Baicalin attenuates laser-induced choroidal neovascularization

Licochalcone A alleviates laser-induced choroidal neovascularization by inhibiting the endothelial-mesenchymal transition via PI3K/AKT signaling pathway

Choroidal neovascularization (CNV) is a hallmark of wet age-related macular degeneration, which severely impairs central vision. Studies have shown that endothelial-mesenchymal transition (EndMT) is involved in the pathogenesis of CNV. Licochalcone A (lico A), a flavonoid extracted from the root of licorice, shows the inhibition on EndMT, but it remains unclear whether it can suppress the formation of CNV. The aim of this study is to investigate the effects of lico A on laser-induced CNV, and EndMT process in vitro and vivo. We established the model of CNV with a krypton laser in Brown-Norway rats and then intraperitoneally injected lico A. Our experimental results demonstrated that the leakage of CNV was relieved, and the area of CNV was reduced in lico A-treated rats. Cell migration and tube formation in oxidized low-density lipoprotein (Ox-LDL)-stimulated HUVECs were inhibited by lico A and promoted by PI3K activator 740Y-P. The protein expressions of snai1 and α-SMA were increased, and CD31 and VE-cadherin were decreased in the model rats of CNV, but partially reversed after treatment with lico A. The expression of CD31 was decreased and α-SMA was increased in OX-LDL-treated HUVECs, which was further strengthened by 740Y-P, while the expression of CD31 was up-regulated and α-SMA was down-regulated in lico A treated HUVECs. Our data revealed that EndMT process was alleviated by lico A. Meanwhile, PI3K/AKT signaling pathway was activated in model rat of CNV and Ox-LDL-stimulated HUVECs, which can be suppressed with treatment of lico A. Our experimental results confirmed for the first time that lico A has the potential to alleviate CNV by inhibiting the endothelial-mesenchymal transition via PI3K/AKT signaling pathway.

Protective and therapeutic effects of Scutellaria baicalensis and its main active ingredients baicalin and baicalein against natural toxicities and physical hazards: a review of mechanisms

OBJECTIVES

Scutellaria baicalensis (SB) has been traditionally used to combat a variety of conditions ranging from ischemic heart disease to cancer. The protective effects of SB are due to the action of two main flavonoids baicalin (BA) and baicalein (BE). This paper aimed to provide a narrative review of the protective and antidotal effects of SB and its main constituents against natural toxicities and physical hazards.

EVIDENCE ACQUISITION

Scientific databases Medline, Scopus, and Web of Science were thoroughly searched, based on different keywords for in vivo, in vitro and clinical studies which reported protective or therapeutic effects of SB or its constituents in natural and physical toxicities.

RESULTS

Numerous studies have reported that treatment with BE, BA, or total SB extract prevents or counteracts the detrimental toxic effects of various natural compounds and physical hazards. The toxic agents include mycotoxins, lipopolysaccharide, multiple plants and animal-derived substances as well as physical factors which negatively affected vital organs such as CNS, liver, kidneys, lung and heart. Increasing the expression of radical scavenging enzymes and glutathione content as well as inhibition of pro-inflammatory cytokines and pro-apoptotic mediators were important mechanisms of action.

CONCLUSION

Different studies on the Chinese skullcap have exhibited that its total root extract, BA or BE can act as potential antidotes or protective agents against the damage induced by natural toxins and physical factors by alleviating oxidative stress and inflammation. However, the scarcity of high-quality clinical evidence means that further clinical studies are required to reach a more definitive conclusion.

Nutraceuticals for the Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and is characterized by degeneration of retinal neurons and neoangiogenesis, causing a severe threat to vision. Nowadays, the principal treatment options for DR are laser photocoagulation, vitreoretinal surgery, or intravitreal injection of drugs targeting vascular endothelial growth factor. However, these treatments only act at advanced stages of DR, have short term efficacy, and cause side effects. Treatment with nutraceuticals (foods providing medical or health benefits) at early stages of DR may represent a reasonable alternative to act upstream of the disease, preventing its progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DR, reducing both the neural and vascular damage typical of DR. Although most studies are limited to animal models and there is the problem of low bioavailability for many nutraceuticals, the use of these compounds may represent a natural alternative method to standard DR treatments.

