Discovery of natural 15-LOX small molecule inhibitors from Chinese herbal medicine using virtual Screening, biological evaluation and molecular dynamics studies

Chinese herbal medicines (CHM) are frequently used to treat different types of inflammatory diseases and 15-Lipoxygenase (15-LOX) is a critical target enzyme for treating various inflammatory diseases. In this study, natural 15-LOX inhibitors were identified in CHM using an approach of virtual screening combined with the biological assays. First, an in-house Chinese medicine database containing 360 compounds was screened using a virtual screening approach based on pharmacophore and molecular docking to uncover several novel potential 15-LOX inhibitors. Secondly, the inhibitory effect of virtual screening hits against the 15-LOX enzyme was validated in an in vitro enzyme inhibition assay. Then, a tumor necrosis factor-α (TNF-α) release assay was carried out to explore the anti-inflammatory response of the active compounds. Furthermore, molecular dynamics (MD) simulation and binding free energy calculation were applied to analyze the process of inhibitors binding and also compared the mode of binding of the inhibitors by using the Molecular Mechanics-Generalized Born Surface Area (MM/GBSA) method. Finally, licochalcone B and eriodictyol were confirmed as inhibitors of the 15-LOX enzyme with IC₅₀ values of 9.67 and 18.99 μM, respectively. In vitro cell-based assay showed that licochalcone B and eriodictyol inhibited the release of TNF-α factor in RAW264.7 cells stimulated by lipopolysaccharides (LPS) in a dose-dependent manner. Molecular dynamics and binding free energy analysis showed that the two 15-LOX-ligand systems immediately attained equilibrium with almost 1 Å fluctuation, the calculated binding free energies were found around -18.89 and -12.96 kcal/mol for licochalcone B and eriodictyol, respectively. Thr412, Arg415, Val420, Thr429, Ile602 and Trp606 were the main amino acid residues for the inhibition of 15-LOX enzyme activity. The current study confirms that licochalcone B and eriodictyol are 15-LOX inhibitors and can suppress the release of the TNF-α factor in RAW264.7 cells stimulated by LPS, thus providing a basis for the follow-up research and development for 15-LOX inhibitors.

HuoXue JieDu formula improves diabetic retinopathy in rats by regulating microRNAs

ETHNOPHARMACOLOGICAL RELEVANCE

HuoXue JieDu Formula (HXJDF) originates from classical formulas and was formed based on clinical experience. It is composed of Euonymus alatus (Thunb.) Siebold, Panax notoginseng (Burkill) F.H. Chen, the roots of Anguina kirilowii (Maxim.) Kuntze, and Coptis omeiensis (C. Chen) C.Y.Cheng. HXJDF prevents the deterioration of diabetic retinopathy.

AIM OF THE STUDY

To evaluate the effects of HXJDF on diabetic retinopathy in rats and investigate the roles of miRNAs in the effects of HXJDF.

MATERIALS AND METHODS

A single intraperitoneal injection of streptozotocin (STZ) (65 mg/kg) was used to induce diabetes in rats. Rats were divided into three groups: normal, diabetic, and diabetic + HXJDF. Rats were treated with HXJDF (15.4 g/kg) or water by oral gavage for twelve weeks. At the end of the treatment, rats were anaesthetized, and retinal haemodynamic changes were measured. Then, the retinas were removed and examined by haematoxylin and eosin (HE) staining and TUNEL assays. In addition, miRNA expression profiling was performed using miRNA microarrays and further validated by quantitative real-time PCR (qRT-PCR).

RESULTS

Diabetes reduced peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV) and central retinal vein velocity (CRV) but increased the resistance index (RI) and pulsatility index (PI). In addition, in the diabetic group, retinal cell arrangement was disordered and loosely arranged, the retinal thickness and retinal ganglion cell (RGC) number decreased, and retinal cell apoptosis increased. In addition, 11 miRNAs were upregulated and 4 miRNAs were downregulated. After treatment, HXJDF improved retinal haemodynamics and morphologic changes, restored retinal thickness and RGC number and decreased retinal cell apoptosis. Furthermore, the changes in miRNA expression were significantly abolished by HXJDF.

CONCLUSION

HXJDF may prevent DR by regulating the expression of miRNAs.

Study on evaluation of toxicology and quality control of Yimusake tablet

ETHNOPHARMACOLOGICAL RELEVANCE

The Yimusake tablet (YMSK-T) is a type of Xinjiang Uygur Medicine, which affects curing diseases of impotence and premature ejaculation. It has remarkable pharmacological effects that mainly involve improving the number and shape of smooth muscle cells in the corpus cavernosum and enhancing the relaxation and contraction function of corpus cavernosum smooth muscle.

