Joana D’arc Felicio

Study of the antitumor potential of Bidens pilosa (Asteraceae) used in Brazilian folk medicine.

AIM OF THE STUDY Bidens pilosa (L.) (Asteraceae) is a medicinal plant traditionally used in Brazil for treating conditions that can be related to cancer. Therefore the present study was carried out to evaluate the antitumor activity of extracts obtained from the aerial parts of this plant species. MATERIALS AND METHODS The crude hydroalcoholic extract (HAE) (water:alcohol, 6:4) and solvent fractions (chloroform=CHCl3,ethyl acetate=EtOAc, methanol=MeOH) were assessed for cytotoxicity assay by the brine shrimp and hemolytic, MTT and NRU assays. The antiproliferative potential of the crude extract and fractions was investigated in vivo using the Ehrlich ascites carcinoma (EAC) in isogenic Balb/c mice that were administered intraperitoneally 150 and 300 mg/kg body weight per day for nine days beginning 24 h after tumor inoculation. RESULTS In in vitro cytotoxicity using Ehrlich ascites carcinoma cell line assay CHCl3 extract proved to be more toxic than the crude HAE with an IC(50) of 97+/-7.2 and 83+/-5.2 microg/mL to NRU and MTT, respectively. Histomorphological evaluations indicated that the treatment with CHCl3 and HAE extracts significantly reduced (P<0.05) body weight, abdominal circumference, tumor volume, packed cell volume and viable cell count, when compared to EAC control group. Furthermore, nonviable tumor cell count increased significantly (P<0.01) only under treatment with CHCl3 or HAE, and this was accompanied by a marked percentage increase in life span (54.2 and 41.7%, respectively). Biochemical assays revealed that CHCl3 and HAE extracts were also able to decrease serum LDH activity (39.5 and 30.6%) and GSH concentration (94.6 and 50.7%) in ascitic fluid, respectively. CONCLUSION The chloroform fraction showed the best and methanolic the worst antitumor activity.

Ageratum conyzoides essential oil as aflatoxin suppressor of Aspergillus flavus.

Aflatoxin B(1) (AFB(1)) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oil of Ageratum conyzoides, on the mycelial growth and aflatoxin B(1) production by Aspergillus flavus were studied. Cultures were incubated in yeast extract-sucrose (YES) broth for days at 25 degrees C at the following different concentrations of the essential oil (from 0.0 to 30mug/mL). The essential oil inhibited fungal growth to different extents depending on the concentration, and completely inhibited aflatoxin production at concentrations above 0.10microg/mL. The analysis of the oil by GC/MS showed that its main components are precocene II (46.35%), precocene I (42.78%), cumarine (5.01%) and Trans-caryophyllene (3.02%). Comparison by transmission electron microscopy of the fungal cells, control and those incubated with different concentrations of essential oil, showed ultra-structural changes which were concentration dependent of the essential oil of A. conyzoides. Such ultra-structural changes were more evident in the endomembrane system, affecting mainly the mitochondria. Degradation was also observed in both surrounding fibrils. The ability to inhibit aflatoxin production as a new biological activity of A.conyzoides L. indicates that it may be considered as a useful tool for a better understanding of the complex pathway of aflatoxin biosynthesis.

Mycobiota and mycotoxins in Brazilian peanut kernels from sowing to harvest

The total mycobiota and the mycotoxin contamination of peanuts were analyzed in plants collected at different stages of the pod maturity sampled in Junqueirópolis, at São Paulo State (Brazil). The prevalent peanut mycobiota were Fusarium spp. and Aspergillus flavus, present in 26% and 17% respectively of the samples analyzed. In soil, the genus Penicillium and Fusarium were most frequently detected, and A. flavus was detected in 8% of the samples. The screening of mycotoxins indicated that aflatoxins and cyclopiazonic acid were present the highest incidence, being detected in 32% of the samples, in concentrations, respectively, from 4.20 microg/kg to 198.84 microg/kg and from 260 microg/kg to 600 microg/kg. Fumonisins were not detected by HPLC. All data were correlated with the occurrence of wind-dispersed fungi and the environmental and soil conditions. Results indicate that good management of the agricultural environment may offer a way to reduce mycotoxins and the toxigenic fungal contamination in peanuts preharvest because the pods are exposed to different environmental conditions during their formation until harvest, and the optimal conditions for mycotoxin production and fungal growth are frequently found in the crop fields.

A resveratrol dimer from Parthenocissus tricuspidata

The tricuspidatol-A, rel-2R,2′R-(4-hydroxyphenyl),3R,3′R-(3,5-dihydroxyphenyl) tetrahydrofuran, a new resveratrol dimer was isolated from the stemwood of Parthenocissus tricuspidata. Its structure was established on the basis of spectroscopic evidence and biosynthetic considerations.

