Seasonal variation of the major secondary metabolites present in the extract of Eremanthus mattogrossensis Less (Asteraceae: Vernonieae) leaves

The species Eremanthus mattogrossensis, known as "veludo do cerrado" (cerrado velvet), is native to the Brazilian Cerrado. Because the amount of metabolites present in plants may be influenced by biological and environmental factors, here we conducted an HPLC-DAD-MS/MS investigation of the metabolite concentrations found in the MeOH/H2O extract of the leaves of this species. The main compounds were identified and quantified, and the metabolites were grouped by chemical class (caffeoylquinic acids, flavonoids, and sesquiterpene lactone). Statistical analysis indicated a straight correlation between the quantity of metabolites and seasonality, suggesting that environmental properties elicit important metabolic responses.

Influence of the use of rice bran extract as a source of nutrients on xylitol production

Xylose-to-xylitol bioconversion using 2.5 or 10% (v/v) rice bran extract was performed to verify the influence of this source of nutrients on Candida guilliermondii metabolism. Semisynthetic medium (SM) and sugarcane bagasse hemicellulosic hydrolysate detoxified with ion-exchange resins (HIE) or with alteration in pH combined with adsorption onto activated charcoal (HAC) were fermented in 125 mL Erlenmeyer flasks at 30 ºC and 200 rpm for 72 hours. Activated charcoal supplemented with 2.5% (v/v) rice bran extract was fermented by C. guilliermondii in a MULTIGEN stirred tank reactor using pH 5.0 and 22.9/hour oxygen transfer volumetric coefficient. Higher values of xylitol productivity (0.70, 0.71, and 0.62 g.Lh-1) and xylose-to-xylitol conversion yield (0.71, 0.69, and 0.63 g.g-1) were obtained with 2.5% (v/v) rice bran in semisynthetic medium, ion-exchange resins, and activated charcoal, respectively. Moreover, during batch fermentation, the xylitol volumetric productivity and fermentation efficiency values obtained were 0.53 g.Lh-1 and 61.1%, respectively.

Effects of a cyanobacterial extract containing-anatoxin-a(s) on the cardiac rhythm of Leurolestes circunvagans

This work presents the effects of an anatoxin-a(s)-containing extract on a cockroach semi-isolated heart preparation and the results supporting the extract s biological activity on acetylcholinesterase (purified from ell). The presence of the toxin in cyanobacterial strains Anabaena spiroides (ITEP-024, ITEP-025 and ITEP-026) isolated from the Tapacurá reservoir in Pernambuco, Brazil, was confirmed by means of liquid chromatography coupled to an ion-trap mass spectrometer. The anticholinesterase activity was assessed biochemically by the Ellman test and was confirmed by measuring the cockroach s heart rate. The concentration of the extract containing the tested anatoxin-a(s) (antx-a(s)) (10, 16 and 100 μg.μL-1) inhibited the eel acetylcholinesterase (AChE) by more than 90%. The cockroach cardiac frequency increased by a maximum of about 20% within 29 min after the addition of 2.5x10³ μg of extract containing antxa (s).g-1 bw (n=9, p<0.05). Our results strongly indicate that antx-a(s) is capable of exerting biological effects on cockroach, indicating that more research might be conducted to determine its role in the environment, especially on insects.