The tanshinones from the plant of Salvia miltiorrhiza

Six undescribed tanshinones, (+)-2-Cl-tanshindiol C (1), (-)-2-Cl-tanshindiol C (2), (+)-tanshinoic acid D (3), (-)-tanshinoic acid D (4), (-)-tanshinoic acid E (5), and (+)-tanshinoic acid E (6), were isolated from the rhizome of Salvia miltiorrhiza Bunge. Their structures were elucidated based on the spectroscopic data (UV, IR, HR-ESI-MS, and NMR). The bioactive assays of all these compounds for the antioxidant activities in cardiomyocytes upon hypoxia stimulation were evaluated. The results suggested that compounds 5 and 6 exhibited good antioxidant activities in cardiomyocytes and the cell survival rates were 46.3% and 57.9% (10^-5 mol/L), respectively.

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.

Tanshinones and their Derivatives: Heterocyclic Ring-Fused Diterpenes of Biological Interest

The available scientific literature regarding tanshinones is very abundant, and after its review, it is noticeable that most of the articles focus on the properties of tanshinone I, cryptotanshinone, tanshinone IIA, sodium tanshinone IIA sulfonate and the dried root extract of Salvia miltiorrhiza (Tan- Shen). However, although these products have demonstrated important biological properties in both in vitro and in vivo models, their poor solubility and bioavailability have limited their clinical applications. For these reasons, many studies have focused on the search for new pharmaceutical formulations for tanshinones, as well as the synthesis of new derivatives that improve their biological properties. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2015) on tanshinones in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we offer an update on the last five years of new research on these quinones, focusing on their synthesis, biological activity on noncommunicable diseases and drug delivery systems, to support future research on its clinical applications.

BIMP-Catalyzed 1,3-Prototropic Shift for the Highly Enantioselective Synthesis of Conjugated Cyclohexenones

A bifunctional iminophosphorane (BIMP)-catalysed enantioselective synthesis of α,β-unsaturated cyclohexenones through a facially selective 1,3-prototropic shift of β,γ-unsaturated prochiral isomers, under mild reaction conditions and in short reaction times, on a range of structurally diverse substrates, is reported. α,β-Unsaturated cyclohexenone products primed for downstream derivatisation were obtained in high yields (up to 99 %) and consistently high enantioselectivity (up to 99 % ee). Computational studies into the reaction mechanism and origins of enantioselectivity, including multivariate linear regression of TS energy, were carried out and the obtained data were found to be in good agreement with experimental findings.

Tunable luminescence of a synthesized furophenanthraquinone derivative: interactions with different solvents

The synthesis is described of a luminescent furophenanthraquinone derivative, 9-methoxyphenanthro[4,3-b]furan-4,5-dione (MPFD). The biological importance of tetracyclic furophenanthraquinones was considered and the tunable luminescence of MPFD in different solvents was studied to explore the nature of the specific interactions between MPFD and solvents. Observation of dual emission bands and identical nature of the fluorescence excitation spectra of MPFD monitored at the emission wavelength in polar solvents indicated the formation of two different types of species in the excited state, probably due to proton transfer from the solvent to MPFD. Luminescence intensity due to anionic species was found to be increased and the corresponding peak was red shifted with increase in the proton-donating ability of the solvents, acting as an acid with respect to MPFD. Availability of more acidic protons in the solvent facilitated this phenomenon occurring in the excited state. MPFD also interacted with halogen-containing solvents by forming electron donor-acceptor charge transfer (CT) complexes. This CT complex formation was dependent on the number of chlorine atoms; the position of the corresponding luminescence band varied with the polarity of the solvent. Extent of the CT increased with increase in the number of chlorine atoms in the dichloro, trichloro and tetrachloro solvents, whereas the luminescence peak due to the CT complex was found to be blue shifted with decrease in solvent polarity. Interaction of the synthesized bioactive MPFD with different solvents deserves biological importance as proton transfer and CT play pivotal roles in biology.

Biomimetic synthesis of the natural product salviadione and its hybrids: discovery of tissue-specific anti-inflammatory agents for acute lung injury

Biomimetic synthesis of the natural product salviadione and its hybrids was achieved leading to tissue-specific anti-inflammatory agents for acute lung injury.

Acute lung injury (ALI) is an inflammatory disease with no effective pharmacological treatment. The therapeutic potential of the anti-inflammatory natural product tanshinone IIA (2) for ALI is seriously impaired by its poor pharmacokinetic (PK) properties. Inspired by the unique benzo[def]carbazole-3,5-dione (BCD) core of the natural product salviadione (5), a series of furan-fused BCD hybrids of 5 with 2 was rationally designed with the aim to improve both PK properties and the anti-inflammatory activity. A biomimetic synthetic approach featuring one-pot tandem N-heterocyclization was first developed for convenient assembly of salviadione (56% overall yield over 2 steps) and the designed hybrids (35–85% yields in one step). Compared to 2, most of the resulting compounds exhibited a markedly enhanced inhibitory effect against LPS-induced release of pro-inflammatory cytokines in macrophages. Particularly, compound 15a not only possessed the most potent activity in vitro, but also exhibited significantly improved metabolic stability (4- to 7-fold enhancement), pharmacokinetic properties (T_1/2 = 4.05 h; F = 30.2%), and preferable lung tissue distribution (11- to 300-fold selectivity). An in vivo study in mice showed that pretreatment with 15a at 5 mg kg^–1 distinctly attenuated LPS-induced ALI via lung tissue-specific anti-inflammatory actions, indicating that the furan-fused BCD core presents a unique chemotype with promising therapeutic potential for ALI.

Discovery of Indoleamine 2,3-Dioxygenase 1 (IDO-1) Inhibitors Based on Ortho-Naphthaquinone-Containing Natural Product

There is great interest in developing small molecules agents capable of reversing tumor immune escape to restore the body’s immune system. As an immunosuppressive enzyme, indoleamine 2,3-dioxygenase 1 (IDO-1) is considered a promising target for oncology immunotherapy. Currently, none of IDO-1 inhibitors have been launched for clinical practice yet. Thus, the discovery of new IDO-1 inhibitors is still in great demand. Herein, a series of diverse ortho-naphthaquinone containing natural product derivatives were synthesized as novel IDO-1 inhibitors. Among them, 1-ene-3-ketone-17-hydroxyl derivative 12 exhibited significantly improved enzymatic and cellular inhibitory activity against IDO-1 when compared to initial lead compounds. Besides, the molecular docking study disclosed that the two most potent compounds 11 and 12 have more interactions within the binding pocket of IDO-1 via hydrogen-bonding, which may account for their higher IDO-1 inhibitory activity.