ABSTRACT
Extratos aquosos da planta medicinal Achillea millefolium contêm macromoléculas de interesse para desenvolver fitodefensivos para a agricultura. Duas frações de mil folhas foram obtidas por ultrafiltração, E1 (contendo moléculas maiores que 30 kDa), e E3 (peptídeos entre 1 e 10 kDa) que inibiram o crescimento das bactérias fitopatogênicas Ralstonia solanacearum, gram-negativa, e Clavibacter michiganensis subsp. michiganensis, gram-positiva, com dependência de concentração. Os valores de concentração inibitória mínima (CIM) para ambos os extratos e bactérias foram baixos, entre 20 e 80µM. A CIM relativa à proteína total evidenciou a presença de macromoléculas muito ativas em E3, embora com baixa concentração proteica. E3 se aplica à prospecção de peptídeos antimicrobianos. Estimar a CIM relativa à quantidade de amostra vegetal valorizou o potencial antimicrobiano natural de E1, que contém alta concentração proteica. E1e E3 se aplicam ao desenvolvimento de fitodefensivos para uso biotecnológico. A ultrafiltração fracionou as amostras de forma nativa, rápida, e com baixo custo; além de dessalinizar, clarificar, purificar, e concentrar E1 e E3. Esse estudo inédito sobre a separômica e a ação antimicrobiana de extratos macromoleculares aquosos de mil folhas sugere que plantas cicatrizantes podem apresentar grande potencial para desenvolver fitodefensivos agrícolas naturais não danosos, à semelhança de medicamentos fitoterápicos.
Aqueous extracts from the medicinal plant Achillea millefolium contain macromolecules of interest to develop agrochemicals for agriculture. Two fractions of "mil folhas" were obtained by ultrafiltration, E1 (containing molecules larger than 30 kDa) and E3 (peptides between 1 and 10 kDa), which inhibited the growth of phytopathogenic bacteria Ralstonia solanacearum, gram-negative, and Clavibacter michiganensis subsp. michiganensis, gram-positive, concentration-dependent. The values of minimum inhibitory concentration (MIC) for both extracts and both bacteria were low, ranging from 20 to 80µM. The MIC relative to total protein evidenced the presence of very active macromolecules in E3, although showing low protein concentration. E3 applies to the prospection of antimicrobial peptides. The estimated MIC relative to the amount of plant sample valued the natural antimicrobial potential of E1, which contains high protein concentration. E1 and E3 can be used in the development of agrochemicals for biotechnological purposes. The ultrafiltration procedure fractionated the samples in a rapid and native way and at a low cost; it also desalted, clarified, concentrated and purified both E1 and E3. This pioneering study on the separomics and on the antimicrobial activity of macromolecular aqueous extracts from "mil folhas" suggests that healing plants have great potential to develop non-harmful agricultural natural agrochemicals, similarly to the available phytotherapic drugs.
Subject(s)
Plants, Medicinal/classification , Agrochemicals/administration & dosage , Achillea/adverse effects , Plant Extracts/adverse effects , Microbial Sensitivity Tests/methods , Antimicrobial Cationic Peptides , Ralstonia solanacearumABSTRACT
Pectin lyase (PL) induction by organic and inorganic components of yeast extract (YE) was evaluated in Penicillium griseoroseum, cultured in a mineral medium containing sucrose, by determining PL activity (A235) and mycelial growth (mycelial dry weight). The lowest YE concentration that promoted significant PL induction without acting as a carbon source for the fungus corresponded to 0.0075%. Neither calcined YE nor a nutrient solution containing micronutrients induced PL production, indicating that the inducer was an organic compound. Vitamins, phospholipid components, amino acids, and nitrogenous bases were tested in place of YE and promoted no significant PL induction. A PL inducer compound was found to be soluble in the nucleotide fraction obtained during extraction of YE. The inducer was shown to be a thermostable polar substance dialyzable at 2000 Daltons, hydrolyzable by HCl, and activated by boiling for up to 60 min. Cyclic AMP (cAMP) exogenously added to the culture medium at 5 and 10 mM was capable of inducing PL in P. griseoroseum grown on sucrose, suggesting that at least one compound may be present in YE acting in a cooperative fashion for the maintenance of high levels of cAMP into the cell. PL activity and the level of cAMP inside the fungal cells increased after the addition of YE to the culture medium, suggesting the participation of this messenger in this enzyme's synthesis.
