FUNDAMENTOS DE TURBIDIMETRIA PDF

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Herbal medicines have been widely used around the world since ancient times. The advancement of phytochemical and phytopharmacological sciences has enabled elucidation of the composition and biological activities of several medicinal plant products.

The effectiveness of many species of medicinal plants depends on the supply of active compounds. Most of the biologically active constituents of extracts, such as flavonoids, tannins, and terpenoids, are highly soluble in water, but have low absorption, because they are unable to cross the lipid membranes of the cells, have excessively high molecular size, or are poorly absorbed, resulting in loss of bioavailability and efficacy.

Some extracts are not used clinically because of these obstacles. It has been widely proposed to combine herbal medicine with nanotechnology, because nanostructured systems might be able to potentiate the action of plant extracts, reducing the required dose and side effects, and improving activity.

Nanosystems can deliver the active constituent at a sufficient concentration during the entire treatment period, directing it to the desired site of action. Conventional treatments do not meet these requirements. The purpose of this study is to review nanotechnology-based drug delivery systems and herbal medicines. Knowledge and use of plants as herbal medicines has occurred in various populations throughout human evolution, beginning when man was learning to select plants for food, and to relieve ailments and diseases.

Allopathic treatments are currently more widely used than traditional medicines, especially in developed countries. However, most developing countries continue to use these natural medicines, most likely because obtaining a synthetic drug is expensive.

Currently, despite marketing and encouragement from the pharmaceutical industry during the development of allopathic medicines, a large segment of the population in many countries continues to utilize complementary practices for their health care. Many of these practices are derived from medicinal plants. However, due to economic, political, and social changes that have occurred worldwide, the therapeutic use of these natural resources, which are mainly used by people who cannot afford different treatments, has greatly diminished.

Elucidating the chemical composition of medicinal plants and their popular uses has become a research focus for all scientific communities. This research may lead to increasingly innovative products, with fewer side effects than existing drugs. However, except when they are used for local health care needs, a low percentage of plants have been tested for their medicinal potential. Therefore, there is a lack of information to describe any true potential. The biological activity of medicinal plants from all over the world has been studied by several groups of researchers.

These studies are based on the popular uses of different species, 9 as well as on popular knowledge and scientific studies describing medical plant use, with a focus on how these plants could benefit the pharmaceutical industry. The chemical complexity of extracts is an extremely important consideration for the success of a formulation, because the formulation must also release the active ingredient. Consequently, vehicles must concurrently improve the solubility of the drug, minimize the degradation process, reduce any toxicity, and mask any bad taste, while controlling the active absorption and biological response.

Phytochemical and phytopharmacological sciences have already established the composition and biological activities of several medicinal plant products. Most of the biologically active constituents of extracts, such as flavonoids, tannins, and terpenoids, are highly water-soluble, but demonstrate a low absorption, because they are unable to cross lipid membranes, have high molecular sizes, and demonstrate poor absorption, resulting in loss of bioavailability and efficacy.

Some studies have shown that herbal medicines have good activity in assays in vitro, which are not reproducible in experiments in vivo. Furthermore, some essential substances are rarely used, because they are incompatible with other components in the formulation, or have undesirable properties.

These technological discoveries have revolutionized drug delivery. The new drug delivery systems have the ability not only to increase the effectiveness of active components, but also to reintroduce other components that were discarded because they were not useful in formulation. Moreover, the ability to improve new substances, such as by increasing selectivity and efficacy, protecting against thermal- or photo-degradation, reducing side effects, and controlling the release of active constituents, before they are introduced to the market or used therapeutically, makes this approach even more attractive.

Along with advances in recent decades related to drug development, there is an urgent need for developments in nanoscience and nanotechnology that relate to the use of nanoscale materials, which, to date, have only been a focus of the cosmetics industry. Scientific advances can revolutionize, and enhance, solutions to problematic aspects of formulation preparation.

This technology can also be used to target the distribution of a substance toward specific tissues or organs. Pharmaceutical industries have become increasingly interested in nanotechnological advances because these developments provide advantages, such as modified release systems, and the potential to develop new formulations that were previously not possible due to several aspects related to the active constituents.

Although nanotechnology contributions are advantageous for several medicinal areas, it is essential to highlight some of the disadvantages. Clinical researchers have mentioned some negative factors, such as high cost, difficulty of scaling up processes, and the easy inhalability of nanoparticles, which can result in dangerous lung diseases, and often lead to other diseases that can lead to changes in homeostasis, or even death.

The strategy of applying nanotechnology to plant extracts has been widely cited in the literature, because nanostructured systems could potentiate action of plant extracts, promote sustained release of active constituents, reduce the required dose, decrease side effects, and improve activity.

