Background:Excoecaria lucida Sw. (Euphorbiaceae) is a plant conventionally used throughout the Caribbean in the treatment of infectious diseases.Objective:To evaluate, using bioassay-guided fractionation, the in vitro cytotoxicity and antimicrobial activity of E. lucida leaves.Materials and Methods:A 95% ethanol crude extract was dried and fractionated by solid-liquid separation in four phases (hexane, dichloromethane, ethyl acetate, and butanol). Antimicrobial activity (3 bacteria, 6 yeasts, and 2 fungi) was evaluated by the dilution method with resazurin (2048, 512, 128, 32, and 8 μg/mL). The cytotoxicity assays were evaluated in two cell lines: MRC-5 and RAW 264.7; calculating the selectivity index. Assays were performed for the total extract, the isolated compound with the highest yield, and the ethyl acetate and butanol phases. Isolated compounds were characterized by nuclear magnetic resonance and mass spectrometry techniques.Results:Fractionation process led to the isolation of ellagic acid (784.29 mg), 3,3',4'-tri-O-methyl ellagic 4-O-β-D-glucopyranoside acid (6.1 mg), and corilagin (6.91 mg). The most active were ethyl acetate phase and ellagic acid with IC50= 128 μg/mL against seven and five different species of microorganisms, respectively. The total extract (IC50=512 μg/mL) and the ethyl acetate phase (IC50=128 μg/mL) were cytotoxic in both cell lines, while butanol phase and ellagic acid both with IC50>2048 μg/mL seemed to be safer.Conclusions:The results obtained indicate that the Excoecaria leaves can be conventionally used as antimicrobial, but it should be present that some cytotoxicity could appear. In addition, the three identified compounds were reported for the first time in the species.SUMMARYExcoecaria lucida leaves (Euphorbiaceae) are used by the Cuban population due to their antimicrobial activity. This ethnopharmacological knowledge is confirmed by the integrated antibacterial and antifungal in vitro screening developed, using the bioassay-guided fractionation method.Abbreviations Used: MRC-5-SV2: Diploid human lung fibroblasts cells, RAW 264.7: Murine macrophages cells, IC50: Inhibitory Concentration 50%, ATCC: American Type Culture Collection, CCEBI: Culture Collection of Industrial Biotechnology Center, CECT: Spanish Culture Collection Type, CFU: Colony forming units, CC50: 50% cytotoxic concentration, CO2: Carbon dioxide, SI: Selectivity index, IR: Infrared spectroscopy, 1H NMR: Nuclear Magnetic Resonance of hydrogen, 13C NMR: Nuclear Magnetic Resonance of carbon, HMQC: Heteronuclear Multiple-Quantum Correlation, HMBC: Heteronuclear Multiple Bond Correlation, COSY: Correlation Spectroscopy, NOESY: Nuclear Overhauser Effect Spectroscopy, KBr: Potassium bromide, DMSO-D6: Deuterated dimethyl sulfoxide, LC.MS: Liquid Chromatography-Mass Spectrometry, [α]D: Optical rotation, EL1: ellagic acid, EL2: 3,3’,4’-tri-O-methyl ellagic 4-O-β-D-glucopyranoside acid, EL3: corilagin, Active (+), inactive (-).

Plectranthus neochilus Schltr. (Lamiaceae) is a plant recently introduced in Cuba. Worldwide, it is an ethnomedicinal alternative for its use against microbial infections, but the Cuban population use the extracts to treat sleep disorders. To address this apparent incongruity, four collections (from different seasonal conditions in the year) of Cuban P. neochilus cultivars were analyzed in terms of their pharmacognostic characteristics. Three extracts using fresh and dried leaves were chemically and biologically characterized. UPLC-DAD-MS/MS analysis was performed to determine their chemical composition, while a panel of nine microorganisms was used to evaluate their antimicrobial activity. Finally, cytotoxic effects of different fractions were measured in three cell lines by the resazurin viability assay. In contrast to previously reported micro and macromorphological properties of P. neochilus, the leaves from the Cuban cultivars did not present glandular trichomes, nor did they produce quantifiable levels of essential oils. Moreover, aqueous extracts used by the population revealed no significant antimicrobial activity and were not cytotoxic. The three extracts showed a similar phytochemical composition, i.e., eight flavonoids, seven abietane diterpenes, and rosmarinic acid as the major constituent, most of them reported for the first time in this species. The low yield of essential oil, the absence of glandular trichomes, compounds with a high level of oxidation, and a moderate antimicrobial activity detected were the most distinctive pharmacognostic and biological characteristics of P. neochilus grown in Cuba. These aspects could explain its non-use as an antimicrobial.

Croton linearis Jacq. is an aromatic shrub that has been utilized in traditional medicine in the Bahamas, Jamaica, and Cuba. Recent studies have revealed the antiprotozoal potential of its leaves. The present work is aimed to identify the volatile constituents of essential oil from the stems of C. linearis (CLS-EO) and evaluate its in vitro antileishmanial activity. In addition, an in silico study of the molecular interactions was performed using molecular docking. A gas chromatographic–mass spectrometric analysis of CLS-EO identified 1,8-cineole (27.8%), α-pinene (11.1%), cis-sabinene (8.1%), p-cymene (5.7%), α-terpineol (4.4%), epi-γ-eudesmol (4.2%), linalool (3.9%), and terpinen-4-ol (2.6%) as major constituents. The evaluation of antileishmanial activity showed that CLS-EO has good activity on both parasite forms (IC50Promastigote = 21.4 ± 0.1 μg/mL; IC50Amastigote = 18.9 ± 0.3 μg/mL), with a CC50 of 49.0 ± 5.0 μg/mL on peritoneal macrophages from BALB/c mice (selectivity index = 2 and 3 using the promastigote and amastigote results). Molecular docking showed good binding of epi-γ-eudesmol with different target enzymes of Leishmania. This study is the first report of the chemical composition and anti-Leishmania evaluation of CLS-EO. These findings provide support for further studies of the antileishmanial effect of this product.