ABSTRACT
The metabolite profiling of plant extracts always represents an exciting challenge, as the chemical diversity of natural products is still far beyond the researchers' imagination, even focusing on a plant that is thought to have already been broadly investigated. Herein UHPLC-HRMS/MS techniques were applied to an alcoholic crude extract from nettle leaves and proved to be a precious tool for the disclosure of secondary metabolites never found before. Hydroxycinnamic acid derivatives were the most representative constituents, with a 2-caffeoilisocitric acid cyclodimer described for the first time, besides four C-glycosylated flavones, bearing a 3-hydroxy-3-methylglutaryl function. This deep investigation paves the way for the isolation and full characterization of these molecules by means of spectroscopic techniques. Moreover, based on preliminary cytotoxicity evaluation, further research on the use of this nettle extract as a valuable nutraceutical product is encouraged.
Subject(s)
Urtica dioica , Disclosure , Plant Extracts , Plant Leaves , Tandem Mass SpectrometryABSTRACT
Nowadays, advanced extraction techniques and highly sensitive metabolic profiling methods are effectively employed to get new information on plant chemical constituents. Among them wild medicinal plants or their parts, with large and ancient use in folk medicine, are investigated for their potential functional use and cultivation. In this context, Inula viscosa leaves engaged our attention. A simple experimental design, based on Soxhlet extraction and chromatographic fractionation, allowed us to obtain the investigated polyphenol fraction (IvE). UHPLC-HRMS analyses revealed shikimoyl depsides of caffeic acid and unusual dihydrobenzofuran lignans as main secondary metabolites. These compounds, together with cinchonain-type phenols, and hydroxycinnamoyl flavonol glycosides, are reported for the first time in inula. Overall, forty-three secondary metabolites were identified. The extract exerted a remarkable antiradical activity towards DPPH⢠and ABTS+â¢. Furthermore, it was able to inhibit cell viability and mitochondrial redox activity of neuroblastoma, hepatoblastoma and colon carcinoma cells, whereas it did not affect cell density of HaCaT cells immortalized human keratinocytes. As detected by the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate, the inhibitory responses seemed to be related to IvE-induced increase of intracellular reactive oxygen species (ROS). The obtained results highlighted that inula leaves, nowadays even undervalued and unexplored, could be considered a renewable source of nutraceutical compounds.
Subject(s)
Antioxidants/pharmacology , Inula/chemistry , Plant Extracts/pharmacology , Plant Leaves/chemistry , Polyphenols/pharmacology , Antioxidants/chemistry , Antioxidants/isolation & purification , Benzothiazoles/antagonists & inhibitors , Biphenyl Compounds/antagonists & inhibitors , Cell Proliferation/drug effects , Cell Survival/drug effects , Cells, Cultured , Chromatography, High Pressure Liquid , Humans , Mitochondria/drug effects , Mitochondria/metabolism , Molecular Structure , Picrates/antagonists & inhibitors , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Polyphenols/chemistry , Polyphenols/isolation & purification , Reactive Oxygen Species/metabolism , Sulfonic Acids/antagonists & inhibitors , Tandem Mass SpectrometryABSTRACT
Paronychia argentea Lam., belonging to the Caryophyllaceae family, is a perennial plant widely distributed in Algeria. Even though this plant is used in the Algerian popular medicine, its phytochemical characterization is incomplete. In this study, the flavonoid profile and the in vitro antioxidant activity of the ethanolic extract, decoction and infusion of P. argentea aerial parts are reported. Flavonoids were analyzed by means of high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry. Eleven compounds were identified and six of them, including isorhamnetin-3-O-dihexoside, quercetin-3-O-glucoside, quercetinmethylether-O-hexoside, quercetin, jaceosidin and isorhamnetin, were described in this plant for the first time. The ethanol extract showed the highest flavonoid content, followed by the decoction and the infusion (25.4 ± 0.8 mg/g of DM, 8.4 ± 0.5 mg/g of DM, 0.2 mg/g of DM, respectively), while the best antioxidant activity was shown by the decoction (RC0.5 = 178 µg/mL for reducing power, 72.4% of inhibition of lipid peroxidation, IC50 = 27.38µ g/mL for DPPH radical scavenging activity and 59.7% of inhibition of NO radical). These results showed that P. argentea decoction could be considered as a valuable source of flavonoids and antioxidants that might contribute to the valorization of the phytotherapeutic potential of this plant.