AIM OF THE STUDY

The YMSK-T prescription, which consists of 11 traditional herbs, has significant pharmacological effects, however the evaluation of toxicology and quality control of the preparation has not yet been reported. Therefore, in this study, we evaluated the toxicology and quality control of YMSK-T to ensure its safety and effectiveness in clinical applications.

MATERIALS AND METHODS

Male rats were divided into three groups and were given continuous gavage administration of high, medium and low concentrations of YMSK-T. To determine hematopoietic parameters, orbital blood was collected at regular intervals. At termination of the experiment, rats were dissected for histopathological examination. According to the function of the prescription medicinal materials, seven active components were selected for content determination under the same chromatographic condition of using 0.2% aqueous phosphoric acid (solvent A) and acetonitrile (solvent B) with a 40 min post time: 0-13 min, 20% →30% B; 13-26 min, 30% →72% B; 26-38 min, 72% →92% B; 38-40 min, 92% →96% B. The column was maintained at 25 °C and the total sample injection was 10 μL.

RESULTS

Our data showed that using a large dose (400X the dosage used in humans) of YMSK-T resulted in myocardium and liver damage, and eventually death of the rats. At sub-chronic toxicity, no significant differences were observed among indexes about relative organ weight, hematology, serum biochemistry and histopathological examination, and rats behaved normally. Our results also demonstrated that the YMSK-T dosage used was not toxic in the normal range. The linearity of each component was sufficient (correlation coefficients>0.9997). Moreover, the relative standard deviations of precision, repeatability, stability, and recovery were less than 2.0%, which showed that the method for determination of content was stable and reliable.

CONCLUSIONS

YMSK-T has been found to be relatively safe in a rat model, and the method of content determination can be used for quality control of YMSK-T. Toxicology and quality control studies indicated that, the drug is safe and effective for clinical application.

The extraordinary transformation of traditional Chinese medicine: processing with liquid excipients

Context: The Chinese medicinal materials originate from animals, plants, or minerals must undergo appropriate treatment before use as decoction pieces. Processing of Chinese medicines with liquid excipients is a pharmaceutical technique that transforms medicinal raw materials into decoction pieces which are significantly different from the original form. During processing, significant changes occur in chemical constituents, which inevitably affects clinical efficacy. At present, the liquid materials in processing mainly involve wine, vinegar, honey, saline water, ginger juice, herbal juice, etc.Objective: This review introduces the typical methods of liquid excipients processing, summarizes the influence on chemical composition, pharmacological efficacy, and expounds the ways and mechanisms of liquid excipients to change the properties of drugs, enhance the efficacy, eliminate or reduce toxicity and adverse reaction.Methods: English and Chinese literature from 1986 to 2020 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2015, and CNKI (Chinese). Liquid excipients, processing, pharmacological effects, synergism, chemical constitution, traditional Chinese medicine (TCM) were used as the key words.Results: Liquid excipients play a key role in the application of TCM. Processing with proper liquid excipients can change the content of toxic or active components by physical or chemical transformation, decrease or increase drug dissolution, alter drug pharmacokinetics, or exert their own pharmacological effects. Thus, processing with liquid excipients is essential to ensure the safety and efficacy of TCM in clinic.Conclusion: This article could be helpful for researchers who are interested in traditional Chinese herbs processed with liquid excipients.

Associating 197 Chinese herbal medicine with drug targets and diseases using the similarity ensemble approach

Chinese herbal medicine (CHM) addresses complex diseases through polypharmacological interactions. However, systematic studies of herbal medicine pharmacology remain challenging due to the complexity of CHM ingredients and their interactions with various targets. In this study, we aim to address this challenge with computational approaches. We investigated the herb-target-disease associations of 197 commonly prescribed CHMs using the similarity ensemble approach and DisGeNET database. We demonstrated that this method can be applied to associate herbs with their putative targets. In the case study of three well-known herbs, Radix Glycyrrhizae, Flos Lonicerae, and Rhizoma Coptidis, approximately 70% of the predicted targets were supported by scientific literature. By linking 406 targets to 2439 annotated diseases, we further analyzed the pharmacological functions of 197 herbs. Finally, we proposed a strategy of target-oriented herbal formula design and illustrated the target profiles for four common chronic diseases, namely, Alzheimer's disease, depressive disorder, hypertensive disease, and non-insulin-dependent diabetes mellitus. This computational approach holds great potential in the target identification of herbs, understanding the molecular mechanisms of CHM, and designing novel herbal formulas.

