-α, TGF-β, MMPs, VEGF, interleukins, Bcl-2, caspases, HIF-1α, EMT proteins, Nrf-2, etc., which play a pivotal role in the molecular mechanism of chronic diseases. Overwhelming pieces of evidence expound on the anti-inflammatory, anti-bacterial, anti-viral, and anti-cancer potentials of this flavonoid, which makes it an engrossing compound for research. Numerous preclinical and clinical studies also displayed the promising potential of OA against cancer, cardiovascular diseases, inflammation, neurological disorders, rheumatoid arthritis, osteoarthritis, etc. Therefore, the current review focuses on delineating the role of OA in combating different chronic diseases and highlighting the intrinsic molecular mechanisms of its action.

Cancer Chemotherapy via Natural Bioactive Compounds

BACKGROUND

Cancer-induced mortality is increasingly prevalent globally which skyrocketed the necessity to discover new/novel safe and effective anticancer drugs. Cancer is characterized by the continuous multiplication of cells in the human which is unable to control. Scientific research is drawing its attention towards naturally-derived bioactive compounds as they have fewer side effects compared to the current synthetic drugs used for chemotherapy.

OBJECTIVE

Drugs isolated from natural sources and their role in the manipulation of epigenetic markers in cancer are discussed briefly in this review article.

METHODS

With advancing medicinal plant biotechnology and microbiology in the past century, several anticancer phytomedicines were developed. Modern pharmacopeia contains at least 25% herbal-based remedy including clinically used anticancer drugs. These drugs mainly include the podophyllotoxin derivatives vinca alkaloids, curcumin, mistletoe plant extracts, taxanes, camptothecin, combretastatin, and others including colchicine, artesunate, homoharringtonine, ellipticine, roscovitine, maytanasin, tapsigargin,andbruceantin.

RESULTS

Compounds (psammaplin, didemnin, dolastin, ecteinascidin,and halichondrin) isolated from marine sources and animals such as microalgae, cyanobacteria, heterotrophic bacteria, invertebrates. They have been evaluated for their anticancer activity on cells and experimental animal models and used chemotherapy.Drug induced manipulation of epigenetic markers plays an important role in the treatment of cancer.

CONCLUSION

The development of a new drug from isolated bioactive compounds of plant sources has been a feasible way to lower the toxicity and increase their effectiveness against cancer. Potential anticancer therapeutic leads obtained from various ethnomedicinal plants, foods, marine, and microorganisms are showing effective yet realistically safe pharmacological activity. This review will highlight important plant-based bioactive compounds like curcumin, stilbenes, terpenes, other polyphenolic phyto-compounds, and structurally related families that are used to prevent/ ameliorate cancer. However, a contribution from all possible fields of science is still a prerequisite for discovering safe and effective anticancer drugs.

Oroxylin a Attenuates Limb Ischemia by Promoting Angiogenesis via Modulation of Endothelial Cell Migration

Oroxylin A (OA) has been shown to simultaneously increase coronary flow and provide a strong anti-inflammatory effect. In this study, we described the angiogenic properties of OA. OA treatment accelerated perfusion recovery, reduced tissue injury, and promoted angiogenesis after hindlimb ischemia (HLI). In addition, OA regulated the secretion of multiple cytokines, including vascular endothelial growth factor A (VEGFA), angiopoietin-2 (ANG-2), fibroblast growth factor-basic (FGF-2), and platelet derived growth factor BB (PDGF-BB). Specifically, those multiple cytokines were involved in cell migration, cell population proliferation, and angiogenesis. These effects were observed at 3, 7, and 14 days after HLI. In skeletal muscle cells, OA promoted the release of VEGFA and ANG-2. After OA treatment, the conditioned medium derived from skeletal muscle cells was found to significantly induce endothelial cell (EC) proliferation. OA also induced EC migration by activating the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil kinase 2 (ROCK-II) signaling pathway and the T-box20 (TBX20)/prokineticin 2 (PROK2) signaling pathway. In addition, OA was able to downregulate the number of macrophages and neutrophils, along with the secretion of interleukin-1β, at 3 days after HLI. These results expanded current knowledge about the beneficial effects of OA in angiogenesis and blood flow recovery. This research could open new directions for the development of novel therapeutic intervention for patients with peripheral artery disease (PAD).

OroxylinA reverses lipopolysaccharide-induced adhesion molecule expression and endothelial barrier disruption in the rat aorta

