Unveiling the Mode of Action of Two Antibacterial Tanshinone Derivatives

Cryptotanshinone-Induced Permeabilization of Model Phospholipid Membranes: A Biophysical Study

The Danshen terpenoid cryptotanshinone (CPT) is gaining enormous interest in light of its various outstanding biological activities. Among those, CPT has been shown to interact with cell membranes and, for instance, to have antibacterial activity. Several works have shown that CPT alone, or in combination with other drugs, can effectively act as an antibiotic against various infectious bacteria. Some authors have related the mechanism underlying this action to CPT-membrane interaction. This work shows that CPT readily partitions into phosphatidylcholine membranes, but there is a limiting capacity of accommodation of ca. 1 mol CPT to 3 mol phospholipid. The addition of CPT to unilamellar liposomes composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) causes membrane permeabilization, as shown by fluorescent probe leakage. This process has been kinetically studied, as well as its modulation by incorporation of phosphatidylethanolamine or phosphatidylglycerol, as a model for pathogenic cell membranes. The thermotropic behavior of 1,2-dimyristoylphosphatidylcholine (DMPC) model membranes is weakly affected by CPT, but the terpenoid causes significant dehydration of the polar region of the bilayer and weak disordering of the acyl chain palisade, as observed in Fourier-transform infrared spectroscopy (FTIR) results. Small-angle X-ray scattering (SAXS) shows that CPT increases DMPC bilayer thickness, which could be due to localization near the phospholipid/water interface. Molecular dynamics (MD) simulations show that the lateral diffusion coefficient of the phospholipid increases with the presence of CPT. CPT extends from the polar head region to the center of the bilayer, being centered between the carbonyl groups and the unsaturated region of the POPC, where there is greater overlap. Interestingly, the free energy profiles of a water molecule crossing the lipid membrane show that the POPC membrane becomes more permeable in the presence of CPT. In summary, our results show that CPT perturbs the physicochemical properties of the phospholipid membrane and compromises its barrier function, which could be of relevance to explain part of its antimicrobial or anticancer activities.

Scaffold Hybrid of the Natural Product Tanshinone I with Piperidine for the Discovery of a Potent NLRP3 Inflammasome Inhibitor

Natural products provide inspiration and have proven to be the most valuable source for drug discovery. Herein, we report a scaffold hybrid strategy of Tanshinone I for the discovery of NLRP3 inflammasome inhibitors. 36 compounds were designed and synthesized, and the cheminformatic analyses showed that these compounds occupy a unique chemical space. The biological evaluation identified compounds 5j, 12a, and 12d as NLRP3 inflammasome inhibitors with significant potency, selectivity, and drug-likeness. Mechanistic studies revealed that these Tanshinone I derivatives could inhibit the degradation of the protein NLRP3 and block the oligomerization of NLRP3-induced apoptosis-associated speck-like proteins, thus inhibiting NLRP3 inflammasome activation. In addition, the water solubility, in vitro metabolic stability, and oral bioavailability of these compounds were also greatly improved compared to Tanshinone I. Therefore, this protocol provides a new structural evolution of Tanshinone I and a new class of potent NLRP3 inflammasome inhibitors.

Multifaceted Pharmacological Potentials of Curcumin, Genistein, and Tanshinone IIA through Proteomic Approaches: An In-Depth Review

