RESUMO
FTIR (Fourier transform infrared spectroscopy) is one analytical technique of the absorption of infrared radiation. FTIR can also be used as a tool to characterize profiles of biomolecules in bacterial cells, which can be useful in differentiating different bacteria. Considering that different bacterial species have different molecular compositions, it will then result in unique FTIR spectra for each species and even bacterial strains. Having this important tool, here, we have developed a methodology aimed at refining the analysis and classification of the FTIR absorption spectra obtained from samples of Staphylococcus aureus, with the implementation of machine learning algorithms. In the first stage, the system conforming to four specified species groups, Control, Amoxicillin induced (AMO), Gentamicin induced (GEN), and Erythromycin induced (ERY), was analyzed. Then, in the second stage, five hidden samples were identified and correctly classified as with/without resistance to induced antibiotics. The total analyses were performed in three windows, Carbohydrates, Fatty Acids, and Proteins, of five hundred spectra. The protocol for acquiring the spectral data from the antibiotic-resistant bacteria via FTIR spectroscopy developed by Soares et al. was implemented here due to demonstrating high accuracy and sensitivity. The present study focuses on the prediction of antibiotic-induced samples through the implementation of the hierarchical cluster analysis (HCA), principal component analysis (PCA) algorithm, and calculation of confusion matrices (CMs) applied to the FTIR absorption spectra data. The data analysis process developed here has the main objective of obtaining knowledge about the intrinsic behavior of S. aureus samples within the analysis regions of the FTIR absorption spectra. The results yielded values with 0.7 to 1 accuracy and high values of sensitivity and specificity for the species identification in the CM calculations. Such results provide important information on antibiotic resistance in samples of S. aureus bacteria for potential application in the detection of antibiotic resistance in clinical use.
RESUMO
Hojas de las plantas Hura crepitans y Codiaeum variegatum se recolectaron en la ciudad de Medellín (Colombia), para determinar la actividad biológica (Actividad citotóxica [AC] y antiviral [AAV]) de cuatro extractos de éstas (hexánico, en acetato de etilo, metanólico y acuoso) sobre los virus de Estomatitis Vesicular (VSV) serotipos Indiana y New Jersey y Herpes Virus Bovino tipo-1 cepa Bogotá (BHV-1B). El tamizaje de actividad biológica de los extractos se realizó en monocapas de células BHK-21. Luego los extractos promisorios, pasaron a la fase cuantitativa de AAV por el ensayo de MTT [3-(4,5-dimethylthiazol–2-yl)-2,5-diphenyltetrazolium bromide] para determinar la concentración citotóxica 50 (CC50), la concentración inhibitoria 50 (IC50) y el índice de selectividad (IS). Ninguno de los extractos de las cuatro plantas presentó AAV contra VSV, mientras que los extractos hexánico, en acetato de etilo y metanólico de H. crepitans confirieron resistencia a la infección por BHV-1B con IC50 de 17.41, 7.87 y 2.75 µ g/ml, respectivamente. El extracto con mejor IS (relación entre IC50 y CC50) fue el hexánico de H. crepitans (IS > 17.4). Estos resultados sugieren que pueden existir compuestos en el extracto hexánico de H. crepitans con una actividad promisoria anti BHV-1B. Este estudio es pionero en demostrar actividad antiviral de extractos de plantas de la especie Euphorbiaceae contra BHV-1B.
Leaves from Hura crepitans and Codiaeum variegatum plants were collected in Medellín, Colombia to determine its cytotoxic [CA] and antiviral activity [AVA]. Four extracts were prepared using hexane, ethyl acetate, methanol and water; the antiviral activity was tested against Vesicular Stomatitis Virus (VSV), serotypes Indiana and New Jersey and Bovine Herpes Virus (type 1 Bogotá strain). The preliminary biological activity of each of the eight extracts was determined on BHK-21 cell monolayers using 96 well-plates. Then, promissory extracts were further tested using the MTT [3-(4,5-dimethylthiazol–2-yl)-2,5-diphenyltetrazolium bromide] assay to determine the cytotoxic concentration 50 (CC50), the inhibitory concentration 50 (IC50 ), and the selectivity index (SI). None of the evaluated plants exhibited AVA against VSV, whereas the extracts in hexane, ethyl acetate and methanol from Hura crepitans protected cell monolayer from infection against BHV-Bogotá with IC50 of 17.41, 7.87 and 2.75 µ g/ml respectively. The best IS was hexane of H. crepitans (SI > 17.4). These results suggest that this extract contains antiviral compounds. This research is pioneer demonstrating AVA against BHV-1B in extracts from plants of the Euphorbiaceae family.