Systems pharmacology reveals the unique mechanism features of Shenzhu Capsule for treatment of ulcerative colitis in comparison with synthetic drugs

In clinic, both synthetic drugs and Shenzhu Capsule (SZC), one kind of traditional Chinese medicines (TCMs), are used to treat ulcerative colitis (UC). In our study, a systems pharmacology approach was employed to elucidate the chemical and mechanism differences between SZC and synthetic drugs in treating UC. First, the compound databases were constructed for SZC and synthetic drugs. Then, the targets of SZC were predicted with on-line tools and validated using molecular docking method. Finally, chemical space, targets, and pathways of SZC and synthetic drugs were compared. Results showed that atractylenolide I, atractylone, kaempferol, etc., were bioactive compounds of SZC. Comparison of SZC and synthetic drugs showed that (1) in chemical space, the area of SZC encompasses the area of synthetic drugs; (2) SZC can act on more targets and pathways than synthetic drugs; (3) SZC can not only regulate immune and inflammatory reactions but also act on ulcerative colitis complications (bloody diarrhea) and prevent UC to develop into colorectal cancer whereas synthetic drugs mainly regulate immune and inflammatory reactions. Our study could help us to understand the compound and mechanism differences between TCM and synthetic drugs.

Catalyst-Free sp3 C-H Acyloxylation: Regioselective Synthesis of 1-Acyloxy Derivatives of the Natural Product Tanshinone IIA

Tanshinone IIA is a valuable bioactive natural product isolated from the well-known Chinese herb Danshen. Structural manipulation of the A-ring of tanshinone IIA is rather limited. In this study, a substrate tautomerization-induced catalyst-free benzylic sp³ C-H acyloxylation approach is reported that allows the direct introduction of various acyloxy groups at the A-ring benzylic methylene of various tanshinone IIA substrates, thus avoiding the use of expensive transition metal catalysts and the production of harmful byproducts. This approach features a unique acid-induced reversible enolization/oxa-conjugate addition process followed by oxidation to exclusively give a series of diverse 1-acyloxylated derivatives under simple conditions in a regioselective manner. Compared with the literature procedures, this protocol demonstrates a higher efficiency, a more robust functional-group tolerance, atom economy, and lower cost.

[Impact of ″imprinting templates″ characteristics of traditional Chinese medicine injection supramolecules on (anaphylactoid) hypersensibility]

The (anaphylactoid) hypersensibility mechanism of ″imprinting templates″ characteristics of traditional Chinese medicine (TCM) injection supramolecules was clarified to lay the foundation to build safety evaluation method. Based on the previous publication on special impact of Chinese medicine theories on supramolcular chemistry, combined with the natural origination of (anaphylactoid) hypersensitized special rules as well as the sensitization phenomenon of cordate houttuynia injection, the impact of the structure characteristics of ″imprinting templates″ in TCM injection supramolecules on its (anaphylactoid) hypersensibility was clarified. In Chinese medicine injections, the supramolecular structures can independently be generated, showing overall apparent (anaphylactoid) hypersensibility nature, and their structure characteristics were dependent on the strength. In addition, (anaphylactoid) hypersensitive critical supramolecular structure was present. When it was administrated by ″injection″, it's structure was not easy to be destroyed, often showing apparent immunogenicity, whereas if it was administrated by ″oral″, the structure would be destroyed by the gastrointestinal tract, showing weaker or no apparent immunogenicity. Therefore, there are differences in (anaphylactoid) hypersensibility between ″injection″ and ″oral″ administration of TCM. TCM injections would produce the supramolecules between ″molecular society″ by independent reaction of supramolecular ″imprinting template″ (chemical determinants), showing apparent immune process of recognition, copying, and storage. Single molecule is a special example for this. The screening of anaphylactoid (sensitinogen) includes the single ingredients and their forming supramolecules for TCM injection. This is the unique feature for safety evaluation of Chinese medicine injection.

Asymmetric synthesis and evaluation of danshensu-cysteine conjugates as novel potential anti-apoptotic drug candidates

We have previously reported that the danshensu-cysteine conjugate N-((R)-3-benzylthio-1-methoxy-1-oxo-2-propanyl)-2-acetoxy-3-(3,4-diacetoxyphenyl) propanamide (DSC) is a potent anti-oxidative and anti-apoptotic agent. Herein, we further design and asymmetrically synthesize two diastereoisomers of DSC and explore their potential bioactivities. Our results show that DSC and its two diastereoisomers exert similar protective effects in hydrogen peroxide (H₂O₂)-induced cellular injury in SH-SY5Y cells, as evidenced by the increase of cell viability, superoxide dismutase (SOD), and reduced glutathione (GSH) activity, and glutathione peroxidase (GPx) expression, and the decrease of cellular morphological changes and nuclear condensation, lactate dehydrogenase (LDH) release, and malondialdehyde (MDA) production. In H₂O₂-stimulated human umbilical vein endothelial cells (HUVEC), DSC concentration-dependently attenuates H₂O₂-induced cell death, LDH release, mitochondrial membrane potential collapse, and modulates the expression of apoptosis-related proteins (Bcl-2, Bax, caspase-3, and caspase-9). Our results provide strong evidence that DSC and its two diastereoisomers have similar anti-oxidative activity and that DSC exerts significant vascular-protective effects, at least in part, through inhibition of apoptosis and modulation of endogenous antioxidant enzymes.

