Mônica Cristina Barroso Martins

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.

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.

Produção de compostos fenólicos a partir de células imobilizadas do líquen Parmotrema andinum (Müll. Arg.) Hale e avaliação de atividade antimicrobiana

A utilizacao de metabolitos secundarios obtidos de liquens, na industria farmaceutica, de cosmetico, textil e de alimentos deve ser criteriosa, visto que a extracao e isolamento desses metabolitos requerem uma grande quantidade de biomassa dificilmente renovavel, devido ao crescimento lento do liquen. Atualmente, e possivel obter substâncias liquenicas tanto por cultivo de tecidos, como por imobilizacoes celulares e enzimaticas, a partir do talo in natura, utilizando pequena quantidade de material liquenico. Portanto, este trabalho objetiva investigar a producao de compostos fenolicos a partir de celulas imobilizadas de Parmotrema andinum (Mull. Arg.) Hale utilizando acetato de sodio como precursor da biossintese dos fenois. Ensaios de atividade antimicrobiana com extratos orgânicos do talo in natura, eluatos celulares e do acido lecanorico isolado de P. andinum Hale demonstraram acao contra bacterias Gram-positivas. Atraves de testes biocromatograficos foi possivel associar a atividade antibacteriana ao acido lecanorico e uma substância nao identificada presente na especie. As substâncias produzidas atraves de imobilizacao celular nao exibiram acao inibitoria frente os microrganismos testados.

Toxicity of Usnic Acid from Cladonia substellata (Lichen) to embryos and adults of Biomphalaria glabrata

This study reports the molluscicidal activity of usnic acid isolated from Cladonia substellata Vanio (lichen) on embryos at various stages of development and in adult mollusks of Biomphalaria glabrata. The toxicity of usnic acid was also evaluated through Artemia salina larvae mortality. Usnic acid was extracted with diethyl ether, isolated, purified, and its structure confirmed by analyzing the spectra of proton nuclear magnetic resonance. LC90 for 24 h of exposure were 1.62, 4.45, 5.36, and 4.49 μg mL-1 for blastula, gastrula, trocophore, and veliger embryonic stages, respectively, and 3.45 μg mL-1 for adult snails; LC50 of usnic acid against A. salina was 2.46 μg mL-1. LC90 assessed 7 days after exposure was 2.56 μg mL-1 for adult mollusks. In conclusion, these findings demonstrate that under laboratory conditions usnic acid has teratogenic and molluscicide potential to control the aquatic snail B. glabrata and may prove to be a promising candidate in the search for new molluscicide agents, but further detailed studies on its molluscicidal effect and possible environmental effects are needed.

Laboratory assessment of divaricatic acid against Biomphalaria glabrata and Schistosoma mansoni cercariae

In this study, the molluscicidal and antiparasitic activities of divaricatic acid was evaluated, targeting the mollusc Biomphalaria glabrata and cercariae of the helminth Schistosoma mansoni. In addition, the environmental toxicity of divaricatic acid was assessed by bioassay using the microcrustacean Artemia salina. Divaricatic acid showed high toxicity against both adult snails (5μg/mL) and embryos (20μg/mL after 6h of exposure). Similar activity was observed in Schistosoma mansoni cercariae after only a short exposure time (10μg/mL after 30min of exposure). The divaricatic acid did not show toxicity in the acute test using Artemia salina at concentrations equal to or below 200μg/mL. The divaricatic acid proved to be a promising substance for the elimination of the snail Biomphalaria glabrata, an intermediate host of schistosomiasis, as well as the cercariae of the pathogen, while being non-toxic to the Artemia salina at the same concentrations. This is the first experimental observation of the molluscicidal and cercaricide activity of divaricatic acid.

Dataset on usnic acid from Cladonia substellata Vainio (Lichen) schistosomiasis mansoni's vector control and environmental toxicity

This text presents complementary data corresponding to schistosomiasis mansonis vector control and enviromental toxicity using usnic acid. These informations support our research article “Toxicity of Usnic Acid from Cladonia substellata (Lichen) to embryos and adults of Biomphalaria glabrata” by Araújo et al. [1], and focuses on the analysis of the detailed data regarding the different concentrations of Usnic Acid and their efficiency to B. glabrata mortality and non-viability, as also to environmental toxicity, evaluated by A. salina mortality.

