Synthesis of new ent-labdane diterpene derivatives from andrographolide and evaluation on cytotoxic activities

Synthesis of 12-quinoline substituted andrographolide derivatives and their preliminary evaluation as anti-aggregation drugs

Based on the structure of the natural product andrographolide, a series of novel 12-quinoline substituted derivatives 9 were designed and synthesized. In preliminary biological evaluation, these synthesized compounds showed prominent anti-platelet aggregation activities in response to thrombin and adenosine diphosphate (ADP) agonists. Among them, compound 9o (inhibition rate 55.73%, IC50 0.36 µM/L) had the highest anti-platelet aggregation activity induced by ADP. Compound 9q (inhibition rate 54.31%, IC50 0.30 µM/L) showed the highest anti-platelet aggregation activity induced by thrombin. Most of the derivatives had no significant cytotoxicity. Our research results provide a novel candidate drug structure for anti-platelet aggregation and enrich the scope of application of andrographolide derivatives.

Advances in ameliorating inflammatory diseases and cancers by andrographolide: Pharmacokinetics, pharmacodynamics, and perspective

Andrographolide, a well-known natural lactone having a range of pharmacological actions in traditional Chinese medicine. It has long been used to cure a variety of ailments. In this review, we cover the pharmacokinetics and pharmacological activity of andrographolide which supports its further clinical application in cancers and inflammatory diseases. Growing evidence shows a good therapeutic effect in inflammatory diseases, including liver diseases, joint diseases, respiratory system diseases, nervous system diseases, heart diseases, inflammatory bowel diseases, and inflammatory skin diseases. As a result, the effects of andrographolide on immune cells and the processes that underpin them are discussed. The preclinical use of andrographolide to different organs in response to malignancies such as colorectal, liver, gastric, breast, prostate, lung, and oral cancers has also been reviewed. In addition, several clinical trials of andrographolide in inflammatory diseases and cancers have been summarized. This review highlights recent advances in ameliorating inflammatory diseases as well as cancers by andrographolide and its analogs, providing a new perspective for subsequent research of this traditional natural product.

A late-stage diversification via Heck-Matsuda arylation: Straightforward synthesis and cytotoxic/antiproliferative profiling of novel aryl-labdane-type derivatives

In the current study a late-stage diversification of unactivated olefins labd-8(17)-en-15-oic acid (1a) and methyl labd-8(17)-en-15-oate (1b) via Heck-Matsuda arylation is described. The reaction provided straightforward and practical access to a series of novel aryl-labdane-type derivatives (HM adducts 3a-h) in moderate to good yields in a highly regio- and stereoselective manner at room temperature under air atmosphere. The cytotoxic activity of these compounds was investigated in vitro against three different human cell lines (THP-1, K562, MCF-7). Of these, HM adduct 3h showed a selective effect in all cancer cell lines tested and was selected for extended biological investigations in a leukemia cell line (K562), which demonstrated that the cytotoxic/antiproliferative activity observed in this compound might be mediated by induction of cell cycle arrest at the sub-G1 phase and by autophagy-induced cell death. Taken together, these findings indicate that further investigation into the anticancer activity against chronic myeloid leukemia from aryl-labdane-type derivatives may be fruitful.

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.

Synthesis of new ent-labdane diterpene derivatives from andrographolide and evaluation of their anti-inflammatory activities

Two series of andrographolide derivatives with nitrogen-containing heterocycles, phenols and aromatic acids as bioisostere moiety of lactone ring were synthesized. 8 from 18 tested compounds showed stronger inhibitory effect on LPS-induced NO production in RAW264.7 macrophage than hydrocortisone. Among them, compound 8m exhibited the most potent inhibition with IC₅₀ of 3.38 ± 1.03 μM. The structure-activity relationships (SARs) suggested that the replacement of lactone ring with small-molecule phenols could improve the anti-inflammatory efficacy. Furthermore, compound 8m significantly reduced the levels of pro-inflammatory cytokine IL-1β and IL-6 with no influence on cell survival, decreased the expression of iNOS and COX-2, and down-regulated the level and phosphorylation of IκBα, as well as the expression of NF-κB. Also it blocked the nuclear translocation of NF-κB in LPS-induced macrophage. Therefore, the anti-inflammation mechanism of compound 8m was related to the inhibition of COX-2, iNOS and NF-κB signal pathway.

