Biomonitored UHPLC-ESI-QTOF-MS2 and HPLC-UV thermostability study of the aerial parts of Sphagneticola trilobata (L.) Pruski, Asteraceae.

As the temperature of extraction and processing could impact the biological effects of herbal extracts, which have wide chemical diversity, the aim of this work were to investigate the thermostability of herbal derivatives of the aerial parts of Sphagneticola trilobata, a reputed medicinal plant; to biomonitor its oral anti-hyperalgesic effect; and to elucidate the degradation pathways of the major components by UHPLC-ESI-QTOF-MS. The lipophilic markers (kaurenoic acid-KA) and hydrophilic markers [chlorogenic acids; measured as total phenolic compounds (PC), expressed in caffeic acid] were also monitored through a validated HPLC-UV methodology, suitable for quality control and stability studies. The soft extract (drug:solvent ratio of 1:10, ethanol 60% v/v) was exposed to high temperatures (50-180°C). PC showed high thermolability (27.4% of degradation at 150°C), compared to KA (16.5%, at 180°C). These results suggest that the loss of oral anti-hyperalgesic activity observed in the spray-dried extracts (dried at 170°C), compared with the soft and the lyophilized extract may be related to degradation of the active components, especially the polar compounds, i.e. chlorogenic acid derivatives and the four oleanane type triterpenoid saponins. These latter degraded at temperatures above 150°C and vanished at 180°C, as demonstrated in the UHPLC-ESI-QTOF-MS analyses. These results provide a relevant guide for the extraction process of S. trilobata, aimed at preserving the antinociceptive effect.