A combined approach of MALDI-TOF mass spectrometry and multivariate analysis as a potential tool for the detection of SARS-CoV-2 virus in nasopharyngeal swabs.

Coronavirus disease 2019, known as COVID-19, is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The early, sensitive and specific detection of SARS-CoV-2 virus is widely recognized as the critical point in responding to the ongoing outbreak. Currently, the diagnosis is based on molecular real time RT-PCR techniques, although their implementation is being threatened due to the extraordinary demand for supplies worldwide. That is why the development of alternative and / or complementary tests becomes so relevant. Here, we exploit the potential of mass spectrometry technology combined with machine learning algorithms, for the detection of COVID-19 positive and negative protein profiles directly from nasopharyngeal swabs samples. According to the preliminary results obtained, accuracy = 67.66 %, sensitivity = 61.76 %, specificity = 71.72 %, and although these parameters still need to be improved to be used as a screening technique, mass spectrometry-based methods coupled with multivariate analysis showed that it is an interesting tool that deserves to be explored as a complementary diagnostic approach due to the low cost and fast performance. However, further steps, such as the analysis of a large number of samples, should be taken in consideration to determine the applicability of the method developed.

Chemotaxonomic Fingerprinting of Chilean Lichens Through Maldi and Electrospray Ionization Mass Spectrometry

The aim of this work was to study a fast, new, sensitive, and simple method for the chemotaxonomic classification of Chilean lichens (Teloschistes chrysophthalmus, Ramalina farinacea, Usnea pusilla, Ramalina chilensis and Stereocaulon ramulosum) using MALDI-TOF-MS and UPLC-ESI(-)-MS data. Lichens soluble proteins fingerprints were acquired by MALDI-TOF-MS and they were analyzed by chemometric (PCA). Lichens organic extracts fingerprints were obtained by UPLC-ESI(-)-MS. MALDI-TOF-MS associated with chemometric analysis was used to detect new m/z patterns of soluble proteins that were compared with Protein Data Bank of UnitPro. These data also permitted the satisfactory distinction among the families and species. UPLC-ESI(-)-MS fingerprints analyses of the organic extracts showed the presence of five major lichen compounds (atranorin, parietin, teloschistin, ramalinolic and usnic acids). In contrast to other techniques, MALDI-TOF-MS associated with chemometric analysis and UPLC-ESI(-)-MS provided a new, fast and sensitive method for chemotaxonomic characterization of lichens.

Determinação do teor de luteína em hortaliças / Determination of lutein content in vegetables

O objetivo do presente trabalho foi avaliar o teor de lutepina em algumas hortaliças comumente consumidas no estado de Minas Gerais (Brasil), visando fornecer dados para que a população possa conhecer as melhores fontes desse carotenóide. A extração do pigmento foi realizada com acetona, etanol, hexano e tetraidrofurano, por 24 h. Após a extração realizou-se a saponificação com KOH etanólico 10 por cento para eliminar impurezas, como clorofila e ácidos graxos. O teor de lutepina nas hortaliças foi determinado por medidas espetrofotométricas e confirmado por cromatografia a líquido de alta eficiência (CLAE). Pelos resultados obtidos, a acetona foi o solvente mais efetivo para a extração do pigmento. O hexano não se mostrou eficiente para extração d vegetais frescos nssas condições. Couve, rúcula, agrião, mostarda, acelga, espinafre, azedinho e brócolis constituem fotnes ricas em luteína. Deve-se ressaltar o elevado teor desse carotenóide no lobrobô (também conhecido como orapro-nobis) na serralha, no almeirão e na taioba, vegetais nõa-convencionais e de consumo regionalizado.