Phytochemicals possess various intriguing pharmacological properties against diverse pathological conditions. Extensive studies are on-going to understand the structural/functional properties of phytochemicals as well as the molecular mechanisms of their therapeutic function against various disease conditions. Phytochemicals such as curcumin (Cur), genistein (Gen), and tanshinone-IIA (Tan IIA) have multifaceted therapeutic potentials and various efforts are in progress to understand the molecular dynamics of their function with different tools and technologies. Cur is an active lipophilic polyphenol with pleiotropic function, and it has been shown to possess various intriguing properties including antioxidant, anti-inflammatory, anti-microbial, anticancer, and anti-genotoxic properties besides others beneficial properties. Similarly, Gen (an isoflavone) exhibits a wide range of vital functions including antioxidant, anti-inflammatory, pro-apoptotic, anti-proliferative, anti-angiogenic activities etc. In addition, Tan IIA, a lipophilic compound, possesses antioxidant, anti-angiogenic, anti-inflammatory, anticancer activities, and so on. Over the last few decades, the field of proteomics has garnered great momentum mainly attributed to the recent advancement in mass spectrometry (MS) techniques. It is envisaged that the proteomics technology has considerably contributed to the biomedical research endeavors lately. Interestingly, they have also been explored as a reliable approach to understand the molecular intricacies related to phytochemical-based therapeutic interventions. The present review provides an overview of the proteomics studies performed to unravel the underlying molecular intricacies of various phytochemicals such as Cur, Gen, and Tan IIA. This in-depth study will help the researchers in better understanding of the pharmacological potential of the phytochemicals at the proteomics level. Certainly, this review will be highly instrumental in catalyzing the translational shift from phytochemical-based biomedical research to clinical practice in the near future.

Research and Development of Natural Product Tanshinone I: Pharmacology, Total Synthesis, and Structure Modifications

Salvia miltiorrhiza (S. miltiorrhiza), which has been used for thousands of years to treat cardiovascular diseases, is a well-known Chinese medicinal plant. The fat-soluble tanshinones in S. miltiorrhiza are important biologically active ingredients including tanshinone I, tanshinone IIA, dihydrotanshinone, and cryptotanshinone. Tanshinone I, a natural diterpenoid quinone compound widely used in traditional Chinese medicine, has a wide range of biological effects including anti-cancer, antioxidant, neuroprotective, and anti-inflammatory activities. To further improve its potency, water solubility, and bioavailability, tanshinone I can be used as a platform for drug discovery to generate high-quality drug candidates with unique targets and enhanced drug properties. Numerous derivatives of tanshinone I have been developed and have contributed to major advances in the identification of new drugs to treat human cancers and other diseases and in the study of related molecular mechanisms. This review focuses on the structural modification, total synthesis, and pharmacology of tanshinone I. We hope that this review will help understanding the research progress in this field and provide constructive suggestions for further research on tanshinone I.

The anti-infective activity of Salvia miltiorrhiza against Staphylococcus aureus by attenuating accessory gene regulator system-mediated virulence

Due to the rapid evolution of antibiotic resistance in Staphylococcus aureus, antivirulence therapy may be a promising alternative for the effective control of the spread of resistant pathogens. The Chinese Materia Medica has been widely used for the treatment of diseases and production of health foods, and it remains a valuable resource for the discovery of compounds possessing antivirulence activity. Through a Caenorhabditis elegans infection model, an EtOAc-soluble fraction of 80% EtOH extract of Salvia miltiorrhiza Bunge (SMEA) was found to possess potential anti-infective activity against S. aureus. Then, several in vitro assays indicated that SMEA had robust antivirulence activity at the dose of 400 μg mL^-1, reducing hemolytic activity and α-hemolysin expression in S. aureus. Furthermore, at 100 mg kg^-1, SMEA reduced abscess formation in the main organs of mice challenged with S. aureus. In order to identify the bioactive components of SMEA and investigate the mechanisms underlying the antivirulence activity, SMEA was separated using bioassay-guided fractionation. As a result, eight compounds were identified in SMEA. Among them, tanshinone IIB (TNB) showed strong antivirulence activity both in vitro and in vivo. Furthermore, at 24 μg mL^-1, TNB significantly reduced the expression of RNAIII and psmα, indicating that the mechanism underlying TNB activity was related to the accessory gene regulator quorum sensing system. In conclusion, TNB's antivirulence properties make it a promising candidate for drug development against S. aureus infections.

