Development of a naringenin microemulsion as a prospective ophthalmic delivery system for the treatment of corneal neovascularization: in vitro and in vivo evaluation.

Naringenin, a flavonoid, possesses antiangiogenic potential and inhibits corneal neovascularization (CNV); however, its therapeutic use is restricted due to poor solubility and limited bioavailability. In this study, we developed a naringenin microemulsion (NAR-ME) for inhibiting CNV. NAR-ME formulation was composed of triacetin (oil phase), Cremophor RH40 (CRH40), PEG400, and water, its droplet size was 13.22 ± 0.13 nm with a narrow size distribution (0.112 ± 0.0014). The results demonstrated that NAR-ME released higher and permeated more drug than NAR suspension (NAR-Susp) in in vitro drug release and ex vivo corneal permeation study. Human corneal epithelial cells (HCECs) toxicity study showed no toxicity with NAR-ME, which is consistent with the result of ocular irritation study. NAR-ME had high bioavailability 1.45-fold, 2.15-fold, and 1.35-fold higher than NAR-Susp in the cornea, conjunctiva, and aqueous humor, respectively. Moreover, NAR-ME (0.5% NAR) presented efficacy comparable to that of dexamethasone (0.025%) in the inhibition of CNV in mice CNV model induced by alkali burning, resulting from the attenuation of corneal vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP-14) expression. In conclusion, the optimized NAR-ME formulation demonstrated excellent physicochemical properties and good tolerance, enhanced ocular bioavailability and corneal permeability. This formulation is promising, safe, and effective for the treatment of CNV.

Pharmacokinetic parameters of ifosfamide in mouse pre-administered with grapefruit juice or naringin.

Grapefruit juice (GFJ) and naringin when consumed previously or together with medications may alter their bioavailavility and consequently the clinical effect. Ifosfamide (IF) is an antitumoral agent prescribed against various types of cancer. Nevertheless, there is no information regarding its interaction with the ingestion of GFJ or naringin. The aims of the present report were validating a method for the quantitation of IF in the plasma of mouse, and determine if mice pretreated with GFJ or naringin may modify the IF pharmacokinetics. Our HPLC results to quantify IF showed adequate intra and inter-day precision (RSD < 15%) and accuracy (RE < 15%) indicating reliability. Also, the administration of GFJ or naringin increased Cmax of IF 22.9% and 17.8%, respectively, and decreased Tmax of IF 19.2 and 53.8%, respectively. The concentration of IF was higher when GFJ (71.35 ± 3.5 µg/mL) was administered with respect to that obtained in the combination naringin with IF (64.12 ± µg/mL); however, the time required to reach such concentration was significantly lower when naringin was administered (p < 0.5). We concluded that pre-administering GFJ and naringin to mice increased the Tmax and decreased the Cmax of IF.

Beneficial effects of naringenin in liver diseases: Molecular mechanisms.

Liver diseases are caused by different etiological agents, mainly alcohol consumption, viruses, drug intoxication or malnutrition. Frequently, liver diseases are initiated by oxidative stress and inflammation that lead to the excessive production of extracellular matrix (ECM), followed by a progression to fibrosis, cirrhosis and hepatocellular carcinoma (HCC). It has been reported that some natural products display hepatoprotective properties. Naringenin is a flavonoid with antioxidant, antifibrogenic, anti-inflammatory and anticancer properties that is capable of preventing liver damage caused by different agents. The main protective effects of naringenin in liver diseases are the inhibition of oxidative stress, transforming growth factor (TGF-ß) pathway and the prevention of the transdifferentiation of hepatic stellate cells (HSC), leading to decreased collagen synthesis. Other effects include the inhibition of the mitogen activated protein kinase (MAPK), toll-like receptor (TLR) and TGF-ß non-canonical pathways, the inhibition of which further results in a strong reduction in ECM synthesis and deposition. In addition, naringenin has shown beneficial effects on nonalcoholic fatty liver disease (NAFLD) through the regulation of lipid metabolism, modulating the synthesis and oxidation of lipids and cholesterol. Moreover, naringenin protects from HCC, since it inhibits growth factors such as TGF-ß and vascular endothelial growth factor (VEGF), inducing apoptosis and regulating MAPK pathways. Naringenin is safe and acts by targeting multiple proteins. However, it possesses low bioavailability and high intestinal metabolism. In this regard, formulations, such as nanoparticles or liposomes, have been developed to improve naringenin bioavailability. We conclude that naringenin should be considered in the future as an important candidate in the treatment of different liver diseases.

