The Effect of Standardised Leaf Extracts of Gaultheria procumbens on Multiple Oxidants, Inflammation-Related Enzymes, and Pro-Oxidant and Pro-Inflammatory Functions of Human Neutrophils.

The leaves of Gaultheria procumbens are polyphenol-rich traditional medicines used to treat inflammation-related diseases. The present study aimed to optimise the solvent for the effective recovery of active leaf components through simple direct extraction and verify the biological effects of the selected extract in a model of human neutrophils ex vivo. The extracts were comprehensively standardised, and forty-one individual polyphenols, representing salicylates, catechins, procyanidins, phenolic acids, and flavonoids, were identified by UHPLC-PDA-ESI-MS3. The chosen methanol-water (75:25, v/v) extract (ME) was obtained with the highest extraction yield and total phenolic levels (397.9 mg/g extract's dw), including 98.9 mg/g salicylates and 299.0 mg/g non-salicylate polyphenols. In biological tests, ME revealed a significant and dose-dependent ability to modulate pro-oxidant and pro-inflammatory functions of human neutrophils: it strongly reduced the ROS level and downregulated the release of pro-inflammatory cytokines and tissue remodelling enzymes, especially IL-1ß and elastase 2, in cells stimulated by fMLP, LPS, or fMLP + cytochalasin B. The extracts were also potent direct scavengers of in vivo relevant oxidants (O2•-, •OH, and H2O2) and inhibitors of pro-inflammatory enzymes (cyclooxygenase-2, hyaluronidase, and lipoxygenase). The statistically significant correlations between the tested variables revealed the synergic contribution of individual polyphenols to the observed effects and indicated them as useful active markers for the standardisation of the extract/plant material. Moreover, the safety of ME was confirmed in cytotoxicity tests. The obtained results might partially explain the ethnomedicinal application of G. procumbens leaves and support the usage of the standardised leaf extract in the adjuvant treatment of oxidative stress and inflammation-related chronic diseases.

Biological and chemical insight into Gaultheria procumbens fruits: a rich source of anti-inflammatory and antioxidant salicylate glycosides and procyanidins for food and functional application.

The fruits of Gaultheria procumbens are traditionally used for culinary and healing purposes as anti-inflammatory agents. In the present work, the active components of the fruits were identified (UHPLC-PDA-ESI-MS3, preparative HPLC isolation, and NMR structural studies), and their biological capacity was evaluated in vitro in cell-based and non-cellular models. The fruits were revealed to be the richest known dietary source of salicylates (38.5 mg per g fruit dw). They are also rich in procyanidins (28.5 mg per g fruit dw). Among five tested solvents, acetone was the most efficient in concentrating the phenolic matrix (39 identified compounds; 191.3 mg g-1, 121.7 mg g-1, and 50.9 mg g-1 dry extract for total phenolics, salicylates, and procyanidins, respectively). In comparison to positive controls (dexamethasone, indomethacin, and quercetin), the extract (AE) and pure salicylates exhibited strong inhibitory activity towards pro-inflammatory enzymes (cyclooxygenase-2 and hyaluronidase). The analytes were found to be non-cytotoxic (flow cytometry) towards human neutrophils ex vivo. Moreover, they significantly, in a dose-dependent manner, downregulated the release of ROS, TNF-α, IL-1ß, and elastase-2 and slightly inhibited the secretion of IL-8 and metalloproteinase-9 in the cells. The observed effects might support the usage of G. procumbens fruits as functional components of an anti-inflammatory diet and indicate the potential of AE for use in adjuvant treatment of inflammatory disorders cross-linked with oxidative stress and associated with the excessive production of TNF-α, IL-1ß, and elastase-2.