Growth-inhibitory and apoptosis-inducing effects of tanshinones on hematological malignancy cells and their structure–activity relationship

Reassessing the molecular structures of some previously isolated abietane diterpenoids with a naphthalene moiety and the structure-activity relationship (SAR) of quinone diterpenoids

Crystals of previously described para-naphthoquinone abietane diterpenoids 12,16-dideoxy-aegyptinone B and 12-deoxy-salvipisone were obtained from Zhumeria majdae Rech.f. & Wendelbo. However, single-crystal X-ray diffraction analysis followed by reinterpretation of their NMR data revealed that their structures require revision, and they should be revised to the two ortho-naphthoquinones, zhumerianone C and aethiopinone, respectively. Interestingly, a further search through literature revealed that there were more of such cases, in which differentiation between the ortho-/para-orientation had not been carried out correctly in the structure elucidation of naphthalene containing abietane diterpenoids. Therefore, in the current study, we pointed out some 1D and 2D NMR generalizations that would help the unambiguous deduction of the ortho-/para-orientation of naphthalene containing abietanes and revised the structure of some previously described compounds accordingly. Based on these generalizations, structures of sibiriquinones A and B, sahandinone, and sahandone were revised to the known structures 1,2-didehydromiltirone, miltirone, saprorthoquinone, and sahandone B, respectivelyand tebesinone B, arucadiol, and sahandol II were revised to three undescribed structures. It was also proposed that structures of palmitoyl arucadiol and compounds with the salvifolane skeleton need revision. Furthermore, these structure revisions shed light on the structure-activity relationship of the quinone diterpenoids, approving that the ortho-quinone is the critical structural component for cytotoxicity in these compounds.

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.

Investigation of cytotoxic and apoptotic effects of 63 compounds obtained from Salvia species: Promising anticancer agents

Since ancient time, Salvia L. species have been commonly used to treat colds, bronchitis, tuberculosis, heart diseases, and menstrual and digestive disorders in traditional medicine all around the world. They have been also used as tea and spice. Studies indicated that diterpenes and triterpenes isolated from Salvia species possess various pharmacological and biological effects such as anti-inflammatory, antiviral, cytotoxic, antioxidant, and hepatotoxic activities. Flavones were also shown to have antimicrobial, antioxidant, and cytotoxic potentials. Salvia extracts also exhibit anti-Alzheimer, antiseptic, cardiovascular, antihypertensive, and antituberculous effects. To investigate the effects of 63 secondary metabolites from Salvia species on cell viability and apoptosis, Salvia secondary metabolites including 25 phenolics, 4 fatty acids, 19 abietane diterpenoids, 12 triterpenoids, and three steroids were examined on healthy cell line (PDF), breast cancer (MCF-7), and colon cancer (HT-29) cell lines using MTT method. In addition, the effects of rosmarinic acid, 6,7-dehydroroyleanone, acetyl royleanone, ferruginol, carnosic acid, carnosol, cryptotanshinone, β-sitosterol, and ursolic acid on pro-apoptotic Bax and antiapoptotic Bcl-2 protein expression levels were investigated by Western Blot method. PRACTICAL APPLICATIONS: Phenolic compounds (apigenin, chrysin, and luteolin) and diterpenes (especially dihydrotanshinone I, carnosic acid, and carnosol), and almost all of the triterpenes exhibited high toxic effects on healthy cell line. Cytotoxic effects of cryptotanshinone, 12-hydroxy abieta-1,3,5(10),8,11,13-hexaene, 12-demethylmulticauline, 6,7-dehydroroyleanone, acetyl royleanone, ferruginol, ursolic acid, and 3-acetyl lupeol were relatively higher than their toxic effects. Acetyl royleanone, 6,7-dehydroroyleanone, carnosic acid, and cryptotanshinone were found to have anticancer potential based on their modulating effects on the expression levels of Bax and Bcl-2 proteins which play important roles in the regulation of apoptosis. The results of the present study showed that acetyl royleanone, cryptotanshinone, 6,7-dehydroroyleanone, carnosic acid, and cryptotanshinone have potential to be used in the pharmaceutical industry.

