Synthesis of andrographolide derivatives and their TNF-alpha and IL-6 expression inhibitory activities

Natural products as IL-6 inhibitors for inflammatory diseases: Synthetic and SAR perspective

Interleukin-6 (IL-6), a pleiotropic cytokine, plays a pivotal role in the pathophysiology of various diseases including diabetes, atherosclerosis, Alzheimer's disease, multiple myeloma, rheumatoid arthritis, and prostate cancer. The signaling pathways associated with IL-6 offer promising targets for therapeutic interventions in inflammatory diseases and IL-6-dependent tumors. Although certain anti-IL-6 monoclonal antibodies are currently employed clinically, their usage is hampered by drawbacks such as high cost and potential immunogenicity, limiting their application. Thus, the imperative arises to develop novel small non-peptide molecules acting as IL-6 inhibitors. Various natural products derived from diverse sources have been investigated for their potential to inhibit IL-6 activity. Nevertheless, these natural products remain inadequately explored in terms of their structure-activity relationships. In response, our review aims to provide syntheses and structure activity perspective of natural IL-6 inhibitors. The comprehensive amalgamation of information presented in this review holds the potential to serve as a foundation for forthcoming research endeavors by medicinal chemists, facilitating the design of innovative IL-6 inhibitors to address the complexities of inflammatory diseases.

Dehydroandrographolide alleviates rheumatoid arthritis by inhibiting neutrophil activation via LMIR3 in collagen induced arthritis rats

Rheumatoid arthritis (RA) is an inflammatory disease which causes severe pain and disability. Neutrophils play essential roles in the onset and progression of RA; thus, inhibition of neutrophil activation is becoming a popular therapeutic strategy. Dehydroandrographolide has provided satisfactory outcomes in inflammatory diseases; however, its therapeutic effects and mechanism in RA are not fully understood. Leukocyte mono-immunoglobulin-like receptor 3 (LMIR3) is a negative regulator highly expressed in neutrophils. To determine whether dehydroandrographolide negatively regulated neutrophils activation via LMIR3, cytokines release and collagen-induced arthritis (CIA) rats were used in vitro and in vivo. Biacore, molecular docking analysis and molecular dynamics simulation were performed to prove the target of dehydroandrographolide. Moreover, the downstream signaling pathways of LMIR3 activation were analyzed by western blotting. Results showed that oral dehydroandrographolide administration of 2 mg/kg/day to CIA rats attenuated synovitis and bone and cartilage damage after the 28-day intervention, revealed using HE sections and micro-CT. Dehydroandrographolide significantly inhibited cytokine release and chemotaxis of LPS/TNF-α-activated neutrophils in vitro. Dehydroandrographolide inhibited neutrophils activation via binding to LMIR3. Moreover, dehydroandrographolide up-regulated the phosphorylation of SHP-1 and SHP-2, which are the essential kinases in the LMIR3 signaling pathways. This study revealed that dehydroandrographolide attenuated collagen-induced arthritis by suppressing neutrophil activation via LMIR3.

Andrographolide, diterpenoid constituent of Andrographis paniculata: Review on botany, phytochemistry, molecular docking analysis, and pharmacology

Andrographispaniculata (kalmegh) is also known as "king of bitters", is an herbaceous plant belongs to family Acanthaceae. The therapeutic effect is due to presence of diterpenoid lactone derivatives of A. paniculata mainly andrographolide. The main purpose of this review includes detailed (past and present) study of A. paniculata and its most important component andrographolide a diterpenoid lactone with respect to its botany, phytochemistry, molecular docking analysis and pharmacological effects i.e., therapeutic benefits. In reference to the search, we also compiled variety of dosage forms available, which are made up of A. paniculata extract and Andrographolide such as tablets and capsules. This review also discusses reported methods of extraction of phytoconstituents, pharmacokinetics of main components, their molecular docking analysis data and main therapeutic applications with their proposed mechanism of actions in various diseases. According to data collected, A. paniculata is becoming more and more valuable as a therapeutic herb.

An insight into the pharmacological and analytical potential of Andrographolide

Andrographis paniculata is an annual medicinal herb from the family Acanthaceae. Andrographolide is generally considered an essential bioactive component of plant A. paniculata. Since ancient times, it has been widely recognized for its therapeutic qualities and has attracted the scientific and medical communities' attention. This review summarizes the molecular, clinical, and in vitro research of compound andrographolide and its mechanism of action. Andrographolide, when combined with other enhancing agents, offers a wide variety of health benefits. The therapeutic potential of andrographolide has been exemplified and exhibited by directly regulating genes and indirectly interacting with small molecules and different enzymes. This review compiles and consolidates the pharmacological action of andrographolide and its analogs and deciphers the gaps that have hindered its use in medicinal research.

