A new study revealed the potential analgesic effects of essential oils of O. basilicum leaves on chronic, non-inflammatory fibromyalgia pain. This study entitled “Cyclodextrin-Complexed Ocimum basilicum Leaves Essential Oil Increases Fos Protein Expression in the Central Nervous System and Produce an Antihyperalgesic Effect in Animal Models for Fibromyalgia” was published in International Journal of Molecular Sciences by Simone S. Nascimento and Adriano A. S. Araújo, co-first authors of the study, and led by Dr. Lucindo J. Quintans-Júnior from the Laboratory of Pre-Clinical Pharmacology (LAPEC) at the Federal University of Sergipe in Brazil.
Fibromyalgia is a chronic disorder of the locomotor system, affecting muscular and skeletal systems with unknown causes. This disease is characterized by chronic general pain, presence of tender points on physical examination, and symptoms such as tiredness, morning stiffness, sleep disorders and depression. The standard treatment for fibromyalgia consists mainly of antidepressants, calcium-channel modulators, muscle relaxants and analgesics. However, the prolonged use of these pharmacological compounds induce adverse events and many patients do not respond adequately to these therapies. Therefore, there is an urgent need to discover alternative therapies to overcome the limitations of the current treatments for chronic pain in fibromyalgia.
The screening of natural compounds from medicinal plants or their derived metabolites has been a very useful strategy to discover potential new therapies for several diseases. Essential oils extracted from several aromatic plants from countries like Brazil have been tested due to their unique biological properties. The Ocimum species (Lamiaceae) have been used to treat central nervous system conditions due to their anti-convulsivant, analgesic and anti-inflammatory properties. In particular, the O. basilicum leaf essential oil (LEO) has high content in monoterpenes, such as linalool, and appears to be an attractive choice as a pain reliever. However, the fact that LEO is not soluble in water is one major limitation for its biological application. The use of β-Cyclodextrin (β-CD) has been applied to overcome water insolubility and to increase the pharmacological properties of the leaf’s essential oil.
In this study, the research team used an animal model for fibromyalgia to evaluate the antihyperalgesic activity of LEO, complexed or not with β-CD (LEO/β-CD). After performing behavioral tests, they treated the mice daily with either LEO/β-CD (25, 50 or 100 mg/kg, p.o.), LEO (25 mg/kg, p.o.), tramadol (TRM 4 mg/kg, i.p.) or vehicle (saline), and after 1 hour they assessed the parameters of behavior such as mechanical hyperalgesia (von Frey), motor ordination (Rota-rod) and muscle strength (Grip Strength Metter). Then, the researchers assessed the effect of the tested drugs in the central nervous system (CNS) pathways using immunofluorescence protocol for Fos protein. They observed that all the doses of the drugs, LEO or LEO-βCD, induced a considerable decrease of mechanical hyperalgesia, and there was a significant increase in the expression of Fos protein.
Finally, the authors concluded that their findings show that essential oils such as this one, complexed or not with β-CD, had analgesic effects on chronic non-inflammatory pain in an animal model of fibromyalgia.