Therapeutic Perspectives of 8-Prenylnaringenin, a Potent Phytoestrogen from Hops.

Hop (Humulus lupulus L.), as a key ingredient for beer brewing, is also a source of many biologically active molecules. A notable compound, 8-prenylnaringenin (8-PN), structurally belonging to the group of prenylated flavonoids, was shown to be a potent phytoestrogen, and thus, became the topic of active research. Here, we overview the pharmacological properties of 8-PN and its therapeutic opportunities. Due to its estrogenic effects, administration of 8-PN represents a novel therapeutic approach to the treatment of menopausal and post-menopausal symptoms that occur as a consequence of a progressive decline in hormone levels in women. Application of 8-PN in the treatment of menopause has been clinically examined with promising results. Other activities that have already been assessed include the potential to prevent bone-resorption or inhibition of tumor growth. On the other hand, the use of phytoestrogens is frequently questioned regarding possible adverse effects associated with long-term consumption. In conclusion, we emphasize the implications of using 8-PN in future treatments of menopausal and post-menopausal symptoms, including the need for precise evidence and further investigations to define the safety risks related to its therapeutic use.

The Oral Bioavailability of 8-Prenylnaringenin from Hops (Humulus Lupulus L.) in Healthy Women and Men is Significantly Higher than that of its Positional Isomer 6-Prenylnaringenin in a Randomized Crossover Trial.

SCOPE: Prenylated chalcones and flavonoids from hop (Humulus lupulus L.), such as 6-prenylnaringenin (6-PN) and 8-prenylnaringenin (8-PN), are investigated for their health beneficial and anticancer activities. We, thus, compare the oral bioavailability and safety of 6-PN and 8-PN in healthy young women and men, and investigated their effects on peripheral blood mononuclear cells (PBMC). METHODS AND RESULTS: A double-blind, placebo-controlled, crossover trial is conducted with 16 healthy volunteers (eight women, eight men) given a single oral dose of 500 mg 6-PN, 8-PN, or placebo in random order. Maximum total concentrations of 6-PN and 8-PN in plasma (Cmax ; 543 and 2834 nmol L-1 ) and their respective area under the plasma concentration-time curve (AUC; 3635 and 15801 nmol L-1 × h) are significantly (5.2- and 4.3-fold) higher for 8-PN than for 6-PN (p Ë‚ 0.05). PBMC for ex vivo experiments are isolated from blood sampled before and 6 h after intake of 6-PN, 8-PN, or placebo. Despite the single-treatment regime and low blood concentrations, both 6-PN and 8-PN increase the survival of PBMC relative to control. CONCLUSION: 8-PN is significantly more bioavailable in healthy humans than its isomer 6-PN. Interestingly, 6-PN, despite being less bioavailable, is similarly effective as 8-PN in enhancing PBMC viability.

Baicalein inhibits cervical cancer progression via downregulating long noncoding RNA BDLNR and its downstream PI3K/Akt pathway.

Baicalein, an active flavonoid extracted from the root of Scutellaria baicalensis Georgi, has fascinating anti-cancer effects on many cancers. Our previous study also found that baicalein inhibited cervical cancer cell proliferation and migration, and induced cervical cancer cell apoptosis and cell cycle arrest. However, the molecular mechanisms underlying the anti-cancer effects of baicalein are largely unknown. In this study, we identified a novel long noncoding RNA (lncRNA), which is downregulated by baicalein in a dose- and time-dependent manner in cervical cancer. We named this lncRNA as baicalein down-regulated long noncoding RNA (BDLNR). Gain-of- and loss-of-function assays showed that BDLNR was required for baicalein-induced cell proliferation inhibition, cell death induction, migration inhibition, and in vivo tumor growth inhibition of cervical cancer. Mechanistically, BDLNR physically bound to YBX1, recruited YBX1 to PIK3CA promoter, activated PIK3CA expression and PI3K/Akt pathway. Furthermore, BDLNR was upregulated in cervical cancer and associated with poor prognosis of cervical cancer patients. Collectively, our data demonstrated that BDLNR mediated the anti-cancer effects of baicalein in cervical cancer via activating PI3K/Akt pathway, and implied that BDLNR would be potential therapeutic target for enhancing the anti-cancer effects of baicalein in cervical cancer.