Andrographolide and its derivatives: Current achievements and future perspectives

Natural product andrographolide isolated from the plant Andrographis paniculata shows a plethora of biological activities, including anti-tumor, anti-bacterial, anti-inflammation, anti-virus, anti-fibrosis, anti-obesity, immunomodulatory and hypoglycemic activities. Based on extensive chemical structural modifications, a series of andrographolide derivatives with improved bioavailability and druggability has been developed. Moreover, greater understanding of their mechanisms of action at the molecular and cellular level has been thoroughly investigated. In this review, we give an outlook for the therapeutical potential of andrographolide and its derivatives in diverse diseases and highlighted the drug design, pharmacokinetic and mechanistic studies for the past ten years, together with a brief overview of the pharmacological effects. Notably, we focused to provide a critical enlightenment of the area of andrographolide and its derivatives with the intent of indicating the future perspectives, challenges and limitations. We believe that this review paper will benefit drug discovery where andrographolide was used as a template, shed light on the identification of drug targets for andrographolide and its analogs, as well as increase our knowledge for using them for therapeutic application, including the treatment for various forms of cancers.

Hepatoprotective effect of selected isoandrographolide derivatives on steatotic HepG2 cells and High Fat Diet fed rats

Non-alcoholic Fatty Liver Disease (NAFLD) is one of the growing epidemics of the globe. This study was aimed to evaluate the anti-NAFLD effect of selected IAN derivatives using in silico, in vitro and in vivo models. In silico tools viz., DataWarrior, SwissADME and Gaussian 09 were used to predict the pharmacokinetic properties and electronic distribution patterns of the derivatives; docking analysis was done with Autodock against PPARα. Toxicities of the derivatives were assessed in HepG2 cells using MTT assay. Anti-NAFLD efficacies of the derivatives were assessed in free fatty acid induced steatotic HepG2 cells. In vivo anti-NAFLD effect of active isoandrographolide (IAN) derivative, 19-propionyl isoandrographolide (IAN-19P) was assessed in High Fat Diet fed rats. In silico and in vitro studies indicated that IAN-19P showed improved drug-likeness and drug score. The toxicity of IAN-19P to HepG2 cells was comparatively less than IAN and other derivatives. In free fatty acid induced steatotic HepG2 cells, treatment with IAN-19P significantly lowered intracellular triglyceride content and leakage of LDH and transaminases. Treating High Fat Diet fed animals with IAN-19P significantly lowered plasma lipids, transaminases, LDH and GGT levels. The treatment with IAN-19P upregulated the expressions of PPARα and CPT-1. IAN-19P did not produce any noticeable adverse effect till 2 g/kg concentration in acute and 250 mg/kg concentration in subacute toxicity studies. This study indicated the beneficial effect of IAN-19P for the treatment of NAFLD; however robust investigations are needed to establish the potential of IAN-19P to treat NAFLD.

Biological Activity of Selected Natural and Synthetic Terpenoid Lactones

Terpenoids with lactone moieties have been indicated to possess high bioactivity. Certain terpenoid lactones exist in nature, in plants and animals, but they can also be obtained by chemical synthesis. Terpenoids possessing lactone moieties are known for their cytotoxic, anti-inflammatory, antimicrobial, anticancer, and antimalarial activities. Moreover, one terpenoid lactone, artemisinin, is used as a drug against malaria. Because of these abilities, there is constant interest in new terpenoid lactones that are both isolated and synthesized, and their biological activities have been verified. In some cases, the activity of the terpenoid lactone is specifically connected to the lactone moiety. Recent works have revealed that new terpenoid lactones can demonstrate such functions and are thus considered to be potential active agents against many diseases.

Andrographolide inhibits secretagogue-induced pseudo-allergic reaction

Many kinds of drugs induce pseudo-allergic reactions due to activation of mast cells. We investigated the anti-pseudo-allergic effect of andrographolide (Andro). The effects of Andro on pseudo-allergic reactions were investigated in vivo and in vitro. Andro suppressed compound 48/80 (C48/80) induced pseudo-allergic reactions in mice in a dose-dependent manner. Andro also inhibited C48/80-induced local inflammatory reactions in mice. In vitro studies revealed that Andro reduced C48/80-induced mast cells degranulation. Human phospho-kinase array kit and western blotting showed that Andro could inhibit pseudo-allergic responses via the calcium signaling pathway.

Dehydroandrographolide Inhibits Osteosarcoma Cell Growth and Metastasis by Targeting SATB2-mediated EMT

BACKGROUND

The 12-hydroxy-14-dehydroandrographolide (DP) is a predominant component of the traditional herbal medicine Andrographis paniculata (Burm. f.) Nees (Acanthaceae). Recent studies have shown that DP exhibits potent anti-cancer effects against oral and colon cancer cells.

OBJECTIVE

This investigation examined the potential effects of DP against osteosarcoma cell.

