Rosmarinic acid attenuates development and existing pain in a rat model of neuropathic pain: An evidence of anti-oxidative and anti-inflammatory effects

Abietane Diterpenoids with Antioxidative Damage Activity from Rosmarinus officinalis

Nine new and nineteen known compounds were isolated and identified from Rosmarinus officinalis under the guidance of bioassay and LCMS. They all belonged to abietane diterpenoids which enriched the types of compounds in R. officinalis, especially the discovery of a series of 20-norabietane diterpenoids (4, 6-9, and 26-27). The antioxidative damage activity of the compounds was tested on H₂O₂ damaged SH-SY5Y cells. Compounds 5, 6, and 7 presented moderate ability for promoting the growth of damaged cells. Compounds 10, 11, 13-20, 27, and 28 displayed a high antioxidative damage effect whose cell viability rates were more than 80%. The antioxidative damage effect of 11, 16, 18, and 20 were higher than that of EGCG (positive control) in which 11, 18, and 20 were the acetylated derivatives of carnosic acid (10), 7α-methoxy-isocarnosol (16), and carnosol (19), respectively. It suggested that 10-carboxyl/formyl of abietane diterpenoids was essential for maintaining the antioxidative damage activity and the adjacent hydroxyl groups on the benzene ring was less important for holding the bioactivity. These acetylated derivatives with high bioactivity and stability could be regarded as new sources of antioxidants or antioxidative damage agents being used in the food and medical industry.

Rosmarinic acid exerts a neuroprotective effect on spinal cord injury by suppressing oxidative stress and inflammation via modulating the Nrf2/HO-1 and TLR4/NF-κB pathways

Spinal cord injury (SCI) is a severe central nervous system injury for which few efficacious drugs are available. Rosmarinic acid (RA), a water-soluble polyphenolic phytochemical, has antioxidant, anti-inflammatory, and anti-apoptotic properties. However, the effect of RA on SCI is unclear. We investigated the therapeutic effect and underlying mechanism of RA on SCI. Using a rat model of SCI, we showed that RA improved locomotor recovery after SCI and significantly mitigated neurological deficit, increased neuronal preservation, and reduced apoptosis. Also, RA inhibited activation of microglia and the release of TNF-α, IL-6, and IL-1β and MDA. Moreover, proteomics analyses identified the Nrf2 and NF-κB pathways as targets of RA. Pretreatment with RA increased levels of Nrf2 and HO-1 and reduced those of TLR4 and MyD88 as well as phosphorylation of IκB and subsequent nuclear translocation of NF-κB-p65. Using H2O2- and LPS-induced PC12 cells, we found that RA ameliorated the H2O2-induced decrease in viability and increase in apoptosis and oxidative injury by activating the Nrf2/HO-1 pathway. Also, LPS-induced cytotoxicity and increased apoptosis and inflammatory injury in PC-12 cells were mitigated by RA by inhibiting the TLR4/NF-κB pathway. The Nrf2 inhibitor ML385 weakened the effect of RA on oxidant stress, inflammation and apoptosis in SCI rats, and significantly increased the nuclear translocation of NF-κB. Therefore, the neuroprotective effect on SCI of RA may be due to its antioxidant and anti-inflammatory properties, which are mediated by modulation of the Nrf2/HO-1 and TLR4/NF-κB pathways. Moreover, RA activated Nrf2/HO-1, which amplified its inhibition of the NF-κB pathway.

A Review of the Anti-Inflammatory Effects of Rosmarinic Acid on Inflammatory Diseases

Inflammatory diseases are caused by abnormal immune responses and are characterized by an imbalance of inflammatory mediators and cells. In recent years, the anti-inflammatory activity of natural products has attracted wide attention. Rosmarinic acid (RosA) is a water-soluble phenolic compound that is an ester of caffeic acid and 3, 4-dihydroxyphenyl lactic acid. It is discovered in many plants, like those of the Boraginaceae and Lamiaceae families. RosA has a wide range of pharmacological effects, including anti-oxidative, anti-apoptotic, anti-tumorigenic, and anti-inflammatory effects. The anti-inflammatory effects of RosA have been revealed through in vitro and in vivo studies of various inflammatory diseases like arthritis, colitis, and atopic dermatitis. This article mainly describes the preclinical research of RosA on inflammatory diseases and depicts a small amount of clinical research data. The purpose of this review is to discuss the anti-inflammatory effects of RosA in inflammatory diseases and its underlying mechanism.