Phytochemical and anti-MRSA constituents of Zanthoxylum nitidum

Infectious diseases caused by multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, pose a significant threat to humanity. Persistent and repeated invasive infection with MRSA led to higher morbidity and mortality, and required comprehensive measures in treatment and prevention. Zanthoxylum nitidum (Roxb.) DC. is used as detoxifying, analgesic, and hemostatic herbal medicine for thousands of years. Previously pharmacological studies showed that Z. nitidum had antibacterial bioactivity, but only the MIC of a few compounds, crude extracts, and fractions were reported. In our ongoing endeavor to explore bioactive compounds, two new coumarins, 6-(3-oxo-butyl)-limettin (1) and toddalin I (2), and 24 known compounds were isolated from the roots of Z. nitidum, in which two isoquinoline alkaloids, 6-acetonyl-dihydrofagaridine (16) and 6-acetonyl-dihydrochelerythrine (17) showed anti-MRSA bioactivity in vitro and in vivo. Both 16 and 17 showed synergistic action with ampicillin, which decreased the MIC significantly, and both compounds had a significant ability to destroy bacterial biofilm combined with ampicillin. The combined administration showed a strong scavenging effect on the planktonic bacteria in vitro and cleared skin infection effectively in the model of wound infection in vivo. Furthermore, compound 16 inhibited the efflux of the drug by combining with ampicillin or EtBr, resulting in the MIC decreased obviously. Our investigation supported the traditional use of Z. nitidum in treating infections caused by bacteria, and might provide new natural products to reduce the use of antibiotics and the treatment of drug-resistance bacteria.

Bioguided isolation, identification and bioactivity evaluation of anti-MRSA constituents from Morus alba Linn

ETHNOPHARMACOLOGY RELEVANCE

The root bark of Morus alba Linn. (M. alba), a traditional folk medicine, has been documented in the Chinese Pharmacopoeia, which has been widely used for asthma, fever, pneumonia, edema, vomit, colitis, bronchitis and keratitis diseases. Some of the diseases may be related to respiratory, digestive, urinary tract infections. Although Diels-Alder adducts (DAAs), flavonoids, 2-arylbenzofurans and stilbene compounds have been isolated from the root bark of M. alba, few compounds are reported for their antimicrobial efficacy in vivo and the mechanism.

AIM OF THE STUDY

The aim of the study was to isolate and identify compounds of the root bark of M. alba in view of their anti-MRSA bioactivity, evaluate the anti-MRSA bioactivity of compounds and 60% ethanol elution (MA-6) in vitro and in vivo, and explore preliminary antibacterial mechanism in order to provide natural resources against MRSA infection.

MATERIALS AND METHODS

Systematic phytochemical investigations were carried out according to the thin layer chromatography (TLC) of the active fraction MA-6 to find more anti-MRSA ingredients. The compounds of the root bark of M. alba were separated by column chromatography and identified by LC-MS/MS and NMR spectroscopy. The anti-MRSA efficacy of the active ingredients were evaluated by broth microdilution method and a murine infection model. The mode of action of compounds was explored by time-kill curve and post-contact effect. The preliminary mechanism of compounds against MRSA was explored by drug efflux pumps and bacterial biofilms.

RESULTS

Chemical isolation resulted in twenty-nine known compounds, most with one or more geranyl and prenyl units exhibited superior anti-MRSA bioactivity, with MIC values of 2-16 μg/mL. In addition, the mode of action indicated that compounds presented persistent antimicrobial effect, which also produced concentration-dependent and time-dependent killing activity or property. Preliminary mechanism showed that the compound kuwanon O (29) damaged the bacterial cell membranes, leading to the accumulation of antibiotics inside bacterial cells, moreover, MA-6 and kuwanon O (29) inhibited the efflux of drugs by combining with methicillin or ethidium bromide (EtBr), resulting in the MICs of EtBr and methicillin were obviously decreased three-fold. The anti-MRSA efficacy in vivo indicated that the active fraction MA-6 could reduce bacteria in spleen, liver, kidney and mortality of acutely infectious mice, which was better than the positive drug berberine chloride.

CONCLUSION

Experimental investigation showed that the MA-6 and compound 29 have promising bioactivity against MRSA in vitro and in vivo, which might be used as a potential source of new antibacterial medicine or a potential efflux pump inhibitor against MRSA infection.