METHODS

A cell analyzer was used to measure cell viability. The cell growth and proliferation were performed by Flow cytometry and BrdU incorporation assay. The cell migration and invasion were determined by wound healing and transwell assay. The expression of EMT related proteins was examined by Western blot analysis.

RESULTS

In this study, we found that DP treatment repressed osteosarcoma (OS) cell growth in a dose-dependent manner. DP treatment significantly inhibited OS cell proliferation by arresting the cell cycle at G2/M phase. In addition, DP treatment effectively inhibited the migration and invasion abilities of OS cells through wound healing and Transwell tests. Mechanistic studies revealed that DP treatment effectively rescued the epithelialmesenchymal transition (EMT), while forced expression of SATB2 in OS cells markedly reversed the pharmacological effect of DP on EMT.

CONCLUSION

Our data demonstrated that DP repressed OS cell growth through inhibition of proliferation and cell cycle arrest; DP also inhibited metastatic capability of OS cells through a reversal of EMT by targeting SATB2. These findings demonstrate DP's potential as a therapeutic drug for OS treatment.

Phytochemical andrographolide modulates NF-κB and JNK in human neuroblastoma SH-SY5Y cells, a cell model for Parkinson's disease

Andrographis paniculata has been an important plant for traditional medicine in Asia for centuries. Andrographolide is the primary bioactive phytochemical from the plant and is known to exhibit many different protective effects through modulation of various proteins and signaling pathways. Andrographolide has been reported to exert anti-inflammatory and neuroprotective effects as well as being an antioxidant itself. We therefore studied whether andrographolide could provide protective effects to the SH-SY5Y neuroblastoma cell model for Parkinson's disease. In this study, we observed andrographolide inhibiting activation of NF-κB p65 (nuclear factor kappa-light-chain-enhancer of activated B cells) and JNK MAPK (c-Jun N-terminal Kinase Mitogen-Activated Protein Kinase) pathways, however, it did not provide any protective effect against induced stress in the SH-SY5Y cells. We propose the sustained low-level activation of JNK and the inhibition of NF-κB promoted ROS (Reactive Oxygen Species) production that yielded the observed cell death. Therefore, the protective effects observed with andrographolide appear to be cell/tissue specific responses.

A panoramic review of IL-6: Structure, pathophysiological roles and inhibitors

Interleukin-6 (IL-6) is a pleiotropic pro-inflammatory cytokine. Its deregulation is associated with chronic inflammation, and multifactorial auto-immune disorders. It mediates its biological roles through a hexameric complex composed of IL-6 itself, its receptor IL-6R, and glycoprotein 130 (IL-6/IL-6R/gp130). This complex, in turn, activates different signaling mechanisms (classical and trans-signaling) to execute various biochemical functions. The trans-signaling mechanism activates various pathological routes, like JAK/STAT3, Ras/MAPK, PI3K-PKB/Akt, and regulation of CD4+ T cells and VEGF levels, which cause cancer, multiple sclerosis, rheumatoid arthritis, anemia, inflammatory bowel disease, Crohn's disease, and Alzheimer's disease. Involvement of IL-6 in pathophysiology of these complex diseases makes it an important target for the treatment of these diseases. Though some anti-IL-6 monoclonal antibodies are being used clinically, but their high cost, only parenteral administration, and possibility of immunogenicity have limited their use, and warranted the development of novel small non-peptide molecules as IL-6 inhibitors. In the present report, all molecules reported in literature as IL-6 inhibitors have been classified as IL-6 production, IL-6R, and IL-6 signaling inhibitors. Reports available till date are critically studied to identify important and salient structural features common in these molecules. These analyses would assist medicinal chemists to design novel and potent IL-6 production and signaling inhibitors, through knowledge- and/or computer-based approaches, for the treatment of complex multifactorial diseases.

Neuroprotection of Andrographolide Against Microglia-Mediated Inflammatory Injury and Oxidative Damage in PC12 Neurons

Andrographolide from leaves of Andrographis paniculata has been known to possess various bioactivities. In the present study, we aimed to explore the neuroprotection of andrographolide against inflammation-mediated injury and oxidative damage. In initial studies, our findings showed that pretreatment with andrographolide could effectively reduce neuronal cell death caused by LPS-induced conditioned supernatants. The further results indicated that this neuroprotective effect may be mainly due to the inhibition on the production of NO, TNF-α, IL-6, ROS, iNOS and enhancement of expression of anti-inflammatory marker CD206. Moreover, mechanism study revealed that the anti-inflammatory activity of andrographolide may be related to the suppression of nuclear translocation of NF-κB as well as the activation of Nrf2 and HO-1. Our study also showed that andrographolide could scavenge ROS and protect PC12 cells against H₂O₂- and 6-OHDA-mediated oxidative damage. In addition, several derivatives of andrographolide were prepared for evaluating the role of 3, 14, 19-hydroxy group on anti-inflammatory effect and cytoprotection of andrographolide. In conclusion, andrographolide protected neurons against inflammation-mediated injury via NF-κB inhibition and Nrf2/HO-1 activation and resisted oxidative damage via inhibiting ROS production. Our results will contribute to further exploration of the therapeutic potential of andrographolide in relation to neuroinflammation and neurodegenerative diseases.

