Ivana Barbosa Suffredini

Antibacterial and cytotoxic activity of Brazilian plant extracts--Clusiaceae.

Twelve extracts obtained from nine plants belonging to six different genera of Clusiaceae were analyzed against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria using the microdilution broth assay. Tovomita aff. longifolia, T. brasiliensis, Clusia columnaris, Garcinia madruno, Haploclathra paniculata, and Caraipa grandifolia extracts showed significant results against the bacteria. The organic extract obtained from the leaves of T. aff. longifolia showed minimal inhibitory concentration (MIC) = 70 microg/ml and minimal bactericidal concentration (MBC) = 90 microg/ml against E. faecalis and the organic extract made with the stem of C. columnaris showed MIC = 180 microg/ml and MBC = 270 microg/ml against P. aeruginosa. None of the antibacterial extracts showed lethal activity against brine shrimp nauplii. On the other hand, both aqueous and organic extracts obtained from the aerial organs of Vismia guianensis that were cytotoxic to brine shrimp nauplii did not show a significant antibacterial activity in the assay.

Antibacterial activity of Brazilian Amazon plant extracts

Infections caused by multiresistant bacteria are a widespread problem, especially in intensive care units. New antibiotics are necessary, and we need to search for alternatives, including natural products. Brazil is one of the hottest spots in the world in terms of biodiversity, but little is known about the chemical and pharmacological properties of most of the plants found in the Amazon rain forest and the Atlantic Forest. We screened 1,220 organic and aqueous extracts, obtained from Amazon and Atlantic rain forest plants, against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and E. coli. Seventeen organic and aqueous extracts obtained from 16 plants showed activity against both Gram-positive bacteria. None of the extracts showed relevant activity against the Gram-negative E. coli and Pseudomonas aeruginosa.

Discovery of new antitumoral and antibacterial drugs from brazilian plant extracts using high throughput screening

Plants have played a significant role in the treatment of cancer and infectious diseases for the last four decades. The discovery and introduction to market of paclitaxel, the vinca alkaloids, etoposide, and many antibacterial drugs support drug discovery programs based on natural products. Natural products have been rediscovered as important tools for drug development despite advances in combinatorial chemistry, due to the complex molecular structures able to interact with mammalian cell targets. The Brazilian flora, the most diverse in the world, has become an interesting spot to prospect for new chemical leads or hits due to its species diversity and associated chemical richness. Screening programs have been established in Brazil as a strategy to identify potentially active substances. High throughput screening techniques allow for the analysis of large numbers of extracts in a relatively short period of time, and can be considered one of the most efficient ways of finding new leads from natural products. An updated review of the current status of the biological screening program is presented and recent results from new antitumoral and antibacterial chemical leads are discussed.

Antibacterial activity of Apocynaceae extracts and MIC of Tabernaemontana angulata stem organic extract

Trinta e oito extratos orgânicos e aquosos obtidos de 11 especies de Apocynaceae foram submetidos a triagem utilizando o metodo da microdiluicao em caldo contra Staphylococcus aureus, Pseudomonas aeruginosa e Candida albicans. O extrato orgânico obtido do caule de Tabernaemontana angulata apresentou atividade contra a bacteria Gram positiva S. aureus. A concentracao inibitoria minima verificada para esse extrato variou de 2,50 a 1,25 mg/mL. Cloranfenicol foi utilizado como antimicrobiano padrao. A analise fitoquimica indicou a presenca de triterpenos e alcaloides no extrato ativo.

Cytotoxic Molecules from Natural Sources: Tapping the Brazilian Biodiversity

The use of plant miscellaneous preparations as an alternative to the treatment of cancer is a reality today due to the massive marketing of natural medicines versus anticancer chemotherapy. Although this situation is controversial and has not led to any significant benefits to patients, plants may play a significant role in the treatment of cancer. Historically, natural leads have evolved to some of the outstanding medicines used nowadays against lung, breast, and ovarian cancers, and leukemia. Natural products are still some of the important sources of new anticancer drugs. The Brazilian flora is considered one of the most diverse in the world, although not many large-scale pharmacological and phytochemical studies have been conducted so far. We present the updated status and results of the research developed by Brazilian research centers on anticancer active substances derived from natural sources, mainly plants from the Brazilian Rain Forests, focusing on their potential effectiveness and difficulties.

Antiulcer action of Microgramma squamulosa (Kaulf.) Sota

Microgramma squamulosa (Kaulf.) Sota (Polypodiaceae) is commonly used as an antiulcer agent in the state of São Paulo, mainly in the upper land. The present work aims to study the antiulcer action of the crude extract of the plant rhizome and its toxicity. The effective dose was determined through acute ulcer induction test by stress. Using a determined dose, we performed a test against ulcer through acute induction by ethanol and hydrochloric acid, using cimetidine and misoprostol as reference drugs in both tests. The same extract, its ethanol and ethanol + water (1:1) fractions and the reference drug cimetidine were tested through subchronic induction test with acetic acid. The subchronic toxicity test was performed using a dose of 800 mg/kg of the crude extract, orally administered for 30 days. Finally the extracts and fractions were analysed in order to determine the main chemical groups of substances.