Design, synthesis and biological evaluation of tanshinone IIA-based analogues: Potent inhibitors of microtubule formation and angiogenesis

We report the structural optimization of tanshinone IIA, a natural product which possesses anti-tumor properties but low water-solubility, weak antiproliferative activity and poor PK properties. A new series of ring A/C/D modified tanshinone analogues were synthesized and studied for their antiproliferative capacities against six human cancer cell lines. SAR study revealed that ring A cleavage of tanshinone IIA led to improved anti-cancer activity. Introduction of a methoxy group to the phenyl ring could enhance the anti-cancer activity even further. Compound 2f with methoxy group at C-8 position was selected as an early lead with IC₅₀ values of 0.28-3.16 μM against six tested cell lines. 2f could bind to tubulin colchicine site, inhibit tubulin assembly and disrupt the normal formation of microtubule networks. Cellular mechanistic studies revealed that 2f induced apoptotic cell death of A549 cells in a dose-dependent manner. In vitro investigations showed that 2f impeded the tubule-formation of HUVECs and potently inhibited the proliferation, migration and invasion of A549 cells as well as HUVECs. Furthermore, the in vivo anti-angiogenic effect of 2f was confirmed via a zebrafish model test. The satisfactory physicochemical property and metabolic stability of 2f, as well as improved water-solubility, further suggested that 2f could serve as a promising tubulin inhibitor and anti-angiogenic agent.

The Influence of Selected Factors on the Aqueous Cryptotanshinone Solubility

The application of cryptotanshinone (CT), a diterpenoid obtained from the root of Salviae miltiorrhiza, is significantly hindered due to its poor aqueous solubility. The aim of the present research was to develop an optimal solvent for analytical and preparative procedures of prospective dermal hydrogel formulations with CT. The influence of pH, temperature, and cosolvent presence on the solubility of CT was examined. Various components were applied to increase CT solubility, i.e., ethanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-(hydroxymethyl)-1,3-propanediol, 2,2′,2″-nitrilotriethanol, and triisopropanoloamine. The concentration of CT was analyzed by spectral and chromatographic methods, including UV–vis and HPLC methods. The increased solubility of CT was demonstrated in alkaline solvents with ethanol as a cosolvent. CT solutions doped with alcoholamines are more stable compared to CT solutions doped with NaOH.

Tanshinones: An Update in the Medicinal Chemistry in Recent 5 Years

Tanshinones are an important type of natural products isolated from Salvia miltiorrhiza Bunge with various bioactivities. Tanshinone IIa, cryptotanshinone and tanshinone I are three kinds of tanshinones which have been widely investigated. Particularly, sodium tanshinone IIa sulfonate is a water-soluble derivative of tanshinone IIa and it is used in clinical in China for treating cardiovascular diseases. In recent years, there are increasing interests in the investigation of tanshinones derivatives in various diseases. This article presents a review of the anti-atherosclerotic effects, cardioprotective effects, anticancer activities, antibacterial activities and antiviral activities of tanshinones and structural modification work in recent years.

Tanshinone I and Tanshinone IIA/B attenuate LPS-induced mastitis via regulating the NF-κB

BACKGROUND

Mastitis is a common disease occurs in breast-feeding mothers, but published data are poor. This study aimed to study the effects of Tanshinones on treating mastitis.

METHODS

Clinical trials performed in 58 breast-feeding mothers were carried out. B-ultrasound and blood test were used to measure the size of breast mass and the change of blood cell counts. BALB/c mice were injected with LPS and then treated by Tanshinone I or Tanshinone IIA/B. Myeloperoxidase (MPO) activity and the release of inflammatory cytokines were tested by MPO kit, RT-qPCR and ELISA. Mouse mammary epithelial cells (mMECs) were isolated and the effects of Tanshinones were measured by conducting CCK-8 assay, flow cytometry, RT-qPCR and ELISA.

