Inula viscosa (L.) Greuter, phytochemical composition, antioxidant, total phenolic content, total flavonoids content and neuroprotective effects

Abstract

Introduction: Inula viscosa (L.) Greuter (DV) has been utilized in folk medicine due to its anti-inflammatory, diuretic, antiseptic, and antiphlogistic properties. Numerous studies highlighted the beneficial impact of (DV) on different diseases, yet research lacks information on its effect on neurodegeneration, specifically concerning neurotoxicity. Methods: The EO chemical composition of (DV) hydroethanolic extract was investigated using GC–MS, while the antioxidant potential was performed using (DPPH) assay and FRAP. Total phenolic content (TPC) and total flavonoid content (TFC) were measured using Folin-Ciocalteu and aluminum chloride methods. Experiments targeted the fastest ligand-gated ion channels involved in excitotoxicity. Hence, (DV) was examined for any inhibitory actions against all AMPARs presented in the CNS via whole-cell patch-clamp electrophysiology on HEK293 cells. Moreover, the effect of (DV) on other AMPAR biophysical parameters such as desensitization and deactivation was assessed. Results: GC–MS revealed the presence of twenty-one components, representing 100% of the total constituents. The major components were patchulane, 3-b-phenoxy-24-nor-cholan-5,20(22)-diene, 3-ethyl- 3 ‑hydroxy-5alpha-androstan-17-one and 𝛾-gurjunene. (DV) showed strong antioxidant activity with an IC50 value (13.5 ± 0.44 μg/ml) compared to Trolox (3.23 ± 0.92 μg/ml). High value for TPC (193.07 ± 9.1 mg Gallic acid eq./g) and TFC (594.9 ± 12.2 mg Rutin eq./g) were found. Of the examined AMPARs, (DV) inhibited GluA1 and GluA2 homomer AMPARs but not GluA3 or GluA4. (DV) inhibited both heterologous expression forms; GluA1/2 and GluA2/3 yet showed considerable significance for GluA1/2. (DV) was also selective to particular AMPAR subunits on the desensitization and deactivation. Conclusions: The current study showed high antioxidant potential, high total phenolics, and flavonoids and demonstrated neuroprotective properties of (DV) concerning neurotoxicity. 1. Introduction Inula viscosa (L.) Greuter (DV) is a popular plant of Mediterranean origin used in traditional medicine. Commonly referred to as Inula , the herbaceous perennial plant belongs to the Asteraceae family, character- ized by having sticky leaves with yellow flowers [ 1 , 2 ]. Various stud- ies have researched the numerous beneficial properties of (DV), specifi- cally antimicrobial, antipyretic, and anti-numerous inflammatory traits [3] . Additionally, many studies identified different biologically active compounds in (DV), i.e., flavonol derivatives and phytochemicals such as polyphenols and sesquiterpenes [4] .