Evaluation of the effect of an organic extract obtained from Ipomoea alba L. on experimental periodontitis in rats

The aim of this study was to evaluate the effect of an organic extract obtained from Ipomoea alba L. (Convolvulaceae or OE 1493), on experimental periodontal disease in rats. Periodontitis was induced in thirty six Wistar rats: a first mandibular molar was randomly assigned to receive a ligature, whereas the contralateral molar was left unligated. Animals were randomly assigned to two groups and treated topically, three times a day, for 11 days, as follows: Control Group - vehicle-treated (n = 18), and Test Group - OE 1493-treated (n = 18). The rats were sacrificed on the 12th day. Morphometrical measurements from the cementoenamel junction to the bone crest were performed to determine alveolar bone loss, using standardized photographs. Single- and multi-dose acute toxicity assays were carried out after OE 1493 treatment. Morphometrical analysis demonstrated that topically-administered OE 1493 showed no effect on reducing bone loss when compared with the control group (p > 0.05). In addition, OE 1493 did not present toxicity. Within the limits of this investigation, it may be concluded that OE 1493 did not show any positive influence on the progression of ligature-induced periodontitis in rats, when administered according to the regimen used in the present study.

In vitro cytotoxic effects of Brazilian plant extracts on squamous cell carcinoma of the oral cavity.

Squamous cell carcinoma (SCC) is the most prevalent cancer of the oral cavity and the fifth most prevalent of all malignancies in males. Many researchers have attempted to develop new treatments that will improve the prognosis of SCC patients. Over 20% of the worlds biodiversity is located within the Brazilian forests, but little is known about the chemical and/or pharmacological potential of these plants. Certain extracts obtained from Amazon and Atlantic Forest plants have previously been shown to have cytotoxic activity against various cancers. The aim of this study was to screen these extracts for cytotoxic activity against oral SCC cells. The extracts were analyzed for activity against the KB-ADL#12 cell line at various concentrations up to a maximum dose of 100 µg/mL. Comparisons with a control group were performed using one-way ANOVA. Significant cytotoxicity was induced by the extracts obtained from the aerial parts of Picrolemma sprucei (Simaroubaceae), from the leaves and stems of Laetia suaveolens (Salicaceae), from the aerial parts of Abarema auriculata (Fabaceae-Mimosoideae) and from the stem of A. auriculata.

Anti-Streptococcal activity of Brazilian Amazon Rain Forest plant extracts presents potential for preventive strategies against dental caries

Caries is a global public health problem, whose control requires the introduction of low-cost treatments, such as strong prevention strategies, minimally invasive techniques and chemical prevention agents. Nature plays an important role as a source of new antibacterial substances that can be used in the prevention of caries, and Brazil is the richest country in terms of biodiversity. Objective In this study, the disk diffusion method (DDM) was used to screen over 2,000 Brazilian Amazon plant extracts against Streptococcus mutans. Material and Methods Seventeen active plant extracts were identified and fractionated. Extracts and their fractions, obtained by liquid-liquid partition, were tested in the DDM assay and in the microdilution broth assay (MBA) to determine their minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs). The extracts were also subjected to antioxidant analysis by thin layer chromatography. Results EB271, obtained from Casearia spruceana, showed significant activity against the bacterium in the DDM assay (20.67±0.52 mm), as did EB1129, obtained from Psychotria sp. (Rubiaceae) (15.04±2.29 mm). EB1493, obtained from Ipomoea alba, was the only extract to show strong activity against Streptococcus mutans (0.08 mg/mL<MIC<0.16 mg/mL; MBC=0.16 mg/mL) in the MBA. Conclusions The active extracts, discovered in the Amazon rain forest, show potential as sources of new antibacterial agents for use as chemical coadjuvants in prevention strategies to treat caries.

The influence of Brazilian plant extracts on Streptococcus mutans biofilm

Nineteen plant extracts obtained from plants from the Brazilian Amazon showed activity against planktonic Streptococcus mutans, an important bacterium involved in the first steps of biofilm formation and the subsequent initiation of several oral diseases. Objective Our goal was to verify whether plant extracts that showed activity against planktonic S. mutans could prevent the organization of or even disrupt a single-species biofilm made by the same bacteria. Material and Methods Plant extracts were tested on a single-bacteria biofilm prepared using the Zürich method. Each plant extract was tested at a concentration 5 times higher than its minimum inhibitory concentration (MIC). Discs of hydroxyapatite were submersed overnight in brain-heart infusion broth enriched with saccharose 5%, which provided sufficient time for biofilm formation. The discs were then submersed in extract solutions for one minute, three times per day, for two subsequent days. The discs were then washed with saline three times, at ten seconds each, after each treatment. Supports were allowed to remain in the enriched medium for one additional night. At the end of the process, the bacteria were removed from the discs by vortexing and were counted. Results Only two of 19 plant extracts showed activity in the present assay: EB1779, obtained from Dioscorea altissima, and EB1673, obtained from Annona hypoglauca. Although the antibacterial activity of the plant extracts was first observed against planktonic S. mutans, influence over biofilm formation was not necessarily observed in the biofilm model. The present results motivate us to find new natural products to be used in dentistry.