Green ultrasound-assisted extraction and optimization of phenolic compounds from Savia officinalis and Olea europaea leaves for antidiabetic nutraceutical applications

This decade, type 2 diabetes and its complications present a major global public health crisis and a significant economic burden, even though it is chronic and often asymptomatic. The global prevalence of diabetes continues to increase at an alarming rate. The International Diabetes Federation estimated that 588.7 million adults aged 20-79 years were living with diabetes worldwide in 2024, with projections reaching 852.5 million by 2050 [1].   The consequences of this issue can lead to serious complications such as amputations, blindness, cardiovascular diseases, heart attacks, cognitive decline, and Alzheimer's disease, all of which place a significant strain on health and social security systems. Therefore, prevention is the key to avoiding this substantial health and economic pressure. In the prevention and overall management of type 2 diabetes, phytotherapy can be highly effective. The current challenge is to identify practical and safe products that contain plant extracts. Our goal is to develop a dietary supplement aimed at preventing Type 2 Diabetes (T2D), particularly during the prediabetes phase, which currently lacks effective therapies. Therefore, the creation of nutraceutical products to support patient care is essential. In this context, we conducted a study presenting original research on the green optimization of polyphenol extraction from Salvia officinalis and Olea europaea for an adjuvant dietary supplement, with a focus on the treatment of type 2 diabetes.
The present study aimed to optimize the green ultrasound-assisted extraction (UAE) process to maximize the recovery of bioactive polyphenols from Salvia officinalis and Olea europaea leaves, two Mediterranean plants used in traditional care for diabetic patients in northern Algeria, with well-documented antioxidant and antidiabetic properties. A Box-Behnken response surface methodology (RSM) was employed to evaluate the effects of glycerol concentration (10-90% v/v), temperature (20-80°C), and sonication time (5-15min) on total polyphenol content (TPC, mg GAE g^-1).
The polynomial model was statistically significant, with a p-value of 0.0029 and a coefficient of determination (R²) of 0.9292, indicating high predictive accuracy. Among the variables analyzed, glycerol concentration had the most significant effect (p < 0.001), whereas sonication temperature had a moderate effect. The optimal extraction conditions were determined to be 50% glycerol, 50°C, and 10 minutes of sonication. Under these conditions, the maximum total phenolic content (TPC) achieved was 185 mg GAE per gram. This result is comparable to that obtained with ethanol-based extraction but was achieved under milder and safer conditions.
A comparative analysis showed that glycerol-based ultrasound-assisted extraction yielded polyphenol levels and antioxidant activity similar to those achieved with ethanol extraction. However, glycerol offers additional benefits such as biodegradability, energy efficiency, and safety suitable for drug use. The extract demonstrated strong DPPH scavenging and α-glucosidase inhibitory activities, highlighting its potential as a functional ingredient for the management of type 2 diabetes mellitus (T2DM).
This study presents a validated framework for green extraction to produce high-value phytochemical extracts. By integrating sustainable solvents with optimized processes, we establish a strong foundation for developing nutraceutical formulations that balance environmental responsibility with therapeutic effectiveness. Specifically, the use of Salvia officinalis and Olea europaea offers the opportunity to supply high-quality raw materials in sufficient quantities to support future enhancements in the pharmaceutical and agri-food sectors.