Naringin suppresses the mitogenic effect of lysophosphatidylcholine on vascular smooth muscle cells

The underlying mechanism of nuclear and mitochondrial DNA damages in triggering cancer incidences: Insights into proteomic and genomic sciences

The attempt of this review article is to determine the impact of nuclear and mitochondrial damages on the propagation of cancer incidences. This review has advanced our understanding to altered genes and their relevant cancerous proteins. The progressive raising effects of free reactive oxygen species ROS and toxicogenic compounds contributed to significant mutation in nuclear and mitochondrial DNA where the incidence of gastric cancer is found to be linked with down regulation of some relevant genes and mutation in some important cellular proteins such as AMP-18 and CA-11. Thereby, the resulting changes in gene mutations induced the apparition of newly polymorphisms eventually leading to unusual cellular expression to mutant proteins. Reduction of these apoptotic growth factors and nuclear damages is increasingly accepted by cell reactivation effect, enhanced cellular signaling and DNA repairs. Acetylation, glycation, pegylation and phosphorylation are among the molecular techniques used in DNA repair for rectifying mutation incidences. In addition, the molecular labeling based fluorescent materials are currently used along with the bioconjugating of signal molecules in targeting disease translocation site, particularly cancers and tumors. These strategies would help in determining relevant compounds capable in overcoming problems of down regulating genes responsible for repair mechanisms. These issues of course need interplay of both proteomic and genomic studies often in combination of molecular engineering to cible the exact expressed gene relevant to these cancerous proteins.

Optimization of extraction flavonoids from Exocarpium Citri Grandis and evaluation its hypoglycemic and hypolipidemic activities

ETHNOPHARMACOLOGICAL RELEVANCE

Exocarpium Citri Grandis (ECG; Huajuhong in Chinese) is a precious traditional Chinese medicine with a history of hundreds of years in China. It has been demonstrated to possess numerous pharmacological properties, including antitussive, expectorant, anti-inflammatory, hypoglycemic, and hypolipidemic. However, no in-depth report exists on the hypoglycemic and hypolipidemic properties of ECG.

AIM OF THE STUDY

This study aimed to evaluate the hypoglycemic and hypolipidemic properties of ECG flavonoids extract in vitro and in vivo so as to lay the foundation for further researches in this field.

MATERIALS AND METHODS

Total flavonoids (TF) and naringin were separately extracted from ECG, and the components of TF were identified by HPLC-MS. The antioxidant capacities of TF and naringin were determined by 2,2,1-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging tests, and digestive enzymes activity inhibition assays in vitro in order to evaluate their hypoglycemic properties. Furthermore, diabetic mice experiments were performed to assess the hypoglycemic and hypolipidemic properties of TF and naringin in vivo.

RESULTS

Five compounds were identified from TF, including naringin, rhoifolin, poncirin, bergaptol, and naringenin. The half maximal inhibitory concentration (IC₅₀) of TF and naringin to DPPH-free radicals were 0.269 and 1.946 mg/mL, respectively. TF and naringin demonstrated a certain inhibitory effect on α-glucosidase and a weaker inhibitory effect on α-amylase. The results of animal experiments showed that TF and naringin had no significant effect on the blood glucose levels, but they could lead to significant (p < 0.05 or p < 0.01) increase in the serum insulin level and high-density lipoprotein cholesterol (HDL-C) levels with concomitant reduction in the total cholesterol (TC), total triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) levels in diabetic mice. In addition, TF and naringin could reduce the liver index of diabetic mice (p < 0.01) and reduce the kidney index at low doses (p < 0.05).

CONCLUSIONS

Our study revealed that the hypoglycemic and hypolipidemic activities of TF is mainly derived from naringin, and other active ingredients in TF also have the effects of alleviating oxidative stress, inhibiting digestive enzyme activity and reducing blood lipids. Our results thus provide a scientific basis for the application of ECG in antidiabetic treatment.

Mitochondrial biogenesis and metabolic hyperactivation limits the application of MTT assay in the estimation of radiation induced growth inhibition

Metabolic viability based high throughput assays like MTT and MTS are widely used in assessing the cell viability. However, alteration in both mitochondrial content and metabolism can influence the metabolic viability of cells and radiation is a potential mitochondrial biogenesis inducer. Therefore, we tested if MTT assay is a true measure of radiation induced cell death in widely used cell lines. Radiation induced cellular growth inhibition was performed by enumerating cell numbers and metabolic viability using MTT assay at 24 and 48 hours (hrs) after exposure. The extent of radiation induced reduction in cell number was found to be larger than the decrease in MTT reduction in all the cell lines tested. We demonstrated that radiation induces PGC-1α and TFAM to stimulate mitochondrial biogenesis leading to increased levels of SDH-A and enhanced metabolic viability. Radiation induced disturbance in calcium (Ca²⁺) homeostasis also plays a crucial role by making the mitochondria hyperactive. These findings suggest that radiation induces mitochondrial biogenesis and hyperactivation leading to increased metabolic viability and MTT reduction. Therefore, conclusions drawn on radiation induced growth inhibition based on metabolic viability assays are likely to be erroneous as it may not correlate with growth inhibition and/or loss of clonogenic survival.

New transition metal complexes containing imidazole rings endowed with potential antiamoebic activity

Imidazole-hydrazones were found to be better antiamoebic lead molecules compared to the standard drug metronidazole (MNZ). Chelation of these bioactive ligands with metals enhanced their activity profiles.