Overview of pharmacological activities of Andrographis paniculata and its major compound andrographolide

Andrographis paniculata (A. paniculata) is a medicinal plant traditionally used as anti-inflammation and anti-bacteria herb. Andrographolide, the major active component of A. paniculata, exhibits diverse pharmacological activities, including anti-inflammation, anti-cancer, anti-obesity, anti-diabetes, and other activities. In this article, we comprehensively review the therapeutic potential of A. paniculata and andrographolide focusing on the mechanisms of action and clinical application. We systemically discuss the structure-activity relationship of andrographolide and derivatives. Despite the various pharmacological activities and formula of A. paniculata and andrographolide, we propose further development of more structural derivatives of andrographolide with reduced toxicity and increased therapeutic efficacy is still needed for the clinical application of this ancient mighty herb and its major component.

Andrographolide, a diterpene lactone from Andrographis paniculata and its therapeutic promises in cancer

The diterpene lactone andrographolide, isolated from Andrographis paniculata, has been proven to possess several important protective biological activities, including antioxidant, anti-inflammatory, immunomodulatory, antiseptic, antimicrobial, cytotoxic, hypolipidemic, cardioprotective, hepatoprotective, and neuroprotective effects. In addition, it has been reported to play a therapeutic role in the treatment of major human diseases, such as Parkinson's disease, rheumatoid arthritis, and colitis. This systematic review aims to highlight andrographolide as a promising agent in cancer treatment. To this purpose, a number of databases were used to search for the cytotoxic/anticancer effects of andrographolide in pre-clinical and clinical studies. Among 1703 identified literature articles, 139 were included in this review; 109 were investigated as non-clinical, whereas 24, 3, and 3 were pre-clinical, clinical, and non-pre-clinical trials, respectively. Among the model systems, cultured cell lines appeared as the most frequently (79.14%) used, followed by in vivo models using rodents, among others. Furthermore, andrographolide was found to exert cytotoxic/anticancer effects on almost all types of cell lines with the underlying mechanisms involving oxidative stress, cell cycle arrest, anti-inflammatory and immune system mediated effects, apoptosis, necrosis, autophagy, inhibition of cell adhesion, proliferation, migration, invasion, anti-angiogenic activity, and other miscellaneous actions. After careful consideration of the relevant evidence, we suggest that andrographolide can be one of the potential agents in the treatment of cancer in the near future.

Semisynthetic Esters of 17-Hydroxycativic Acid with in Vitro Cytotoxic Activity against Leukemia Cell Lines

A collection of sixteen semisynthetic 17-hydroxycativic acid esters with alcohols containing a tertiary amine group was evaluated for their in vitro cytotoxicity against two human cancer cell lines, THP-1 and U937, and for their effects on the cell cycle and cell death. While 17-hydroxycativic acid itself is not cytotoxic, all the esters displayed cytotoxic activity, with 50% growth inhibition (GI₅₀) values ranging between 3.2 and 23.1 µM. In general, the most potent compounds in both cell lines were esters with four carbon long alcohol residues. There was no clear relationship between the identity of the terminal secondary amine and the activity of the compound. Experiments using the 6-(pyrrolidin-1-yl)pentyl ester, 2c, revealed that this compound activates caspases-3/7 and causes poly(ADP-ribose)polymerase 1 (PARP-1) fragmentation in THP-1 and U937 cells, indicating the induction of apoptotic cell death. These results suggest that further investigation into the anticancer activity of diterpene derivatives and other labdane diterpenes may be fruitful.

Synthesis and biological evaluation of new C-12(α/β)-(N-) sulfamoyl-phenylamino-14-deoxy-andrographolide derivatives as potent anti-cancer agents

Andrographolide, the major diterpenoidal constituent of Andrographis paniculata (Acanthaceae) and its derivatives have been reported to possess plethora of biological properties including potent anti-cancer activity. In this work, synthesis and in-vitro anti-cancer evaluation of new C-12-substituted aryl amino 14-deoxy-andrographolide derivatives (III a-f) are reported. The substitutions include various sulfonamide moieties -SO₂-NH-R¹. The new derivatives (III a-e) exhibited improved cytotoxicity (GI₅₀, TGI and LC₅₀) compared to andrographolide (I) and the corresponding 3,14,19-O-triacetyl andrographolide (II) when evaluated against 60 NCI cell line panel. Compounds III c and III e are found to be non-toxic to normal human dermal fibroblasts (NHDF) cells compared to reference drug THZ-1.

