Apple Flavonoids Suppress Carcinogen-Induced DNA Damage in Normal Human Bronchial Epithelial Cells

Scope. Human neoplastic transformation due to DNA damage poses an increasing global healthcare concern. Maintaining genomic integrity is crucial for avoiding tumor initiation and progression. The present study aimed to investigate the efficacy of an apple flavonoid fraction (AF4) against various carcinogen-induced toxicity in normal human bronchial epithelial cells and its mechanism of DNA damage response and repair processes. Methods and Results. AF4-pretreated cells were exposed to nicotine-derived nitrosamine ketones (NNK), NNK acetate (NNK-Ae), methotrexate (MTX), and cisplatin to validate cytotoxicity, total reactive oxygen species, intracellular antioxidants, DNA fragmentation, and DNA tail damage. Furthermore, phosphorylated histone (γ-H2AX) and proteins involved in DNA damage (ATM/ATR, Chk1, Chk2, and p53) and repair (DNA-PKcs and Ku80) mechanisms were evaluated by immunofluorescence and western blotting, respectively. The results revealed that AF4-pretreated cells showed lower cytotoxicity, total ROS generation, and DNA fragmentation along with consequent inhibition of DNA tail moment. An increased level of γ-H2AX and DNA damage proteins was observed in carcinogen-treated cells and that was significantly (p≤0.05) inhibited in AF4-pretreated cells, in an ATR-dependent manner. AF4 pretreatment also facilitated the phosphorylation of DNA-PKcs and thus initiation of repair mechanisms. Conclusion. Apple flavonoids can protect in vitro oxidative DNA damage and facilitate repair mechanisms

Evaluation of Antioxidant, Antidiabetic and Antiobesity Potential of Selected Traditional Medicinal Plants

This study evaluated potential antidiabetic and antiobesity properties in vitro of selected medicinal plants. The hot water (WE) and ethanol extracts (EE) of sweet gale (Myrica gale L.), roseroot (Rhodiola rosea L.), sheep sorrel (Rumex acetosa L.), stinging nettles (Utrica dioica L.) and dandelion (Taraxacum officinale L.) were tested for total antioxidant capacity using ferric reducing antioxidant power (FRAP) and DPPH• scavenging capacity assays, followed by α-amylase, α-glucosidase and formation of advanced glycation end products (AGE) inhibition assays in vitro. Myrica gale EE had the highest total phenolic content (12.4 mmol GAE/L), FRAP value (17.4 mmol TE/L) and DPPH• scavenging activity (IC50 = 3.28 mg/L). Similarly, Myrica gale also exhibited significantly lower IC50 values for the percentage inhibition of α-amylase (IC50 = 62.65 mg/L) and α-glucosidase (IC50 = 27.20 mg/L) compared to acarbose (IC50 = 91.71 mg/L; IC50 = 89.50 mg/L, respectively) (p ≤ 0.05). The 3T3-L1 preadipocyte study also revealed that Myrica gale EE (54.8%) and stinging nettles (62.2% EE; 63.2% WE) significantly inhibited the adipogenesis in adipocytes in vitro (p ≤ 0.05). Polyphenols present in these medicinal plants have the potential to use in managing type 2 diabetes and obesity

Evaluation of In vitro Antidiabetic Potential of Thymus schimperi R. and Thymus vulgaris L.

Diabetes has become the most common metabolic disease worldwide. In particular, type 2 diabetes is the most commonly encountered type of diabetes, which is characterized by impaired insulin secretion and/or action. One of the effective methods to control diabetes is to inhibit the activity of α-amylase and α-glucosidase enzymes which are responsible for the breakdown of starch to more simple sugars, using plant products. This study evaluated the total phenolic (TPC), total flavonoid (TFC), and antidiabetic potential of Thymus schimperi and Thymus vulgaris via in vitro inhibition of α-amylase and α-glucosidase, using the hot water and aqueous: methanol (20:80, v/v) extracts. The α-amylase inhibitory potentials of the extracts were investigated through reducing sugars analysis using 3,5-dinitrosalicylic acid color reagent (DNSA) using starch solution as substrate. The α-glucosidase inhibition was determined by pre-incubating α-glucosidase with different concentrations of the extracts followed by the addition of p-nitrophenylglucopyranoside (pNPG). Aqueous: methanol (20:80, v/v) extract of T. schimperi contained highest TPC (46.01 ± 4.54 mg GAE/g dw) and TFC (14.72 ± 1.14 mg QE/g dw) also showed stronger α-amylase inhibition activity (IC50 = 0.33 ± 0.05 mg/mL) and the hot water extract exhibited stronger α-glucosidase inhibition (IC50 = 0.05 ± 0.01 mg/mL) capacity than that of T. vulgaris. The TPC and TFC were positively related (p < 0.05) with α-amylase inhibition activity but negatively correlated (p > 0.05) with α-glucosidase inhibitory activity. These results indicated that the inhibition of these enzymes can lead to lower postprandial blood glucose. Keywords: α-Amylase, Antidiabetic, Diabetes mellitus, α-Glucosidase, Thymus, Total phenolics DOI: 10.7176/JHMN/69-02 Publication date: December 31st 201