Synthesis of cyclocaric acid A and comparison to material from Cyclocarya paliurus

Components previously reported from Cyclocarya paliurus include the oleananes cyclocaric acids A and B, with cyclocaric acid A possessing an oxetane ring. Isolation of cyclocaric acid A from the plant extract and comparison to the literature report show that the compound originally reported as cyclocaric acid A is, in fact, hederagenin. This was confirmed by independent synthesis of the oxetane and indicates that cyclocaric acid A may not actually be a natural product.

[Synthesis and characterization of 9-O-alkyl substituted palmatine derivatives]

For the establishment of chemical library of protoberberines provided for the bio-activity screening, the target compounds were synthesized by thermal degradation and nucleophilic substitution reactions with the bio-active alkaloid, palmatine (1), as the raw material, and their structures were identified and conformed by 1H-NMR and MS spectra. Among them, 13 compounds were new.

Pharmacological importance of optically active tetrahydro-β-carbolines and synthetic approaches to create the C1 stereocenter

1,2,3,4-Tetrahydro-β-carbolines (THβCs) are a pharmacologically important group of compounds belonging to the indole alkaloids. C1-Substituted optically active THβCs have been the target of extensive synthetic efforts due to the presence of the scaffold in numerous natural products and synthetic targets. This review briefly summarizes the methods to obtain the C1 stereocenter and concentrates on evaluating the pharmacological importance of optically active C1-substituted THβCs, including their PDE5-inhibitory, antimalarial, antiviral and antitumor activities.

[Synthesis of baicalin-copper and baicalin-aluminium complex and its bioactivity]

OBJECTIVE

To study synthesis of baicalin-copper and baicalin-aluminium complex and its antimicrobial, anti-tumor activity and anti-tumor effect against macrophages.

METHOD

Baicalin was reacted with metallic salt under a weak base condition to produce baicalin-copper and baicalin-aluminium complex. Baicalin and its synthesized complex were detected for antimicrobial activity against Staphylococcus aureus, Hay bacillus, Escherichia coli, Salmonella and Candida albicans by twofold broth dilution technique. Their anti-tumor activity against A549 and IC50 of HepG2 cells and anti-tumor effect against macrophages were detected by the MTT. And their phagocytic effect on macrophages was determined by the neutral red assay.

RESULT

The yields of baicalin-copper and baicalin-aluminium complex were 73.93% and 91.08%, respectively. The minimum inhibitory concentration (MIC) value against Staphylococcus aureus, Hay bacillus, Escherichia coli, Salmonella and Candida albicans was 0.0004, 0.0009, 0.0004, 0.0009, 0.000 4 mol x L(-1) for baicalin-copper complex and 0.0011, 0.0011, 0.0011, 0.0011, 0.0005 mol x L(-1) for baicalin-aluminium complex. The IC50 values against A549 and HepG2 cells were 89.6, 22.6 micromol x L(-1) for baicalin-copper complex, and 138.8, 97.2 micromol x L(-1) for baicalin-aluminium complex. The inhibitory ratio of macrophage on A549 cell was 43.52%, 80.89%, 52.66%, respectively, after the macrophages were stimulated by baicalin, baicalin-copper and baicalin-aluminium complex at a concentration of 160 micromol x L(-1).

CONCLUSION

The acute toxicity test in mice showed that the complex was nontoxic to mice. Baicalin-copper complex showed the highest antimicrobial, anti-tumor activity, and the strongest effect on the anti-tumor activity of macrophage, while baicalin showed the lowest activities compared with baicalin-copper and baicalin-aluminium complex.

In silico pharmacology suggests ginger extracts may reduce stroke risks

Aberrations in cyclic adenosine monophosphate (cAMP) signaling cascade has been linked to the allergic responses that associate with the risks of stroke or cardiovascular diseases. Phosphodiesterase 4D (PDE4D) has been shown to be highly involved in cAMP regulation and is hence implied to be a potential drug target in stroke prevention. To identify potential PDE4D inhibitors from traditional Chinese medicine (TCM), we employed machine learning modeling techniques to screen a comprehensive TCM database. The multiple linear regression (MLR) and support vector machine (SVM) models constructed have correlation coefficients of 0.8234 and 0.7854 respectively. Three candidates from the ginger family were identified based on the prediction models. Molecular dynamics simulation further validated the binding stabilities of each candidate in comparison to the control inhibitor L-454560. The intermolecular distances suggested that the candidates could hinder PDE4D from binding to cAMP. Furthermore, the HypoGen validation suggested that top2, top3, and the control L-454560 mapped with the predicted pharmacophores. The results suggested that the 3 compounds identified from the ginger family were capable in inhibiting cAMP binding and hydrolysis by PDE4D. We further identified and characterized the ligand binding properties that are associated with the inhibition of PDE4D.