Barbatic Acid Offers a New Possibility for Control of Biomphalaria Glabrata and Schistosomiasis

This study evaluated the biological activity of an ether extract and barbatic acid (BAR) from Cladia aggregata on embryos and adult mollusks of Biomphalaria glabrata, cercariae of Schistosoma mansoni and the microcrustacean Artemia salina. The ether extract and BAR were obtained by successive extractions with diethyl ether. The obtained extracts were analyzed using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), proton nuclear magnetic resonance (1H-NMR) and infrared (IR) spectroscopy. The results demonstrated that the ether extract exerted embryotoxic effects at 50 and 100 µg/mL and molluscicidal effects at 20 and 25 µg/mL. BAR exhibited no embryotoxicity, and its molluscicidal concentration was equal to that of the ether extract. However, after 60 min of exposure, 1 µg/mL BAR presented cercaricidal activity against the parasite S. mansoni at the second larval stage. Neither substance induced toxicity against A. salina. These results indicate the potential molluscicidal activities of the ether extract and BAR against B. glabrata and S. mansoni cercariae. In addition to these effects, there was a lack of toxicity against the aquatic environment and no damage to the biota, indicating the potential of these products for large-scale control and/or eradication of schistosomiasis.

In Vitro and in Vivo Antineoplastic Activity of Barbatic Acid

Background: Lichen compounds exhibit remarkable biological activity. Several of them are potent anticancer agent and some with low or none toxicity. The aim of this study was perform in vitro and in vivo assessments of the antineoplastic activity of organic extract and barbatic acid (BAR) isolated from the lichen Cladia aggregata (Sw.) Nyl. Methods: In vitro assays were performed with both extract and BAR against HEp-2 (Adenocarcinoma of the Larynx), NCI-H292 (Squamous Cell Lung Carcinoma) and KB (Nasopharyngeal Squamous Cell Carcinoma) cells. The tests were carried out on the Sarcoma-180 BAR, tumor and organs were analyzed histopatologically after 7 days of chemotherapy. Results: Cytotoxic tests with BAR revealed 50% inhibitory concentration (IC 50 ) of 19.06 µg mL -1 for NCI-H292 and 12.0 µg mL -1 for KB and 6.25 µg mL -1 for HEp-2 cells. Tests with Sarcoma-180 demonstrated 46.3% inhibitory activity against the tumor by BAR. This substance showed no significant effect on the expression of argyrophilic nucleolar organizer regions proteins (AgNORs). The histopathology study of neoplastic tissue, demonstrated that cell proliferation was not affected by the antineoplastic action of the compound tested. Conclusions: The results indicate that barbatic acid exhibits significant antineoplastic activity and low toxicity rate.

Sweet Sorghum Establishment after Application of Residual Herbicides.

Imazethapyr, sulfentrazone, clomazone, diclosulam, trifloxysulfuron-sodium and trifluralin are residual herbicides commonly used for weed control in soybean or sugarcane crops. The sorghum crop implanted succeeding sugarcane, can be affected by the carryover effect of these herbicides. In this context, we aim with this work to evaluate the minimum period between application of herbicides with residual effect (imazethapyr, sulfentrazone, clomazone, diclosulam, trifluralin and trifloxysulfuron-sodium) and the planting of sorghum so that there is no impairment in growth and establishment of this crop due to the herbicide carryover effect. The experiment was installed in randomized blocks design with four replications, under field conditions. The herbicides were applied to the previously tillaged soil, with sorghum being planted 0, 14, 28, 42, 56 and 70 days after herbicide application (DAA). The percentage of germination was evaluated daily from planting, and 7, 14, 21 and 28 days after emergence (DAE) of each planting, the phytotoxicity was evaluated. Thirty five DAE of each planting season, ten plants were collected per plot for measurement of leaf area, fresh and dry mass of plants, leaves and stems. The minimum time interval for planting sorghum after application of these herbicides varies, but imazethapyr is highlighted by causing high and durable toxicity to sorghum even when planting sorghum after 70 days of its application.