Chemistry, Pharmacology and Therapeutic Potential of Swertiamarin - A Promising Natural Lead for New Drug Discovery and Development

Gentiopicroside and swertiamarin induce non-selective oxidative stress-mediated cytotoxic effects in human peripheral blood mononuclear cells

Gentiopicroside (Gp) and swertiamarin (Sm), secoiridoid glycosides commonly found in plants of the Gentianaceae family, differ in one functional group. They exhibit promising cytotoxic effects in cancer cell lines and overall protective outcomes, marking them as promising molecules for developing novel pharmaceuticals. To investigate potential variations in cellular sensitivity to compounds of similar molecular structures, we analyzed the mode of Gp and Sm induced cell death in human peripheral blood mononuclear cells (PBMCs) after 48 hours of treatment. The lowest tested concentration that significantly reduces cell viability, 50 μM, was applied. Oxidative stress parameters were estimated by measuring the levels of prooxidative/antioxidative balance, lipid peroxidation products, and 8-oxo-7,8-dihydro-2-deoxyguanosine, while gene expression of DNA repair enzymes was evaluated by employing quantitative real-time PCR. Cellular morphology was analyzed by fluorescent microscopy, and immunoblot analysis of apoptosis and necroptosis-related proteins was used to assess the type of cell death induced by the treatments. The discriminatory impact of Gp/Sm treatments on apoptosis and necroptosis-induced cell death was evaluated by monitoring the cell survival in co-treatment with specific cell death inhibitors. Obtained results show greater cytotoxicity of Gp than Sm suggesting that variations in the molecular structures of the tested compounds can substantially affect their biological effects. Gp/Sm co-treatment with apoptosis and necroptosis inhibitors revealed a distinct, albeit non-specific mechanism of PBMCs cell death. Although the therapeutic may not directly cause a specific type of cell death, its extent can be pivotal in assessing the safety of therapeutic application and developing phytopharmaceuticals with improved features. Since phytopharmaceuticals affect all exposed cells, identification of cytotoxic mechanisms on PBMCs after Gp and Sm treatment is important for addressing the formulation and dosage of potential phytopharmaceuticals.

Iridoids modulate inflammation in diabetic kidney disease: A review

In recent years, preclinical research on diabetic kidney disease (DKD) has surged to the forefront of scientific and clinical attention. DKD has become a pervasive complication of type 2 diabetes. Given the complexity of its etiology and pathological mechanisms, current interventions, including drugs, dietary modifications, exercise, hypoglycemic treatments and lipid-lowering methods, often fall short in achieving desired therapeutic outcomes. Iridoids, primarily derived from the potent components of traditional herbs, have been the subject of long-standing research. Preclinical data suggest that iridoids possess notable renal protective properties; however, there has been no summary of the research on their efficacy in the management and treatment of DKD. This article consolidates findings from in vivo and in vitro research on iridoids in the context of DKD and highlights their shared anti-inflammatory activities in treating this condition. Additionally, it explores how certain iridoid components modify their chemical structures through the regulation of intestinal flora, potentially bolstering their therapeutic effects. This review provides a focused examination of the mechanisms through which iridoids may prevent or treat DKD, offering valuable insights for future research endeavors. Please cite this article as: Zhou TY, Tian N, Li L, Yu R. Iridoids modulate inflammation in diabetic kidney disease: A review. J Integr Med. 2024; 22(3): 210-222.

Protective effect of Enicostemma axillare - Swertiamarin on oxidative stress against nicotine-induced liver damage in SD rats

OBJECTIVE

The current investigation was aimed to determine the hepatoprotective benefits of Swertiamarin (ST) administration against nicotine-induced hepatotoxicity in SD rats.