Kesarwani and Gupta published a review that mentioned several studies which employed nanostructured systems to optimize the properties of plant extracts. Asteraceae and noted that these systems helped the active components from this plant penetrate the cytoplasmic viral barrier. Lamiaceae and reported that the encapsulated extract demonstrated better antimicrobial activity than in free-form preparation, when tested against Escherichia coli , Bacillus subtilis , Pseudomonas aeruginosa , and Staphylococcus aureus.

The effectiveness of medicinal plant species, or herbal medicine, depends on the supply of active compounds. Therefore, new carriers should deliver the active constituent at a sufficient concentration during the entire treatment period, and direct it toward the desired target, because these requirements are not completely obtained by conventional treatments. Partial or total loss of a specific activity can be observed when constituents of an extract are isolated or purified.

Moreover, some components are highly sensitive to the acidic pH of the stomach, which promotes their destruction, and loss of the desired effect, after ingestion.

Currently, nanotechnological processes involving medicinal plants have gained the focus of researchers, who have developed several innovative delivery systems, including polymeric nanoparticles. These materials, made from biodegradable and biocompatible polymers, represent an option for controlled drug delivery.

Polymeric nanoparticles are a promising formulation used for drug delivery systems, because they can be targeted. Polymeric nanoparticles are colloidal systems that work as vectors to control drug release, targeting it toward specific locations. Compared against conventional formulations, polymeric nanoparticles can increase the solubility of constituents, reduce the therapeutic dose, and improve absorption of the active components.

Furthermore, nanoparticles are advantageous when used in blood, because they are stable, non-toxic, nonthrombogenic, nonimmunogenic, noninflammatory, do not activate neutrophils, and avoid the reticuloendothelial system.

Sometimes, polymeric nanoparticles are used to reach specific tissues, or work as a cell surface. These particles are made from natural, or artificial, biodegradable polymers. Natural materials are preferred, because they generally have more advantages, such as the ability to deliver more than one active constituent using the same carrier, increase residence time in the body, provide a sustained release system, and reduce side effects.

They provide various therapeutic advantages in several areas, including routes of administration, site specificity, and increased therapeutic effect, which makes them desirable to researchers. Oral administration of certain conventional formulations may lead to side effects, and the degradation of active constituents is promoted by the acidic pH of the stomach.

These problems might be reduced by polymeric nanoparticles. In ophthalmic administration, nanoparticles control the release of active constituents, increasing ocular bioavailability, and reducing side effects. Polymeric nanoparticles can range from 10—1, nm in diameter, while still protecting drugs efficiently. They can appear as nanocapsules NCs and nanospheres NSs ; these structures differ in their composition and structural organization.

Nanospheres are made only from a polymeric structure, where the active constituent is retained or adsorbed. Although there is increasing search for new types of polymers, some of them have already been used extensively for polymeric nanoparticles, including poly-L-lactic acid PLA and copolymers with glycolic acid PLGA.

Regardless of the chosen method, the products are obtained as aqueous colloidal suspensions. However, some problems can obstruct industrial applicability, for example: nanoparticle precipitation and physicochemical stability problems can be reduced through drying processes, such as sublimation freeze drying , that allow dehydration, while preventing particle aggregation.

Some characteristics of colloidal nanoparticles cause technical difficulties during physicochemical characterization; this includes morphological evaluation, particle size, molecular weight distribution, zeta potential, pH determination, drug concentration inside the nanostructures, drug release kinetics, and stability over an extended period of time. Rajendran et al evaluated the antimicrobial activity of ethanolic, methanolic, petroleum ether, and aqueous extracts of leaves of Ocimum sanctum Lamiaceae OS.

They used an agar diffusion and microdilution technique to determine the minimum inhibitory concentration MIC against B. After this screening, methanolic extracts demonstrated the best antimicrobial activity, and were loaded into sodium alginate chitosan nanoparticles OSN , through a cation-induced, controlled gelation method. The particles were deposited on cotton fabric, using a pad dry cure method.

One of most significant difficulties in chemotherapy is the inability to deliver the active constituent, in appropriate doses, to specific sites affected by the disorder.

Currently, several of the antitumor therapeutics to be found in polymeric nanoparticle formulations have been evaluated in preclinical and clinical studies. Polymeric nanoparticles address problems found in chemotherapy by reducing toxicity, due to the protective barrier that prevents interaction between the active constituents and healthy cells.

Curcumin is a yellow polyphenol, extracted from rhizomes of Curcuma longa Zingiberaceae ; it has demonstrated potent antitumor properties, in several studies involving human tumor cells, and animal models of carcinogenesis.