Synthesis and biological evaluation of oleanolic acid derivatives as inhibitors of protein tyrosine phosphatase 1B

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator in the process of insulin signaling and a promising drug target for diabetes and obesity. Derivatives of oleanolic acid were synthesized and evaluated as PTP1B inhibitors. Several derivatives exhibited moderate to good inhibitory activities against PTP1B, with 25f displaying the most promising inhibition (IC(50) = 3.12 μM). Structure-activity relationship analyses of these derivatives demonstrated that the integrity of the A ring and 12-ene moieties was important in the retention of PTP1B enzyme inhibitory activities. In addition, hydrophilic and acidic groups as well as the distance between the oleanene and acid moieties were associated with PTP1B inhibitory activities. Possible binding modes of 25f were explored by molecular docking simulations.

A synthesis of the carbon skeleton of maoecrystal V

An enantioselective synthesis of the maoecrystal V (1) carbon skeleton is described. The key transformations include arylation of a 1,3-dicarbonyl compound with a triarylbismuth(V) dichloride species, oxidative dearomatization of a phenol, and a subsequent intramolecular Diels-Alder reaction.

[Preparation of the oral self-microemulsifying drug delivery system of GBE50]

To prepare the oral self-microemulsifying drug delivery system (SMEDDS) of GBE50, balance solubility method was used to screen emulsifier and assistant emulsifier; a pseudo-tamary phase diagram was used to prepare microemulsion; and orthogonal design was used to optimize formulation. Self-microemulsifying efficiency, dissolution, stability and pharmacokinetics of the preparation were studied. As a result, GBE50-SMEDDS of IPM, Cremophor EL, 1,2-propanediol and GBE50 could be self emulsified to form stable microemulsion with particle diameter between 20 and 50 nm when emulsifying with water. Its self-microemulsifying efficiency and dissolution are quick with good stability and it has a higher bioavailability than market existing agents Xingling particles. GBE50-SMEDDS is stable and effective.

Rhazinilam and quebrachamine derivatives from Yunnan Kopsia arborea

Three new rhazinilam-derived alkaloids, kopsiyunnanines C1, C2, and C3, and a new quebrachamine-type alkaloid, kopsiyunnanine D, which possess an unusual methoxymethyl or ethoxymethyl function, were isolated from the aerial parts of Yunnan Kopsia arborea. This is the first report of the presence of these functions in natural alkaloids. The structures and absolute configurations of the alkaloids were determined by spectroscopic methods and confirmed by semisynthesis.

Synthesis and antimicrobial activity of 3-octyloxy-8-alkyljatrorrhizine derivatives

By introducing octyloxy to C-3 and alkyl groups to C-8 of jatrorrhizine, a series of 3-octyloxy-8-alkyljatrorrhizine derivatives were synthesized and their antimicrobial activities were evaluated in vitro. The results indicated that the derivatives exhibited high antimicrobial activities, especially against Gram-positive bacteria. The 3-octyloxy-8-butyljatrorrhizine displayed the highest antimicrobial activity in all compounds. Their structure-activity relationships were discussed.

Further studies on CAB approach toward chemical conversion of C19-diterpenoid alkaloids to taxoids: synthesis of the vital intermediate C-nor-aconanone

In the title study, the synthesis of the vital intermediate C-nor-aconanone (3) from 4 was completed through 11 steps, mainly including semipinacol rearrangement, formation of the imines by the treatment of 10 or 20 with NBS, the cleavage of N-C19 bonds in 11 or 21 by treatment with m-CPBA and subsequently with LTA, as well as the rupture of the N-C17 bonds in 22 by a modified Nef reaction (NaH/t-BuOH --> KMnO4/H2O). One-pot procedure was successfully developed starting from 11 or 21 to afford the N,19-seco-C-nor product 15 or 22, respectively, in reasonably good yields.

Fine tuning of a reported synthetic route for biologically active flavonoid, baicalein

A modified procedure of a previous synthetic route for baicalein was developed in order to obtain more than ten grams of baicalein for in vivo test. There were several difficulties in applying the published experimental procedures for a large scale of synthesis. The modified synthetic work was successfully accomplished by reducing amount of strong Lewis acid in Fries rearrangement and using tetrabutylammonium iodide as an additive to speed up the demethylation reaction in refluxing HBr into completion.