Discovery and characterization of natural products as novel indoleamine 2,3-dioxygenase 1 inhibitors through high-throughput screening

Indoleamine 2,3-dioxygenase 1 (IDO1) is emerging as a promising therapeutic target for the treatment of malignant tumors characterized by dysregulated tryptophan metabolism. However, the antitumor efficacy of existing small-molecule IDO1 inhibitors is still unsatisfactory, and the underlying mechanism remains largely undefined. To identify novel IDO1 inhibitors, an in-house natural product library of 2000 natural products was screened for inhibitory activity against recombinant human IDO1. High-throughput fluorescence-based screening identified 79 compounds with inhibitory activity > 30% at 20 μM. Nine natural products were further confirmed to inhibit IDO1 activity by > 30% using Ehrlich’s reagent reaction. Compounds 2, 7, and 8 were demonstrated to inhibit IDO1 activity in a cellular context. Compounds 2 and 7 were more potent against IDO1 than TDO2 in the enzymatic assay. The kinetic studies showed that compound 2 exhibited noncompetitive inhibition, whereas compounds 7 and 8 were graphically well matched with uncompetitive inhibition. Compounds 7 and 8 were found to bind to the ferric-IDO1 enzyme. Docking stimulations showed that the naphthalene ring of compound 8 formed “T-shaped” π–π interactions with Phe-163 and that the 6-methyl-naphthalene group formed additional hydrophobic interactions with IDO1. Compound 8 was identified as a derivative of tanshinone, and preliminary SAR analysis indicated that tanshinone derivatives may be promising hits for the development of IDO1 inhibitors. This study provides new clues for the discovery of IDO1/TDO2 inhibitors with novel scaffolds.

Pharmacological activities of dihydrotanshinone I, a natural product from Salvia miltiorrhiza Bunge

Salvia miltiorrhiza Bunge (Danshen), a famous traditional Chinese herb, has been used clinically for the treatment of various diseases for centuries. Document data showed that tanshinones, a class of lipophilic abietane diterpenes rich in this herb, possess multiple biological effects in vitro and in vivo models. Among which, 15,16-dihydrotanshinone I (DHT) has received much attention in recent years. In this systematical review, we carefully selected, analyzed, and summarized high-quality publications related to pharmacological effects and the underlying mechanisms of DHT. DHT has anti-cancer, cardiovascular protective, anti-inflammation, anti-Alzheimer's disease, and other effects. Furthermore, several molecules such as hypoxia-inducible factor (HIF-1α), human antigen R (HuR), acetylcholinesterase (AchE), etc. have been identified as the potential targets for DHT. The diverse pharmacological activities of DHT provide scientific evidence for the local and traditional uses of Salvia miltiorrhiza Bunge. We concluded that DHT might serve as a lead compound for drug discovery in related diseases while further in-depth investigations are still needed.

Exploring the Mechanism of Danshen against Myelofibrosis by Network Pharmacology and Molecular Docking

Danshen (Salvia miltiorrhiza Bunge), a natural powerful drug for various conditions treatment, has traditionally been used in Asian countries for centuries as anticancer agent, anti-inflammatory agent, and antioxidant. More recently, it is explored in combination with other herbs for skeletal diseases therapy; bone-targeting compounds with pharmacological activities have been isolated from various sources of traditional Chinese medicine (TCM), including Danshen. In this case, some evidence supports that Danshen may treat myelofibrosis (MF) by exerting its antitumor effect. To study the specific mechanism of Danshen in the treatment of MF, we used bioinformatics databases to determine its active ingredients. Then, identification of target proteins related to MF was made using a network pharmacology analysis platform. In our results, 20 key active compounds and 457 key targets of Danshen were identified. In-depth network analysis of the top diseases, functions, and pathways suggested that a common underlying mechanism linked Danshen involvement with MF. Finally, 5 potential targets were confirmed by the analysis; these 5 targets, as well as 20 previously identified compounds, were subjected to molecular docking experiments. The results indicated that cryptotanshinone of Danshen may affect MF by acting on the key genes in the JAK-STAT signalling pathway and the TGF-β signalling pathway.