Andrographis paniculata diterpenoids and ethanolic extract inhibit TNFα-induced ICAM-1 expression in EA.hy926 cells

BACKGROUND

Andrographis paniculata (A. paniculata), a traditional herb in Southeastern Asia, is used to treat inflammation-mediated diseases.

PURPOSE

The two major bioactive diterpenoids in A. paniculata are andrographolide (AND) and 14-deoxy-11,12-didehydroandrographolide (deAND). Because of the anti-inflammatory evidence for AND, we hypothesized that deAND might possess similar potency for inhibiting monocyte adhesion to the vascular endothelium, which is a critical event for atherosclerotic lesion formation.

MATERIAL

In the present study, we used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to determine cell viability. We evaluated the production of intracellular reactive oxygen species (ROS) by using DCFDA assay. We assayed the protein expression by using Western blot analysis, the mRNA expression by using RT-PCR, and the nuclear protein-DNA binding activity by using EMSA.

RESULTS

We showed that pretreatment of EA.hy926 cells with A. paniculata ethanolic extract (APE), deAND, and AND significantly inhibited TNFα-induced ICAM-1 protein and mRNA expression, ICAM-1 promoter activity, and monocyte adhesion. TNFα-stimulated IKKβ phosphorylation, IκBα phosphorylation and degradation, p65 nuclear translocation, and NFκB nuclear protein-DNA binding activity were attenuated by pretreatment with APE, deAND, and AND. APE, deAND, and AND attenuated TNFα-induced Src phosphorylation and membrane translocation of the NOX subunits p47^phox and p67^phox. Both APE and AND induced protein expression of heme oxygenase 1 and the glutamate cysteine ligase modifier subunit and enhanced glutathione content. Pretreatment with AND and deAND inhibited TNFα-induced ROS generation.

CONCLUSION

These results suggest that the mechanism by which APE, deAND, and AND down-regulates TNFα-induced ICAM-1 expression in EA.hy926 cells is via attenuation of activation of the IKK/IκB/NFκB pathway.

Hepatitis C: From inflammatory pathogenesis to anti-inflammatory/hepatoprotective therapy

Hepatitis C virus (HCV) infection commonly causes progressive liver diseases that deteriorate from chronic inflammation to fibrosis, cirrhosis and even to hepatocellular carcinoma. A long-term, persistent and uncontrolled inflammatory response is a hallmark of these diseases and further leads to hepatic injury and more severe disease progression. The levels of inflammatory cytokines and chemokines change with the states of infection and treatment, and therefore, they may serve as candidate biomarkers for disease progression and therapeutic effects. The mechanisms of HCV-induced inflammation involve classic pathogen pattern recognition, inflammasome activation, intrahepatic inflammatory cascade response, and oxidative and endoplasmic reticulum stress. Direct-acting antivirals (DAAs) are the first-choice therapy for effectively eliminating HCV, but DAAs alone are not sufficient to block the uncontrolled inflammation and severe liver injury in HCV-infected individuals. Some patients who achieve a sustained virologic response after DAA therapy are still at a long-term risk for progression to liver cirrhosis and hepatocellular carcinoma. Therefore, coupling with anti-inflammatory/hepatoprotective agents with anti-HCV effects is a promising therapeutic regimen for these patients during or after treatment with DAAs. In this review, we discuss the relationship between inflammatory mediators and HCV infection, summarize the mechanisms of HCV-induced inflammation, and describe the potential roles of anti-inflammatory/hepatoprotective drugs with anti-HCV activity in the treatment of advanced HCV infection.

Dehydroandrographolide inhibits oral cancer cell migration and invasion through NF-κB-, AP-1-, and SP-1-modulated matrix metalloproteinase-2 inhibition

BACKGROUND AND PURPOSE

Oral cancer is a type of head and neck cancer that is characterized by cancerous tissue growth in the oral cavity. Andrographolide and dehydroandrographolide (DA) are the two principal components of Andrographis paniculata (Burm.f.) Nees and are the main contributors to its therapeutic properties. However, the pharmacological activities of DA remain unclear.

EXPERIMENTAL APPROACH

In this study, we used wound closure assay and Boyden chamber assay to determine the effects of DA on oral cancer cell migration and invasion.

