Abstract
Xylella fastidiosa is a plant-pathogenic bacterium that lives inside host xylem vessels, where it forms biofilm which is believed to be responsible for disrupting the passage of water and nutrients. Pectobacterium carotovorum is a Gram-negative plant-specific bacterium that causes not only soft rot in various plant hosts, but also blackleg in potato by plant cell wall degradation. Chagas disease, which is caused by Trypanosoma cruzi, has been commonly treated with nifurtimox and benzonidazole, two drugs that cause several side effects. As a result, the use of natural products for treating bacterial and neglected diseases has increased in recent years and plants have become a promising alternative to developing new medicines. Therefore, this study aimed to determine, for the first time, the chemical composition of essential oil from Psidium guajava flowers (PG-EO) and to evaluate its in vitro anti-Xylella fastidiosa, anti-Pectobacterium carotovorum, anti-Trypanosoma cruzi and cytotoxic activities. PG-EO was obtained by hydrodistillation in a Clevenger apparatus while its chemical composition was determined by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Major compounds identified in PG-EO were α-cadinol (37.8%), β-caryophyllene (12.2%), nerolidol (9.1%), α-selinene (8.8%), β-selinene (7.4%) and caryophyllene oxide (7.2%). Results showed that the PG-EO had strong trypanocidal activity against the trypomastigote forms of Trypanosoma cruzi (IC50 = 14.6 μg/mL), promising antibacterial activity against X. fastidiosa (MIC = 12.5 μg/mL) and P. carotovorum (MIC = 62.5 μg/mL), and moderate cytotoxicity against LLCMK2 adherent epithelial cells in the concentration range (CC50 = 250.5 μg/mL). In short, the PG-EO can be considered a new source of bioactive compounds for the development of pesticides and trypanocide drugs.
Highlights
Xylella fastidiosa, a bacterium found in xylem, is a pathogen that lives in several plant species, such as weeds and fruit trees of economic interest (Coletta‐Filho et al, 2016)
It is important to mention that chemical constituents which predominate in PG-EO had already been previously identified at different concentrations in the essential oil from leaves of this species found in Brazil (Mendes et al, 2018; Souza et al, 2017)
Even though this study is the first report of the chemical composition of PG-EO, it may be noticed that the chemical composition found by this study is similar to the chemical composition which has already been described in the literature for other species belonging to the same genus and Myrtaceae family (Stefanello et al, 2011)
Summary
A bacterium found in xylem, is a pathogen that lives in several plant species, such as weeds and fruit trees of economic interest (Coletta‐Filho et al, 2016). It is responsible for one of the most important plant diseases that has been reported over the last decades, i. In 2002, about a third of the country’s orange groves had been infected by X. fastidiosa, while in 2016, about 43% of all produce had been overrun by the bacterium. It led to losses and posed negative impact on the economy. CVC may have arrived in Brazil from Argentina in the 1980’s when the transportation of infected trees enabled the phytopathogen to quickly disseminate all over South America, where it is endemic (Coletta‐Filho et al, 2016)
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