Vascular dysfunction plays a critical role in the pathogenesis of sepsis. We elucidated the mechanisms underlying the amelioration of lipopolysaccharide (LPS)-induced vascular inflammation by oroxylin A (OroA) post-treatment in rats. The animals were intraperitoneally injected with LPS (10 mg/kg) to induce systemic inflammation and intravenously (iv) administered OroA (15 mg/kg) 6 h after the LPS treatment. The assessments included biochemical changes in peripheral blood, vascular reactivity which was evaluated by blood-vessel myography, morphological/histological assessment of inflammation, toll-like receptor (TLR)-4-mediated interleukin-1-receptor-associated-kinase (IRAK)-4 activation, changes in adhesion molecule expression, and endothelial junctional stability in the aorta. LPS significantly enhanced the proinflammatory cytokine release, increased vascular cell adhesion molecule (VCAM)-1 expression, disrupted endothelial tight junction, reduced vascular endothelial barrier stability, and increased macrophage infiltration and accumulation in the aorta. All observed pathological changes and vascular inflammation were significantly reversed by the OroA post-treatment. Importantly, OroA suppressed the increased adhesion molecule expression and the endothelial barrier disruption by inhibiting LPS-activated IRAK-4-targeted inhibitory nuclear factor kappa B kinase (IKK) α/β complex phosphorylation, without directly affecting the interaction between LPS and TLR-4. Moreover, the iNOS activity induced by the LPS challenge was inhibited by the OroA pretreatment of the isolated aortic rings. These results suggest that OroA regulates the vascular tone by inhibiting vascular hyporeactivity caused by NO overproduction and reverses the endothelial barrier dysfunction and inflammation by inhibiting the IRAK-4-mediated IKKα/β phosphorylation. Overall, these findings suggest OroA administration as a potentially useful therapeutic approach for clinical interventions in septic shock.

Long-Term Exposure to Oroxylin A Inhibits Metastasis by Suppressing CCL2 in Oral Squamous Cell Carcinoma Cells

Oroxylin A (Oro-A), the main bioactive flavonoid extracted from Scutellaria radix, has been reported to inhibit migration in various human cancer cell models. In this study, we further explored the anti-migration effects of Oro-A on oral squamous cell carcinoma (OSCC) cells and investigated the underlying mechanisms. A 24-h (short-term) exposure of OSCC cells to non-cytotoxic concentrations (5⁻20 μM) of Oro-A significantly suppressed cell migration according to a wound-healing assay. Furthermore, a 30-day exposure (long-term) to Oro-A (20 μM), which did not exhibit a cytotoxic effect on OSCC cells, significantly suppressed cell migration more than short-term Oro-A exposure. To uncover the molecular mechanisms underlying the inhibitory effect of long-term Oro-A exposure on OSCC migration, a cDNA microarray and the Ingenuity software were used. Overall, 112 upregulated and 356 downregulated genes were identified in long-term Oro-A-exposed cells compared with untreated OSCC cells. Among them, 75 genes were reported to be associated with cancer cell migration. Consistent with the cDNA microarray results, we found that the expression levels of several cell migration-related genes, such as LCN2, ID-1, MDK, S100A9 and CCL2, were significantly decreased in long-term Oro-A-exposed OSCC cells using a quantitative real-time polymerase chain reaction (Q-PCR) assay. The Western blotting and enzyme-linked immunosorbent assay (ELISA) results also demonstrated that CCL2 expression at the mRNA and protein levels was significantly decreased in long-term Oro-A-exposed OSCC cells compared with untreated OSCC cells. Moreover, the expression levels of downstream CCL2 targets, including p-ERK1/2, NFκB, MMP2, and MMP9, were also decreased in long-term Oro-A-exposed OSCC cells. Further, Oro-A treatment suppressed in vivo metastasis. These results suggest that long-term Oro-A treatment inhibits metastasis via CCL2 signaling in OSCC cells.

Induction of endothelium-dependent constriction of mesenteric arteries in endotoxemic hypotensive shock

BACKGROUND AND PURPOSE

Effective management of hypotension refractory to vasoconstrictors in severe sepsis is limited. A new strategy to ameliorate endotoxemic hypotension by inducing endothelium-dependent constriction of large arteries was assessed.

EXPERIMENTAL APPROACH

Endotoxemia in rats was induced by injection of LPS (10 mg·kg(-1), i.v.). Haemodynamics were measured in vivo, reactivity of isolated mesenteric arteries by myography and expression of proteins and enzyme activities by immunohistochemistry, biochemistry and molecular biology.

KEY RESULTS

Six hours after LPS, the hypotension was promptly reversed following injection (i.v. or i.p.) of oroxylin-A (OroA) . In isolated LPS-treated but not normal mesenteric arteries, OroA (1-10 μM) induced endothelium-dependent, sustained constriction, blocked by endothelin-1 (ET-1) receptor antagonists. OroA further enhanced LPS-induced expression of endothelin-converting enzyme, ET-1 mRNA and proteins and ET-1 release, OroA also enhanced phosphorylation of Rho-associated protein kinase (ROCK) and reversed LPS-induced suppression of RhoA activities in smooth muscle of arteries with endothelium. Activated- phosphorylation of smooth muscle ROCK was blocked by ET-1-receptor antagonists and ROCK inhibitors. Moreover, OroA post-treatment suppressed, via inhibiting NF-κB activation, inducible NOS expression and circulating NO.

