Evaluation of Antioxidant Activity, Toxicity, and Phenolic Profile of Aqueous Extracts of Chamomile (Matricaria chamomilla L.) and Sage (Salvia officinalis L.) Prepared at Different Temperatures

Chamomile and sage are common herbs that are mostly used as infusions due to their beneficial properties. The aims of this study were to determine the total phenolic content, antioxidant activity, and potential toxicity of chamomile and sage aqueous extracts prepared at three different temperatures (25, 80, 100 °C) and finally, to detect their phenolic profiles at the optimum temperature. In order to measure the total phenolic content and antioxidant capacity, Folin–Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) assays were applied, respectively. The extraction temperature at 80 °C was the optimum, with maximal antioxidant activity and the highest total phenolic content for both herbs. Luminescence-based assay demonstrated that all the examined aqueous extracts possessed toxicity towards Vibrio fischeri. Microtox assay demonstrated no correlation with the other two assays, which were positively correlated. The major phenolics of chamomile were rutin trihydrate, ferulic acid, chlorogenic acid, and apigenin-7-O-glucoside; and major phenolics of sage were rosmarinic acid, salvianolic acid K, and luteolin-7-O-glucuronide, as defined by LC-MS of aqueous extracts at 80 °C. It can be concluded that the extraction of herbal aqueous extracts at 80 °C can provide significant bioactive and antioxidant compounds, but their consumption must be in moderation.