High-dose wogonin exacerbates DSS-induced colitis by up-regulating effector T cell function and inhibiting Treg cell.

Wogonin exerts anti-tumour activities via multiple mechanisms. We have identified that high-dose wogonin (50 or 100 mg/kg) could inhibit the growth of transplanted tumours by directly inducing tumour apoptosis and promoting DC, T and NK cell recruitment into tumour tissues to enhance immune surveillance. However, wogonin (20-50 µM) ex vivo prevents inflammation by inhibiting NF-κB and Erk signalling of macrophages and epithelial cells. It is elusive whether high-dose wogonin promotes or prevents inflammation. To investigate the effects of high-dose wogonin on murine colitis induced by dextran sodium sulphate (DSS), mice were co-treated with DSS and various doses of wogonin. Intraperitoneal administration of wogonin (100 mg/kg) exacerbated DSS-induced murine colitis. More CD4+ CD44+ and CD8+ CD44+ cells were located in the inflamed colons in the wogonin (100 mg/kg) treatment group than in the other groups. Frequencies of CD4+ CD25+ CD127- and CD4+ CD25+ Foxp3+ cells in the colons and spleen respectively, were reduced by wogonin treatment. Ex vivo stimulations with high-dose wogonin (50-100 µg/ml equivalent to 176-352 µM) could synergize with IL-2 to promote the functions of CD4+ and CD8+ cells. However, regulatory T cell induction was inhibited. Wogonin stimulated the activation of NF-κB and Erk but down-regulated STAT3 phosphorylation in the CD4+ T cells. Wogonin down-regulated Erk and STAT3-Y705 phosphorylation in the regulatory T cells but promoted NF-κB and STAT3-S727 activation. Our study demonstrated that high-dose wogonin treatments would enhance immune activity by stimulating the effector T cells and by down-regulating regulatory T cells.

Wogonin attenuates etoposide-induced oxidative DNA damage and apoptosis via suppression of oxidative DNA stress and modulation of OGG1 expression.

Damage to DNA can lead to many different acute and chronic pathophysiological conditions, ranging from cancer to endothelial damage. The current study has been initiated to determine whether the flavonoid wogonin can attenuate etoposide-induced oxidative DNA damage and apoptosis in mouse bone marrow cells. We found that oral administration of wogonin before etoposide injection significantly attenuates etoposide-induced oxidative DNA damage and apoptosis in a dose dependent manner. Etoposide induced a significant down-regulation of mRNA expression of the OGG1 repair gene and marked biochemical alterations characteristic of oxidative DNA stress, including increased 8-OHdG, enhanced lipid peroxidation and reduction in reduced glutathione. Prior administration of wogonin ahead of etoposide challenge restored these altered parameters. Importantly, wogonin had no antagonizing effect on etoposide-induce topoisomerase-II inhibition. Conclusively, our study indicates that wogonin has a protective role in the abatement of etoposide-induced oxidative DNA damage and apoptosis in the bone marrow cells of mice via suppression of oxidative DNA stress and enhancing DNA repair through modulation of OGG1 repair gene expression. Therefore, wogonin can be a promising chemoprotective agent and might be useful to avert secondary leukemia and other drug-related cancers in cured cancer patients and medical personnel exposing to the potent carcinogen etoposide.

The isolation of bioactive flavonoids from Jacaranda obtusifolia H. B. K. ssp. rhombifolia (G. F. W. Meijer) Gentry.

The paper describes the bioassay-guided isolation, structure elucidation and anticancer evaluation of five flavonoids (-)-liquiritigenin (1), (-)-neoliquiritin (2), isoliquiritigenin (3), isoliquiritin (4) and formononetin (5) from the twigs of Jacaranda obtusifolia H. B. K. ssp. rhombifolia (G. F. W. Meijer) Gentry. The structures were elucidated based on ¹H, ¹³C NMR, comprehensive 2D NMR, MS analyses and comparison with previously reported spectral data. Compounds 1 and 3 were demonstrated to be inhibitory in vitro against NCI-H187 (small cell lung cancer) with IC50 values of 30.1 and 16.6 µg mL⁻¹, respectively. The isolates were non-cytotoxic to Vero cells (African green monkey kidney).

