Metformin May Alter the Metabolic Reprogramming in Cancer Cells by Disrupting the L-Arginine Metabolism: A Preliminary Computational Study.

Metabolic reprogramming in cancer is considered to be one of the most important hallmarks to drive proliferation, angiogenesis, and invasion. AMP-activated protein kinase activation is one of the established mechanisms for metformin's anti-cancer actions. However, it has been suggested that metformin may exert antitumoral effects by the modulation of other master regulators of cellular energy. Here, based on structural and physicochemical criteria, we tested the hypothesis that metformin may act as an antagonist of L-arginine metabolism and other related metabolic pathways. First, we created a database containing different L-arginine-related metabolites and biguanides. After that, comparisons of structural and physicochemical properties were performed employing different cheminformatic tools. Finally, we performed molecular docking simulations using AutoDock 4.2 to compare the affinities and binding modes of biguanides and L-arginine-related metabolites against their corresponding targets. Our results showed that biguanides, especially metformin and buformin, exhibited a moderate-to-high similarity to the metabolites belonging to the urea cycle, polyamine metabolism, and creatine biosynthesis. The predicted affinities and binding modes for biguanides displayed good concordance with those obtained for some L-arginine-related metabolites, including L-arginine and creatine. In conclusion, metabolic reprogramming in cancer cells by metformin and biguanides may be also driven by metabolic disruption of L-arginine and structurally related compounds.

Enhanced in vitro anticancer activity of yeast expressed recombinant glucose oxidase versus commercial enzyme.

Cancer treatments continue to have many disadvantages. Reactive oxygen species, such as H2O2, in high concentrations, can cause cytotoxicity to cells, being even greater in cancer cells. One of the H2O2-producing enzymes is glucose oxidase; its application in cancer treatment should be explored. In this work, the extracellular expression of the mutated recombinant enzyme glucose oxidase was carried out in the eukaryotic expression system Pichia pastoris SMD1168, through the modification and optimization of the gox gene of Aspergillus niger to improve its expression in yeast and its purification. Also, the secretion signal of the alpha-mating factor from Saccharomyces cerevisiae was added to the gene for extracellular expression, and it was inserted into the expression vector pPIC3.5k. The extracellular expression of the enzyme facilitated purification by anion exchange chromatography; the purification was corroborated by SDS-PAGE, with a molecular weight of its subunit between 63 kDa and 100 kDa. The mutated recombinant enzyme glucose oxidase showed greater anticancer activity compared to the commercial glucose oxidase and could have potential for cancer treatment. KEY POINTS: • Pichia pastoris is an excellent eukaryotic expression system for proteins that need post-translational modifications. • Extracellular expression facilitates protein purification. • Glucose oxidase has potential application in cancer treatment.

Antioxidant and Antiproliferative Activity of The Ethanolic Extract of Equisetum Myriochaetum and Molecular Docking of Its Main Metabolites (Apigenin, Kaempferol, and Quercetin) on ß-Tubulin.

Equisetum myriochaetum is a semi-aquatic plant found on riverbanks that is commonly used in traditional medicine as a diuretic agent. Additionally, the genus Equisetum stands out for its content of the flavonoid kaempferol, a well-known antiproliferative agent. Therefore, in this study, E. myriochaetum ethanolic extract was tested in vitro against a cervical cancer cell line (SiHa). Additionally, the antioxidative activity was evaluated through a 2,2-diphenyl-1-picrilhidrazil (DPPH) assay. Finally, a molecular docking analysis of apigenin, kaempferol, and quercetin on the active site of ß-tubulin was performed to investigate their potential mechanism of action. All fractions of E. myriochaetum ethanolic extract showed antioxidative activity. Fraction 14 displayed an antiproliferative capacity with a half maximal inhibitory concentration (IC50) value of 6.78 µg/mL against SiHa cells.

Chemistry and Pharmacology of Citrus sinensis.

Presently the search for new drugs from natural resources is of growing interest to the pharmaceutical industry. Natural products have been the source of new drugs since ancient times. Plants are a good source of secondary metabolites which have been found to have beneficial properties. The present study is a review of the chemistry and pharmacology of Citrus sinensis. This review reveals the therapeutic potential of C. sinensis as a source of natural compounds with important activities that are beneficial for human health that could be used to develop new drugs.

Plant Secondary Metabolites against Skin Photodamage: Mexican Plants, a Potential Source of UV-Radiation Protectant Molecules.

