Hypericum alpestre extract exhibits in vitro and in vivo anticancer properties by regulating the cellular antioxidant system and metabolic pathway of L-arginine

Conventional treatment methods are not effective enough to fight the rapid increase in cancer cases. The interest is increasing in the investigation of herbal sources for the development of new anticancer therapeutics. This study aims to investigate the antitumor capacity of Hypericum alpestre (H. alpestre) extract in vitro and in vivo, either alone or in combination with the inhibitors of the  l-arginine/polyamine/nitric oxide (NO) pathway, and to characterize its active phytochemicals using advanced chromatographic techniques. Our previous reports suggest beneficial effects of the arginase inhibitor NG-hydroxy-nor- l-arginine and NO inhibitor NG-nitro-Larginine methyl ester in the treatment of breast cancer via downregulation of polyamine and NO synthesis. Here, the antitumor properties of H. alpestre and its combinations were explored in vivo, in a rat model of mammary gland carcinogenesis induced by subcutaneous injection of 7,12-dimethylbenz[a]anthracene. The study revealed strong antiradical activity of H. alpestre aerial part extract in chemical (DPPH/ABTS) tests. In the in vitro antioxidant activity test, the H. alpestre extract demonstrated pro-oxidant characteristics in human colorectal (HT29) cells, which were contingent upon the hemostatic condition of the cells. The H. alpestre extract expressed a cytotoxic effect on HT29 and breast cancer (MCF-7) cells measured by the MTT test. According to comet assay results, H. alpestre extract did not exhibit genotoxic activity nor possessed antigenotoxic properties in HT29 cells. Overall, 233 substances have been identified and annotated in H. alpestre extract using the LC-Q-Orbitrap HRMS system. In vivo experiments using rat breast cancer models revealed that the H. alpestre extract activated the antioxidant enzymes in the liver, brain, and tumors. H. alpestre combined with chemotherapeutic agents attenuated cancer-like histological alterations and showed significant reductions in tumor blood vessel area. Thus, either alone or in combination with Nω -OH-nor- l-arginine and Nω -nitro- l-arginine methyl ester, H. alpestre extract exhibits pro- and antioxidant, antiangiogenic, and cytotoxic effects.

The Action Mechanisms, Anti-Cancer and Antibiotic-Modulation Potential of Vaccinium myrtillus L. Extract

BACKGROUND

Herbal medicinal products containing Vaccinium myrtillus L. (bilberry) fruits and fruit extracts are widely available in the market. Although bilberry leaves and stems are considered as bio-waste, they contain much higher levels of phenolic compounds than fruits. The study aimed to investigate the antimicrobial and anticancer potential of aerial part extracts from Vaccinium myrtillus L. (V. myrtillus, VM) plants harvested at high altitudes in Armenian landscape and characterize the bioactive phytochemicals.

MATERIAL AND METHODS

For evaluation of antioxidant properties, chemical-based tests (total phenolic and flavonoid content, and antiradical activity in 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) tests) and cellular antioxidant activity (CAA) assay were applied. Genotoxicity and anticancer properties of the extract alone and in combination with fluorouracil were explored in human cancer and normal cell lines. Antibacterial properties of V. myrtillus extract alone and in combination with antibiotics, as well as their effect on proton-flux rate through cell membrane were explored on bacterial strains. The characterization of active phytochemicals was done using Liquid Chromatography-Quadrupole-Orbitrap High-Resolution Mass Spectrometry (LC-Q-Orbitrap HRMS).

RESULTS

The V. myrtillus aerial part extract demonstrated promising antioxidant properties in all tests. The selective cytotoxic activity was documented against various cancer cell lines (human colon adenocarcinoma (HT29), human breast cancer (MCF-7) and human cervical carcinoma (HeLa)), while it did not inhibit the growth of tested human normal primary renal mixed epithelial cells (HREC) even at 10-fold higher concentrations. The extract did not have genotoxic properties in comet assay making it a potential source for the development of anticancer preparations. The investigated extract did not directly inhibit the growth of Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium) strains at up to 1 mg/mL concentration. However, V. myrtillus extract enhanced the kanamycin intake and increased its efficiency against E. coli strain. The phytochemical characterization of the extract showed the presence of different groups of phenolics.

CONCLUSIONS

Based on obtained data, we suggest the aerial parts of the V. myrtillus plant as an alternative source of bioactive natural products for food supplements, nutraceuticals, functional foods and medicine.