Development and application of medicinal plant tissue cultures for production of drugs and herbal medicinals in China

In the search for new drugs and natural remedies, medicinal plants or herbs used in folk and traditional medicines are promising candidates. For the naturally rare and slowly growing plant species, plant tissue culture in bioreactors provides a cost-effective, sustainable and well-controlled means for mass production of the active principles of medicinal plants, and enables fuller utilization of their biosynthetic capacity. Recognizing that natural resources and agricultural land in China are limited,many Chinese research groups have engaged in the development of plant tissue culture techniques and processes for the cultivation and rapid propagation of medicinal plants, and for the biosynthesis and biotransformation of phytomedicines. This review primarily aims to provide a comprehensive summary of the major achievements in this and related research areas in China over the last three decades, but also to identify the difficulties and predict future trends in developing plant tissue culture biotechnology for the manufacture of bioactive natural products.

[Structural modification of cyclovirobuxine D and their inhibition activity on lipid peroxidation]

AIM

To search for compounds through structural modification of cyclovirobuxine D, using 20 or 21-aminosteroids as lead compound for the treatment of cerebrovascular diseases with better lipid peroxidation inhibitory activity.

METHODS

According to rational drug design principle, a series of cyclovirobuxine D analogues were prepared, and their bioactivities were tested.

RESULTS

Four new compounds were obtained and confirmed by spectra.

CONCLUSION

Lipid peroxidation inhibitory effects of cyclovirobuxine D analogues were tested by using TBA method. Some compounds showed better activity than that of cyclovirobuxine D.

[Prodrug structural modifications of cyclovirobuxine D and their biological activity]

AIM

To search for compounds for the treatment of cardiovascular diseases through prodrug structural modifications of cyclovirobuxine D, a single efficient composition distilled from Box plant in China, which was used to treat angina and myocardial infarction.

METHODS

According to prodrug design principle, a series of cyclovirobuxine D analogues were prepared, suc as succinate, phosphate and amino acid ester, and their biological activities were tested.

RESULTS

Seven new compounds were obtained and confirmed with 1H NMR, MS, and element analysis.

CONCLUSION

In pharmacology experiment, for treating arrhythmia induced by aconitine, succinate and amino acid ester of cyclovirobuxine D (I and VII) showed better activities than that of cyclovirobuxine D. The normal rhythm of the heart duration of I and VII were ( 11.53 +/- 7.62) min and (12.68 +/- 9.25) min, compared with 0.9% NaCl solution and cyclovirobuxine D, (2.36 +/- 1.68) min and (10.25 +/- 6.59) min (P < 0.01), respectively. Another pharmacology experiment, for treating arrhythmia induced by chloroform, the negative ratio of I and VII were 80% and 82%, compared with 0.9% NaCl solution and cyclovirobuxine D, 43% and 52% (P < 0.05), respectively. The difference between new compounds and cyclovirobuxine D was distinct.

Synthesis and acetylcholinesterase inhibition of derivatives of huperzine B

By targeting dual active sites of AChE, a number of new derivatives of HupB have been synthesized and tested as acetylcholinesterase inhibitors. The most potent compound, bis-HupB 5b is 72-fold more potent in AChE inhibition and 79-fold more selective for AChE versus BChE than HupB.

[Structural modification and bioactivity of cyclovirobuxine D]

AIM

To search for new compounds for the treatment of cardiovascular diseases by structural modification of cyclovirobuxine D.

METHODS

According to rational drug design principle, a series of cyclovirobuxine D analogues were prepared, and their bioactivities were tested.

RESULTS

Ten new compounds were syntheized and confirmed by spectra.

CONCLUSION

Endurance lacking oxygen activity and antiarrhythmia effects of some analogues of cyclovirobuxine D were tested. Some compounds showed better activity than cyclovirobuxine D.

[Semi-synthesis of derivatives with C-3' and C-4' trans-configuration from (+)-praeruptorin A]

AIM

In order to compare the calcium antagonist activity between the derivatives of (+)-praeruptorin A with C-3' and C-4' cis-configuration and trans-configuration, and to look for new active compounds, some derivatives with C-3', C-4' trans-configuration of (+)-praeruptorin A were semi-synthsized.

