Alpha-Lipoic Acid as an Antioxidant Strategy for Managing Neuropathic Pain.

Neuropathic pain (NP) is the most prevalent and debilitating form of chronic pain, caused by injuries or diseases of the somatosensory system. Since current first-line treatments only provide poor symptomatic relief, the search for new therapeutic strategies for managing NP is an active field of investigation. Multiple mechanisms contribute to the genesis and maintenance of NP, including damage caused by oxidative stress. The naturally occurring antioxidant alpha-lipoic acid (ALA) is a promising therapeutic agent for the management of NP. Several pre-clinical in vitro and in vivo studies as well as clinical trials demonstrate the analgesic potential of ALA in the management of NP. The beneficial biological activities of ALA are reflected in the various patents for the development of ALA-based innovative products. This review demonstrates the therapeutic potential of ALA in the management of NP by discussing its analgesic effects by multiple antioxidant mechanisms as well as the use of patented ALA-based products and how technological approaches have been applied to enhance ALA's pharmacological properties.

Citrus limon (L.) Burm f. Essential Oil Has Anxiolytic and Sedative Properties by Modulating GABAA-Receptors

Abstract The high prevalence of anxiety disorders associated with pharmacotherapy side effects have motivated the search for new pharmacological agents. Species from Citrus genus, such as Citrus limon (sicilian lemon), have been used in folk medicine as a potential therapy to minimize emotional disorders. In order to searching for new effective treatments with fewer side effects, the present study evaluated the anxiolytic mechanism of action and the hypnotic-sedative activity from the Citrus limon fruit's peels essential oil (CLEO). Adults male Swiss mice were submitted to barbiturate-induced sleep test; elevated plus-maze (EPM) and light-dark box (LDB) (evaluation of the mechanism of action); rotarod; and catalepsy tests. CLEO oral treatment decreased latency and increased the sleep total time; moreover it induced in animals an increased the number of entries and percentage of time spent into open arms of the EPM; an increased the number of transitions and the percentage of time into light compartment in the LDB; which were only antagonized by flumazenil pretreatment, with no injury at motor function. Thus, results suggest that CLEO treatment induced an anxiolytic behavior suggestively modulated by the benzodiazepine binding site of the GABAA receptor or by an increase of GABAergic neurotransmission, without cause impairment in the motor coordination.

The Antinociceptive Effect of the Leaves and Flowers Ethanolic Extracts of Tabebuia aurea (Silva Manso) Benth & Hook. F. ex S. Moore

ABSTRACT In view of the traditional use of Tabebuia aurea for treating pain and inflammation, the antinociceptive pharmacological potential of T. aurea ethanolic extracts (TAEE) was investigated through in vivo experimental models. First, the MTT assay was conducted to determine the potential cytotoxicity of the TAEEs. Afterwards, the acetic acid-induced writhing test and the formalin-, and glutamate-induced nociception tests were performed on Swiss adult mice treated with TAEEs (100 and 200 mg/kg doses, p.o.), or saline solution (control groups, 10mL/kg, p.o.), or standard drugs: dipyrone 40 mg/kg (p.o.), and morphine 5,7 mg/kg (i.p). In the MTT assay, none of the tested concentrations demonstrated signals of cytotoxicity. In the in vivo experimental models of acetic acid-induced writhing and glutamate-induced nociception, all TAEEs doses were able to statistically reduce the nociceptive response. However, the TAEEs did not show significant decrease in the amount of time that the animals spent licking the stimulated paw in the neurogenic phase of formalin-induced nociception test, differently of what was observed in the inflammatory phase. The results showed that T. aurea species induce an antinociceptive effect in rodents, which encourages the study of new drugs and contributes to the research on natural products.