RESULTS

Patients treated by Cefprozil combined with Tanshinone got better outcomes than patients treated by Cefprozil alone. In animal trials, Tanshinone I and Tanshinone IIA/B significantly reduced MPO activity, and the levels of TNF-α, IL-1β and IL-6 in serum and mammary gland tissues. In mMECs, Tanshinone I and Tanshinone IIA/B attenuated LPS-induced viability loss and apoptosis. And they effectively inhibited the release of TNF-α, IL-1β and IL-6. Also, Tanshinone I and Tanshinone IIA/B significantly attenuated LPS-evoked NF-κB activation.

CONCLUSION

Tanshinone I and Tanshinone IIA/B have potentials in treating mastitis. The beneficial effects might be through regulating NF-κB activation.

Cationic Pyrrolidine/Pyrroline-Substituted Porphyrins as Efficient Photosensitizers against E. coli

New porphyrin–pyrrolidine/pyrroline conjugates were prepared by revisiting 1,3-dipolar cycloaddition reactions between a porphyrinic azomethine ylide and a series of dipolarophiles. Cationic conjugates obtained by alkylation of the pyrrolidine/pyrroline cycloadducts showed ability to generate singlet oxygen and to produce iodine in presence of KI when irradiated with visible light. Some of the cationic derivatives showed photobactericidal properties towards a Gram-negative bioluminescent E. coli. In all cases, these features were significantly improved using KI as coadjutant, allowing, under the tested conditions, the photoinactivation of the bacterium until the detection limit of the method with a drastic reduction of the required photosensitizer concentration and irradiation time. The obtained results showed a high correlation between the ability of the cationic porphyrin derivative to produce singlet oxygen and iodine and its E. coli photoinactivation profile.

Mechanism of tanshinones and phenolic acids from Danshen in the treatment of coronary heart disease based on co-expression network

Background

The tanshinones and phenolic acids in Salvia miltiorrhiza (also named Danshen) have been confirmed for the treatment of coronary heart disease (CHD), but the action mechanisms remain elusive.

Methods

In the current study, the co-expression protein interaction network (Ce-PIN) was used to illustrate the differences between the tanshinones and phenolic acids of Danshen in the treatment of CHD. By integrating the gene expression profile data and protein-protein interactions (PPIs) data, the Ce-PINs of tanshinones and phenolic acids were constructed. Then, the Ce-PINs were analyzed by gene ontology enrichment analyzed based on the optimal algorithm.

Results

It turned out that Danshen is able to treat CHD by regulating the blood circulation, immune response and lipid metabolism. However, phenolic acids may regulate the blood circulation by Extracellular calcium-sensing receptor (CaSR), Endothelin-1 receptor (EDNRA), Endothelin-1 receptor (EDNRB), Kininogen-1 (KNG1), tanshinones may regulate the blood circulation by Guanylate cyclase soluble subunit alpha-1 (GUCY1A3) and Guanylate cyclase soluble subunit beta-1 (GUCY1B3). In addition, both the phenolic acids and tanshinones may regulate the immune response or inflammation by T-cell surface glycoprotein CD4 (CD4), Receptor-type tyrosine-protein phosphatase C (PTPRC).

Conclusion

Through the same targets of the same biological process and different targets of the same biological process, the tanshinones and phenolic acids synergistically treat coronary heart disease.

Up-scaling of tannin-based coagulants for wastewater treatment: performance in a water treatment plant

Tannin extracts from the bark of Acacia mearnsii and wood of Schinopsis balansae, commonly known as Quebracho, were employed. These were modified at laboratory sale via the Mannich aminomethylation with formaldehyde and dimethylamine hydrochloride. Some reaction conditions were varied, namely the formaldehyde dosage and reaction time, while keeping the Mannich solution activation time constant, and their influence on the shear viscosity of the created bio-coagulants was evaluated. The effect of the final pH of the products on their shear viscosity was also analyzed. Up-scaling of the Mannich reaction for tannin from South Africa was performed and the procedure developed at 1-L scale was reproducible in upscaled conditions. One example of a modified South Africa tannin and the modified Quebracho tannin was subsequently selected for the treatment of an industrial wastewater and tested for color and turbidity reduction in jar tests. The effluent treatment was carried out in a single and dual system with cationic synthetic flocculation agents of different charge degree. Good turbidity and decoloration results (93 and 89% reduction, respectively) were obtained with the simultaneous introduction of a cationic, 40% charged polyacrylamide, with minimal dosage (5 ppm) of the latter additive. The tannin-based coagulant from Acacia mearnsii was successfully applied in dual system with cationic polyacrylamide flocculant for industrial wastewater treatment at pilot plant scale. It was shown to satisfactorily treat the water and generate less sludge.