Rosmarinus plants: Key farm concepts towards food applications

Rosmarinus species are aromatic plants that mainly grow in the Mediterranean region. They are widely used in folk medicine, food, and flavor industries and represent a valuable source of biologically active compounds (e.g., terpenoids, flavonoids, and phenolic acids). The extraction of rosemary essential oil is being done using three main methods: carbon dioxide supercritical extraction, steam distillation, and hydrodistillation. Furthermore, interesting antioxidant, antibacterial, antifungal, antileishmanial, anthelmintic, anticancer, anti-inflammatory, antidepressant, and antiamnesic effects have also been broadly recognized for rosemary plant extracts. Thus the present review summarized data on economically important Rosmarinus officinalis species, including isolation, extraction techniques, chemical composition, pharmaceutical, and food applications.

Rosmarinic Acid Protects Adipose Tissue-Derived Mesenchymal Stem Cells in Nutrient-Deficient Conditions

One of the major challenges for stem cell therapy of ischemic organs is that the transplanted cells are confronted with nutrient deficiency and oxidative stress. Previous studies have indicated that pretreatment of stem cells with cytoprotective phytochemicals improves their therapeutic potential. This study was aimed to investigate whether rosmarinic acid can enhance survival of adipose tissue-derived stem cells (ASCs) in nutrient-deficient culture as an in vitro model of ischemia. The ASCs were isolated from subcutaneous adipose tissue of male adult Wistar rats and incubated for 24 h with rosmarinic acid in nutrient-deficient (glucose- and serum-deprived, GSD) culture medium. In a separate experiment, ASCs were pre-incubated for 4 h with rosmarinic acid and then exposed to GSD conditions for 24 h. The viability of ASCs was determined using thiazolyl blue tetrazolium bromide assays. The effect of rosmarinic acid on the cell cycle was evaluated using propidium iodide staining. GSD conditions significantly decreased the viability of ASCs and enhanced the generation of reactive oxygen species (ROS), lipid peroxidation, sub-G1 cell populations, and necrosis. Both pre-incubation and incubation of ASCs with 0.75~6 μM rosmarinic acid significantly increased cell viability in GSD conditions. Rosmarinic acid further decreased the level of ROS, lipid peroxidation, the percent of cells in sub-G1 stage, and necrosis in GSD conditions. These findings suggest that rosmarinic acid enhances survival of ASCs cultured in nutrient-deficient conditions through promoting antioxidant effects. Therefore, rosmarinic acid may help preserve ASCs survival after they are transplanted into ischemic organs.

Harpagophytum procumbens Extract Ameliorates Allodynia and Modulates Oxidative and Antioxidant Stress Pathways in a Rat Model of Spinal Cord Injury

