Protective action of Rosemary extracts obtained by green innovative techniques on neuropathic pain

Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) are today a conceivable reality beyond lab-scale procedures. These techniques can be considered a green processes as they help to greatly accelerate the extraction procedure and reduce energy consumption. In this study were investigated efficiency and selectivity of UAE and MAE to recover the phenolic fraction from rosemary leaves by means of last-generation devices. Different extractive sequences were tested to optimize the recovery and test the ability to fractionate the rosemary phenols. The phenolic content under MAE and UAE was more than 3 times higher than a classic solid-liquid extraction, that requires a time of extraction ten times higher [1]. In particular, by comparison of phenolic fractions and final yields, it was pointed out that high-intensity ultrasound is the most effective and versatile method looking for scaling up. Moreover the findings of our work pointed out that the use of ultrasounds helps to avoid the oxidation processes that produce carnosol and rosmanol from their precursor carnosic acid. Among the 20 different samples, we selected an ultrasound extract characterized by an high concentration of terpenoids (mainly carnosic acid) and by the absence of rosmarinic acid. The pain reliever effect of the extract was evaluated in the rat Chronic Constriction Injury (CCI) model of neuropathy [2]. The sample was daily administered (100 and 300 mg kg-1 per os) starting on day of surgery. On day 14, hyperalgesia (Paw Pressure test), allodynia (Von Frey test) and hind limb weight bearing alterations (Incapacitance test) were significantly reduced by the extract treatment. In conclusion this carnosic acid-enriched rosemary extract can prevent the painful neuropathy due to the traumatic lesion of the sciatic nerve