Ahmed Zayed, Meryem El Jemli, Mourad Kharbach, My El Abbes Faouzi, Rasha Ali Radwan, Shahira M Ezzat
The investigated Moroccan herbal teas exhibited variable antioxidant and digestive-enzyme inhibitory activities that were associated with their phenolic composition. Variability among samples may reflect differences in plant species and environmental or agronomic factors. These findings provide comparative in vitro evidence supporting the traditional use of Moroccan herbal teas and highlight several species as promising sources of bioactive phenolics. However, the present findings do not establish therapeutic efficacy, and further in vivo, mechanistic, pharmacokinetic, and clinical studies are required to confirm their efficacy, safety, and clinical relevance.
BACKGROUND: Traditional Moroccan herbal teas are widely consumed and have been traditionally used for managing chronic metabolic disorders, particularly type 2 diabetes mellitus (T2DM). Although these preparations have a long history of ethnomedicinal use, their phenolic composition and biological activities remain insufficiently characterized. Scientific validation is needed to support their traditional application and provide evidence for their potential relevance to T2DM management. This study aimed to characterize the phenolic profile, antioxidant potential, and carbohydrate-digestive enzyme inhibitory activity of 21 traditional Moroccan herbal teas used for glycaemic control.
METHODS: Phenolic constituents were identified and quantified using HPLC-MS. Antioxidant capacity was evaluated through DPPH, ABTS, and FRAP assays. Inhibitory effects on α-amylase and α-glucosidase were assessed in vitro. Correlation analyses were conducted to explore associations between phenolic constituents and biological activities.
FINDINGS: Marked variability in total phenolic content (TPC) was observed, with Mentha × piperita and Thymus broussonetii exhibiting the highest levels at 883.2 ± 13.0 and 746.8 ± 22.4 mg GAE/g dry weight, respectively. Antioxidant activity varied substantially among the investigated teas, with T. broussonetii (FRAP reducing power: 423.6 ± 9.8 µg/mL) and Mentha rotundifolia (162.6 ± 0.6 µg/mL) showing significant reducing capacities. TPC exhibited strong positive correlations with antioxidant indices (r = 0.93-0.96). Pelargonium graveolens presented potent α-amylase inhibition (IC50 = 2.98 ± 1.7 µg/mL), whereas Mentha viridis and Calamintha officinalis were among the most active α-glucosidase inhibitors (IC50 = 1.9 ± 0.4 and 1.2 ± 0.1 µg/mL, respectively). Negative correlations were found between rutin (r = - 0.49) and gallic acid (r = - 0.44) contents and α-amylase IC50 values.
CONCLUSION: The investigated Moroccan herbal teas exhibited variable antioxidant and digestive-enzyme inhibitory activities that were associated with their phenolic composition. Variability among samples may reflect differences in plant species and environmental or agronomic factors. These findings provide comparative in vitro evidence supporting the traditional use of Moroccan herbal teas and highlight several species as promising sources of bioactive phenolics. However, the present findings do not establish therapeutic efficacy, and further in vivo, mechanistic, pharmacokinetic, and clinical studies are required to confirm their efficacy, safety, and clinical relevance.