Synthesis of naringin 6"-ricinoleate using immobilized lipase

Abstract

Graphical abstract

DNA adducts with antioxidant flavonoids: morin, apigenin, and naringin

Flavonoids have recently attracted a great interest as potential therapeutic drugs against a wide range of free-radical-mediated diseases. The anticancer and antiviral activities of these natural products are implicated in their mechanism of actions. While the antioxidant activity of these natural polyphenolic compounds is well known, their bindings to DNA are not fully investigated. This study was designed to examine the interactions of morin (Mor), naringin (Nar), and apigenin (Api) with calf thymus DNA in aqueous solution at physiological conditions, using constant DNA concentration (6.25 mM) and various drug/DNA(phosphate) ratios of 1/40 to 1. FTIR and UV-Vis spectroscopic methods were used to determine the ligand binding modes, the binding constant, and the stability of DNA in flavonoid-DNA complexes in aqueous solution. Spectroscopic evidence shows both intercalation and external binding of flavonoids to DNA duplex with overall binding constants of K(morin) = 5.99 x 10(3) M(-1), K(apigenin) = 7.10 x 10(4) M(-1), and K(naringin) = 3.10 x 10(3) M(-1). The affinity of ligand-DNA binding is in the order of apigenin > morin > naringin. DNA aggregation and a partial B- to A-DNA transition occurs upon morin, apigenin, and naringin complexation.

RNA binding to antioxidant flavonoids

Flavonoids are an interesting group of natural polyphenolic compounds that exhibit extensive bioactivities such as scavenging free radical, antitumor and antiproliferative effects. The anticancer and antiviral effects of these natural products are attributed to their potential biomedical applications. While flavonoids complexation with DNA is known, their bindings to RNA are not fully investigated. This study was designed to examine the interactions of three flavonoids; morin (Mor), apigenin (Api) and naringin (Nar) with yeast RNA in aqueous solution at physiological conditions, using constant RNA concentration (6.25 mM) and various pigment/RNA (phosphate) ratios of 1/120 to 1/1. FTIR, UV-visible spectroscopic methods were used to determine the ligand binding modes, the binding constant and the stability of RNA in flavonoid-RNA complexes in aqueous solution. Spectroscopic evidence showed major binding of flavonoids to RNA with overall binding constants of K(morin) = 9.150 x 10(3) M(-1), K(apigenin)=4.967 x 10(4) M(-1), and K(naringin)=1.144 x 10(4) M(-1). The affinity of flavonoid-RNA binding is in the order of apigenin>naringin>morin. No biopolymer secondary structural changes were observed upon flavonoid interaction and RNA remains in the A-family structure in these pigment complexes.

Lysophosphatidylethanolamine in Grifola frondosa as a neurotrophic activator via activation of MAPK

We found that Grifola frondosa extracts induced the activation of mitogen-activated protein kinase (MAPK) in cultured PC12 cells, a line of rat pheochromocytoma cells. The active substance was isolated by a few chromatographic steps, including high-performance liquid chromatography, and was identified to be lysophosphatidylethanolamine (LPE) from various structural analyses. LPE from G. frondosa (GLPE) was confirmed to induce the activation of MAPK of cultured PC12 cells and was found to suppress cell condensation and DNA ladder generation evoked by serum deprivation, suggesting that the GLPE had antiapoptotic effects. Moreover, GLPE caused morphological changes in and upregulation of neurofilament M expression of PC12 cells, demonstrating that the GLPE could induce neuronal differentiation of these cells. The activation of MAPK by GLPE was suppressed by AG1478, an antagonist of epidermal growth factor receptor (EGFR), and by U0126, an inhibitor of MAPK kinase (MEK1/2), but not by K252a, an inhibitor of TrkA, or by pertussis toxin. These results demonstrate that GLPE induced the MAPK cascade [EGFR-MEK1/2-extracellular signal-regulated protein kinases (ERK1/2)] of PC12 cells, the activation of which induced neuronal differentiation and suppressed serum deprivation-induced apoptosis. This study has clarified for the first time the involvement of the MAPK signal cascade in LPE actions.

Reduction of MTT by flavonoids in the absence of cells

The tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) is used to determine cell viability in assays of cell proliferation and cytotoxicity. MTT is reduced in metabolically active cells to yield an insoluble purple formazan product. However, in this study, using a colorimetric method with MTT, we demonstrated that luteolin and quercetin (both are flavonoids) can reduce MTT in the absence of living cells. We also examined effects of some experimental conditions on the reaction, such as concentrations of flavonoids, incubation time, the structure and the existing form in solvents of flavonoids. The maximal absorbance values, which were 0.355 (luteolin) and 0.491 (quercetin), were observed when the concentrations of flavonoids were 200 microg/ml. Incubating MTT with flavonoids for 8 h, the absorbance values got the maximum, which were 0.320 (luteolin) and 0.398 (quercetin). The ability of flavonoids reducing MTT in RPMI-1640 with 10% fetal calf serum was higher than that in anhydrous ethanol. And the ability of quercetin reducing MTT was higher than that of luteolin both in RPMI-1640 with 10% fetal calf serum and anhydrous ethanol. Based on the results, this undescribed reaction can significantly influence the results of experiments using the MTT assay to measure the effects of flavonoids on cell growth.