KEY RESULTS

DA treatment significantly inhibited the migration and invasion abilities of SCC9 cells in vitro. Gelatin zymography and Western blotting results revealed that DA inhibited MMP-2 activity and reduced its protein levels. DA inhibited the phosphorylation of ERK1/2, p38, and JNK 1/2 in SCC9 cells. According to the mRNA levels detected using real-time PCR, DA inhibited MMP-2 expression in SCC9 cells. This inhibitory effect was associated with the upregulation of the TIMP-2 and downregulation of NF-κB, AP-1, and SP-1 expression. In addition, DA suppressed carcinoma-associated epithelial-mesenchymal transition in SCC9 cells. Finally, DA administration effectively suppressed MMP-2 expression and tumor metastases in the oral carcinoma xenograft mouse model in vivo.

CONCLUSIONS & IMPLICATIONS

DA inhibits the invasion of human oral cancer cells and is a potential chemopreventive agent against oral cancer metastasis.

Activity of andrographolide against dengue virus

Dengue is the most prevalent arthropod-transmitted viral illness of humans, with an estimated 100 million symptomatic infections occurring each year and more than 2.5 billion people living at risk of infection. There are no approved antiviral agents against dengue virus, and there is only limited introduction of a dengue vaccine in some countries. Andrographolide is derived from Andrographis paniculata, a medicinal plant traditionally used to treat a number of conditions including infections. The antiviral activity of andrographolide against dengue virus (DENV) serotype 2 was evaluated in two cell lines (HepG2 and HeLa) while the activity against DENV 4 was evaluated in one cell line (HepG2). Results showed that andrographolide had significant anti-DENV activity in both cell lines, reducing both the levels of cellular infection and virus output, with 50% effective concentrations (EC₅₀) for DENV 2 of 21.304 μM and 22.739 μM for HepG2 and HeLa respectively. Time of addition studies showed that the activity of andrographolide was confined to a post-infection stage. These results suggest that andrographolide has the potential for further development as an anti-viral agent for dengue virus infection.

Dehydroandrographolide, an iNOS inhibitor, extracted from Andrographis paniculata (Burm.f.) Nees, induces autophagy in human oral cancer cells

Autophagy, which is constitutively executed at the basal level in all cells, promotes cellular homeostasis by regulating the turnover of organelles and proteins. Andrographolide and dehydroandrographolide (DA) are the two principle components of Andrographis paniculata (Burm.f.) Nees. and are the main contributors to its therapeutic properties. However, the pharmacological activities of dehydroandrographolide (DA) remain unclear. In this study, DA induces oral cancer cell death by activating autophagy. Treatment with autophagy inhibitors inhibited DA-induced human oral cancer cell death. In addition, DA increased LC3-II expression and reduced p53 expression in a time- and concentration-dependent manner. Furthermore, DA induced autophagy and decreased cell viability through modulation of p53 expression. DA-induced autophagy was triggered by an activation of JNK1/2 and an inhibition of Akt and p38. In conclusion, this study demonstrated that DA induced autophagy in human oral cancer cells by modulating p53 expression, activating JNK1/2, and inhibiting Akt and p38. Finally, an administration of DA effectively suppressed the tumor formation in the oral carcinoma xenograft model in vivo. This is the first study to reveal the novel function of DA in activating autophagy, suggesting that DA could serve as a new and potential chemopreventive agent for treating human oral cancer.

Andrographolide suppresses epithelial mesenchymal transition by inhibition of MAPK signalling pathway in lens epithelial cells

Epithelial mesenchymal transition (EMT) of lens epithelial cells (LECs) may contribute to the development of posterior capsular opacification (PCO), which leads to visual impairment. Andrographolide has been shown to have therapeutic potential against various cancers. However, its effect on human LECs is still unknown. The purpose of this study is to evaluate the effect of andrographolide on EMT induced by growth factors in the fetal human lens epithelial cell line (FHL 124). Initially the LECs were treated with growth factors (TGF-beta 2 and bFGF) to induce EMT. Subsequently these EMT-induced cells were treated with andrographolide at 100 and 500 nM concentrations for 24 h. Our results showed that FHL 124 cells treated with growth factors had a significant decrease in protein and m-RNA levels of epithelial markers pax6 and E-Cadherin. After administering andrographolide, these levels significantly increased. It was noticed that EMT markers alpha-SMA, fibronectin and collagen IV significantly decreased after treatment with andrographolide when compared to the other group. Treatment with andrographolide significantly inhibited phosphorylation of ERK and JNK. Cell cycle analysis showed that andrographolide did not arrest cells at G0/G1 or G2/M at tested concentrations. Our findings suggest that andrographolide helps sustain epithelial characteristics by modulating EMT markers and inhibiting the mitogen-activated protein kinase (MAPK) signalling pathway in LECs. Hence it can prove to be useful in curbing EMT-mediated PCO.

