Athenolide A, a New Steroidal Lactone from the Leaves of Athenaea martiana (Solanaceae) Determined by Means of HPLC-HR-MS-SPE-NMR Analysis.

Athenaea (Solanaceae) is an endemic genus belonging to the Brazilian Atlantic Rainforest. Recently, botanical investigations suggested the re-evaluation of the generic status of the genus Athenaea as a synonym of Aureliana. In this study, the first investigation of the Athenaea genus performed on Athenaea martiana by means of HPLC-HR-MS-SPE-NMR combined with high-resolution radical scavenging profile led to identification of several phenolic acids as radical scavengers: protocatechuic acid (1), 4-hydroxybenzoic acid (2), caffeic acid (3), vanillic acid (4), and ferulic acid (6). Additional analysis revealed a new steroidal lactone, named athenolide A (9). Their structures were elucidated by extensive use of NMR spectroscopy as well as HR-MS. Chemotaxonomic considerations based on these results supported the chemical relationships between the Athenaea and Aureliana genera, in agreement with the recent botanical findings.

Dual high-resolution inhibition profiling and HPLC-HRMS-SPE-NMR analysis for identification of α-glucosidase and radical scavenging inhibitors in Solanum americanum Mill.

Solanum americanum is one of the most prominent species used to treat type 2 diabetes in Guatemala. In our ongoing efforts to find antidiabetic and antioxidative compounds from natural sources, an ethyl acetate extract of this medicinal herb was investigated using dual high-resolution α-glucosidase/radical scavenging inhibition profiling. The high-resolution biochromatograms obtained by this technique were used to target subsequent structural elucidation by HPLC-HRMS-SPE-NMR analysis towards the bioactive constituents. This led to identification of 4-hydroxybenzoic acid (1) and 3-indolecarboxylic acid (6) associated with radical scavenging activity, and the amide alkaloids N-trans-p-coumaroyloctopamine (3), N-trans-p-feruloyloctopamine (4), N-trans-p-coumaroyltyramine (8) and N-trans-p-feruloyltyramine (9) correlated with α-glucosidase inhibitory activity as well as radical scavenging activity. Further analysis revealed a new lactone, methyl 5-ethyl-4-hydroxy-5-methyl-2-oxotetrahydro-2H-pyran-4-carboxylate (7) and a new steroid with a rare F ring (11). Corchorifatty acid B (12) was reported for the first time in the Solanaceae family. Their structures were elucidated by extensive use of 1D and 2D NMR spectroscopy as well as HRMS analysis.