Risk of macular degeneration affected by polymorphisms in Matrix metalloproteinase-2: A case-control study in Chinese Han population

The purpose of this study was to investigate the correlation of single nucleotide polymorphisms (SNPs) in Matrix metalloproteinase -2 (MMP-2) gene and the risk of age-related macular degeneration (AMD) in Chinese Han population.A total of 126 AMD patients and 141 healthy controls participated in this study. Genotypes of MMP-2 gene polymorphisms were identified by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). χtest was used to detect the differences of genotypes and alleles frequencies between case and control groups. Relative risk of AMD was evaluated by odds ratios (ORs) with 95% confidence intervals (CIs).Distribution of variant allele carriers (computed tomography + TT genotypes) of MMP-2 gene rs243865 SNP was significantly different between case and control groups, and might act as protective factors for the onset of AMD (P = .044, OR = 0.583, 95% CI = 0.344-0.987). Nevertheless, the T allele might reduce the AMD risk (P = .030, OR = 0.611, 95% CI = 0.390-0.956). However, no significant association existed between rs243865 and AMD risk in the subgroup analysis based on age. GA + AA genotypes of rs243866 SNP may associate with a decreased risk of AMD in the age≤65 years subgroup (P = .028, OR = 0.399, 95% CI = 0.174-0.915).MMP-2 gene rs243865 and rs243866 SNPs associated with the risk of AMD. Further studies should be performed to confirm the results.

The effect of baicalin in a mouse model of retinopathy of prematurity

Baicalin is a flavonoid derived from the dried root of Scutellaria baicalensis. In this study, oxygen-induced retinopathy was used to characterize the anti-angiogenic properties of baicalin in mice. Pups were exposed to a hyperbaric oxygen environment to induce retinal angiogenesis and were subjected to intraperitoneal injection of baicalin. Avascular area, neovascular tufts, and neovascular lumens were quantified from digital images. Compared to the vehicle, baicalin clearly reduced the central avascular zone and the number of neovascular tufts and lumens. High-dose baicalin (10 mg/kg) significantly reduced the expression of matrix metalloproteinase-2 (MMP-2), MMP-9, angiotensin II, and vascular endothelial growth factor (VEGF). These results show that baicalin is a powerful antiangiogenic compound that attenuates new vessel formation in the retina after systemic administration, and is a candidate substance for therapeutic inhibition of retinal angiogenesis. [BMB Reports 2015; 48(5): 271-276]

Natural product inhibitors of ocular angiogenesis

Natural products are characterized by high chemical diversity and biochemical specificity; therefore, they are appealing as lead compounds for drug discovery. Given the importance of angiogenesis to many pathologies, numerous natural products have been explored as potential anti-angiogenic drugs. Ocular angiogenesis underlies blinding eye diseases such as retinopathy of prematurity (ROP) in children, proliferative diabetic retinopathy (DR) in adults of working age, and age-related macular degeneration (AMD) in the elderly. Despite the presence of effective therapy in many cases, these diseases are still a significant health burden. Anti-VEGF biologics are the standard of care, but may cause ocular or systemic side effects after intraocular administration and patients may be refractory. Many anti-angiogenic compounds inhibit tumor growth and metastasis alone or in combination therapy, but a more select subset of them has been tested in the context of ocular neovascular diseases. Here, we review the promise of natural products as anti-angiogenic agents, with a specific focus on retinal and choroidal neovascularization. The multifunctional curcumin and the chalcone isoliquiritigenin have demonstrated promising anti-angiogenic effects in mouse models of DR and choroidal neovascularization (CNV) respectively. The homoisoflavanone cremastranone and the flavonoid deguelin have been shown to inhibit ocular neovascularization in more than one disease model. The isoflavone genistein and the flavone apigenin on the other hand are showing potential in the prevention of retinal and choroidal angiogenesis with long-term administration. Many other products with anti-angiogenic potential in vitro such as the lactone withaferin A, the flavonol quercetin, and the stilbenoid combretastatin A4 are awaiting investigation in different ocular disease-relevant animal models. These natural products may serve as lead compounds for the design of more specific, efficacious, and affordable drugs with minimal side effects.