In situ imaging and proteome profiling indicate andrographolide is a highly promiscuous compound

Natural products represent an enormous source of pharmacologically useful compounds, and are often used as the starting point in modern drug discovery. Many biologically interesting natural products are however not being pursued as potential drug candidates, partly due to a lack of well-defined mechanism-of-action. Traditional in vitro methods for target identification of natural products based on affinity protein enrichment from crude cellular lysates cannot faithfully recapitulate protein-drug interactions in living cells. Reported herein are dual-purpose probes inspired by the natural product andrographolide, capable of both reaction-based, real-time bioimaging and in situ proteome profiling/target identification in live mammalian cells. Our results confirm that andrographolide is a highly promiscuous compound and engaged in covalent interactions with numerous previously unknown cellular targets in cell type-specific manner. We caution its potential therapeutic effects should be further investigated in detail.

Structure–activity relationship of terpenes with anti-inflammatory profile – a systematic review

Inflammation is a complex biological response that in spite of having available treatments, their side effects limit their usefulness. Because of this, natural products have been the subject of incessant studies, among which the class of terpenes stands out. They have been the source of study for the development of anti-inflammatory drugs, once their chemical diversity is well suited to provide skeleton for future anti-inflammatory drugs. This systematic review reports the studies present in the literature that evaluate the anti-inflammatory activity of terpenes suffering any change in their structures, assessing whether these changes also brought changes in their effects. The search terms anti-inflammatory agents, terpenes, and structure–activity relationship were used to retrieve English language articles in SCOPUS, PUBMED and EMBASE published between January 2002 and August 2013. Twenty-seven papers were found concerning the structural modification of terpenes with the evaluation of antiinflammatory activity. The data reviewed here suggest that modified terpenes are an interesting tool for the development of new anti-inflammatory drugs.

An in vitro study of anti-inflammatory activity of standardised Andrographis paniculata extracts and pure andrographolide

BACKGROUND

The anti-inflammatory activity of Andrographis paniculata (Acanthaceae), a traditional medicine widely used in Asia, is commonly attributed to andrographolide, its main secondary metabolite. Commercial A. paniculata extracts are standardised to andrographolide content. We undertook the present study to investigate 1) how selective enrichment of andrographolide in commercial A. paniculata extracts affects the variability of non-standardised phytochemical components and 2) if variability in the non-standardised components of the extract affects the pharmacological activity of andrographolide itself.

METHODS

We characterized 12 commercial, standardised (≥30% andrographolide) batches of A. paniculata extracts from India by HPLC profiling. We determined the antioxidant capacity of the extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, oxygen radical antioxidant capacity (ORAC) and a Folin-Ciocalteu (FC) antioxidant assays. Their anti-inflammatory activity was assessed by assaying their inhibitory effect on the release of tumor necrosis factor alpha (TNF-α) in the human monocytic cell line THP-1.

RESULTS

The andrographolide content in the samples was close to the claimed value (32.2 ± 2.1%, range 27.5 to 35.9%). Twenty-one non-standardised constituents exhibited more than 2-fold variation in HPLC peak intensities in the tested batches. The chlorogenic acid content of the batches varied more than 30-fold. The DPPH free radical scavenging activity varied ~3-fold, the ORAC and FC antioxidant capacity varied ~1.5 fold among batches. In contrast, the TNF-α inhibitory activity of the extracts exhibited little variation and comparison with pure andrographolide indicated that it was mostly due to their andrographolide content.

CONCLUSIONS

Standardised A. paniculata extracts contained the claimed amount of andrographolide but exhibited considerable phytochemical background variation. DPPH radical scavenging activity of the extracts was mostly due to the flavonoid/phenlycarboxylic acid compounds in the extracts. The inhibitory effect of andrographolide on the release of TNF-α was little affected by the quantitative variation of the non-standardised constituents.

Regioselective glucuronidation of andrographolide and its major derivatives: metabolite identification, isozyme contribution, and species differences

Andrographolide (AND) and two of its derivatives, deoxyandrographolide (DEO) and dehydroandrographolide (DEH), are widely used in clinical practice as anti-inflammatory agents. However, UDP-glucuronosyltransferase (UGT)-mediated phase II metabolism of these compounds is not fully understood. In this study, glucuronidation of AND, DEO, and DEH was characterized using liver microsomes and recombinant UGT enzymes. We isolated six glucuronides and identified them using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. We also systematically analyzed various kinetic parameters (K m, V max, and CLint) for glucuronidation of AND, DEO, and DEH. Among 12 commercially available UGT enzymes, UGT1A3, 1A4, 2B4, and 2B7 exhibited metabolic activities toward AND, DEO, and DEH. Further, UGT2B7 made the greatest contribution to glucuronidation of all three anti-inflammatory agents. Regioselective glucuronidation showed considerable species differences. 19-O-Glucuronides were present in liver microsomes from all species except rats. 3-O-Glucuronides were produced by pig and cynomolgus monkey liver microsomes for all compounds, and 3-O-glucuronide of DEH was detected in mouse and rat liver microsomes (RLM). Variations in K m values were 48.6-fold (1.93-93.6 μM) and 49.5-fold (2.01-99.1 μM) for 19-O-glucuronide and 3-O-glucuronide formation, respectively. Total intrinsic clearances (CLint) for 3-O- and 19-O-glucuronidation varied 4.8-fold (22.7-110 μL min(-1) mg(-1)), 10.6-fold (94.2-991 μL min(-1) mg(-1)), and 8.3-fold (122-1,010 μL min(-1) mg(-1)), for AND, DEH, and DEO, respectively. Our results indicate that UGT2B7 is the major UGT enzyme involved in the metabolism of AND, DEO, and DEH. Metabolic pathways in the glucuronidation of AND, DEO, and DEH showed considerable species differences.