SmbHLH3 acts as a transcription repressor for both phenolic acids and tanshinone biosynthesis in Salvia miltiorrhiza hairy roots

Phenolic acids and tanshinones are the two groups of pharmaceutically active metabolites in Salvia miltiorrhiza Bunge. Their contents are the key quality indicator to evaluate S. miltiorrhiza. bHLH transcription factors have important roles in regulation of plant specialised metabolism. In this study, an endogenous bHLH transcription factor, SmbHLH3, was identified and functionally analyzed. SmbHLH3 was presented in all the six tissues and mostly expressed in fibrous roots and flowers. It was localized to the nucleus. Overexpression of SmbHLH3 decreased both phenolic acids and tanshinones contents. Contents of caffeic acid and rosmarinic acid were both decreased to 50% of the control. And accumulation of salvianolic acid B was decreased as much as 62%. Content of cryptotanshinone, dihydrotanshinone I, tanshinone I and tanshinone IIA in SmbHLH3-overexpression lines were reduced 97%, 62%, 86% and 91%, respectively. In the transgenic lines, expression of C4H1, TAT and HPPR in phenolic acids pathways were reduced to about 43%, 66% and 77% of the control, respectively. For tanshinone biosynthetic pathways, transcripts of DXS3, DXR, HMGR1, KSL1, CPS1 and CYP76AH1 were reduced to 46%, 65%, 78%, 57%, 27% and 62% of the control, respectively. There was an E/G-box specific binding site in SmbHLH3, which may bind the E/G-box present in promoter region of these biosynthetic pathway genes. Y1H results indicated that SmbHLH3 could bind the promoter of TAT, HPPR, KSL1 and CYP76AH1. These findings indicated that SmbHLH3 downregulate both phenolic acids and tanshinone accumulation through directly suppressing the transcription of key enzyme genes.

Overexpression of SmbHLH148 induced biosynthesis of tanshinones as well as phenolic acids in Salvia miltiorrhiza hairy roots

SmbHLH148 activated the whole biosynthetic pathways of phenolic acids and tanshinones, thus upregulated the production of both the two groups of pharmaceutical ingredients in Salvia miltiorrhiza. Phenolic acids and tanshinones are the two important groups of pharmaceutical ingredients presented in Salvia miltiorrhiza Bunge. The bHLH transcription factors could regulate secondary metabolism efficiently in plants. However, there are only some MYCs have been studied on regulation of either phenolic acids or tanshinones biosynthesis. In this study, a bHLH TF named SmbHLH148, which is homologous to AtbHLH148, AtbHLH147 and CubHLH1, was isolated and functionally characterized from S. miltiorrhiza. Transcription of SmbHLH148 could be intensely induced by ABA and also be moderately induced by MeJA and GA. SmbHLH148 is present in all the six tissues and mostly expressed in fibrous root and flowers. Subcellular localization analysis found that SmbHLH148 was localized in the nucleus. Overexpression of SmbHLH148 significantly increased not only three phenolic acids components accumulation but also three tanshinones content. Content of caffeic acid, rosmarinic acid and salvianolic acid B were reached to 2.87-, 4.00- and 5.99-fold of the control in the ObHLH148-3, respectively. Content of dihydrotanshinone I, cryptotanshinone, and tanshinone I were also present highest in ObHLH148-3, reached 2.5-, 5.04- and 3.97-fold of the control, respectively. Expression analysis of pathway genes of phenolic acids and tanshinones in transgenic lines showed that most of them were obviously upregulated. Moreover, transcription of AREB and JAZs were also induced in SmbHLH148 overexpression lines. These results suggested that SmbHLH148 might be taken part in ABA and MeJA signaling and activated almost the whole biosynthetic pathways of phenolic acids and tanshinones, thus the production of phenolic acids and tanshinones were upregulated.

