Nicácio Henrique da Silva

In vitro and in vivo properties of usnic acid encapsulated into PLGA-microspheres.

Microparticles will probably play a promising role in the future of chemotherapy. These polymeric delivery systems are capable of maximizing the therapeutic activity while reducing side effects of anti-cancer agents. Usnic acid (UA) is a secondary metabolite produced by lichens, which exhibits an anti-tumour activity. In this study, PLGA-microspheres containing usnic acid from Cladonia substellata were prepared by the double emulsion method, with or without PEG as stabilizer. The morphology of the microspheres was examined by optical and scanning electron microscopy. The in vitro kinetic profile of usnic acid loaded-microspheres was carried out by dissolution testing. The usnic acid content was analysed by HPLC. The cytotoxicity of free and encapsulated usnic acid was evaluated against HEp-2 cells using the MTT method. The anti-tumour assay was performed in mice against Sarcoma-180 tumour (UA 15 mg kg−1 weight body/day) during 7 days. Animals were then sacrificed and tumour and organs were excised for histopathological analysis. Microspheres presented a smooth spherical surface with a mean diameter of 7.02 ± 2.72 µm. The usnic acid encapsulation efficiency was ∼100% (UA 10 mg 460 mg−1 microspheres). A maximum release of 92% was achieved at the fifth day. The IC50 values for free and encapsulated usnic acid were 12 and 14 µg ml−1, respectively. The encapsulation of usnic acid into microspheres promoted an increase of 21% in the tumour inhibition as compared with the free usnic acid treatment. In summary, usnic acid was efficiently encapsulated into PLGA-microspheres and the microencapsulation improved its anti-tumour activity.

Study of carbohydrates present in the cladodes of Opuntia ficus-indica (fodder palm), according to age and season

Tipos e conteudo de carboidratos foram avaliados por metodos quimicos (ensaios espectrofotometricos) e fisico-quimicos (Cromatografia de Camada Delgada - CCD e Cromatografia Liquida de Alta Eficiencia - CLAE), em algumas variedades de Opuntia ficus-indica. As amostras estudadas compreenderam quatro variedades de palma (gigante, copena F1, clone 20 e palma redonda). Os resultados demonstraram que as quatro variedades de palma contem uma boa quantidade de acucares neutros e acidos nas estacoes do ano verao e inverno. Entretanto, amostras coletadas no verao apresentaram um alto conteudo de carboidratos, especialmente glicose, frutose, galactose, xilose e arabinose. O cladodio terciario (cladodio mais antigo) apresentou quase o dobro do conteudo de acucar encontrado nos cladodios quaternarios (cladodios mais jovens). Polissacarideos pecticos foram sequencialmente extraidos com agua a 60 oC e solucao de EDTA a 60 oC, resultando em uma Pectina Soluvel em Agua (PSA) e Pectina Soluvel em Quelante (PSQ), respectivamente. Acidos galacturonicos foram detectados em fracoes PSA e PSQ. Entretanto a fracao PSQ apresentou o mais alto conteudo de acucar acido.

Usnic acid potassium salt: an alternative for the control of Biomphalaria glabrata (Say, 1818).

In Brazil, the snail Biomphalaria glabrata is the most important vector of schistosomiasis due to its wide geographical distribution, high infection rate and efficient disease transmission. Among the methods of schistosomiasis control, the World Health Organization recommends the use of synthetic molluscicides, such as niclosamide. However, different substances of natural origin have been tested as alternatives for the control or eradication of mollusks. The literature describes the antitumor, antimicrobial and antiviral properties of usnic acid as well as other important activities of common interest between medicine and the environment. However, usnic acid has a low degree of water solubility, which can be a limiting factor for its use, especially in aquatic environments, since the organic solvents commonly used to solubilize this substance can have toxic effects on aquatic biota. Thus, the aim of the present study was to test the potassium salt of usnic acid (potassium usnate) with regard to molluscicidal activity and toxicity to brine shrimp (Artemia salina). To obtain potassium usnate, usnic acid was extracted with diethyl ether isolated and purified from the lichen Cladonia substellata. Biological assays were performed with embryos and adult snails of B. glabrata exposed for 24 h to the usnate solution solubilized in dechlorinated water at 2.5; 5 and 10 µg/ml for embryos, 0.5; 0.9; 1;5 and 10 µg/ml for mollusks and 0.5; 1; 5; 10 µg/ml for A. salina. The lowest lethal concentration for the embryos and adult snails was 10 and 1 µg/ml, respectively. No toxicity to A. salina was found. The results show that modified usnic acid has increased solubility (100%) without losing its biological activity and may be a viable alternative for the control of B. glabrata.