This active constituent is highly potent, and nontoxic. The bioactive agent, found in turmeric, is used as an alternative drug for treating several disorders.

However, its clinical applications are limited, because it has low aqueous solubility and bioavailability. Various studies of polymeric nanoparticles have solved some formulation problems, such as the hydrophobic properties of some constituents, such as curcumin.

Bisht et al synthesized a mixture containing curcumin-loaded polymeric nanoparticles, using aggregated structures containing randomly crosslinked copolymers of N-isopropylacrylamide, N-vinylpyrrolidone, and poly ethylene glycol monoacrylate.

Physicochemical characterization, via dynamic light scattering and transmission electron microscopy TEM measurements, confirmed that these polymeric nanoparticles had a favorable size distribution of 50 nm.

Nanocurcumin revealed therapeutic efficacy in vitro against various human pancreatic tumor cells, confirmed by cell viability and clonogenic assays.

Nanocurcumin provided an opportunity to extend the clinical use of curcumin via aqueous dispersion. The encapsulation efficiency was Curcumin-loaded polymeric nanoparticles nanocurcumin were prepared using a process based on the wet-milling technique; nanoparticles were obtained with a narrow size distribution of 2—40 nm. Antimicrobial activity was evaluated using a microplate dilution technique against S.

The water solubility and small size of nanocurcumin nanoparticles enhanced antimicrobial activity, relative to free curcumin. The antibacterial activity of nanocurcumin was more pronounced than its antifungal activity. Among bacteria, gram-positive strains were more sensitive. TEM analysis revealed that when the nanoparticles were introduced into a bacterium, they completely destroyed the cell wall, resulting in bacterial cell death. It has several pharmacological effects, including anti-inflammatory, antithrombotic, antirheumatic, antioxidant, with anxiolytic, central nervous system depressant, and muscle relaxant activities.

In addition, it has potent antitumor activity. However, when this active constituent was loaded in polymeric nanoparticles, vascular administration was possible, as shown by Zheng et al. They developed a new formulation containing HN-loaded polymeric nanoparticles for vascular administration, obtaining better results, relative to free HN. Khuda-Bukhsh et al formulated polymeric nanocapsules containing coumarin 7-hydroxymethoxy HMC , which was isolated from an ethanolic extract of Gelsemium sempervirens J.

According to the in vitro evaluations, HMC has a pronounced anti-tumoral activity, but further studies were discontinued because of its hydrophobicity. A new formulation containing HMC-loaded polymeric nanoparticles demonstrated much better bioavailability than the free active constituent. Harungana madagascariensis Lam. Ex Poir Hypericaceae is widely known for its antibacterial, antifungal, and antiviral properties. Moulari et al evaluated and compared the in vitro and ex vivo antibacterial activity of ethanolic extract of H.

Ex vivo antibacterial activity was evaluated for S. A thin-layer chromatographic analysis revealed that, of the seven components found in the chromatogram of the HLE solution, only two were found in the HLE-loaded nanoparticles, including the flavonoid fraction, which is responsible for the antibacterial properties.

ONESIMO BECERRIL INSTALACIONES ELECTRICAS PDF

Meaning of "turbidimetria" in the Portuguese dictionary

Reactive oxygen and nitrogen species, antioxidants and markers of oxidative damage in human blood: main analytical methods for their determination. We review here the chemistry of reactive oxygen and nitrogen species, their biological sources and targets; particularly, biomolecules implicated in the redox balance of the human blood, and appraise the analytical methods available for their detection and quantification. Those biomolecules are represented by the enzymatic antioxidant defense machinery, whereas coadjutant reducing protection is provided by several low molecular weight molecules. Biomolecules can be injured by RONS yielding a large repertoire of oxidized products, some of which can be taken as biomarkers of oxidative damage. Their reliable determination is of utmost interest for their potentiality in diagnosis, prevention and treatment of maladies. Keywords: biomarkers of oxidative stress; oxidative and nitrosative stress; antioxidants. No sangue circulam importantes antioxidantes, a exemplo das vitaminas C, E, b-caroteno etc.

LA REGOLA DI SAN BENEDETTO DA NORCIA PDF

Nanotechnology-based drug delivery systems and herbal medicines: a review.

Either your web browser doesn't support Javascript or it is currently turned off. In the latter case, please turn on Javascript support in your web browser and reload this page. Herbal medicines have been widely used around the world since ancient times. The advancement of phytochemical and phytopharmacological sciences has enabled elucidation of the composition and biological activities of several medicinal plant products.

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