Combinatorial antitumor effect of naringenin and curcumin elicit angioinhibitory activities in vivo.

Curcumin has long been used as an antioxidative, antiinflammatory, and modulator of pathological angiogenesis, whereas naringenin is a well-known immunomodulator. In this report, we investigated the effect of curcumin and naringenin on the growth of Ehrlich ascites carcinoma tumor model. To achieve this, Swiss albino mice were implanted intraperitoneally with 1 × 106 Ehrlich ascites carcinoma cells followed by the administration of oral doses of naringenin and curcumin either individually (50 mg/kg body weight) or in combination (20 mg/kg body weight each). A marked reduction has been seen in the total number of cells (80%) and accumulation of ascetic fluid (55%) when these drugs were administered together. These drugs proved to be an effective angio-inhibitory compound and confirmed by different in vivo assay systems, viz. peritoneal/skin angiogenesis and chorioallantoic membrane assay. Antiangiogenic and antiproliferative effect of these compounds alone or in combination was further corroborated with immunoblot results where we confirmed the downregulation of vascular endothelial growth factor, Hif1α, heat shock protein 90, and p-Akt. Furthermore, treatment with naringenin and curcumin alone or in combination substantially improved hepatocellular architecture and no noticeable neoplastic lesions or cellular alteration were reported. These outcomes put forward a plausible clinical application of these diet-derived compounds, as both angioinhibitory and antitumor in association with conventional therapy.

Effects of baicalein on the pharmacokinetics of tamoxifen and its main metabolite, 4-hydroxytamoxifen, in rats: possible role of cytochrome P450 3A4 and P-glycoprotein inhibition by baicalein.

The purpose of this study was to investigate the effects of baicalein on the pharmacokinetics of tamoxifen and its active metabolite, 4-hydroxytamoxifen, in rats. Tamoxifen and baicalein interact with cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp), and the increase in the use of health supplements may result in baicalein being taken concomitantly with tamoxifen as a combination therapy to treat orprevent cancer diseases. Pharmacokinetic parameters of tamoxifen and 4-hydroxytamoxifen were determined in rats after an oral administration of tamoxifen (10 mg/kg) to rats in the presence and absence of baicalein (0.5, 3, and 10 mg/kg). Compared to the oral control group (given tamoxifen alone), the area under the plasma concentration-time curve and the peak plasma concentration of tamoxifen were significantly increased by 47.6-89.1% and 54.8-100.0%, respectively. The total body clearance was significantly decreased (3 and 10 mg/kg) by baicalein. Consequently, the absolute bioavailability of tamoxifen in the presence of baicalein (3 and 10 mg/kg) was significantly increased by 47.5-89.1% compared with the oral control group (20.2%). The metabolite-parent AUC ratio of tamoxifen was significantly reduced, implying that the formation of 4-hydroxytamoxifen was considerably affected by baicalein. Baicalein enhanced the oral bioavailability of tamoxifen, which may be mainly attributable to inhibition of the CYP3A4-mediated metabolism of tamoxifen in the small intestine and/or in the liver, and inhibition of the P-gp efflux pump in the small intestine and/or reduction of total body clearance by baicalein.

Naringin attenuates acute lung injury in LPS-treated mice by inhibiting NF-κB pathway.

Naringin has been reported as an effective anti-inflammatory compound. We previously showed that naringin had antitussive effect on experimentally induced cough in guinea pigs. However, the effects and mechanism of naringin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice are not fully understood. In this study, our aim was to evaluate the anti-inflammatory activities of naringin on LPS-induced ALI in mice and clarify its underlying mechanisms of action. We found that in vivo pretreatment with naringin markedly decreased the lung wet weight to dry weight ratio, and led to significant attenuation of LPS-induced evident lung histopathological changes. Meanwhile, naringin significantly reduced bronchoalveolar lavage fluid (BALF) total cell and neutrophil (PMN) counts after LPS challenge. Furthermore, naringin inhibited myeloperoxidase (MPO: a marker enzyme of neutrophil granule) and inducible nitric oxide synthase (iNOS) activities in lung tissue and alleviated LPS-induced tumor neurosis factor-α (TNF-α) secretion in BALF in a dose-dependent manner. Additionally, Western blotting showed that naringin efficiently blunt NF-κB activation by inhibiting the degradation of IĸB-α and the translocation of p65. Taken together, these results suggest that naringin shows anti-inflammatory effects through inhibiting lung edema, MPO and iNOS activities, TNF-α secretion and pulmonary neutrophil infiltration by blockade of NF-κB in LPS-induced ALI.

