| dc.description.abstract | The use of plants for medicinal purposes is an ancient practice among different cultures, due to
the phytochemical properties present in plant species. From the elements that compose the plants,
bioactive substances of pharmacological interest are extracted, since drugs based on natural
products can be an alternative proposal in medicinal treatment. Given this scenario, this
environmental research aimed to evaluate the bacteriostatic sensitivity of bioactive extracts of
plant species: Z. officinale and H. coronarium, against the bacterial strain of Escherichia coli (E.
coli). For this purpose it was accomplished by gas chromatography coupled to mass spectrometry
(GC-MS), the phytochemical analysis of the extracts of the plants, in different fractions of
solvents, being them: hexane (HX), ethyl ether (ET), chloroform (CL), ethyl acetate (EA) and
aqueous (AQ), by polarity criteria; later it was evaluated if there are differences in the chemical
composition of the extracts of Z. officinale and H. coronarium and the antimicrobial activity of
organic extracts through the broth microdilution technique (MIC). The following microbial
strains were used in the experiment: E. coli ATCC 25922 and four environmental strains (S1, S2,
S3, S4), isolated in previous studies, and water samples from Lajeado Pardo river, in Frederico
Westphalen - RS. The overall yield for Z. officinale was 22.699% while for H. coronarium it was
31.276%, from the extractions by different solvents, AQ and HX showed the highest yields. The
GC-MS revealed the presence of four phytocompounds in the extracts of H. coronarium and
seven in Z. officinale, belonging to the class of terpenes (volatiles), acyclic monoterpenes,
alkaloids, similar in both plants, with distinct percentages. The antibacterial activity was
observed in extracts HX, ET, CL and AE, at the lowest concentrations against standard E. coli,
for both plant species. On the other hand, in the isolates it was obtained results of minimum
inhibitory concentration (MIC) in the same extracts of H. coronarium and Z. officinale, but high,
for MIC against environmental strains. As for the minimum lethal concentration (MIC) results
were obtained with the extracts, against E. coli strains, but it was not the aimed one, among the
environmental strains. However, there were significant results for MIC, in the extracts of H.
coronarium, over the ones evidenced in Z. officinale, in the highest concentrations tested, against
E. coli ATCC strain. The aqueous extracts of both plant species were unexpressive for
bacteriostatic action, for example at the concentrations tested. Collectively, this study suggests
that from the chromatographic analysis of H. coronarium and Z. officinale there was equity
among the phytocompounds revealed in the vegetal species, being the most satisfactory results
of the experiment, evident in the apolar fractions HX, ET, CL and AE, against E. coli while the
environmental strains showed greater resistance to the organic extracts tested. The species Z.
officinale showed significant MIC against the environmental strain S3, highlighting the potential
of this plant versus the bacterial strain E. coli. | |