Cytotoxic effects of solvent-extracted active components of Salvia miltiorrhiza Bunge on human cancer cell lines

Herbal extracts and dietary supplements may be extracted from the medicinal plants used in traditional Chinese medicine, and are used increasingly commonly worldwide for their benefits to health and quality of life. Thus, ensuring that they are safe for human consumption is a critical issue for the preparation of plant extracts as dietary supplements. The present study investigated extracts of Salvia miltiorrhiza Bunge (S. miltiorrhiza), traditionally used in Asian countries to treat a variety of conditions, as a dietary supplement or as an ingredient in functional foods. Dried S. miltiorrhiza root was extracted with various solvents and under varying extraction conditions, and the effects of the extracts on the viability of five human cancer cell lines were compared. Extracts obtained using 100% ethanol and 100% acetone as solvents exhibited more potent effects compared with extracts obtained using 70 and 30% aqueous ethanol. Furthermore, the active components of S. miltiorrhiza ethanol extracts, known as tanshinones, were investigated. Dihydrotanshinone I was observed to exhibit a higher cytotoxic potential compared with the other tanshinones in the majority of the examined cell lines. Conversely, cryptotanshinone exhibited weak anti-cancer activity. In summary, the results of the present study suggest that the active components obtained from an ethanol extract of S. miltiorrhiza possess the potential to be used as ingredients in functional and health care foods that may be used to improve the effectiveness of chemotherapeutics in the prevention and/or treatment of cancer.

Signal transducer and activators of transcription 3 regulates cryptotanshinone-induced apoptosis in human mucoepidermoid carcinoma cells

Background:

Cryptotanshinone (CT) is a biologically active compound from the root of Salvia miltiorrhiza that has been reported to induce apoptosis in various cancer cell lines; but, it has not yet been fully explored in human mucoepidermoid carcinoma (MEC).

Objective:

Here, we demonstrated the apoptotic effects and its related mechanism in MC-3 and YD-15 human MEC cell lines.

Materials and Methods:

The effects of CT on apoptotic activity were evaluated by cell proliferation assay, Western blotting, 4’-6-diamidino-2-phenylindole staining, reverse transcription-polymerase chain reaction, and luciferase assay.

Results:

Our data show that CT treatment of MC-3 cells results in anti-proliferative and apoptotic activities in MC-3 and it is accompanied by a decrease in phosphorylation and dimerization of signal transducer and activators of transcription 3 (STAT3). CT decreased the expression levels of myeloid cell leukemia-1 (Mcl-1) and surviving, whereas Bcl-xL expression was not changed. CT clearly regulates survivin protein at a transcriptional level and alters Mcl-1 through proteasome-dependent protein degradation. In addition, CT-induced apoptotic cell death in YD-15, another human MEC cell line, was associated with the inhibition of STAT3 phosphorylation.

Conclusion:

These data suggest that CT could be a good apoptotic inducer through modification of STAT3 signaling in human MEC cell lines.

Cryptotanshinone inhibits human glioma cell proliferation by suppressing STAT3 signaling

Malignant gliomas (MGs) are among the most aggressive types of cancers in the human brain. Frequent tumor recurrence caused by a lack of effective therapeutic approaches results in a poor prognosis. Signal transducer and activator of transcription 3 (STAT3), an oncogenic protein, is constitutively activated in MGs and predicts a poor clinical outcome. STAT3 therefore is considered to be a promising target for the treatment of MGs. Cryptotanshinone (CTS), the main bioactive compound from the root of Salvia miltiorrhiza Bunge, has been reported to have various pharmacological effects. However, little is known about its function in MG cells. In this study, we evaluated the effect of CTS on the proliferation of human glioma cell lines (T98G and U87). Our results revealed that CTS significantly suppresses glioma cell proliferation. The phosphorylation of STAT3 Tyr705, but not Ser727, was inhibited by CTS, and STAT3 nuclear translocation was attenuated. Overexpression of constitutively active mutant STAT3C reversed the inhibitory effect of CTS, while knockdown STAT3 showed a similar inhibitory effect as CTS treatment. Following the downregulation of STAT3-regulated proteins cyclinD1 and survivin, cell cycle progression significantly arrested in G1/G0 phase. These results indicate that CTS may be a potential antiproliferation agent for the treatment of MGs and that its mechanism may be related to the inhibition of STAT3 signaling.