Novel potential agents for ulcerative colitis by molecular topology: suppression of IL-6 production in Caco-2 and RAW 264.7 cell lines

Ulcerative colitis (UC) is an immune-mediated chronic and relapsing intestinal inflammatory disease. Interleukin (IL)-6, a pro-inflammatory cytokine, plays a key role in the uncontrolled intestinal inflammatory process, which is a main characteristic of UC. In this work, a quantitative structure-activity relationship model based on molecular topology (MT) has been built up to predict the IL-6 mediated anti-UC activity. After an external validation of the model, a virtual screening of the MicroSource Pure Natural Products Collection and Sigma-Aldrich databases was carried out looking for potential new active compounds. From the entire set of compounds labeled as active by the model, four of them, namely alizarin-3-methylimino-N,N-diacetic acid (AMA), Calcein, (+)-dibenzyl-L-tartrate (DLT), and Ro 41-0960, were tested in vitro by determination of IL-6 production in two cell lines (RAW 264.7 and Caco-2). The results demonstrate that three of them were able to significantly reduce IL-6 levels in both cell lines and particularly one, namely Ro 41-0960. These results confirm MT's efficacy as a tool for the selection of compounds potentially active in UC.

AP-1/IRF-3 Targeted Anti-Inflammatory Activity of Andrographolide Isolated from Andrographis paniculata

Andrographolide (AG) is an abundant component of plants of the genus Andrographis and has a number of beneficial properties including neuroprotective, anticancer, anti-inflammatory, and antidiabetic effects. Despite numerous pharmacological studies, the precise mechanism of AG is still ambiguous. Thus, in the present study, we investigated the molecular mechanisms of AG and its target proteins as they pertain to anti-inflammatory responses. AG suppressed the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂), as well as the mRNA abundance of inducible NO synthase (iNOS), tumor necrosis factor-alpha (TNF-α), cyclooxygenase (COX)-2, and interferon-beta (IFN-β) in a dose-dependent manner in both lipopolysaccharide- (LPS-) activated RAW264.7 cells and peritoneal macrophages. AG also substantially ameliorated the symptoms of LPS-induced hepatitis and EtOH/HCl-induced gastritis in mice. Based on the results of luciferase reporter gene assays, kinase assays, and measurement of nuclear levels of transcription factors, the anti-inflammatory effects of AG were found to be clearly mediated by inhibition of both (1) extracellular signal-regulated kinase (ERK)/activator protein (AP)-1 and (2) IκB kinase ε (IKKε)/interferon regulatory factor (IRF)-3 pathways. In conclusion, we detected a novel molecular signaling pathway by which AG can suppress inflammatory responses. Thus, AG is a promising anti-inflammatory drug with two pharmacological targets.

Regio- and stereoselective synthesis of a library of bioactive dispiro-oxindolo/acenaphthoquino andrographolides via 1,3-dipolar cycloaddition reaction under microwave irradiation

Dispiro-pyrrolidino/pyrrolizidino fused oxindoles/acenaphthoquinones have been derived from andrographolide via azomethine ylide cycloaddition to the conjugated double-bond under microwave (MW) irradiation. The reactions are chemo-, stereo-, and regioselective in nature. Change in amino acid from sarcosine/N-benzyl glycine to l-proline changes the regiochemistry. A representative library of 40 compounds along with in vitro anticancer evaluation is reported.

Andrographolide and its analogues: versatile bioactive molecules for combating inflammation and cancer