Human skin works as a barrier against the adverse effects of environmental agents, including ultraviolet radiation (UVR). Exposure to UVR is associated with a variety of harmful effects on the skin, and it is one of the most common health concerns. Solar UVR constitutes the major etiological factor in the development of cutaneous malignancy. However, more than 90% of skin cancer cases could be avoided with appropriate preventive measures such as regular sunscreen use. Plants, constantly irradiated by sunlight, are able to synthesize specialized molecules to fight against UVR damage. Phenolic compounds, alkaloids and carotenoids constitute the major plant secondary metabolism compounds with relevant UVR protection activities. Hence, plants are an important source of molecules used to avoid UVR damage, reduce photoaging and prevent skin cancers and related illnesses. Due to its significance, we reviewed the main plant secondary metabolites related to UVR protection and its reported mechanisms. In addition, we summarized the research in Mexican plants related to UV protection. We presented the most studied Mexican plants and the photoprotective molecules found in them. Additionally, we analyzed the studies conducted to elucidate the mechanism of photoprotection of those molecules and their potential use as ingredients in sunscreen formulas.

Synthesis of silver nanoparticles using a Mentha spicata extract and evaluation of its anticancer and cytotoxic activity.

In this study, silver nanoparticles (NP) were synthesized by two methods: using an aqueous extract of Mentha spicata leaves and using citrate ions as stabilizing agent, and the cytotoxicity and anticancer activity of both NP were evaluated in vitro. The particles synthesized with the aqueous extract were spherical with a size ranging from 15 to 45 nm. These NP decreased cell viability in all of the cells studied; however, the IC50 could only be estimated in the Chang liver cells (IC50 = 21.37 µg/mL). These particles also decreased the generation of reactive oxygen species in Chang and SiHa cells. Additionally, the dispersions decreased the activity of caspase-3. There was no significant difference between the biological activities of the NP obtained with the aqueous extract and the NP synthesized using citrate ions. This study showed that an aqueous extract of M. spicata is an excellent alternative for the synthesis of silver NP. These NP showed cytotoxicity and anticancer activity in vitro. Although more experiments are required, the cell death occurs probably through a mechanism different from apoptosis.

Synthesis and photodynamic activity of unsymmetrical A3B tetraarylporphyrins functionalized with l-glutamate and their Zn(II) and Cu(II) metal complex derivatives.

Four novel unsymmetrical A3B porphyrins 1, 2, 3 and 4 were synthesized following Lindsey procedure. Porphyrins 3 and 4 include one and three l-glutamate groups, respectively, and all porphyrins were metallated with Zn(II) (1a-4a) or Cu(II) (1b-4b). Porphyrins and metalloporphyrins presented values of singlet oxygen quantum yields (ΦD) ranging from 0.21 to 0.67. The tetraaryl derivatives in this study showed phototoxicity in SiHa cells with IC50 values ranging from <0.01 to 6.56±0.11µM, the metalloporphyrin 4a showed the lowest IC50 value. Comparing the phototoxic activity between all porphyrins, functionalization of porphyrins with glutamate increased 100 times phototoxic activity (1 (IC50 4.81±0.34µM) vs. 3 (IC50 0.04±0.02µM) and 2 (IC50 5.19±0.42µM) vs. 4 (IC50 0.05±0.01µM)). This increased activity could be attributed to reduced hydrophobicity and increased ΦΔ, given by functionalization with l-glutamate. Metalloporphyrins 3a (IC50 0.04±0.01µM) and 4a (IC50<0.01µM) presented the best values ​​of phototoxic activity. Therefore, functionalization and zinc metalation increased the phototoxic activity. SiHa cells treated with porphyrins 3, 4, 3a and 4a at a final concentration of 10µM, showed increased activity of caspase-3 enzyme compared to the negative control; indicating the induction of apoptosis. Differential gene expression pattern in SiHa cells was determined; treatments with metalloporphyrins 4a and 4b were performed, respectively, comparing the expression with untreated control. Treatments in both cases showed similar gene expression pattern in upregulated genes, since they share about 25 biological pathways and a large number of genes. According to the new photophysical properties related to the structural improvement and phototoxic activity, these molecules may have the potential application as photosensitizers in the photodynamic therapy.

An analysis of unused and expired medications in Mexican households.