MATERIAL AND METHODS

A total of 48 adult male SD rats were allocated into six groups using a fully randomised approach. As a control, group I was given oral (PO) normal saline. For 65 days, the animals in groups II, III, IV, V and VI received 2.5mg/kg/day of nicotine intraperitoneally (IP), 100mg/kg/day of ST orally (PO), 200mg/kg/day of ST orally (PO), 2.5mg/kg/day of nicotine (IP)+100mg/kg/day of ST (PO), and 2.5mg/kg/day of nicotine (IP)+200mg/kg/day of ST (PO), respectively. Animals were killed on 66thday, liver tissue was removed and used for histopathological analysis as well as biochemical testing (oxidative stress parameters and liver function enzymes).

RESULTS

When compared to control animals, the animals in group II showed a substantial rise in their aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine levels (P˂0.001). Furthermore, compared to control animals, these animals displayed enhanced hepatic oxidative stress as indicated by significantly higher Malondialdehyde (MDA) levels (P˂0.001) and lower levels of Catalase (CAT), Glutathione (GSH), Glutathione peroxidase (GSH-Px) and Superoxide dismutase (SOD) (P˂0.001). Further, more histological anomalies were seen in the liver of nicotine-treated rats compared to control rats, including significant vacuolization, poor tissue architecture, the growth of pycnotic nuclei, and dilated sinusoids. Contrary to nicotine-treated rats, the co-administration of ST and nicotine was observed to prevent the abnormalities caused by nicotine (groups V and VI).

CONCLUSION

The results of the current study show that nicotine can seriously harm liver tissue and that swertiamarin can prevent the harmful effects of nicotine on rat liver. Future research is necessary to delve deeply into the mechanisms behind swertiamarin protective impact against nicotine-induced hepatotoxicity.

Genomic characterization of WRKY transcription factors related to secoiridoid biosynthesis in Gentiana macrophylla

Gentiana macrophylla is one of Chinese herbal medicines in which 4 kinds of iridoids or secoiridoids, such as loganic acid, sweroside, swertiamarin, and gentiopicroside, are identified as the dominant medicinal secondary metabolites. WRKY, as a large family of transcription factors (TFs), plays an important role in the synthesis of secondary metabolites in plants. Therefore, WRKY genes involved in the biosynthesis of secoiridoids in G. macrophylla were systematically studied. First, a comprehensive genome-wide analysis was performed, and 42 GmWRKY genes were identified, which were unevenly distributed in 12 chromosomes. Accordingly, gene structure, collinearity, sequence alignment, phylogenetic, conserved motif and promoter analyses were performed, and the GmWRKY proteins were divided into three subfamilies based on phylogenetic and multiple sequence alignment analyses. Moreover, the enzyme-encoding genes of the secoiridoid biosynthesis pathway and their promoters were then analysed, and the contents of the four secoiridoids were determined in different tissues. Accordingly, correlation analysis was performed using Pearson's correlation coefficient to construct WRKY gene-enzyme-encoding genes and WRKY gene-metabolite networks. Meanwhile, G. macrophylla seedlings were treated with methyl jasmonate (MeJA) to detect the dynamic change trend of GmWRKYs, biosynthetic genes, and medicinal ingredient accumulation. Thus, a total of 12 GmWRKYs were identified to be involved in the biosynthesis of secoiridoids, of which 8 (GmWRKY1, 6, 12, 17, 33, 34, 38 and 39) were found to regulate the synthesis of gentiopicroside, and 4 (GmWRKY7, 14, 26 and 41) were found to regulate the synthesis of loganic acid. Taken together, this study systematically identified WRKY transcription factors related to the biosynthesis of secoiridoids in G. macrophylla, which could be used as a cue for further investigation of WRKY gene functions in secondary metabolite accumulation.