METHODS

(+)-Praeruptorin A was isolated from the root of Peucedanum praeruptorum. Basic hydrolysis of (+)-praeruptorin A was carried out. From the alkaline hydrolysis product (2), eight new products (5-12) with C-3', C-4' trans-configuration were semi-synthsized whose C-3' was linked to angeloyloxy and C-4' was linked to various acyloxy, using respective acids as acylating agents, DCC as a dehydrant, DMAP as catalyst. From the alkaline hydrolysis product (4), five new products (13-17) with C-3', C-4' trans-configuration were obtained whose C-3', C-4' is linked to various same acyloxys, using respective acids as acylating agents, DCC as dehydrant, DMAP as catalyst. Also from the alkaline hydrolysis product (4), using respective acyl chlorides as acylating agents, anhydrous dichloromethane containing minor pyridine as a solvent, the improved Schotten-Baumann reactions were carried out, two new products (18, 20) with C-3', C-4' trans-configuration were obtained whose only C-3' linked to acyloxy and two other new products (19, 21) with C-3', C-4' trans-configuration were obtained whose C-3' and C-4' linked two acyloxys. The structures of all the products were elucidated by spectral analyses including IR, 1HNMR and EIMS. The calcium antagonist activity of all of the products were tested by inhibition of the systole of rat artery ring.

RESULTS

Seventeen compounds with C-3', C-4' trans-configuration were semi-synthesized from (+)-praeruptorin A for the first time and their calcium antagonist activity were evaluated.

CONCLUSION

All of the derivatives were new compounds. Bioactivity assay indicated that some new compounds with C-3', C-4' trans-configuration showed obvious calcium antagonist activity, but they are not as strong as (+)-praeruptorin A. The activity of some products was shown to be similar to that of the derivatives with C-3', C-4' cis-configuration for the first time.

[Studies on structure modification of (+)-praeruptorin A]

AIM

In order to look for new active compounds, the structure of (+)-praeruptorin A is modified.

METHODS

(+)-Praeruptorin A was isolated from the root of Peucedanum praeruptorum, basic hydrolysis of (+)-praeruptorin A and acyled reactions of hydrolysis product of (+)-praeruptorin A were carried out.

RESULTS

Eighteen compounds were semi-synthesized from (+)-praeruptorin A.

CONCLUSION

Fourteen compounds (5-18) among them are new compounds. Preliminary bioactivity assay indicated that the new compounds show calcium antagonist activity, but they are not as strong as (+)-praeruptorin A.

Synthesis of oligosaccharide derivatives related to those from sanqi, a Chinese herbal medicine from Panax notoginseng

Oligosaccharide derivatives from sanqi, a Chinese herbal medicine derived from Panax notoginseng, methyl beta-D-galactopyranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->6)]-alpha-D-galactopyranoside, diosgenyl beta-D-galactopyranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->6)]-alpha-D-galactopyranoside, and methyl beta-D-galactopyranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->6)]-alpha-D-galactopyranosyl-(1-->4)-beta-D-galactopyranosyl-(1-->3)-[alpha-L-arabinofuranosyl-(1-->6)]-alpha-D-galactopyranoside, were synthesized under standard glycosylation conditions. An unexpected alpha-(1-->4) linkage was formed predominantly in the presence of neighboring participation group during regioselective synthesis of hexasaccharide via 3+3 strategy.

Fluoro artemisinins: difluoromethylene ketones

The reactions of the ring-contracted aldehydes, derived from anhydrodihydroartemisinin, with gem-difluoroenoxysilanes in the presence of BF(3).Et(2)O afforded the corresponding difluoromethylene ketol adducts in good yields. Similar Lewis acid catalyzed reactions of dihydroartemisinin acetate with the difluoroenoxysilanes provided the 10-substituted difluoromethylene ketones in good to moderate yields. Interestingly enough, the course and the stereochemistry of these reactions are highly dependent on the nature of the Lewis acids used; the addition reaction was accompanied by epimerization at C-9, and the stereochemistry at C-10 depends on the difluoroenoxysilane used. The best results were obtained using SnCl(4) to give the 9alpha,10beta-stereoisomer in high stereoselectivity. When 0.4 equiv of SnCl(4) was used for the reaction with the alpha-(4-methoxyphenylenoxysilane)-beta,beta-difluoroenoxysilane, however, a rearrangement of the endoperoxide was observed.

Gastric-mucous membrane protection activity of coptisine derivatives

Coptisine and 8-oxocoptisine were isolated as principles of the gastric-mucous membrane protection from Coptidis rhizoma. The two compounds showed stronger activity than cimetidine and sucralfate. We prepared several derivatives having a partial structure of coptisine from commercially available starting materials. The compounds obtained were tested for gastric-mucous membrane protective activity and a correlation between activity and structure was studied. Our results suggest that the partial charge of the catechol skeleton is related to activity.