1. Andrographis paniculata (Burm. f) Nees, commonly known as 'king of bitters', is a herbaceous plant belonging to the Family Acanthaceae. It has been widely used for centuries in Asian countries like China, India, Thailand and Malaysia for the treatment of sore throat, flu and upper respiratory tract infections. 2. Andrographolide, 14-deoxy-11,12-didehydroandrographolide and neoandrographolide are examples of the major labdane diterpenoids isolated from A. paniculata. These bioactive molecules have exhibited varying degrees of anti-inflammatory and anticancer activities in both in vitro and in vivo experimental models of inflammation and cancer. 3. Extensive libraries of andrographolide analogues have been synthesised mainly by modifying the α,β-unsaturated γ-butyrolactone moiety, the two double bonds Δ(8,(17)) and Δ(12,(13)) and the three hydroxyls at C-3 (secondary), C-14 (allylic) and C-19 (primary). Many of these synthetic analogues exhibit superior anticancer activity over the naturally occurring andrographolides. 4. Andrographolide and its derivatives have been shown to have anti-inflammatory effects in experimental models of asthma, stroke and arthritis, as well as in patients with upper respiratory tract infections. Andrographolide reduces the production of cytokines, chemokines, adhesion molecules, nitric oxide and lipid mediators, probably via inhibition of the nuclear factor (NF)-κB signalling pathway. 5. The anticancer mechanisms for andrographolide include inhibition of Janus tyrosine kinases-signal transducers and activators of transcription, phosphatidylinositol 3-kinase and NF-κB signalling pathways, suppression of heat shock protein 90, cyclins and cyclin-dependent kinases, metalloproteinases and growth factors, and the induction of tumour suppressor proteins p53 and p21, leading to inhibition of cancer cell proliferation, survival, metastasis and angiogenesis. 6. Andrographolide drug discovery is a promising strategy for the development of a novel class of anti-inflammatory and anticancer drugs.

Modifications of andrographolide to increase some biological activities: a patent review (2006 - 2011)

INTRODUCTION

Andrographis paniculata Nees, Acanthaceae, is a well-recognised medicinal plant in Asia. It has been reported to possess a variety of biological activities. The main constituent of A. paniculata is andrographolide (Androg). Since the plant is known to treat many diseases, Androg was modified for many biological activities to treat and prevent a variety of diseases.

AREA COVERED

This review surveys the patents from 2006 to 15 November 2011 for antibacterials, antivirals, antidiabetic, anticancer, analgesic, antipyretic and anti-inflammatory analogues. SciFinder database was used to search for the patent work using the keywords 'andrographolide', 'andrographolide derivatives', 'andrographolide analogues' and later additional limits, that is, 'patent' and 'years', 'Clinical trial' and 'years' were searched. Espacenet was also searched for 'andrographolide', 'andrographolide derivatives' and 'andrographolide analogues'.

EXPERT OPINION

Androg is a good pharmacophore for many pharmacological activities. Esterification at either one or more of the three hydroxyls with short/long chains, heterocyclic, aromatic fatty acids was attempted and tested for a variety of activities. Most of the responses were positive. Other modifications were epoxidation at Δ(7(18)) along with esterifications with various carboxylic acids for anticancer activity. 15-Alkylidene analogues were investigated for α-glucosidase inhibition. The improvement of activities have not yet been proven to be due to the increase in the ability of analogues to reach the targets as prodrugs or the new feature structures fitted to the receptors. It seems that substitution with active compounds, such as lipoic acid, is a new trend for modification.

Microbial transformation of deoxyandrographolide and their inhibitory activity on LPS-induced NO production in RAW 264.7 macrophages

A series of analogues of deoxyandrographolide (1) transformed by Cunninghamella blakesleana AS 3.2004 were isolated and identified by spectral methods including 2D NMR. Among them, 3-oxo-17,19-dihydroxy-7,13-ent-labdadien-15,16-olide (9), 3-oxo-19-hydroxy-1,13-ent-labdadien-15,16-olide (16), 3-oxo-1β-hydroxy-14-deoxy-andrographolide (17) and 3-oxo-2β-hydroxy-14-deoxyandrographolide (18) are new compounds. And their structure-activity relationships (SAR) of inhibitory activity on LPS-induced NO production in RAW 264.7 macrophage cells were also discussed.

Andrographolide, an herbal medicine, inhibits interleukin-6 expression and suppresses prostate cancer cell growth

Elevated interleukin-6 (IL-6), a major mediator of the inflammatory response, has been implicated in androgen receptor (AR) activation, cellular growth and differentiation, plays important roles in the development and progression of prostate cancer, and is a potential target in cancer therapy. Through drug screening using human prostate cancer cells expressing IL-6 autocrine loop, we found that andrographolide, a diterpenoid lactone isolated from a traditional Chinese and Indian medicinal plant Andrographis paniculata, could inhibit IL-6 expression and suppress IL-6-mediated signals. Andrographolide inhibits IL-6 expression at both mRNA and protein levels in a dose-dependent manner. Andrographolide suppresses both IL-6 autocrine loop- and paracrine loop-induced cell signaling including Stat3 and Erk phosphorylation. Furthermore, andrographolide inhibits cell viability and induces apoptotic cell death in both androgen-stimulated and castration-resistant human prostate cancer cells without causing significant toxicity to normal immortalized prostate epithelial cells. Moreover, treatment of andrographolide to mice bearing castration-resistant DU145 human prostate tumors that express constitutive IL-6 autocrine loop significantly suppresses tumor growth. Taken together, these results demonstrate that andrographolide could be developed as a therapeutic agent to treat both androgen-stimulated and castration-resistant prostate cancer possibly by suppressing IL-6 expression and IL-6-induced signaling.