Anti-inflammatory, analgesic, and antipyretic potential of Oxystelma esculentum (L. f.) Sm. using in vitro, in vivo, and in silico studies

The objective of the current study was to evaluate the anti-inflammatory, analgesic, and antipyretic potential of Oxystelma esculentum using different animal models. The phytochemical profile was determined by assessing its total phenolic content (TPC) and total flavonoid content (TFC), followed by the high-performance liquid chromatography (HPLC) technique. The in vitro anti-inflammatory potential of O. esculentum ethanolic extract (OEE) was evaluated by lipoxygenase enzyme inhibition activity and a human red blood cell (HRBC) membrane stability assay. The in vivo anti-inflammatory potential of the plant was determined by the carrageenan-induced paw edema test, and the analgesic potential by the hot plate test, tail-flick test, formalin-induced analgesia, acetic acid-induced writhing activities, and yeast-induced elevation of body temperature. The values of total phenolic content (212.6 ± 3.18 µg GAE/g) and total flavonoid content (37.6 ± 1.76 µg QE/g) were observed. The results showed that OEE exhibited significant antioxidant capacity in DPPH (2,2-diphenyl-1-picrylhydrazyl) (266.3 ± 7.35 μmol TE/g), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (1,066.3 ± 7.53 μmol TE/g), and FRAP (ferric reducing antioxidant power) (483.6 ± 3.84 μmol TE/g) assays. The HPLC analysis demonstrated phytocompounds with anti-inflammatory potential, such as chlorogenic acid, gallic acid, 4-hydroxybenzoic acid, caffeic acid, ferulic acid, and coumarin. The plant showed in vitro anti-inflammatory activity through the inhibition of lipoxygenase enzyme with a high percentage (56.66%) and HRBC membrane stability (67.29%). In in vivo studies, OEE exhibited significant (p < 0.05) anti-inflammatory (carrageenan-induced paw edema model), analgesic (hot plate test, tail-flick test, formalin-induced analgesia, and acetic acid-induced writhing), and antipyretic (rectal temperature reduction) responses at different doses (100, 300, and 500 mg/kg). Molecular docking studies showed significant binding affinities of phytocompounds compared to indomethacin and predicted various binding interactions for stable conformations. The results of in vitro, in vivo, and in silico studies supported the anti-inflammatory, analgesic, and antipyretic potential of O. esculentum.

The dual face of microglia (M1/M2) as a potential target in the protective effect of nutraceuticals against neurodegenerative diseases

The pathophysiology of different neurodegenerative illnesses is significantly influenced by the polarization regulation of microglia and macrophages. Traditional classifications of macrophage phenotypes include the pro-inflammatory M1 and the anti-inflammatory M2 phenotypes. Numerous studies demonstrated dynamic non-coding RNA modifications, which are catalyzed by microglia-induced neuroinflammation. Different nutraceuticals focus on the polarization of M1/M2 phenotypes of microglia and macrophages, offering a potent defense against neurodegeneration. Caeminaxin A, curcumin, aromatic-turmerone, myricetin, aurantiamide, 3,6'-disinapoylsucrose, and resveratrol reduced M1 microglial inflammatory markers while increased M2 indicators in Alzheimer's disease. Amyloid beta-induced microglial M1 activation was suppressed by andrographolide, sulforaphane, triptolide, xanthoceraside, piperlongumine, and novel plant extracts which also prevented microglia-mediated necroptosis and apoptosis. Asarone, galangin, baicalein, and a-mangostin reduced oxidative stress and pro-inflammatory cytokines, such as interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha in M1-activated microglia in Parkinson's disease. Additionally, myrcene, icariin, and tenuigenin prevented the nod-like receptor family pyrin domain-containing 3 inflammasome and microglial neurotoxicity, while a-cyperone, citronellol, nobiletin, and taurine prevented NADPH oxidase 2 and nuclear factor kappa B activation. Furthermore, other nutraceuticals like plantamajoside, swertiamarin, urolithin A, kurarinone, Daphne genkwa flower, and Boswellia serrata extracts showed promising neuroprotection in treating Parkinson's disease. In Huntington's disease, elderberry, curcumin, iresine celosia, Schisandra chinensis, gintonin, and pomiferin showed promising results against microglial activation and improved patient symptoms. Meanwhile, linolenic acid, resveratrol, Huperzia serrata, icariin, and baicalein protected against activated macrophages and microglia in experimental autoimmune encephalomyelitis and multiple sclerosis. Additionally, emodin, esters of gallic and rosmarinic acids, Agathisflavone, and sinomenine offered promising multiple sclerosis treatments. This review highlights the therapeutic potential of using nutraceuticals to treat neurodegenerative diseases involving microglial-related pathways.

