Preparation and biological evaluation of alkyl dihydroxybenzoates (AD) as useful agents to combat citrus canker

Abstract

Citrus canker is one of the most aggressive among citrus disease, affecting all types of important citrus crops. The disease, caused by bacillus Xanthomonas citri subsp. citri (Xac), occurs in the central orange juice producing countries, including Brazil and USA. For the canker chemical control, inefficient substances have been used, including copper-containing compounds. Thus, efforts are urgently necessary to identify and develop innovative anti-Xac compounds. First, we will prepared 36 alkyl dihydroxybenzoates (AD), which will be evaluated against Xac by in vitro assays. The AD toxicity will be evaluated against human hepatocarcinoma cells (HepG2). The selectivity index (SI) of AD will be calculated from the values of concentration able to kill 50% of hepatocytes (CC50) and values of minimum bactericidal concentration (MBC). SI = CC50/MBC. Compounds with values of SI equal or superior 10 will be submitted to inhibitory bacterial division assays, using FtsZ sedimentation and GTP hydrolysis methods. After in vitro assays, the three top compounds with highest SI values will be submitted to in vivo assays, including anti-citrus canker on Citrus limonia leaves, phytotoxicity against cucumber (Cucumis sativus) and corn (Zea mays), as well as toxicity against zebrafish (Danio rerio). The data obtained from previous research of our group, involving in vitro and in vivo activity demonstrated by compounds strucuturally similar to AD, and the data obtained by postgraduate student, as well as the insert of this investigation into Fapesp-NWO project corroborate the praticability and internationalization of our proposal. The conclusion of this project led to results of scientific relevance and interest by research, development and innovation sections of industry of pesticides.