Investigation of the in vitro antidiabetic and anti-alzheimer effects of salvia dorystoechas (syn: dorystoechas hastata) plant extract

In recent years, plant-based bioactive compounds targeting metabolic and neurodegenerative diseases—and especially plants rich in such compounds—have come to the forefront of scientific research. This study aimed to comprehensively characterize the phenolic compound profiles of different fractions obtained from the methanol extract of Dorystoechas hastata (D. hastata), an endemic species native to southwestern Turkey, and to evaluate the in vitro inhibitory effects of these fractions on acetylcholinesterase (AChE), α-amylase, and α-glucosidase enzymes. The primary objective was to investigate the antidiabetic and anti-Alzheimer potential of fractions with high phenolic content and to elucidate the relationship between the fractionation of D. hastata and its enzyme inhibition capacity. In this study, total phenolic content was determined using the Folin-Ciocalteu method, and total flavonoid content was measured using the AlCl3 method. The inhibition assays were performed using commonly accepted protocols: acetylcholinesterase inhibition was assessed by the Ellman method, α-amylase inhibition by the starch-iodine method, and α-glucosidase inhibition by the p-nitrophenyl-α-D-glucopyranoside (pNPG) method. Kinetic analyses were conducted by linearizing the Michaelis-Menten plots to calculate Km and Vmax values. Data were statistically analyzed using ANOVA, with a significance level set at p < 0.05. Fractions of methanol, hexane, chloroform, and water were obtained from the methanol extract through maceration and systematically analyzed. UHPLC-MS/MS profiling revealed that the methanol fraction was particularly rich in carnosic acid (5622.18 µg/g), carnosol (2790.19 µg/g), and rutin (2272.38 µg/g). Notably, eight compounds, including rutin, were reported for the first time in D. hastata, contributing significantly to the chemotaxonomic data of the species. The methanol fraction exhibited the highest total phenolic content at 300.93 ± 7.66 mg GAE/g extract, while the water fraction showed the highest total flavonoid content at 49.39 ± 0.22 mg QE/g extract. The enzyme inhibition assays demonstrated strong biological activity. For acetylcholinesterase, the methanol and hexane fractions showed inhibition rates exceeding 40% at a concentration of 10 µg/mL, whereas the chloroform and water fractions exhibited around 25% inhibition. The hexane fraction demonstrated the highest α-amylase inhibition at 86% (50 µg/mL), while α-glucosidase inhibition ranged between 50% and 75% across all fractions at 10 µg/mL concentration. These findings indicate that D. hastata is rich in bioactive compounds with potential efficacy against chronic conditions such as type 2 diabetes and Alzheimer's disease. The data suggest that the plant holds promise for development as a functional food supplement or phytotherapeutic product. However, to confirm this potential, further advanced toxicological, pharmacodynamic, and clinical studies are required. Future research will be essential to more clearly establish the efficacy of D. hastata.