Cladia aggregata (lichen) from Brazilian northeast: chemical characterization and antimicrobial activity

A composicao quimica e a atividade antimicrobiana da Cladia aggregata (Sw.) Nyl. foram avaliadas. O acido barbatico, um depsideo obtido da C. aggregata, foi espectroscopicamente analisado e testado, bem como o extrato orgânico. o extrato e a substância purificada foram testadas contra 4 linhagens de Staphylococcus aureus multi resistentes. A estrutura do acido barbatico foi confirmada atraves de ensaios de CCD, CLAE, IV, RMN (1H;13C), UV e analise elementar (r). O biocromatograma mostrou a acao deste composto junto com outras substâncias contidas no extrato orgânico, sugerindo a acao sinergica, a CMI do acido barbatico mostrou o mesmo nivel de inibicao de outras substâncias liquenicas.

(E)-Caryophyllene and α-Humulene: Aedes aegypti Oviposition Deterrents Elucidated by Gas Chromatography-Electrophysiological Assay of Commiphora leptophloeos Leaf Oil.

Aedes aegypti is responsible for the transmission of dengue, a disease that infects millions of people each year. Although essential oils are well recognized as sources of compounds with repellent and larvicidal activities against the dengue mosquito, much less is known about their oviposition deterrent effects. Commiphora leptophloeos, a tree native to South America, has important pharmacological properties, but the chemical profile and applicability of its essential oil in controlling the spread of the dengue mosquito have not been investigated. The aim of this study was to determine the composition of C. leptophloeos leaf oil and to evaluate its larvicidal and oviposition deterrent effects against A. aegypti. Fifty-five components of the essential oil were detected by gas chromatography (GC)—mass spectrometry, with α-phellandrene (26.3%), (E)-caryophyllene (18.0%) and β-phellandrene (12.9%) identified as the major constituents. Bioassays showed that the oil exhibited strong oviposition deterrent effects against A. aegypti at concentrations between 25 and 100 ppm, and possessed good larvicidal activity (LC50 = 99.4 ppm). Analysis of the oil by GC coupled with electroantennographic detection established that seven constituents could trigger antennal depolarization in A. aegypti gravid females. Two of these components, namely (E)-caryophyllene and α-humulene, were present in substantial proportions in the oil, and oviposition deterrence assays confirmed that both were significantly active at concentrations equivalent to those present in the oil. It is concluded that these sesquiterpenes are responsible, at least in part, for the deterrent effect of the oil. The oviposition deterrent activity of the leaf oil of C. leptophloeos is one of the most potent reported so far, suggesting that it could represent an interesting alternative to synthetic insecticides. The results of this study highlight the importance of integrating chemical and electrophysiological methods for screening natural compounds for their potential in combating vectors of insect-borne diseases.

Usnic acid-loaded nanocapsules: an evaluation of cytotoxicity

The aim of the present study is the design of nanocapsules containing usnic acid (UA-NC) and the evaluation of their physicochemical properties, in vitro kinetic profile and cytotoxic effect on human lung carcinoma cells. The usnic acid was encapsulated into nanocapsules prepared with a copolymer of lactic and glycolic acid using an interfacial deposition of a preformed polymer on oil-in-water emulsion. The cytotoxicity of nanocapsules was evaluated by the MTT method. UA-NC were obtained with a mean diameter of 324 ± 88 nm. An encapsulation ratio of 99.4 ± 0.16% was attained at an usnic acid concentration of 1 mg/ml. An usnic acid release of 78.3% from nanocapsules within 48 h was achieved. Concentrations required to inhibit 50% of cell growth were 10.0 and 11.5 μg/ml for free and encapsulated usnic acid, respectively. In conclusion, usnic acid was, for the first time, efficiently encapsulated into PLGA nanocapsules, providing a suitable dosage form for introducing usnic acid in in vivo studies, the use of which has been limited by its poor solubility and toxic properties.

