ABSTRACT
Chemical profiling of both fruit and aerial part extracts of Euphorbia abyssinica via ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) showed them to be a rich source of diverse compounds. A total of 39 compounds in both extracts including flavonoids and phenolic compounds were identified as predominant metabolites. The antioxidant activity of both extracts was evaluated using three different in vitro assays (DPPH, ABTS, and FRAP assays). The E. abyssinica fruit extract demonstrated more potent activity compared to the aerial part extract (IC50 of 85.1 ± 1.07 and 562.3 ± 1.01 µg/mL, respectively) in the DPPH assay. Furthermore, using ABTS and FRAP assays, the antioxidant capacities of the fruit extract were 1063.03 ± 37.8 and 1476.5 ± 95.6, respectively, calculated as µM Trolox equivalent/mg extract. One of the existing markers for cancer chemoprevention is the induction of phase II detoxifying enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1), which plays a vital role in cytoprotection against oxidative damage. The extracts were assessed to test their chemopreventive potential via NQO1 enzyme induction. The methanolic extract of fruits demonstrated a concentration-dependent increase in the cancer chemopreventive marker enzyme NQO1 at the protein expression level in a murine hepatoma cell line (Hepa1c1c7). The interaction with Kelch-like ECH-associated protein 1 (KEAP1) is an essential transcription factor that controls the expression of the NQO1 enzyme. The demonstrated induction of NQO1 by the fruit extract is consistent with a molecular docking study of the effect of dereplicated compounds on the KEAP1 target. Among the dereplicated compounds, hesperidin, naringin, and rutin have been established as promising inducer compounds for the chemopreventive marker NQO1. Our results highlight the E. abyssinica fruit extract as a future chemopreventive lead.
ABSTRACT
Aspergillus niger and Penicillium chrysogenum were able to grow on Czapek Dox medium amended with elevated concentrations [up to 500 ppm active ingredient (ai)] of the fungicide copper oxychloride. Solubilization of the fungicide in solid medium was evident by the appearance of a clear (halo) zone underneath and around the growing colonies. The halo formed with A. niger, grown on fungicide-containing nitrate nitrogen medium, was found subsequently to enclose concentric rings of newly crystalline precipitate. These crystals were extracted, examined by scanning electron microscopy and IR, and identified as copper oxalate. The supplemented nitrogen source to the medium greatly affected both fungicide solubilization and fungal tolerance. Ratios of fungicide solubilization rate (R(S)) in relation to the colony growth rate (R(G)) were significantly higher on ammonium than on nitrate nitrogen medium for both fungal strains. Growth ratios (the colony extension rate in the presence of a given concentration of the fungicide in relation to the control colony growth rate) of A. niger were markedly lower on ammonium than on nitrate nitrogen medium. The cellular copper contents, taken up from the fungicide, and the medium titratable acidity were higher in ammonium than in nitrate medium for both fungi. These results suggested fungal possession of variable tolerance mechanisms to this fungicide by complexation and/or precipitation of copper in the medium. Additionally, this work emphasizes the activity of fungi in transformation of insoluble inorganic metal-containing fungicides into insoluble organic metal compounds, which has a potentiality in metal cycling in biogeochemical and environmental context.
