The genus Hymenaea belongs to the family Fabaceae, subfamily Caesalpinoideae, and comprises approximately sixteen species distributed from the West Indies to South America1. H. stigonocarpa Mart. ex Hayne is a medicinal species commonly found in the Cerrado (Brazilian savannah) and popularly known as jatobá-do-cerrado. Ethnopharmacological data reveal the therapeutic use of stem bark and fruits from this plant, which are widely used in Brazilian folk medicine as decoction or infusion to various diseases2. Previous chemical investigations of different parts from the H. stigonocarpa tree have revealed the presence of sesquiterpenoids, diterpenoids, coumarins, fatty acids, alkaloids, steroids, phenolic compounds, flavonoids, and proanthocyanidins. These metabolites have been associated with antibacterial, antitermitic, antioxidant, antidiarrheal, gastroprotective, cicatrizing, and anti-inflammatory activities. Since the isolation of compounds from crude extracts is a laborious, time-consuming and expensive task, the fast, efficient, and reliable identification of known compounds (dereplication) is essential in order to avoid reisolation and speed up the discovery of newly bioactive metabolites. In this context, LC-MS/MS is a powerful tool that combines chromatographic separation and fragmentation patterns, which provide unique structural information and therefore enables identification of a wide range of compounds. The aim of this work was to apply LC-HRMS and LC-MS/MS to analyze and profile the chemical composition of the ethanolic extract of leaves (EEL) from H. stigonocarpa. An in house database containing information on 138 previously reported compounds from Hymenaea genus was created to assist the LC-MS-based dereplication. This approach allowed the preliminary identification of a total of 23 compounds, mostly reported for the first time for this species: two fatty acids (arachidic acid; 9-octadecenoic acid), one sesquiterpenoid (levomenol) and eight diterpenoids (eperua-7,13-dien-15-oic acid; ozic acid; methyl zanzibarate; 13-hydroxy−1(10),14-ent-halimadien-18-oic acid; copalic acid; ent-labd-8(17)-en-15ethylacetate; kauran−16-α-ol; labd−8(20)-en−15-oic acid, 19-methoxy-, methyl ester; ent-pinifolic acid). The antimicrobial activity of the EEL was evaluated against some periodontal anaerobic bacteria. The obtained MIC values are listed in Table 1. Concerning the antimicrobial assay about extracts from natural sources, the inhibition of the microorganisms´ growth at concentrations below 100 µg mL−1 is considered very promising in the search for new anti-infection agents4. Therefore, the EEL was active against some bacteria and the class of compounds possibly responsible for the inhibitory action may be of the diterpenoids, since authors5 have emphasized that these metabolites promote lysis and disruption of the bacterial cell membrane.
Table 1. In vitro antimicrobial activity (MIC) in µg mL-1 of the EEL against periodontal bacteria.
1 Boniface, P. K.; et al. Journal of Ethnopharmacology 2017, 206, 193-223.
2 Monteiro, A. F.; et al. Journal of Natural Products 2015, 78(6), 1451-1455.
3 Gaudencio, S. P.; PEREIRA, F. Natural Product Reports 2015, 32(6), 779-810.
4 Gibbons, S. Planta Medica 2008, 74(6), 594-602.
5 Urzúa, A.; et al. Molecules 2008, 13, 882-891.