Species difference in the effect of grapefruit juice on intestinal absorption of talinolol between human and rat.

Bioavailability of talinolol, a beta(1)-adrenergic receptor antagonist, was enhanced by coadministration with grapefruit juice (GFJ) in rats, whereas GFJ ingestion markedly reduced the absorption of talinolol in humans. Because our recent study indicated that the inhibitory effect of GFJ on organic anion-transporting polypeptide (Oatp)- and P-gp-mediated talinolol absorption depends on the concentration of naringin in ingested GFJ, the apparent inconsistent findings may be explained by the species difference in the affinity of naringin for OATP/Oatp and P-gp multidrug resistance 1 (MDR1/Mdr1) between humans and rats. Although human MDR1-mediated talinolol transport was not inhibited by 2000 microM naringin, naringin inhibited human OATP1A2-, rat Oatp1a5-, and rat Mdr1a-mediated talinolol transport with IC(50) values of 343, 12.7, and 604 microM, respectively, in LLC-PK1 cell and Xenopus laevis oocyte systems. Because the naringin concentration in commercially prepared GFJ was found to be approximately 1200 microM, these results suggested that GFJ would reduce the intestinal absorption of talinolol through inhibition of OATP1A2-mediated talinolol uptake in humans, whereas an increase of talinolol absorption is mainly through inhibition of Mdr1a-mediated efflux in rats. The rat intestinal permeability of talinolol measured by the in situ closed loop method was indeed significantly increased in the presence of GFJ, whereas a significant decrease was observed with 6-fold diluted GFJ, in which the naringin concentration was approximately 200 microM. The present study indicated that the species difference in the effect of GFJ on intestinal absorption of talinolol between humans and rats may be due to differences in the affinity of naringin for OATP/Oatp and MDR1/Mdr1 transporters between the two species.

Effects of the chemically synthesized flavanone 7-(O-prenyl)naringenin-4'-acetate on the estrogen signaling pathway in vivo and in vitro.

The flavanone naringenin is known to possess only weak estrogenic properties, but some of its derivatives such as 8-prenylnaringenin are potent phytoestrogens. The aim of this study was to further clarify structure-function relationships of flavanones regarding their estrogenic or antiestrogenic properties by characterizing the new chemically synthesized naringenin derivative 7-(O-prenyl)naringenin-4'-acetate (7-O-PN). A yeast based reporter gene assay and MVLN cells, a MCF-7-derived cell line that possesses a luciferase reporter gene under the control of a vitellogenin estrogen responsive element, were used to investigate estrogenic actions of 7-O-PN in vitro. Estradiol (E2) has been used as a positive control. Subsequently a 3-day rat uterotrophic assay was performed to test for estrogenic effects. In addition, mRNA expression of estrogen sensitive genes in the uteri of these rats was measured using real time rtPCR. While E2 leads to a strong dose dependent signal in the yeast based reporter gene assay and in MVLN cells, 7-O-PN shows mild E2 antagonistic properties at concentrations 10(-8) and 10(-7)M, E2 agonistic properties at 10(-6) and 10(-5)M in MVLN cells and no effects on the yeast based system. In contrast to E2 treatment, 7-O-PN treatment did not increase uterus wet weight compared to the negative control. These findings are supported by mRNA expression studies of proliferation markers. Additionally, mRNA expression studies of estrogen regulated genes revealed very strong antiestrogenic properties of 7-O-PN regarding regulation of complement C3 expression while some estrogenic effects could be observed on the expression of estrogen receptor beta, clusterin and possibly on progesterone receptor and vascular endothelial growth factor.