Overexpression of SmbHLH10 enhances tanshinones biosynthesis in Salvia miltiorrhiza hairy roots

The bHLH transcription factors have important role in regulation of plant growth, development, and secondary metabolism. Tanshinones are the major pharmaceutical components present in Salvia miltiorrhiza Bunge. It has been reported that bHLHs have functions in terpenoids biosynthesis. Here, we got a bHLH family member named SmbHLH10 which could positively regulate tanshinones biosynthesis in S. miltiorrhiza hairy roots. In the SmbHLH10-overexpressing line 6, four major tanshinones contents were reaching 2.51-fold (dihydrotanshinone I), 2.84-fold (cryptotanshinone), 2.89- fold (tanshinone I), 2.68-fold (tanshinone II A) of WT, respectively. The variation in tanshinones biosynthetic pathway gene transcription was generally consistent with tanshinones content. DXS2, DXS3 and DXR of MEP pathway were induced substantially, reaching 10-fold, 3-fold, 5.74-fold higher of the WT, respectively. The downstream pathway genes CPS1, CPS5 and CYP76AH1 were highest in line OE-SmbHLH10-6, reached 4.93, 16.29 and 3.27-fold of the WT, respectively, while KSL1's expression was highest in line OE-SmbHLH10-4, 4.64-fold of WT. Yeast one-hybrid assays results showed that SmbHLH10 could binds the predicted G-box motifs within the promoters of DXS2, CPS1 and CPS5. These findings indicated that SmbHLH10 could directly binds to G-box in the pathway genes' promotor, activate their expression and then upregulate tanshinones biosynthesis.

Novel small molecules affecting cell membrane as potential therapeutics for avian pathogenic Escherichia coli

Avian pathogenic Escherichia coli (APEC), a most common bacterial pathogen of poultry, causes multiple extra-intestinal diseases in poultry which results in significant economic losses to the poultry industry worldwide. In addition, APEC are a subgroup of extra-intestinal pathogenic E. coli (ExPEC), and APEC contaminated poultry products are a potential source of foodborne ExPEC infections to humans and transfer of antimicrobial resistant genes. The emergence of multi-drug resistant APEC strains and the limited efficacy of vaccines necessitate novel APEC control approaches. Here, we screened a small molecule (SM) library and identified 11 SMs bactericidal to APEC. The identified SMs were effective against multiple APEC serotypes, biofilm embedded APEC, antimicrobials resistant APECs, and other pathogenic E. coli strains. Microscopy revealed that these SMs affect the APEC cell membrane. Exposure of SMs to APEC revealed no resistance. Most SMs showed low toxicity towards chicken and human cells and reduced the intracellular APEC load. Treatment with most SMs extended the wax moth larval survival and reduced the intra-larval APEC load. Our studies could facilitate the development of antimicrobial therapeutics for the effective management of APEC infections in poultry as well as other E. coli related foodborne zoonosis, including APEC related ExPEC infections in humans.

In Vitro Antibacterial Activity of Teixobactin Derivatives on Clinically Relevant Bacterial Isolates