Anti-cancer effect of in vivo inhibition of nitric oxide synthase in a rat model of breast cancer

Increased expression of nitric oxide synthase (NOS) is associated with different cancers such as cervical, breast, lung, brain, and spinal cord. Inhibition of NOS activity has been suggested as potential tool to prevent breast cancer. The anti-tumor therapeutic effect of L-nitro arginine methyl ester (L-NAME), NOS inhibitor, using in vivo models is currently under investigation. We hypothesized that L-NAME will show an anti-tumor effect by delaying a progression of breast cancer via a modulation of cell death and proliferation, and angiogenesis. We used a novel model of anti-cancer treatment by the administration of L-NAME (30 mg/kg in a day, intraperitoneal) injected every third day for five weeks to rat model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast tumor. Concentrations of nitrite anions, polyamines, malondialdehyde, NH₄⁺ levels, and arginase activity in the blood were decreased in DMBA + L-NAME-treated rats compared with DMBA rats. The mortality rates, tumor number, weight, and volume, as well as the histopathological grade of breast cancer were also significantly reduced. In addition, L-NAME treatment showed a delay in tumor formation, and in body weight compared with rats administrated only with DMBA. In conclusion, our data show that L-NAME is a promising anti-cancer agent to treat breast cancer, which can lead to development of anti-tumor therapeutic tools in future.

Screening revealed the strong cytotoxic activity of <i>Alchemilla smirnovii</i> and <i>Hypericum alpestre</i> ethanol extracts on different cancer cell lines

<abstract> <p>Compounds of plant origin are considered promising alternative approaches in the development of medicines for the prevention and treatment of cancer. The large diversity of herbal species still requires careful exploration as a source for new anticancer compounds. The goal of the study was to screen different herbal extracts traditionally used in Armenian folk medicine for their cytotoxic effect against some cancer cell lines, and to find the prospective plant species among them. The cytotoxicity of the plant ethanol extracts was evaluated with MTT test against HeLa (human cervical carcinoma) and A549 (human lung adenocarcinoma) cells. Antioxidant properties were assessed with DPPH free radical scavenging assay. Five of the tested ten herbal extracts exhibited significant growth-inhibiting activity on HeLa cells. Moreover, <italic>Alchemilla smirnovii</italic> and <italic>Hypericum alpestre</italic> extracts also showed potent cytotoxicity on human lung adenocarcinoma cells. These two plants possessed high antiradical activity as well. Their DPPH stoichiometric values were 0.4234 and 0.14437 respectively, meaning that 1 µg of plant extract brought the reduction of DPPH equal to the respective stoichiometric values in µg. Thus, <italic>A. smirnovii</italic> and <italic>H. alpestre</italic> extracts expressed themselves as potent cytotoxic and antioxidant agents and could have promising anticancer potential. Further evaluation of their <italic>in vivo</italic> anticancer properties has much interest.</p> </abstract>

The effects of NO on the urea cycle pathway in short-term intermittent hypobaric hypoxia in rats

Short-term hypoxic states can influence the health and life activities of lowlanders who travel shortly to high altitudes, in transitory situations, such as surgical ischemia-reperfusion (to one or several organs), and in some sporting activities, such as parachuting and extreme skiing, mountain rescue teams, regular commercial flight crews, in which the subject may not even notice the hypoxia. NO is an integral part of the human physiological response to hypoxia. Until recently, the urea cycle (UC) was only considered as an important mechanism for neutralizing ammonia. We are the first to reveal an interrelation in hypoxic states between the activities of NO-synthase and UC enzymes in male rats' liver, kidney and brain. In the presented work, we have shown that during short-term intermittent hypobaric hypoxia (IHH) all enzymes of UC play an important role in the maintenance of NO quantity. The results allow thinking that kidney and brain argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL) and liver ASS and ASL can be different isoenzymes. It is worth mentioning that the results have revealed new sides of l-arginine metabolism in a hypoxic state in male rats.

The potential therapeutic effect of NG-hydroxy-nor-L-arginine in 7,12-dimethylbenz(a)anthracene-induced breast cancer in rats

Advances in our understanding of the metabolism and molecular functions of arginine and their alterations in cancer have led to resurgence in the interest of targeting arginine catabolism as an anticancer strategy. Therefore, arginase inhibitors have been proposed as a way to treat cancer. In this study, the anti-tumor potential of the arginase inhibition by N^G-hydroxy-nor-L-arginine (nor-NOHA) (3 mg/kg/day, i.p.), administered for 5 weeks (parallel tumors development, every 3th day) against 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis in rats has been investigated. Treatment by nor-NOHA has obvious inhibition effects on development of carcinogenesis in rats was shown. That was seen in downregulation of rats' tumors size and number, mortality rate, in stopped alteration of tissue histopathology, in decrease of polyamines, NO and MDA (malondialdeide) concentrations (in blood). Results have shown arginase and NO-synthase can cooperate to restrain quantities of polyamines and NO for cancer progression. The results obtained can serve as a base to use this model for determination of productive, noncytotoxic antitumor and immune modulating concentration of anticancer agents. Perspectives of targeting arginase and NOS in cancer management can ground application in clinical medicine.