Therapeutic Potential of Essential Oils Focusing on Diterpenes

Among all plant derivates, essential oils (EOs) have gained the attention of many scientists. Diterpenes, a family of components present in some EO, are becoming a milestone in the EOs world. The goal of this review is to describe a scenario of diterpenes taking into health-consumption deportment. Previous studies revealed that diterpenes have antioxidant, antimicrobial, antiviral, antiprotozoal, cytotoxic, anticancer, antigenotoxic, antimutagenic, chemopreventive, antiinflammatory, antinociceptive, immunostimulatory, organoprotective, antidiabetic, lipid-lowering, antiallergic, antiplatelet, antithrombotic, and antitoxin activities. In conclusion, diterpenes may be an immense featuring concern in pharmaceutical consumption from a drug discovery point of view. Copyright © 2016 John Wiley & Sons, Ltd.

In vitro Metabolism of Sodium 9-dehydro-17-hydro-andrographolide-19-yl Sulfate in Rat Liver S9 by Liquid Chromatography-Mass Spectrometry Method

Background:

Sodium 9-dehydro-17-hydro-andrographolide-19-yl sulfate (DHAS) is the active ingredient of Xiyanping injection, a traditional Chinese medicine in clinical use. However, there has been no report about the metabolic rate and metabolites of DHAS in vitro.

Materials and Methods:

In this article, DHAS was incubated with rat liver S9, and liquid chromatography/mass spectrometry (LC/MS) was used for the metabolism study. The residual concentrations of substrate were determined by ultra-high-performance liquid chromatography-electrospray ionization–tandem mass spectrometry method for the metabolic rate study of DHAS in liver S9. Metabolites were identified by the (UPLC-TOF-MS^E) Ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry method.

Results:

The calibration curves of DHAS were linear over the concentration range from 0.75 μM to 75.22 μM with correlation coefficients >0.99. The lower limit of quantification was 0.150 μM for DHAS. The determination recoveries of DHAS were in the range of 84.9–90.6%. The t_½ and CL_int of DHAS in rat liver S9 were 98.6 ± 2.1 min and 3.5 ± 0.1 mL/min/g, respectively. Five metabolites were preliminarily identified based on the high resolution mass spectrum data in comparison with related references. These metabolites were mainly the products of dehydration and hydrogenation of DHAS.

Conclusion:

The present in vitro metabolic study of DHAS provided valuable information about the metabolic rate and potential metabolites of DHAS, which are important for future in vivo metabolism studies of DHAS and the discovery of more active andrographolide derivatives.

SUMMARY

In this paper, sodium 9-dehydro-17-hydro-andrographolide-19-yl sulfate (DHAS) metabolism in vitro has been investigated with rat liver S9 using liquid chromatography-mass spectrometry (LC-MS). The result of quantitative analysis showed that DHAS had a long t1/2, which indicated its high metabolic stability. Five metabolites of DHAS were identified in the incubation system based on the high resolution mass spectrum data in comparison with related references, particularly dehydrated and hydrogenated products. The results would provide certain references to screen out more active andrographolide derivative for pre-clinically.

Abbreviations used: MRM: Multiple reaction monitoring, DHAS: Sodium 9-dehydro-17-hydro-andrographolide-19-yl sulfate, IS: Internal standard.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, pimaranes, abietanes, kauranes, cembranes and their cyclization products. The literature from January to December, 2015 is reviewed.

The semi-synthesis of novel andrographolide analogues and anti-influenza virus activity evaluation of their derivatives

Two novel andrographolide analogues with the structural motif of Δ(8,17)-alkene exo-to-endo isomerization, AI78 and AI89, were semi-synthesized firstly. Two series of derivatives were designed and synthesized based on the synthetic pathway (including series I: olefin isomerizing to endocyclic Δ(8,9) and series II: olefin isomerizing to endocyclic Δ(7,8)). The anti-influenza virus activity in vitro for all derivatives was evaluated. Among the compounds synthesized, compound 38 with benzyl amino group showed the greatest potency against H3N2 and was approximately 1.5-fold more potent than that of Lianbizhi, andrographolide analogue used clinically in China. Adamantyl derivative, 43, presented the lowest toxicity, with a higher TC50 and TI values than Lianbizhi. The structure-activity relationships studies of the synthetic analogues indicated that the endocyclic Δ(7,8)-double bond is preferable for anti-viral effect. Furthermore, the introduction of the fatty amino attached to the rigid skeleton at C-17 is beneficial for activity.