Toxicological and pharmacological evaluation of Discaria americana Gillies & Hook (Rhamnaceae) in mice

Medicinal plants (e.g. Discaria americana) have been used by populations for centuries. However, popular use is not enough to validate these plants as safe and effective medicinal products. The present study sought to evaluate the acute and subacute toxicity as well as the anxiolytic and antinociceptive effects of D. americana root bark and aerial parts extracts in mice. In acute toxicity studies, mice were treated with single intraperitoneal doses of the aforementioned extracts. Subacute toxicity studies were performed by oral administration of the extracts over 14 days. Anxiolytic studies consisted of the elevated plus maze method, and antinociceptive studies were based on the hot plate test. The LD50 value for D. americana aerial parts extract was established at >500 mg/kg, and for the root bark extract, 400 mg/kg. D. americana aerial parts extract produced anxiolytic (250 mg/kg) and antinociceptive effects (125, 200 and 250 mg/kg). Conversely, D. americana root bark extract showed neither anxiolytic nor antinociceptive effects in mice.As plantas medicinais (i. e. Discaria americana) têm sido utilizadas pela população por séculos, entretanto, o conhecimento popular não é suficiente para validá-las como medicamentos seguros e/ou efetivos. Assim, o presente estudo teve por objetivo avaliar a toxicidade aguda e subaguda, bem como o efeito ansiolítico e antinociceptivo dos extratos da casca da raiz e das partes aéreas da D. americana em camundongos. A toxicidade aguda foi avaliada pela administração dos extratos, via intraperitoneal. Para o estudo da toxicidade subaguda os animais foram tratados oralmente com os extratos por 14 dias. O efeito ansiolítico dos extratos foi determinado através do modelo do labirinto em cruz elevado e o efeito antinociceptivo, mediante o teste da placa quente. O valor da DL50 para o extrato das partes aéreas da D. americana foi definido como > 500 mg/kg, enquanto que para o extrato da casca da raiz foi estabelecido em 400 mg/kg. O extrato das partes aéreas da D. americana apresentou atividade ansiolítica (250 mg/kg) e antinociceptiva (125, 200 e 250 mg/kg). O extrato da casca da raiz da D. americana não apresentou efeito ansiolítico nem antinociceptivo

Developments in AI and Machine Learning for Neuroimaging

This paper reviews guidelines on how medical imaging analysis can be enhanced by Artificial Intelligence (AI) and Machine Learning (ML). In addition to outlining current and potential future developments, we also provide background information on chemical imaging and discuss the advantages of Explainable AI. We hypothesize that it is a matter of AI to find an invariably recurring parameter that has escaped human attention (e.g. due to noisy data). There is great potential in AI to illuminate the feature space of successful models

How important is the quenching influence of the transition metal ions in the design of fluorescent PET sensors?

The fluorescence response of a nitrobenzoxadiazole fluorophore, attached to an amine receptor through a spacer unit, in the presence of a strongly quenching metal ion Cr3+ is reported. It is shown that the supramolecular system exhibits considerable enhancement of fluorescence in the presence of the metal ion, despite the quenching nature of the metal ion. This observation is rationalised in terms of the excited state lifetime of the fluorophore and the possible implication of this result in the design of fluorosensors for the quenching transition metal ions is discussed

Transition metal ion induced fluorescence enhancement of 4-(N, N-dimethylethylenediamino)-7-nitrobenz-2-oxa-1, 3-diazole

The photophysical properties of a structurally simple fluorophore-spacer-receptor supramolecular system involving nitrobenzoxadiazole (NBD) fluorophore, NEA, and its fluorescence response toward the quenching transition metal ions are reported. It is shown that efficient through-space intramolecular photoinduced electron transfer (PET) between the NBD fluorophore and the amino group, used here as a receptor for metal ions and protons, is responsible for extremely low fluorescence quantum yield and lifetime of NEA compared to the system NAM which contains the same fluorophore but does not possess the receptor moiety. The interaction between the NBD moiety and the metal ions in the ground and excited state is evident from the metal ion induced changes in the absorption spectra and fluorescence quenching of NAM. It is shown that despite a strong interaction between the NBD fluorophore and the quenching metal ions, NEA exhibits considerable enhancement of fluorescence rather than quenching in the presence of the transition metal ions. The results show that for an efficiently PET-quenched supramolecular system, the quenching influence of the transition metal ions is not important at moderate concentrations of the ions. This implies that efficient and structurally simple fluorosensors for the quenching metal ions can simply be developed by maximizing PET in the supramolecular systems without paying much attention to the quenching influence of the ions

Modulation of metal-fluorophore communication to developstructurally simple fluorescent sensors for transition metal ions

Fluorophores 2a and 2b show significant fluorescence enhancement in the presence of transition metal ions