Spinal cord injury (SCI) is a deliberating disorder with impairments in locomotor deficits and incapacitating sensory abnormalities. Harpagophytum procumbens (Hp) is a botanical widely used for treating inflammation and pain related to various inflammatory and musculoskeletal conditions. Using a modified rodent contusion model of SCI, we explored the effects of this botanical on locomotor function and responses to mechanical stimuli, and examined possible neurochemical changes associated with SCI-induced allodynia. Following spinal cord contusion at T10 level, Hp (300 mg/kg, p.o.) or vehicle (water) was administered daily starting 24 h post-surgery, and behavioral measurements made every-other day until sacrifice (Day 21). Hp treatment markedly ameliorated the contusion-induced decrease in locomotor function and increased sensitivity to mechanical stimuli. Determination of Iba1 expression in spinal cord tissues indicated microglial infiltration starting 3 days post-injury. SCI results in increased levels of 4-hydroxynonenal, an oxidative stress product and proalgesic, which was diminished at 7 days by treatment with Hp. SCI also enhanced antioxidant heme oxygenase-1 (HO-1) expression. Concurrent studies of cultured murine BV-2 microglial cells revealed that Hp suppressed oxidative/nitrosative stress and inflammatory responses, including production of nitric oxide and reactive oxygen species, phosphorylation of cytosolic phospholipases A₂, and upregulation of the antioxidative stress pathway involving the nuclear factor erythroid 2-related factor 2 and HO-1. These results support the use of Hp for management of allodynia by providing resilience against the neuroinflammation and pain associated with SCI and other neuropathological conditions.

Rosmarinic acid improves oxidative stress parameters and mitochondrial respiratory chain activity following 4-aminopyridine and picrotoxin-induced seizure in mice

Studies have indicated that epilepsy, an important neurological disease, can generate oxidative stress and mitochondrial dysfunction, among other damages to the brain. In this context, the use of antioxidant compounds could provide neuroprotection and help to reduce the damage caused by epileptic seizures and thereby the use of anticonvulsant drugs. Rosmarinic acid (RA) is an ester of caffeic acid and 3,4-dihydroxyphenylactic acid that prevents cell damage caused by free radicals, acting as an antioxidant. It also presents anti-inflammatory, antimutagenic, and antiapoptotic properties. In this work, we used two models of acute seizure, 4-aminopyridine (4-AP) and picrotoxin (PTX)-induced seizures in mice, to investigate the anticonvulsant, antioxidant, and neuroprotective profile of RA. Diazepam and valproic acid, antiepileptic drugs already used in the treatment of epilepsy, were used as positive controls. Although RA could not prevent seizures in the models used in this study, neither enhance the latency time to first seizure at the tested doses, it exhibited an antioxidant and neuroprotective effect. RA (8 and 16 mg/kg) decreased reactive oxygen species production, superoxide dismutase activity, and DNA damage, measured in hippocampus, after seizures induced by PTX and 4-AP. Catalase activity was decreased by RA only after seizures induced by 4-AP. The activity of the mitochondrial complex II was increased by RA in hippocampus samples after both seizure models. The results obtained in this study suggest that RA is able to reduce cell damage generated by the 4-AP and PTX seizures and therefore could represent a potential candidate in reducing pathophysiological processes involved in epilepsy.

Enhancement of biocompatibility and carbohydrate absorption control potential of rosmarinic acid through crosslinking into microparticles

Rosmarinic acid (RA), a bioflavonoid and antioxidant that exists in plants of the Lamiaceae family, was crosslinked into particles as poly(Rosmarinic Acid) (p(RA)) via an emulsion crosslinking method. The particles were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance 13C NMR spectroscopy, and thermal gravimetric analysis. The zeta potential values of p(RA) particles were determined at different pHs; the isoelectric point was estimated as pH 1.2. The release of monomeric RA from the particles at 37.5 °C was found to be similar at different pHs, 1.0, 7.4, and 11.0. The effects of p(RA) on hemolysis and coagulation were found to be minimal. The antioxidant activity of p(RA) particles and RA monomer were almost indistinguishable suggesting that p(RA) particles may be used as an antioxidant. On a per weight basis, p(RA) particles were ~66% less cytotoxic to mammalian cells that RA monomer, as assessed using COS-1 cells. In addition, p(RA) was an 8.6-fold stronger inhibitor of α-glycosidase than RA; the IC50s of the monomer and particles were 0.121 and 0.014 mg/mL, respectively. The strong inhibitory effect of p(RA) on α-glycosidase, coupled with its reduced cytotoxicity and antioxidant activity, provide new opportunities for the use of p(RA).

