Hypericum triquetrifolium and H. neurocalycinum as Sources of Antioxidants and Multi-Target Bioactive Compounds: A Comprehensive Characterization Combining In Vitro Bioassays and Integrated NMR and LC-MS Characterization by Using a Multivariate Approach.

Hypericum triquetrifolium and H. neurocalycinum were evaluated for their phytochemical content and in vitro bioactivity. NMR analyses were performed on the methanol extract of the aerial parts of H. triquetrifolium to establish the main classes of phytoconstituents. Then, LC-DAD-MSn analyses were performed in order to compare the composition of aerial parts and roots extracts of both Hypericum species, obtained using either methanol or water as solvents. Results, processed using multivariate data analysis, showed a significantly higher phenolic content of methanol extracts compared to water extracts, while minor qualitative differences were observed between the two. Distinctive flavonoid and PAC patterns were observed for H. triquetrifolium and H. neurocalycinum, and specific compounds were exclusively detected in one or the other species. Specifically, the phloroglucinols 7-epiclusianone, hyperfirin and hyperforin were present only in H. neurocalycinum, while hyperforin was detected only in H. triquetrifolium. Extracts were assayed using different in vitro tests to evaluate their antioxidant properties and their inhibitory activity against several enzymes, showing significant antioxidant and metal chelating activities. Furthermore, inhibitory properties against acetylcholinesterase, butyrylcholinesterase and tyrosinase were observed. Multivariate approaches were used to correlate biological data with the phytochemical composition of the different extracts. The results, showing positive correlations between specific chemical constituents and the measured bioactivities, represent preliminary data that could guide future studies aimed at isolating bioactive constituents from H. neurocalycinum and H. triquetrifolium for further pharmacological evaluations.

Utilisation of Rhododendron luteum Sweet bioactive compounds as valuable source of enzymes inhibitors, antioxidant, and anticancer agents.

Ethnobotanical evidences report the use of Rhododendron luteum Sweet (Ericaceae) in traditional medicinal systems. However, R. luteum has been associated to the occurrence of 'mad honey' poisoning. In the present study, the ethyl acetate, methanol, and water extracts of R. luteum were investigated for their in vitro antioxidant, enzyme inhibition, and cytotoxic properties. The cytotoxicity of R. luteum extracts on A549 lung cancer cell line was evaluated using MTT cell viability assay. Besides, HPLC-ESI-MSn approach was employed to elucidate the secondary metabolite profiles of R. luteum in order to establish any structure-activity relationship. Methanol and water extracts of R. luteum possessed highest radical scavenging and reducing properties while the ethyl acetate extract showed highest metal chelating properties. In terms of enzyme inhibition, the methanol and ethyl acetate extracts of R. luteum, possessing epigallocatechin, were active inhibitors of cholinesterase enzymes, α-glucosidase, and tyrosinase. Water extract caused growth inhibition of A549 cells with 207.2 µg/ml IC50 value. Though R. luteum has received little scientific attention due to the occurrence of grayanotoxins in the plant, however, data presented in this work shows promising biological activity of R. luteum and highlighted its role as a potential source of antioxidant and key enzyme inhibitors.