Cardioprotective Role of Swertiamarin, a Plant Glycoside Against Experimentally Induced Myocardial Infarction via Antioxidant and Anti-inflammatory Functions

The study examined the protective effects of swertiamarin on rats with experimentally induced myocardial infarction. Three to six week-old male albino Wistar rats were used in this study and experimental myocardial infarction (MI) was induced using isoproterenol. Our results showed that swertiamarin restored the alteration in heart weight, body weight, and heart weight/tibia length ratio of MI-induced rats to basal levels significantly (p < 0.05). Swertiamarin significantly (p < 0.05) restored the levels of cardiac pathophysiological marker creatine kinase (CKMB), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine transaminase (ALT), and cardiac troponin I (cTn-1) to near normalcy in MI-induced rats. Levels of oxidative stress markers malondialdehyde (MDA), protein carbonyls (PC), and levels of Vitamin C and Vitamin E were significantly (p < 0.05) reverted to near basal levels in MI-induced rats by swertiamarin. Levels of the antioxidant glutathione (GSH) and antioxidant enzymes which include superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-s-transferase (GST), glutathione reductase (GR), and plasma total antioxidant capacity (TAC) were (p < 0.05) brought to near normalcy in MI-induced rats by swertiamarin. Levels of sodium (Na), potassium (k), and calcium (Ca) ATPases were significantly (p < 0.05) restored to near normalcy in MI-induced rats by swertiamarin. Status of pro-inflammatory cytokines including tumor necrosis factor (TNF-α), interleukin-6 (IL-6), and histological aberrations were also significantly (p < 0.05) restored to near normalcy in MI-induced rats by swertiamarin. Together, our results concluded that swertiamarin exerts significant cardioprotective functions in experimental MI in rats.

Chromatographic analysis of selected phytosterols from Cyathea and their characterization by in silico docking to potential therapeutic targets

Separation and quantification of lupeol, stigmasterol and swertiamarin in ethanolic extracts of selected Cyathea species have been developed using HPTLC and an attempt is made to explore the biopotential of phytochemicals against various proteins by computational analysis. Compounds were separated using the specific mobile phase and the developed plates were sprayed with respective spraying reagents. The 3D structure of the receptor proteins viz., 1VSN, 5BNQ, 6HN8, 7DN4 and 3TJU, and the 3D SDF structures of ligands like lupeol, stigmasterol and swertiamarin were retrieved from the Protein Data Bank (PDB) and NCBI-Pub Chem Compound database respectively. The Argus 4.0.1 is computer generated drug design screening software is employed to analyze the binding affinity of test compounds against the selected proteins in the form of E-values versus potential drug targets. The docking result was saved and visualized using Discovery Studio Visualizer. The terpenoid band with Rf value 0.79 depicted the presence of lupeol in C. gigantea (0.04%) and C. crinita (0.02%). The steroid band with Rf value 0.41 confirmed the presence of stigmasterol with varied frequency viz., C. nilgirensis (0.33%), C. gigantea (0.29%) and C. crinita (0.52%). Lupeol, stigmasterol and swertiamarin showed the interaction against the studied proteins viz., 1VSN, 5BNQ, 6HN8, 7DN4, 3TJU with varied energy values and interacting residues. The results of the virtual screening and molecular docking analysis suggest that the phytochemical compounds of Cyathea species viz., lupeol and stigmasterol were identified as possible lead molecules to fight against cancer and cytotoxicity.

Swertia chirayita: A comprehensive review on traditional uses, phytochemistry, quality assessment and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia chirayita (Roxb.) H. Karst. is a traditionally used, well-recognized medicinal plant of the family Gentianaceae with significant therapeutic potential. It has been traditionally used to cure various ailments such as fever, vomiting, jaundice, digestive disorders, heart diseases, diabetes, malaria, scorpion bite, and skin diseases.

