Anti-inflammatory and central and peripheral anti-nociceptive activities of α-asarone through the inhibition of TNF-α production, leukocyte recruitment and iNOS expression, and participation of the adenosinergic and opioidergic systems

The novel anti-fibrillary effects of volatile compounds α-asarone and β-caryophyllene on tau protein: Towards promising therapeutic agents for Alzheimer's disease

The abnormal deposition of tau protein is one of the critical causes of tauopathies including Alzheimer's disease (AD). In recent years, there has been great interest in the use of essential oils and volatile compounds in aromatherapy for treating AD, since volatile compounds can directly reach the brain through intranasal administration. The volatile compounds α-asarone (ASA) and β-caryophyllene (BCP) have revealed various important neuroprotective properties, useful in treating AD. In this study, the volatile compounds ASA and BCP were assessed for their effectiveness in preventing tau fibrillation, disassembly of pre-formed tau fibrils, and disaggregation of tau aggregates. SDS-PAGE and AFM analyses revealed that ASA and BCP inhibited tau fibrillation/aggregation and decreased the mean size of tau oligomers. Tau samples treated with ASA and BCP, showed a reduction in ThT and ANS fluorescence intensities, and a decrease in the β-sheet content. Additionally, ASA and BCP disassembled the pre-formed tau fibrils to the granular and linear oligomeric intermediates. Treatment of neuroblastoma SH-SY5Y cells with tau samples treated with ASA and BCP, revealed protective effects as shown by reduced toxicity of the cells, due to the inhibition of tau fibrillation/aggregation. Overall, ASA and BCP appeared to be promising therapeutic candidates for AD.

Alpha-Asarone modulates kynurenine disposal in muscle and mediates resilience to stress-induced depression via PGC-1α induction

INTRODUCTION

Kynurenine (KYN) accumulation in periphery induces brain injury, responsible for depression. α-Asarone is a simple phenylpropanoids that exerts beneficial effects on central nervous system. However, the effect of α-asarone on periphery is unexplored.

AIMS

Here, we investigated its protective role against depression from the aspect of KYN metabolism in skeletal muscle.

METHODS

The antidepressant effects of α-asarone were evaluated in chronic mild stress (CMS) and muscle-specific PGC-1α-deficient mice. The effects of KYN metabolism were determined in mice and C2C12 myoblasts.

RESULTS

α-Asarone exerted antidepressant effects in CMS and KYN-challenged mice via modulating KYN metabolism. In myoblasts, α-asarone regulated PGC-1α induction via cAMP/CREB signaling and upregulated KYN aminotransferases (KATs) to increase KYN clearance in a manner dependent on PGC-1α. KAT function is coupled with malate-aspartate shuttle (MAS), while α-asarone combated oxidative stress to protect MAS and mitochondrial integrity by raising the NAD⁺ /NADH ratio, ensuring effective KYN disposal. In support, the antidepressant effect of α-asarone was diminished by muscle-specific PGC-1α deficient mice subjected to KYN challenge.

CONCLUSION

KATs coupled with MAS to clear KYN in muscle. α-Asarone increased PGC-1α induction and promoted KYN disposal in muscle, suggesting that protection of mitochondria is a way for pharmacological intervention to depression.

Phytochemical composition, bioactive properties, and toxicological profile of Tetrapleura tetraptera