Fungi, mycotoxins and phytoalexin in peanut varieties, during plant growth in the field

The aim of the present study was to analyze the mycobiota, occurrence of mycotoxins (aflatoxins and cyclopiazonic acid), and production of phytoalexin (trans-resveratrol) in two peanut varieties (Runner IAC 886 and Caiapó) during plant growth in the field. Climatic factors (rainfall, relative humidity and temperature) and water activity were also evaluated. The results showed a predominance of Fusarium spp. in kernels and pods, followed by Penicillium spp. and Aspergillus flavus. Aflatoxins were detected in 20% and 10% of samples of the IAC 886 and Caiapó varieties, respectively. Analysis showed that 65% of kernel samples of the IAC 886 variety and 25% of the Caiapó variety were contaminated with cyclopiazonic acid. trans-Resveratrol was detected in 6.7% of kernel samples of the IAC 886 variety and in 20% of the Caiapó variety. However, trans-resveratrol was found in 73.3% of leaf samples in the two varieties studied.

Evaluation of antifungal activity of seaweed extracts

Seaweeds are subject to numerous biological interactions and sometimes to extreme abiotic conditions, so they have developed among other defense mechanisms, the ability to produce biologically active substances. Thus, these organisms produce mainly terpenes and phenols. Among others, the antifungal activity, due to its importance in human and animal health and the production of agricultural products, has been the subject of several studies. In the present work, this activity was investigated in ten seaweeds extracts, by direct bioautography assays, compared to Colletotrichum lagenarium and disk diffusion assay, compared to Aspergillus flavus. The organisms studied were: Stypopodium zonale, Laurencia dendroidea, Ascophyllum nodosum, Sargassum muticum, Pelvetia canaliculata, Fucus spiralis, Sargassum filipendula, Sargassum stenophyllum, Laminaria hyperborea and Gracilaria edulis. S. zonale, L. dendroidea, P. canaliculata, S. muticum, A. nodosum and F. spiralis extracts significantly inhibited the C. lagenarium growth, but not inhibited significantly the A. flavus growth. The presence of terpenes in all of these extracts was confirmed by thin layer chromatography whereas the presence of phenolic compounds was confirmed only in extracts of P. canaliculata, A. nodosum and S. muticum. In chemical study by column chromatography, followed by gas chromatography/mass spectrometry analysis, the terpenes neophytadiene, cartilagineol, obtusol elatol; and the ester ethyl hexadecanoate were identified in the L. dendroidea extract. This is the first report on the activity of seaweed extracts against C. lagenarium, a fungus bearing agricultural importance.

ACTIVITY OF THE AQUEOUS EXTRACT FROM POLYMNIA SONCHIFOLIA LEAVES ON GROWTH AND PRODUCTION OF AFLATOXIN B1 BY ASPERGILLUS FLAVUS

The aqueous extract from Polymnia sonchifolia leaves (AE) was tested for inhibitory activity on aflatoxin B1(AFB1) production and growth of Aspergillus flavus. The cytotoxicity of AE on Vero cells was also performed. Suspensions of A. flavus spores were inoculated into 50 mL of YES medium together with different concentrations of the AE. The aflatoxin B1 was extracted, analyzed by thin layer chromatography and quantified by photodensitometry. All the concentrations of AE induced inhibition of AFB1 production. The aqueous extract showed in vitro cytotoxicity to Vero cells only at concentrations above 500 µg/mL.

Potential of essential oils for protection of grains contaminated by aflatoxin produced by Aspergillus flavus

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 μL for oregano and 50, 30, 15, and 10 μL for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B1 production was evaluated inoculating suspensions of A. flavus containing 1.3 × 105 spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans.

Evaluation of antifungal activity of Pittosporum undulatum L. essential oil against Aspergillus flavus and aflatoxin production

A presenca de micotoxinas como resultado do ataque fungico pode ocorrer antes, apos e durante a colheita e tambem no armazenamento de graos e alimentos. Considerando as propriedades inibitorias dos oleos essenciais de plantas no desenvolvimento do micelio dos fungos e a importâncias do Aspergillus flavus, principal produtor de aflatoxinas, relatou-se neste trabalho, a atividade toxica do oleo essencial do Pittosporum undulatum em cultura de A. flavus. Os oleos essenciais de P. undulatum foram obtidos a partir de folhas coletadas em diferentes meses e analisado por CG/EM. Os oleos se mostraram ricos em hidrocarbonetos, monoterpenos e sesquiterpenos e foi observada uma significante variacao na composicao quimica destes oleos nos diferentes meses de coleta. Os oleos essenciais mostraram diferentes espectros de inibicao do crescimento de A. flavus, porem todos foram capazes de inibir a producao de aflatoxina B1.

Monoterpene alkaloids from Tecoma stans

Abstract Phytochemical investigation of an ethanolic extract from fruits of Tecoma stans have led to the isolation of two novel monoterpenic alkaloids, 7-hy