AIM OF REVIEW

The present review emphasized the traditional uses, phytochemistry, pharmacology, toxicology, chemical profiling, and structural identification of isolated compounds by analytical and spectroscopic techniques. This review demonstrates the possibility of advanced ethnopharmacological research.

MATERIALS AND METHODS

The literature on S. chirayita was obtained from bibliographic databases like Web of Science, PubMed, Science-Direct, American Chemical Society (ACS), Google Scholar, and SciFinder. The compiled review is covered up until March 2022.

RESULTS

Approximately, 123 specialized metabolites including xanthones, seco-iridoids, terpenoids, alkaloids, and flavonoids have been isolated and characterized from S. chirayita. The extract and isolated compounds exhibited a wide spectrum of pharmacological effects such as anti-inflammatory, antioxidant, antitumor, hepatoprotective, antiviral, antimalarial, and antibacterial offering scientific evidence for traditional claims of this medicinal plant. In addition, various analytical methods using HPTLC, UPLC, HPLC, LC-MS, and GC-MS have also been documented to determine the phytochemicals of S. chirayita.

CONCLUSION

The current article provides information on traditional usage, phytochemistry, chemical profiling, structure elucidation, pharmacological efficacy, toxicity, and future prospects of S. chirayita. This plant has long been traditionally used in a variety of ways by indigenous people. Numerous phytoconstituents and several pharmacological activities have been reported in S. chirayita. However, there are still some scientific gaps such as identification of bioactive compounds, structure-activity relationship and mechanistic action of isolated bioactive compounds, development of effective analytical methods for comprehensive quality control, and safety profiles that need to be addressed.

Neuroprotective Effect of Swertiamarin in a Rotenone Model of Parkinson's Disease: Role of Neuroinflammation and Alpha-Synuclein Accumulation

Parkinson's disease (PD) is a progressive neurodegenerative disease with no permanent cure affecting around 1% of the population over 65. There is an urgency to search for a disease-modifying agent with fewer untoward effects. PD pathology involves the accumulation of toxic alpha-synuclein (α-syn) and neuronal inflammation leading to the degeneration of dopaminergic (DAergic) neurons. Swertiamarin (SWE), a well-studied natural product, possesses a strong anti-inflammatory effect. It is a secoiridoid glycoside isolated from Enicostemma littorale Blume. SWE showed a reversal effect on the α-syn accumulation in the 6-hydroxydopamine (6-OHDA)-induced Caenorhabditis elegans model of PD. However, there are no reports in the literature citing the effect of SWE as a neuroprotective agent in rodents. The present study aimed to evaluate the anti-inflammatory activity of SWE against lipopolysaccharide (LPS)-induced C6 glial cell activation and its neuroprotective effect in the intrastriatal rotenone mouse PD model. SWE treatment showed a significant reduction in interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) levels in LPS-induced C6 glial cell activation. Further, our studies demonstrated the suppression of microglial and astroglial activation in substantia nigra (SN) after administration of SWE (100 mg/kg, intraperitoneally) in a rotenone mouse model. Moreover, SWE alleviated the rotenone-induced α-syn overexpression in the striatum and SN. SWE ameliorated the motor impairment against rotenone-induced neurotoxicity and mitigated the loss of DAergic neurons in the nigrostriatal pathway. Therefore, SWE has the potential to develop as an adjunct therapy for PD, but it warrants further mechanistic studies.

Therapeutic potential of plant iridoids in depression: a review

CONTEXT

Depression is a mental disorder characterized by low mood, reduced interest, impaired cognitive function, and vegetative symptoms such as sleep disturbances or poor appetite. Iridoids are the active constituents in several Chinese classical antidepressant formulae such as Yueju Pill, Zhi-Zi-Hou-Po Decoction, Zhi-Zi-Chi Decoction, and Baihe Dihuang Decoction. Parallel to their wide usages, iridoids are considered potential lead compounds for the treatment of neurological diseases.