CONCLUSIONS AND IMPLICATIONS

Reversal of endotoxemic hypotensive by OroA was due to release of endothelial ET-1, upregulated by LPS, from mesenteric arteries, inducing prompt and sustained vasoconstriction via activation of vascular smooth muscle RhoA/ROCK-pathway. In late endotoxemia, OroA-induced vasoconstriction was partly due to decreased circulating NO. Activation of endothelium-dependent constriction in large resistance arteries and suppression of systemic inflammation offer new strategies for acute management of endotoxemic hypotensive shock.

Protective effect of oroxylin A against lipopolysaccharide and/or D-galactosamine-induced acute liver injury in mice

BACKGROUND

Oroxylin A, a natural flavonoid isolated from Scutellariae baicalensis, has been reported to possess a wide spectrum of pharmacologic activities. However, the effects of oroxylin A on liver injury are poor understood. The purpose of this study was to investigate the effects of oroxylin A on acute liver injury in mice induced by lipopolysaccharide and/or D-galactosamine (LPS and/or D-GalN).

METHODS

Mice acute liver injury model was induced by LPS (50 μg/kg) and/or GalN (800 mg/kg). Serum alanine aminotransferase, aspartate aminotransferase, and tumor necrosis factor-α levels, hepatic tissue histology, malondialdehyde content, and myeloperoxidase activity were analyzed. Meanwhile, nuclear factor kappa B (NF-κB), heme oxygenase-1 (HO-1), and nuclear factor erythroid2-related factor 2 (Nrf2) expression were detected by Western blotting.

RESULTS

The results showed that oroxylin A dose-dependently inhibited LPS and/or GalN-induced serum alanine aminotransferase, aspartate aminotransferase, and tumor necrosis factor-α levels. Hepatic malondialdehyde content and myeloperoxidase activity were also suppressed by oroxylin A. We also found that oroxylin A inhibited LPS and/or GalN-induced toll like receptor 4 (TLR4) expression and NF-κB activation. In addition, oroxylin A upregulated the expression of Nrf2 and HO-1 in a dose-dependent manner.

CONCLUSIONS

In conclusion, oroxylin A protected against LPS and/or GalN-induced liver injury through activating Nrf2 and inhibiting TLR4 signaling pathway.

The coronary dilation effect of shen fu injection was mediated through NO

OBJECTIVES

Shen Fu Injection (SF), which consisted of Red ginseng extraction injection (RG) and prepared aconite extraction injection (RA), is a traditional Chinese medicine mainly used for various cardiac diseases. This study is to analyse SF's effects on cardiac performance and coronary circulation. And the coronary dilating effect and mechanism of the above three injections were also explored.

METHODS

Mature male guinea pigs were used as our animal model. We employed two types of perfusion methods (constant pressure and constant flow) in vitro, using Langendorff heart preparations to observe the cardiac function and coronary response to SF (1/200). The coronary dilation effects of the above three injections (1/800, 1/400 and 1/200) were recorded at basal coronary resting tone and when coronary vessels were pre-contracted with a thromboxane A2 analogue (U46619), in the presence or the absence of the inhibitor of nitric oxide synthesis (L-NAME, 10-4 M), the blocker of Ca2+-activated potassium channel(TEA, 10-3 M), or the blocker of adenosine triphosphate (ATP)-sensitive potassium channel (glybenclamide) (10-5 M).

RESULTS

When perfused with constant pressure, SF significantly increased coronary flow, left ventricular developed pressure (LVDP) and the rate-pressure product (RPP). When perfused with constant flow, SF produced a significant reduction in the coronary perfusion pressure (CPP), LVDP and RPP. The coronary vasodilatation response of the above three injections can be reduced by L-NAME but was unaffected by TEA or glybenclamide when coronary vessels were pre-contracted with U46619 but not at resting tone. SF, RG and RA can all up-regulate eNOS expression in the human umbilical vein cells (EA.hy926).

CONCLUSION

We demonstrated that SF does not contribute to the inotropic change of myocardium whose improvement is due to alternation of coronary flow. The coronary dilation effect of SF was mediated through RG and RA, via promoting NO release.

A review on the role of nutraceuticals as simple as se(2+) to complex organic molecules such as glycyrrhizin that prevent as well as cure diseases

Nutraceuticals are nutritional medicines which are present in edible food items. Most of them are antioxidants with various other biological properties viz, anti inflammatory, anti atherogenic, anticancer, anti viral, anti aging properties etc. They are as simple as minerals like Se(2+) to complex organic molecules such as glycyrrhizin (Ca(2+), K(+) salts of glycyrrhizic acid). They can prevent as well as cure various diseases. Most of the medical people are not aware of the importance of the nutraceuticals as such matters are not part of their text books. Many still think that vitamins are the major nutritional medicines. Actually other dietary principles like terpenes, carotenes, phytosterols, polyphenols, flavanoids, di and poly sulphides, their sulfoxides and their precursor amino acids are necessary to scavenge free radicals in the body which are reactive oxygen species to protect and maintain the vitamin levels in the body. They down regulate the activities of those enzymes which are increased in diseases and they increase those that remove oxidants and detoxify carcinogens. They are immune boosters too. Recently glucosinolates, non toxic alkaloids, certain proteins and even fiber are included in the list of nutraceuticals.