BACKGROUND: Unsafe storage of unused medications at home leads to an increased risk of toxicity, accidental childhood poisoning or risk for suicide, whereas an improper disposal of unwanted/expired medications from household raises concern about environmental pollution. OBJECTIVE: The aim of the study was to characterize expired medications collected according to the types of therapeutic groups, pharmaceutical dosage forms, expiration dates and were prescribed or over the counter drugs, and whether they came from Mexican health system or purchased by patients themselves. SETTING: The study was conducted in the metropolitan area of Monterrey during a 12-month period from March 2012 to February 2013. METHOD: Unused/expired drugs were collected according to the collection and disposal of expired medication program instituted by the Department of Health of the State of Nuevo León. Pharmacists and students from The Autonomous University of Nuevo León recorded types of therapeutic groups, total of medicines in each group, among other classification criteria. MAIN OUTCOME MEASURE: The proportion of every collected therapeutic group, type of dosage forms, and expiration date. RESULTS: The amount of medications classified was 22,140 items corresponding to a 30 % of the total collected medications in that period of time; most of them belonged to the non-steroidal anti-inflammatory drugs (16.11 %). According to the pharmaceutical dosage forms, results showed that a high percentage were solid dosage forms (73.39 %), of the total unused/expired medications, most of them were prescription drugs (91 %) which were purchased at private pharmacies. Expiration date of medications ranges from 1995 to 2016, being 2011 the outstanding year (36.66 %). CONCLUSION: Addressing the aspect of unused drug disposition constitutes a challenge for Mexican government, due to health implications related to inadequate disposition. No matter how efficient the programs of collection and disposal of expired drugs are, none of them can collect all unused or expired drugs, that is the reason why the best approach might be to prevent this need.

Biodistribution and long-term fate of silver nanoparticles functionalized with bovine serum albumin in rats.

Silver nanocrystals (Ag NCs) hold promising antibiotic and antiviral properties in biological systems. The biodistribution of silver nanostructures injected into animals in vivo is currently unknown, remaining as a fundamental issue for potential therapeutic applications. Here, we injected Ag NCs capped with bovine serum albumin (BSA) in live rats to elucidate their fate in several organs including liver, heart and brain. Very significant accumulations of nanoparticles were confirmed by inductively coupled plasma mass spectroscopy (ICPMS) and transmission electron microscopy (TEM) techniques on the liver and heart. In contrast, the brain tissue did not reveal evidence of particles content. Our results suggest that Ag+ permeated across the blood-brain barrier (BBB), and followed swift clearance from the organ.

The bioactivity of plant extracts against representative bacterial pathogens of the lower respiratory tract.

BACKGROUND: Lower respiratory tract infections are a major cause of illness and death. Such infections are common in intensive care units (ICU) and their lethality persists despite advances in diagnosis, treatment and prevention. In Mexico, some plants are used in traditional medicine to treat respiratory diseases or ailments such as cough, bronchitis, tuberculosis and other infections. Medical knowledge derived from traditional societies has motivated searches for new bioactive molecules derived from plants that show potent activity against bacterial pathogens. Therefore, the aim of this study was to evaluate the effect of hexanic, chloroformic (CLO), methanolic (MET) and aqueous extracts from various plants used in Mexican traditional medicine on various microorganisms associated with respiratory disease. METHODS: thirty-five extracts prepared from nine plants used in Mexican traditional medicine for the treatment of respiratory infections were evaluated against 15 control bacterial species and clinical isolates. RESULTS: Both chloroformic (CLO) and methanolic (MET) extracts of Larrea tridentata were active against Methicillin-resistant S. aureus, B. subtilis and L. monocytogenes. A MET extract of L. tridentata was also active against S. aureus, S. pneumoniae, S. maltophilia, E. faecalis and H. influenzae and the CLO extract was active against A. baumannii. An Aqueous extract of M. acumitata and a MET extract of N. officinale were active against S. pneumoniae. CLO and MET extracts of L. tridentata were active against clinical isolates of S. aureus, S. pneumoniae and E. faecalis. CONCLUSION: Overall, our results support the potential use of L. tridentata as a source of antibacterial compounds.

Activity against drug resistant-tuberculosis strains of plants used in Mexican traditional medicine to treat tuberculosis and other respiratory diseases.

Tuberculosis (TB) kills about 3 million people per year worldwide. Furthermore, TB is an infectious disease associated with HIV patients, and there is a rise in multidrug-resistant TB (MDR-TB) cases around the world. There is a need for new anti-TB agents. The study evaluated the antimycobacterial activity of nine plants used in Mexican traditional medicine to treat tuberculosis and other respiratory diseases. Nasturtium officinale showed the best activity (MIC = 100 microg/mL) against the sensitive Mycobacterium tuberculosis. The following plants were active also but at 200 microg/mL: Citrus sinensis, Citrus aurantifolia, Foeniculum vulgare, Larrea tridentata, Musa acuminata and Olea europaea. Contrary to the above data, activity against drug-resistant variants of M. tuberculosis was more evident, e.g. N. officinale was the most potent (MIC < or = 100 microg/mL) against the four mono-resistant variants tested; F. vulgare and O. europaea were active against all the resistant variants (MICs < or = 100 microg/mL). The most susceptible variant was the isoniazid resistant, being inhibited by C. aurantifolia, C. sinensis and O. europaea (MIC = 25 microg/mL). These data point to the importance of biological testing of extracts against drug-resistant M. tuberculosis isolates, and the bioguided assay of these extracts for the identification of lead compounds against MDR-TB isolates.