Novel Docosahexaenoic Acid Ester of Phloridzin Inhibits Proliferation and Triggers Apoptosis in an In Vitro Model of Skin Cancer

Skin cancer is among the most common cancer types accompanied by rapidly increasing incidence rates, thus making the development of more efficient therapeutic approaches a necessity. Recent studies have revealed the potential role of decosahexaenoic acid ester of phloridzin (PZDHA) in suppressing proliferation of liver, breast, and blood cancer cell lines. In the present study, we investigated the cytotoxic potential of PZDHA in an in vitro model of skin cancer consisting of melanoma (A375), epidermoid carcinoma (A431), and non-tumorigenic (HaCaT) cell lines. Decosahexaenoic acid ester of phloridzin led to increased cytotoxicity in all cell lines as revealed by cell viability assays. However, growth inhibition and induction of both apoptosis and necrosis was more evident in melanoma (A375) and epidermoid carcinoma (A431) cells, whereas non-tumorigenic keratinocytes (HaCaT) appeared to be more resistant as detected by flow cytometry. More specifically, PZDHA-induced cell cycle growth arrest at the G2/M phase in A375 and A431 cells in contrast to HaCaT cells, which were growth arrested at the G0/G1 phase. Elevated intracellular generation of reactive oxygen species ROS was detected in all cell lines. Overall, our findings support the potential of PZDHA as a novel therapeutic means against human skin cancer

Storage Temperature Impacts on Anthocyanins Degradation, Color Changes and Haze Development in Juice of “Merlot” and “Ruby” Grapes (Vitis vinifera)

This study evaluated the degradation kinetics of selected anthocyanins and the change in polymeric color, browning index, and haze development of grape juices from “Merlot” and “Ruby” grape cultivars stored at 5, 25, and 35°C for up to 360 days. Five major anthocyanins namely malvidin-3-O-glucoside (M3G), delphinidin-3-O-glucoside (D3G), petunidin-3-O-glucoside (Pt3G), peonidin-3-O-glucoside (Pn3G), and cyanidin-3-O-glucoside (C3G) were identified. Juice from “Merlot” had significantly higher (p < 0.05) content of all individual anthocyanins as compared to “Ruby.” During the long-term storage, total, and individual anthocyanins from both cultivars degraded following first-order reaction kinetics at the rate strongly dependent on temperature. At the end of the storage, noticeably higher loss of anthocyanins (95–99.9%) was observed at 25 and 35°C as compared to storage at 5°C [50–60% (“Merlot”); 74–81% (“Ruby”)]. Considerably lower rate of decay was observed at 5°C (k = 0.01–0.04) as compared to 25 (k = 0.04–0.14) and 35°C (k = 0.05–0.14) storage temperatures. The most temperature sensitive anthocyanin compounds were C3G (Ea = 66.5 kJ/mol) and D3G (Ea = 63.3 kJ/mol). At higher storage temperatures, significant (p < 0.05) and strong negative correlations were observed between anthocyanin concentrations and the levels of haze, polymeric and brown color development during storage. Storing grape juice, at lower temperature conditions could reduce the continuous loss of biologically active anthocyanins as well as the development of haze and brown color

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer

Inhibition of Oxidation of Aqueous Emulsions of Omega-3 Fatty Acids and Fish Oil by Phloretin and Phloridzin

The antioxidant properties of two apple dihydrochalcones, namely phloretin and phloridzin, were evaluated and compared with those of α-tocopherol and butylated hydroxytoluene (BHT). The effects were studied in an oil-in-water emulsion system containing methyl linolenate (ML), methyl eicosapentaenoate (MEPA), and methyl docosahexaenoate (MDHA) in which oxidation was initiated by the peroxyl radical generator 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH) and in fish oil where oxidation was initiated thermally. In the emulsion system, phloretin (1 and 5 mM) completely inhibited the oxidation of ML tested as evidenced by the thiobarbituric acid reactive substances (TBARS) assay. Under the same conditions, phloridzin was less effective than phloretin, but still more effective than α-tocopherol. Both phloretin and phloridzin molecules had a marginal inhibitory effect against oxidation of fish oil induced by heating at 70 °C for 3 hours, when compared to BHT. These results indicate that phloretin and phloridzin have the potential to suppress lipid oxidation in polyunsaturated fatty acid (PUFA) containing foods