The use of medicinal plants has gained renewed wide popularity in Africa, Asia, and most parts of the world because of the decreasing efficacy of synthetic drugs. Thus, natural products serve as a potent source of alternative remedy. Tetrapleura tetraptera is a medicinal plant with cultural and traditional significance in West Africa. In addition to the plant being commonly used as a spice in the preparation of traditional spicy food for postpartum care it is also widely used to constitute herbal concoctions and decoctions for treatment of diseases. This review aimed to provide an up-to-date information on the ethnomedicinal uses, pharmacological activities and phytoconstituents of T. tetraptera. Preclinical studies regarding the plant's toxicity profile were also reviewed. For this updated review, literature search was done on PubMed, Science Direct, Wiley, and Google Scholar databases using the relevant keywords. The review used a total of 106 papers that met the inclusion criteria from January 1989 - February 2022 and summarised the bioactivities that have been reported for the rich phytoconstituents of T. tetraptera studied using various chemical methods. Considering the huge report, the review focused on the antimicrobial and antiinflammatory activities of the plant extracts and isolated compounds. Aridan, aridanin and several bioactive compounds of T. tetraptera have shown pharmacological activities though their mechanisms of action are yet to be fully understood. This study also highlighted the influence of plant parts and extraction solvents on its biological activities. It also presented data on the toxicological profile of the plant extracts using different models. From cultural uses to modern pharmacological research the bioactive compounds of T. tetraptera have proved effective in infectious disease management. We hope that this paper provided a robust summary of the biological activities and toxicological profile of T. tetraptera, thus calling for more research into the pharmacological and pharmacokinetic activities of natural products to help combat the growing threat of drug resistance and provide guidelines for their ethnomedicinal uses.

α-Asarone alleviates allergic asthma by stabilizing mast cells through inhibition of ERK/JAK2-STAT3 pathway

Asthma is a heterogeneous disease related to numerous inflammatory cells, among which mast cells play an important role in the early stages of asthma. Therefore, treatment of asthma targeting mast cells is of great research value. α-Asarone is an important anti-inflammatory component of the traditional Chinese medicine Acorus calamus L, which has a variety of medicinal values. To investigate whether α-asarone can alleviate asthma symptoms and its mechanism. In this study, we investigated the effect of α-asarone on mast cell activation in vivo and in vitro. The release of chemokines or cytokines, AHR (airway hyperresponsiveness), and mast cell activation were examined in a mast cell-dependent asthma model. Western blot was performed to determine the underlying pathway. α-Asarone inhibited the degranulation of LAD2 (laboratory allergic disease 2) cells and decreased IL-8, MCP-1, histamine, and TNF-α in vitro. α-Asarone reduced paw swelling and leakage of Evans blue, as well as serum histamine, CCL2, and TNF-α in vivo. In the asthma model, α-asarone showed an inhibitory effect on AHR, inflammation, mast cells activation, infiltration of inflammatory cells, and the release of IL-5 and IL-13 in lung tissue. α-Asarone decreased the levels of phosphorylated JAK2, phosphorylated ERK, and phosphorylated STAT3 induced by C48/80. Our findings suggest that α-asarone alleviates allergic asthma by inhibiting mast cell activation through the ERK/JAK2-STAT3 pathway.

Research progress on mechanism of Chinese Kaiqiao herbs in management of neuropathic pain

The Chinese herbal medicine for Kaiqiao, such as borneol, musk, grassleaf sweetflag rhizome, storax and camphor, have been prescribed in traditional Chinese medicine for thousands of years and now are widely used for neuropathic pain, the main components of which are annular compounds. Studies have shown that their analgesic mechanisms include regulating the expression of γ-aminobutyric acid, N-methyl- D-aspartic acid and other receptors; regulating ion channel function; inhibiting inflammatory response, oxidative stress and apoptosis; regulating neurotransmission and neuronal excitability; and participating in neuroprotection and neurological repair. It is suggested that the mechanisms of action of Kaiqiao herbs in central nervous system analgesia should be further explored; high-quality rapid screening of drug targets may be used, and the targeted agents using the characteristics of Kaiqiao herbs would be developed. This article reviews the research progress on the effect mechanism of traditional Kaiqiao herbs in the treatment of neuropathic pain to provide further research directions.

Molecular Mechanisms and Therapeutic Potential of α- and β-Asarone in the Treatment of Neurological Disorders