Evaluation of Antioxidant, Immunomodulatory, and Cytotoxic Action of Fractions from Eugenia uniflora L. and Eugenia malaccensis L.: Correlation with Polyphenol and Flavanoid Content

An increasing number of biological activities presented by medicinal plants has been investigated over the years, and they are used in the search for new substances with lower side effects. Eugenia uniflora L. and Eugenia malaccensis L. (Myrtaceae) have many folk uses in various countries. This current study was designed to quantify the polyphenols and flavonoids contents and evaluate the immunomodulatory, antioxidant, and cytotoxic potentials of fractions from E. uniflora L. and E. malaccensis L. It was observed that the polyphenol content was higher in ethyl acetate fractions. These fractions have high antioxidant potential. E. malaccensis L. seeds showed the largest DPPH radical scavenger capacity (EC50 = 22.62). The fractions of E. malaccensis L. leaves showed lower antioxidant capacity. The samples did not alter the profile of proinflammatory cytokines and nitric oxide release. The results indicate that species of the family Myrtaceae are rich in compounds with antioxidant capacity, which can help reduce the inflammatory response.

Influência de poluentes atmosféricos em Belo Jardim (PE) utilizando Cladonia verticillaris (líquen) como biomonitor

Cladonia verticillaris used in this study was collected in the cerrado vegetation of Saloa (PE, Brazil) and transplanted in plastic containers on soil from the collection place to Belo Jardim (PE) that possesses lead smelters and battery industries. The experiments were disposed at eleven different places for evaluating the dispersion of pollutants and their effects on the biomonitor. The exposed lichens were collected over eight months and submitted to thin layer and high performance liquid chromatographies, and scanning electron microscopy. C. verticillaris placed in the vicinity of the emission sources demonstrated alteration in its metabolism, decreasing the production of its major compound, fumarprotocetraric acid, and deterioration of its external and internal surfaces.

Ultrastructural Analysis of Leishmania infantum chagasi Promastigotes Forms Treated In Vitro with Usnic Acid

Leishmaniasis is considered by the World Health Organization as one of the infectious parasitic diseases endemic of great relevance and a global public health problem. Pentavalent antimonials used for treatment of this disease are limited and new phytochemicals emerge as an alternative to existing treatments, due to the low toxicity and cost reduction. Usnic acid is uniquely found in lichens and is especially abundant in genera such as Alectoria, Cladonia, Evernia, Lecanora, Ramalina, and Usnea. Usnic acid has been shown to exhibit antiviral, antiprotozoal, antiproliferative, anti-inflammatory, and analgesic activity. The aim of this study was to evaluate the antileishmanial activity of usnic acid on Leishmania infantum chagasi promastigotes and the occurrence of drug-induced ultrastructural damage in the parasite. Usnic acid was effective against the promastigote forms (IC50 = 18.30 ± 2.00 µg/mL). Structural and ultrastructural aspects of parasite were analyzed. Morphological alterations were observed as blebs in cell membrane and shapes given off, increasing the number of cytoplasmic vacuoles, and cellular and mitochondrial swelling, with loss of cell polarity. We concluded that the usnic acid presented antileishmanial activity against promastigote forms of Leishmania infantum chagasi and structural and ultrastructural analysis reinforces its cytotoxicity. Further, in vitro studies are warranted to further evaluate this potential.

Atividade antimicrobiana de derivados fenólicos do líquen Ramalina sorediosa (B. de Lesd.) Laundron

The antimicrobian activity of crude extracts from Ramalina sorediosa was detected by the diffusion disc-paper method. Two phenolic compounds from the lichen considered active were detected by using biochromathograhyc technique. Two of those compounds were identified through thin layer chromatographic technique (TLC) as been usnic acid and the second one, wich is present in higher concentration when compared with the other substances, was the homosekikaik acid. The TLC and high-pressure liquid chromatography (HPLC) assays still detected the salazanic acid presence. The obtained data make it possible to attribute the antibiotic activity of this species to a synergic association of those two substances.