OBJECTIVE

The review summarizes the therapeutic potential and molecular mechanisms of iridoids in the prevention or treatment of depression and contributes to identifying research gaps in iridoids as potential antidepressant medication.

METHODS

The following key phrases were sought in PubMed, Google Scholar, Web of Science, and China National Knowledge Internet (CNKI) without time limitation to search all relevant articles with in vivo or in vitro experimental studies as comprehensively as possible: ('iridoid' or 'seciridoid' or 'depression'). This review extracted the experimental data on the therapeutic potential and molecular mechanism of plant-derived iridoids for depression.

RESULTS

Plant iridoids (i.e., catalpol, geniposide, loganin), and secoiridoids (i.e., morroniside, gentiopicroside, oleuropein, swertiamarin), all showed significant improvement effects on depression.

DISCUSSION AND CONCLUSIONS

Iridoids exert antidepressant effects by elevating monoamine neurotransmitters, reducing pro-inflammatory factors, inhibiting hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, increasing brain-derived neurotrophic factor (BDNF) and its receptors, and elevating intestinal microbial abundance. Further detailed studies on the pharmacokinetics, bioavailability, and key molecular targets of iridoids are also required in future research, ultimately to provide improvements to current antidepressant medications.

Natural drugs targeting inflammation pathways can be used to treat atherosclerosis

Atherosclerosis (AS) is the chronic gradual degradation of arteries in combination with inflammation. Currently, the main research focus has been on interactions between inflammatory cells, inflammatory mediators, and immune mechanisms, while some studies have reported natural drugs were exerting a critical role against AS, whereas the usage of natural drugs was always limited by various factors such as poor penetration across biological barriers, low bioavailability, and unclear mechanisms. Herein, we reviewed the potential targets for inflammation against AS, discussed the underlying mechanisms of natural drugs for AS, particularly highlighted the dilemma of current research, and finally, offered perspectives in this field.

Medicinal plants' proposed nanocomposites for the management of endocrine disorders

Extensive attention has been focused on herbal medicine for the treatment of different endocrine disorders. In fact, compelling scientific evidence indicates that natural compounds might act as endocrine modulators by mimicking, stimulating, or inhibiting the actions of different hormones, such as thyroid, sex, steroidal, and glucose regulating hormones. These potentials might be effectively employed for therapeutic purposes related to the endocrine system as novel complementary choices. Nevertheless, despite the remarkable therapeutic effects, inadequate targeting efficiency and low aqueous solubility of the bioactive components are still essential challenges in their clinical accreditation. On the other hand, nanotechnology has pushed the wheels of combining inorganic nanoparticles with biological structures of medicinal bioactive compounds as one of the utmost exciting fields of research. Nanoparticle conjugations create an inclusive array of applications that provide greater compliance, higher bioavailability, and lower dosage. This can safeguard the global availability of these wealthy natural sources, regardless of their biological occurrence. This review inspects future challenges of medicinal plants in various endocrine disorders for safe and alternative treatments with examples of their nanoparticle formulations.

Genetic Manipulation and Bioreactor Culture of Plants as a Tool for Industry and Its Applications

In recent years, there has been a considerable increase in interest in the use of transgenic plants as sources of valuable secondary metabolites or recombinant proteins. This has been facilitated by the advent of genetic engineering technology with the possibility for direct modification of the expression of genes related to the biosynthesis of biologically active compounds. A wide range of research projects have yielded a number of efficient plant systems that produce specific secondary metabolites or recombinant proteins. Furthermore, the use of bioreactors allows production to be increased to industrial scales, which can quickly and cheaply deliver large amounts of material in a short time. The resulting plant production systems can function as small factories, and many of them that are targeted at a specific operation have been patented. This review paper summarizes the key research in the last ten years regarding the use of transgenic plants as small, green biofactories for the bioreactor-based production of secondary metabolites and recombinant proteins; it simultaneously examines the production of metabolites and recombinant proteins on an industrial scale and presents the current state of available patents in the field.