Neurological disorders are important causes of morbidity and mortality around the world. The increasing prevalence of neurological disorders, associated with an aging population, has intensified the societal burden associated with these diseases, for which no effective treatment strategies currently exist. Therefore, the identification and development of novel therapeutic approaches, able to halt or reverse neuronal loss by targeting the underlying causal factors that lead to neurodegeneration and neuronal cell death, are urgently necessary. Plants and other natural products have been explored as sources of safe, naturally occurring secondary metabolites with potential neuroprotective properties. The secondary metabolites α- and β-asarone can be found in high levels in the rhizomes of the medicinal plant Acorus calamus (L.). α- and β-asarone exhibit multiple pharmacological properties including antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. This paper aims to provide an overview of the current research on the therapeutic potential of α- and β-asarone in the treatment of neurological disorders, particularly neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), as well as cerebral ischemic disease, and epilepsy. Current research indicates that α- and β-asarone exert neuroprotective effects by mitigating oxidative stress, abnormal protein accumulation, neuroinflammation, neurotrophic factor deficit, and promoting neuronal cell survival, as well as activating various neuroprotective signalling pathways. Although the beneficial effects exerted by α- and β-asarone have been demonstrated through in vitro and in vivo animal studies, additional research is required to translate laboratory results into safe and effective therapies for patients with AD, PD, and other neurological and neurodegenerative diseases.

Clinical-like cryotherapy in acute knee arthritis of the knee improves inflammation signs, pain, joint swelling, and motor performance in mice

To assess the effects of clinical-like cryotherapy on inflammatory signs (in vivo neutrophil migration, cytokines, and joint inflammation), pain, joint swelling, balance, and motor coordination in mice with knee arthritis. Young C57BL/6 mice were randomly divided into three groups (8 to 10 mice per group): Control group: mice with no intervention; antigen-induced arthritis (AIA) group: mice sensitized and immunized with intra-articular (i.a.) injection of methylated bovine serum albumin (mBSA); and AIA + cryotherapy group: mice sensitized, immunized with i.a. injection of mBSA, and submitted to a clinical-like cryotherapy protocol. After 21 days of sensitization, AIA and AIA + cryotherapy groups received i.a. injection of mBSA (100 μg/joint) to induce joint inflammation, and a clinical-like cryotherapy protocol was applied to AIA + cryotherapy group (crushed ice bag, two cryotherapy sessions of 20 min every two hours). Experimental analysis was conducted in the initial (immediately after i.a. injection of mBSA) and final periods (two hours after the second cryotherapy session). The number of synovial fluid neutrophils, cytokine levels, joint histology, pain, joint swelling, and motor performance were also analyzed. Our results showed that clinical-like cryotherapy in mice with acute knee arthritis reduced inflammatory signs, pain, and joint swelling, and improved balance and motor coordination.

Anti-inflammatory and antinociceptive activities of a phenylpropanoid-enriched fraction of Duguetia furfuracea

A previous study reported the in vivo anti-inflammatory and antinociceptive activities of essential oil of the underground stem bark of Duguetia furfuracea, termed EODf. This study aimed to obtain a phenylpropanoid-enriched fraction from the D. furfuracea (EFDf) essential oil and to investigate its anti-inflammatory and antinociceptive effects. The chemical composition of the EFDf was determined by gas chromatography-mass spectrometry (GC-MS). The in vivo anti-inflammatory activity was evaluated with a lipopolysaccharide (LPS)-induced paw oedema model. The effects of the EFDf on the polymorphonuclear leukocyte recruitment and the inducible nitric oxide synthase (iNOS) expression were evaluated in mice footpads. Moreover, the in vivo antinociceptive effect was assayed using the formalin test and the LPS-induced thermal hyperalgesia model. In the EFDf, 8 major compounds were identified, with α-asarone (36.4%) and 2,4,5-trimethoxystyrene (27.8%) the main constituents. A higher concentration of phenylpropanoid derivatives was found in the EFDf, 64.2% compared to the EODf (38%). The oral (p.o.) treatment with the EFDf at a dose of 3 mg/kg significantly attenuated the paw oedema, polymorphonuclear leukocyte migration, iNOS expression, and tumour necrosis factor alpha (TNF-α) production. The EFDf (10 and 30 mg/kg) also inhibited both phases of the formalin test and caused a significant increase in the reaction time in the LPS-induced thermal hyperalgesia model. Finally, EFDf-treated animals did not show any alteration of motor coordination. The results suggest that the enrichment of 2,4,5-trimethoxystyrene and α-asarone enhances the anti-inflammatory activity of the EFDf compared to the EODf. In contrast, the antinociception promoted by the EFDf was similar to the EODf and was mediated via activation of adenosinergic and opioidergic receptors.