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Certain members of the genus Eugenia are used as foods. One of these species is Eugenia umbelliflora, which is used for its fruits. The aim of the study was to isolate the constituents of the CH2Cl2 fraction obtained from E. umbelliflora O. Berg (Myrtaceae) and also to evaluate its antimicrobial properties. Two new meroterpenoids, eugenial C (3) and eugenial D (4) were isolated from the unripe fruits of E. umbelliflora and their structures established mainly by extensive NMR spectroscopy. In previous studies, the CH2Cl2 extract showed significant antibacterial activity, which can be attributed to meroterpenoids isolated in this study. The compounds eugenials C and D exhibited potent activity against Bacillus subtilis and Staphylococcus aureus and different strains of MRSA and activity similar to those of the antibiotics used in antimicrobial therapies.

This study evaluated extracts, fractions, and isolated compounds from some selected Brazilian medicinal plants against strains of promastigotes of Leishmania amazonensis and L. brasiliensis in vitro. The cell viability was determined, comparing the results with reference standards. The dichloromethane fractions of the roots, stems, and leaves of Allamanda schottii showed IC50 values between 14.0 and 2.0 μg/mL. Plumericin was the main active compound, with IC50 of 0.3 and 0.04 μg/mL against the two species of Leishmania analyzed. The hexane extract of Eugenia umbelliflora fruits showed IC50 of 14.3 and 5.7 μg/mL against L. amazonensis and L. brasiliensis, respectively. The methanolic extracts of the seeds of Garcinia achachairu and guttiferone A presented IC50 values of 35.9 and 10.4 μg/mL, against L. amazonensis, respectively. The ethanolic extracts of the stem barks of Rapanea ferruginea and the isolated compound, myrsinoic acid B, presented activity against L. brasiliensis with IC50 of 24.1 and 6.1 μg/mL. Chloroform fraction of Solanum sisymbriifolium exhibited IC50 of 33.8 and 20.5 μg/mL, and cilistol A was the main active principle, with IC50 of 6.6 and 3.1 μg/mL against L. amazonensis and L. brasiliensis, respectively. It is concluded that the analyzed plants are promising as new and effective antiparasitic agents.

The use of medicinal plants concomitantly with conventional drugs can result in herb−drug interactions that cause fluctuations in drug bioavailability and consequent therapeutic failure and/or toxic effects. The CYP superfamily of enzymes plays an important role in herb−drug interactions. Among CYP enzymes, CYP3A4 and CYP2D6 are the most relevant since they metabolize about 50% and 30% of the drugs on the market, respectively. Thus, the main goal of this study was to evaluate the occurrence of in vitro interactions between medicinal plant extracts and drug substrates of CYP3A4 and CYP2D6 enzymes. Standardized extracts from nine medicinal plants (Bauhinia forficata, Cecropia glaziovii, Cimicif uga racemosa, Cynara scolymus, Echinacea sp., Ginkgo biloba, Glycine max, Ilex paraguariensis, and Matricaria recutita) were evaluated for their potential interactions mediated by CYP3A4 and CYP2D6 enzymes. Among the extracts tested, C. glaziovii (red embauba) showed the most relevant inhibitory effects of CYP3A4 and CYP2D6 activity, while I. paraguariensis (yerba mate) inhibited CYP3A4 activity. Both extracts were chemically analyzed by UPLC-MS/MS, and these inhibitory effects could lead to clinically potential and relevant interactions with the drug substrates of these isoenzymes.

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Introduction Eugenia umbelliflora fruits are an important source of phloroglucinols, as eugenial C and eugenial D, related to antimicrobial activity against Staphylococcus aureus. However, for the establishment of new antimicrobial substances, it is essential to know their stability profile, in view of driving the administration route and the release system development. Methodology The in silico approaches, based on the Fukui indices and bond dissociation analysis, were performed. Eugenial C and eugenial D, isolated from the green fruits of E. umbelliflora, with purity > 90%, were submitted to stress degradation including: acid (0.5 mM hydrochloric acid) and alkaline (0.5 mM sodium hydroxide) hydrolysis, and oxidation (0.25% hydrogen peroxide), in different periods, monitoring by high‐performance liquid chromatography with ultraviolet detector (HPLC‐UV). Eugenial C was also submitted to UV‐visible radiation (2,400 lux/h) and dry/humid heating (40°C, 75% relative humidity). Results In silico studies indicated that both molecules have regions of high susceptibility to nucleophilic and electrophilic attack as well as sites likely to suffer auto‐oxidation. Under in vitro tests, both phloroglucinols proved to be very unstable under hydrolysis (eugenial C and D were degraded 23.8% and 89.0% in acid and 78.4% and 97.8% in alkaline conditions, respectively) and oxidation (eugenial C and D degraded 31.9% and 28.6%, respectively), both during 5 min. Eugenial C degraded 12.6% and 63.8% under dry and humid heat, respectively, without photosensitivity. Conclusion The in vitro stress tests monitored by HPLC‐UV were in agreement with in silico degradation prediction. Phloroglucinols could be unstable if administered by oral route and also under environmental conditions demanding a protective release system.