Alpha-lipoic acid reduces nociception by reducing oxidative stress and neuroinflammation in a model of complex regional pain syndrome type I in mice.

Complex regional pain syndrome type I (CRPS-I) is a disabling pain condition without adequate treatment. Chronic post-ischemia pain injury (CPIP) is a model of CRPS-I that causes allodynia, spontaneous pain, inflammation, vascular injury, and oxidative stress formation. Antioxidants, such as alpha lipoic acid (ALA), have shown a therapeutic potential for CRPS-I pain control. Thus, we aim to evaluate if ALA repeated treatment modulates neuroinflammation in a model of CRPS-I in mice. We used male C57BL/6 mice to induce the CPIP model (O-ring torniquet for 2 h in the hindlimb). For the treatment with ALA or vehicle (Veh) mice were randomly separated in four groups and received 100 mg/kg orally once daily for 15 days (CPIP-ALA, CPIP-Veh, Control-ALA, and Control-Veh). We evaluated different behavioral tests including von Frey (mechanical stimulus), acetone (cold thermal stimulus), rotarod, open field, hind paw edema determination, and nest-building (spontaneous pain behavior). Also, hydrogen peroxide (H2O2) levels, NADPH oxidase and superoxide dismutase (SOD) activity in the sciatic nerve and spinal cord, and Iba1, Nrf2, and Gfap in spinal cord were evaluated at 16 days after CPIP or sham induction. Repeated ALA treatment reduced CPIP-induced mechanical and cold allodynia and restored nest-building capacity without causing locomotor or body weight alteration. ALA treatment reduced SOD and NADPH oxidase activity, and H2O2 production in the spinal cord and sciatic nerve. CPIP-induced neuroinflammation in the spinal cord was associated with astrocyte activation and elevated Nfr2, which were reduced by ALA. ALA repeated treatment prevents nociception by reducing oxidative stress and neuroinflammation in a model of CRPS-I in mice.

Evaluation of the analgesic effect of ɑ-lipoic acid in treating pain disorders: A systematic review and meta-analysis of randomized controlled trials.

Neuropathic pain is the most prevalent form of chronic pain caused by a disease of the nervous system, such as diabetic polyneuropathy. ɑ-Lipoic acid (ALA) is an antioxidant that has been widely studied for the treatment of pain symptoms in diverse conditions. Therefore, this study aimed to investigate the efficacy of ALA in the treatment of different types of pain through a systematic review and meta-analysis of randomized clinical trials. The study protocol was registered in the International Prospective Registry of Systematic Reviews (CRD42021261971). A search of the databases resulted in 1154 articles, 16 of which were included in the review (9 studies with diabetic polyneuropathy and 7 studies with other painful conditions). Most of the included studies had a low risk of bias. ALA showed efficacy for the treatment of headache, carpal tunnel syndrome and burning mouth syndrome. Meta-analysis was conducted only with the studies using diabetic polyneuropathy. Compared to placebo, ALA treatment decreased the total symptom score (TSS). The subgroup meta-analysis indicated a decrease of stabbing pain, burning, paraesthesia, and numbness in ALA-treated patients compared to placebo. In addition, both routes of administration, intravenous and oral, demonstrated the efficacy to reduce TSS. Therefore, ALA should be used to treat diabetic polyneuropathy pain symptoms. However, the standardization of treatment time and the dose may advance for the approval of ALA for clinical use in diabetic polyneuroneuropathy.

Tucumã (Astrocaryum aculeatum) extract: phytochemical characterization, acute and subacute oral toxicity studies in Wistar rats.

Natural products are often used by the population to treat and/or prevent several disorders. Tucumã is an Amazonian fruit widely consumed by local population and no in vivo toxicity studies regarding its safety are available in the literature to date. Therefore, the phytochemical characterization, acute and repeated dose 28-day oral toxicities of crude extract of tucumã's pulp (CETP) in Wistar rats were evaluated. For the CETP preparation, tucumã pulp was crushed and placed into sealed amber glass jars containing absolute ethanol solution for extraction. CETP phytochemical analyses evidenced the presence of carotenoids, flavonoids, unsaturated and satured fatty acids, and triterpenes. In the acute toxicity, female rats from the test group were treated with CETP at single dose of 2000 mg/kg. For the repeated dose toxicity, CETP was administered to male and female rats at doses of 200, 400 and 600 mg/kg, for 28 days. Body weight was recorded during the experiment and blood, liver and kidney were collected for further analysis. No mortality or toxicity signs were observed during the studies. CETP was classified as safe (category 5, OECD guide), in acute toxicity. In repeated dose study was observed alterations in some biochemical parameters, as well as in oxidative damage and enzymatic activity. Histopathological findings showed renal damage in male rats at higher dose. The data obtained suggest that CETP did not induced toxicity after exposure to a single or repeated doses in female rats. However, in males may be considered safe when given repeatedly in low doses.

Acute toxicity and antimicrobial activity of leaf tincture Baccharis trimera (Less).

BACKGROUND: The present study aimed to evaluate the possible acute oral toxicity of Baccharistrimera leaf dye as well as its antimicrobial activity. METHOD: Organization for Economic co-operation and development (OECD) 423 was used to assess acute oral toxicity and as per protocol a dose of 2000 mg/kg of tincture was administered to Wistar rats, male and female, and observed for 14 days. Biochemical and hematological analyzes were performed with sample collected of rat. The dye was evaluated for antimicrobial activity by agar diffusion and microdilution methods, which allow to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) and antibiofilm potential. RESULTS: The results showed that there was no loss of animals and no significant changes in hematological and biochemical parameters after oral administration of 2000 mg/kg of tincture and was considered safe by the OECD, classified as category 5. The dyeing also showed an important antimicrobial activity against gram positive and gram negative bacteria also significantly decreased the microbial biofilm. CONCLUSION: The tincture of B.trimera leaf when given orally once can be considered safe and has a relevant antimicrobial potential that should be elucidated in subsequent research.

Safety assessment of Morus nigra L. leaves: Acute and subacute oral toxicity studies in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Morus nigra L. is a plant native to Asia, and well adapted to the Brazilian climate. It is popularly known as "amoreira preta", and is part of the National List of Plants of Interest to the Brazilian Unified Health System. It is used in folk medicine mainly to soften the effects of menopause, as anti-inflammatory, antidiabetic and antihypertensive. However, information on safe doses and use is still precarious. AIM OF THE STUDY: To identify the chemical composition of the ethanolic extract of Morus nigra L. leaves (EEMN), as well as perform a toxicological study in male and female rats. MATERIALS AND METHODS: The chemical composition of the extract was performed by HPLC/DAD. In the acute study, the dose administered was 2000 mg/kg, and signs of toxicity and mortality was observed. In the sub-acute study, the extract was administered at doses of 500, 750 and 1000 mg/kg for 28 days. Behavioral changes, object recognition test, renal and hepatic tissue assessments, biochemical and hematological parameters were determined. The extract was administered orally to male and female rats in both studies. RESULTS: Quercetin and caffeic acid showed as major compounds in the extract. In the acute treatment, the extract was classified as safe (category 5), according to the protocol. In the subacute study, there was a decrease in AST in males (750 and 1000 mg/kg) and females (1000 mg/kg), reduction of total cholesterol in females (750 and 1000 mg/kg), and increase in renal and hepatic change the LPO levels. CONCLUSION: The present investigation showed that EEMN did not present significant toxic effects when administered orally. Moreover, presented a potentially protective action of organs and possesses hypocholesterolemic activity, thus, it is shown as a promising natural source to be used in pharmacology.