C-H insertion approach to the synthesis of endo,exo-furofuranones: synthesis of (+/-)-asarinin, (+/-)-epimagnolin A, and (+/-)-fargesin

A series of novel 5-aryl-4-aryloxymethyl-3-diazotetrahydrofuran-2-ones (12, 24, and 35a/b) have been prepared and found to undergo regio- and stereoselective C-H insertion reactions to afford 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane-8-ones (18, 26, and 36a/b) with endo,exo stereochemistry. Subsequent reduction of the lactone ring and cyclization of the resulting diols 27 and 37a/b permitted the synthesis of three endo,exo-furofuran lignans: asarinin (2), fargesin (3), and epimagnolin A (4). En route to the key diazo compounds 24 and 35a/b, a modified procedure for the Ghosez keteniminium-olefin cyclization was developed, which was required to minimize the decomposition of acid-sensitive functional groups such as electron-rich benzylic ethers that were present in the target compounds 2-4.

Synthesis of new artemisinin analogues from artemisinic acid modified at C-3 and C-13 and their antimalarial activity

Artemisinic acid (2) was modified through allylic oxidation at C-3 or conjugate addition at C-13 to afford 12 methyl artemisinate derivatives (4-15). Photooxidation of the derivatives yielded eight new artemisinin analogues, including 13-cyanoartemisinin (16), 13-methoxycarbonyl artemisinin (17), 13-methoxyartemisinin (18), 13-ethylsulfonylartemisinin (19), 13-nitromethylartemisinin (20), 13-(1-nitroethyl)artemisinin (21), (3R)-3-hydroxyartemisinin (22), and (3R)-3-acetoxyartemisinin (23). Among the analogues, only compound 20 had antimalarial activity comparable to artemisinin (1).

[The preparation and bioactivities of chiral analogs of baogongteng A]

Eight chiral analogs of baogongteng A were prepared from (+/-)-3 alpha-hydroxy-6 beta-acetoxytropane by chemical resolution. In myotic or mydriatic tests in rabbits, (-)-3 alpha-paramethyl benzenesulfonyloxy-6 beta-acetoxytropane showed cholinergic activities, while (+)-3 alpha-benzoyloxy-6 beta-acetoxytropane and (+)-3 alpha-parachloro benzoyloxy-6 beta-acetoxytropane showed anticholinergic activities.

Structure-activity relationships of the antimalarial agent artemisinin. 2. Effect of heteroatom substitution at O-11: synthesis and bioassay of N-alkyl-11-aza-9-desmethylartemisinins

A novel class of artemisinin analogs, N-alkyl-11-aza-9-desmethylartemisinins 17-29, were synthesized via ozonolysis and acid-catalyzed cyclization of precursor amides 5-16. These amides were prepared through condensation of an activated ester of the known intermediate acid 2 with the corresponding primary amine. The analogs were tested in vitro against W-2 and D-6 strains of Plasmodium falciparum and found in some cases to be more active than artemisinin. A comparison of the in vitro testing methods of Milhous and Makler was conducted and gave similar relative antimalarial activities for these artemisinin analogs. Log P values were determined for most of the compounds, but no apparent correlation between log P and in vitro activity was found.

Antimalarial activity of novel ring-contracted artemisinin derivatives

Bromoacetal 2 undergoes a novel ring-contracted reaction to give the aldehyde 3 in the presence of DBU or triethylamine. The aldehyde 3 is reduced to the alcohol 4 and oxidized to the carboxylic acid 5. The alcohol 4 reacts with dihydroartemisinin to give the two diastereoisomers 38 and 39. All the compounds were tested for antimalarial activity in mice infected with chloroquine sensitive Plasmodium berghei. If the activity of a compound was comparable to that of the standard compound, such as arteether, it was tested against chloroquine resistant NS strain infection in mice. Initially the compounds were administered subcutaneously, and if found to be active, they were tested by oral route. The antimalarial activity of compounds 19, 38, and 39 was found to be comparable to that of arteether when tested in K-173-infected mice. They were also active against chloroquine resistant NS strain infection in mice.

Extraction of artemisinin and artemisinic acid: preparation of artemether and new analogues

The preparation of artemether from artemisinin is reviewed. Firstly, the extraction of artemisinin from Artemisia annua is described and an estimation of the yield per hectare based on literature data is given. Artemisinin is reduced with sodium borohydride to produce dihydroartemisinin as a mixture of epimers. The mixture is treated with methanol and an acid catalyst to provide artemether. Increasing demand for use of artemether places pressure on the supply of artemisinin, and an alternative means of preparing the drug from artemisinic acid, an abundant constituent of A. annua, which could triple current yields, is described. In anticipation of problems of drug resistance emerging with the continued use of artemether and artesunate to treat malaria, development of new derivatives of artemisinin which have enhanced stability is required. Examples of such derivatives which have been prepared in our laboratories, or proposed, are described.