In silico and in vitro degradation studies of isolated phloroglucinols eugenial C and eugenial D from Eugenia umbelliflora fruits.

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.

Characterization and evaluation of the cytotoxic potential of the essential oil of Chenopodium ambrosioides

Abstract The essential oil of Chenopodium ambrosioides L., Amaranthaceae, was obtained by steam distillation in a Clevenger apparatus and characterization was performed using chromatographic and spectroscopic assays (GC-FID, GC/MS, 1H NMR). Two major compounds were identified: p-cymene (42.32%) and ascaridole (49.77%). The ethanolic extract and hydrolate were fractionated by liquid–liquid partitioning and the compounds were characterized by GC/MS. The essential oil, ethanol extract and fractions by partitioning with dicloromethane, ethyl acetate and butanol were tested in tumor cell lines (K562, NALM6, B15, and RAJI). Significant cytotoxic activity was found for essential oil (IC50 = 1.0 µg/ml) for RAJI cells and fraction dicloromethane (IC50 = 34.0 µg/ml) and ethanol extract (IC50 = 47.0 µg/ml) for K562 cells. The activity of the essential oil of C. ambrosioides is probably related to the large amount of ascaridol, since the other major compound, p-cymene, is recognized as a potent anti-inflammatory and has low cytotoxic activity.