Caracterização química e atividade Alelopática in silico e in vitro do óleo essencial das folhas de Syzygium cumini (L.) Skeels

Abstract

The Myrtaceae family is well known for its production of essential oils, with the species Syzygium cumini (L.) Skeels being widely reported in the literature due to its biological properties, known both by folk medicine and the scientific community. S. cumini is popularly known as: Olive tree, Jamelão or Jambolão, and is a species that produces essential oils with different biological activities such as: Antimicrobial, Antitumor, Anticholinesterase and Antiparasitic. Essential oils are volatile compounds and have been the subject of several scientific studies because they contain active ingredients of industrial interest, constituting a sustainable alternative to numerous synthetic chemical products. However, to date, no reports of their allelopathic activity have been found. Research centers investigate the activity of bioactive compounds using computational tools, among which Molecular Docking stands out, which can be used to analyze the activity of molecules of pharmacological interest on enzymes such as those in the seed germination process. In this sense, the objective of this work was to evaluate the yield, chemical profile and allelopathic activity of the essential oil from the leaves of S. cumini. The essential oil was obtained from the hydrodistillation extraction of fresh leaves in a Clevenger apparatus and its compounds were characterized by Gas Chromatography Coupled to Mass Spectrometry. Virtual in silico screening was performed by obtaining the ligands using the ChemDraw software (version 12) and subsequently transformed into 3D in the Chem3D software. These ligands were selected from the major compounds of the essential oil of Syzygium cumini (L.) Skeels and were evaluated in silico by molecular modeling using the Hermes Gold software against the Apo mannanase 26 A protein under PDB code (1R70). The in vitro allelopathic assay was performed in a germination chamber at 25 °C and 12 h of photoperiod, using concentrations of 0.001; 0.01; 0.1 and 1% of the essential oil on 20 seeds of each crop: lettuce, tomato and biquinho pepper. The following variables were evaluated: Germination Percentage, Average Germination Time, Germination Speed, Germination Speed Index and Average Root Length statistically monitored by the SISVAR software. The essential oil presented a yield of 0.25% (v/m) and the major components identified were: cis-β-ocimene (22.4%), β-pinene (8.7%), limonene (8.4%), α-Terpineol (8.0%), α-pinene (6.2%), trans-caryophyllene (6.2%). The in silico allelopathic activity test was confirmed by calculating the root mean square deviation (RMSD), whose value presented was 0.36 A, and ChemScore scoring function. The ligands SC02, SC03 and SC06, despite presenting a scoring function close to that of the original ligand of the enzyme Apo mannanase 26 A, favored molecular interactions of pharmacological interest. The essential oil inhibited the germination of lettuce, tomato and biquinho pepper seeds, in addition to causing a delay in germination time. Thus, the allelopathic activity is due to the presence of chemical constituents of the essential oil of S. cumini, such as monoterpenes. The essential oil of S. cumini presented allelopathic activity in both tests, and future studies are necessary to investigate the mechanism of action of the components of this essential oil against other enzymes of the seed germination process and the possible development of formulations with bioherbicidal potential.