Salvia officinalis, Rosmarinic and Caffeic Acids Attenuate Neuropathic Pain and Improve Function Recovery after Sciatic Nerve Chronic Constriction in Mice

The leaves of Salvia officinalis L. have a traditional reputation for the management of pain in Morocco. This study was conducted to investigate the curative effects of Salvia officinalis (SO) and its major constituents Rosmarinic (ROS) and Caffeic acids (CAF) on peripheral neuropathic pain in mice. Chronic constriction injury (CCI) was induced in mice, and neuropathic pain behaviors tests were evaluated by mechanical, chemical, thermal sensation tests and functional recovery of the sciatic nerve at different time intervals, i.e., (day 0, 1, 7, 14, and 21). Ethanolic extract of SO (100 and 200 mg/kg, p.o.), ROS (10 and 20 mg/kg, i.p.), CAF (30 and 40 mg/kg, i.p.), and CLOM (5 mg/kg, i.p., a positive control) was given for 21 days after surgery. Hematological and biochemical parameters were also measured as well as histopathological analysis. CCI produced significant development in mechanical and thermal hyperalgesia, cold allodynia, and rise in the sciatic functional index in mice. Chronic treatments with SO extract, ROS, CAF, and CLOM for 3 weeks significantly increased mechanical sensibility, cold, and thermal withdrawal latency and enhanced functional recovery of the injured nerve. The same treatments remarkably ameliorated hematological parameters and did not alter biochemical levels. The histopathological findings had revealed the protective effect of SO, ROS, and CAF against the CCI-induced damage. Our data support the use of SO in folk medicine to alleviate pain. Their main phenolic constituents could be promising antineuropathic compounds, which may be attributed to their biological activities including anti-inflammatory, antioxidant, and neuroprotective effects. SO leaves may be a good candidate to treat neuropathic pain.

Rosmarinic acid elicits neuroprotection in ischemic stroke via Nrf2 and heme oxygenase 1 signaling

Rosmarinic acid (RA) can elicit a neuroprotective effect against ischemic stroke, but the precise molecular mechanism remains poorly understood. In this study, an experimental ischemic stroke model was established in CD-1 mice (Beijing Vital River Laboratory Animal Technology, Beijing, China) by occluding the right middle cerebral artery for 1 hour and allowing reperfusion for 24 hours. After intraperitoneally injecting model mice with 10, 20, or 40 mg/kg RA, functional neurological deficits were evaluated using modified Longa scores. Subsequently, cerebral infarct volume was measured using TTC staining and ischemic brain tissue was examined for cell apoptosis with TUNEL staining. Superoxide dismutase activity and malondialdehyde levels were measured by spectrophometry. Expression of heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), Bcl-2, Bax, Akt, and phospho-Ser473 Akt proteins in ischemic brain tissue was detected by western blot, while mRNA levels of Nrf2, HO-1, Bcl-2, and Bax were analyzed using real time quantitative PCR. In addition, HO-1 enzyme activity was measured spectrophotometrically. RA (20 and 40 mg/kg) greatly improved neurological function, reduced infarct volume, decreased cell apoptosis, upregulated Bcl-2 protein and mRNA expression, downregulated Bax protein and mRNA expression, increased HO-1 and Nrf2 protein and mRNA expression, increased superoxide dismutase activity, and decreased malondialdehyde levels in ischemic brain tissue of model mice. However, intraperitoneal injection of a HO-1 inhibitor (10 mg/kg zinc protoporphyrin IX) reversed the neuroprotective effects of RA on HO-1 enzyme activity and Bcl-2 and Bax protein expression. The PI3K/Akt signaling pathway inhibitor LY294002 (10 mM) inhibited Akt phosphorylation, as well as Nrf2 and HO-1 expression. Our findings suggest that RA has anti-oxidative and anti-apoptotic properties that protect against ischemic stroke by a mechanism involving upregulation of Nrf2 and HO-1 expression via the PI3K/Akt signaling pathway.