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) are included on the WHO high priority list of pathogens that require urgent intervention. Hence emphasis needs to be placed on developing novel class of molecules to tackle these pathogens. Teixobactin is a new class of antibiotic that has demonstrated antimicrobial activity against common bacteria. Here we examined the antimicrobial properties of three Teixobactin derivatives against clinically relevant bacterial isolates taken from South African patients. The minimum inhibitory concentration (MIC), the minimal bactericidal concentration (MBC), the effect of serum on MICs and the time-kill kinetics studies of our synthesized Teixobactin derivatives (3, 4, and 5) were ascertained following the CLSI 2017 guidelines and using the broth microdilution method. Haemolysis on red blood cells (RBCs) and cytotoxicity on peripheral blood mononuclear cells (PBMCs) were performed to determine the safety of these compounds. The MICs of 3, 4, and 5 against reference strains were 4–64 μg/ml, 2–64 μg/ml, and 0.5–64 μg/ml, respectively. The MICs observed for MRSA were (3) 32 μg/ml, (4) 2–4 μg/ml and (5) 2–4 μg/ml whilst those for VRE were (3) 8–16 μg/ml, (4) 4 μg/ml and (5) 2–16 μg/ml, respectively. In the presence of 50% human serum, there was no significant effect on the MICs. The compounds did not exhibit any effect on cell viability at their effective concentrations. Teixobactin derivatives (3, 4, and 5) inhibited bacterial growth in drug-resistant bacteria and hence emerge as potential antimicrobial agents. Molecular dynamic simulations suggested that the most dominant binding mode of Lys10-teixobactin (4) to lipid II is through the amide protons of the cycle, which is identical to data described in the literature for the natural teixobactin hence predicting the possibility of a similar mechanism of action.

Tanshinones and mental diseases: from chemistry to medicine

The prevalence of mental diseases, especially neurodegenerative disorders, is ever-increasing, while treatment options for such disorders are limited and insufficient. In this scarcity of available medication, it is a feasible strategy to search for potential drugs among natural compounds, such as those found in plants. One such plant source is the root of Chinese sage, Salvia miltiorrhiza Bunge (Labiatae), which contains several compounds reported to possess neuroprotective activities. The most important of these compounds are tanshinones, which have been reported to possess ameliorative activity against a myriad of mental diseases such as Alzheimer’s disease, cerebral ischemia/reperfusion injury, and glioma, along with promoting neuronal differentiation and manifesting antinociceptive and anticonvulsant outcomes. This review offers a critical evaluation of the utility of tanshinones to treat mental illnesses, and sheds light on the underlying mechanisms through which these naturally occurring compounds confer neuroprotection.

Molecular Mechanisms of Cardioprotective Actions of Tanshinones

Tanshinones are lipophilic compounds derived fromSalvia miltiorrhiza(Danshen) that has been widely used to treat coronary heart diseases in China. The cardioprotective actions of tanshinones have been extensively studied in various models of myocardial infarction, cardiac ischemia reperfusion injury, cardiac hypertrophy, atherosclerosis, hypoxia, and cardiomyopathy. This review outlines the recent development in understanding the molecular mechanisms and signaling pathways involved in the cardioprotective actions of tanshinones, in particular on mitochondrial apoptosis, calcium, nitric oxide, ROS, TNF-α, PKC, PI3K/Akt, IKK/NF-κB, and TGF-β1/Smad mechanisms, which highlights the potential of these compounds as therapeutic agents for treating cardiovascular diseases.

Antibacterial Activity of Shikimic Acid from Pine Needles of Cedrus deodara against Staphylococcus aureus through Damage to Cell Membrane

Shikimic acid (SA) has been reported to possess antibacterial activity against Staphylococcus aureus, whereas the mode of action of SA is still elusive. In this study, the antibacterial activity and mechanism of SA toward S. aureus by cell membrane damage was investigated. After SA treatment, massive K⁺ and nucleotide leakage from S. aureus, and a significant change in the membrane potential was observed, suggesting SA may act on the membrane by destroying the cell membrane permeability. Through transmission electron microscopic observations we further confirmed that SA can disrupt the cell membrane and membrane integrity. Meanwhile, SA was found to be capable of reducing the membrane fluidity of the S. aureus cell. Moreover, the fluorescence experiments indicated that SA could quench fluorescence of Phe residues of the membrane proteins, thus demonstrating that SA can bind to S. aureus membrane proteins. Therefore, these results showed the antibacterial activity of SA against S. aureus could be caused by the interactions of SA with S. aureus membrane proteins and lipids, resulting in causing cell membrane dysfunction and bacterial damage or even death. This study reveals the potential use of SA as an antibacterial agent.