Syntheses and bioactivities of songorine derivatives as novel G protein-coupled receptor antagonists

Features of Intracellular Signal Transduction in Neural Stem Cells under the Influence of Alkaloid Songorine, an Agonist of Fibroblast Growth Factor Receptors

We performed a comparative in vitro study of the involvement of NF-κB, PI3K, cAMP, ERK1/2, p38, JAKs, STAT3, JNK, and p53-dependent intracellular signaling in the functioning of neural stem cells (NSC) under the influence of basic fibroblast growth factor (FGF) and FGF receptor agonist, diterpene alkaloid songorine. The significant differences in FGFR-mediated intracellular signaling in NSC were revealed for these ligands. In both cases, stimulation of progenitor cell proliferation occurs with the participation of NF-κB, PI3K, ERK1/2, JAKs, and STAT3, while JNK and p53, on the contrary, inhibit cell cycle progression. However, under the influence of songorin, cAMP- and p38-mediated cascades are additionally involved in the transmission of the NSC division-activating signal. In addition, unlike FGF, the alkaloid stimulates progenitor cell differentiation by activating ERK1/2, p38, JNK, p53, and STAT3.

A review: Pharmacokinetics and pharmacology of aminoalcohol-diterpenoid alkaloids from Aconitum species

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitum medicinal materials, such as Aconitum carmichaelii Debeaux (Chinese: Wutou/) and Aconitum kusnezoffii Reichb. (Chinese: Caowu/), are a kind of important Traditional Chinese Medicine (TCM) with great medicinal value. Statistics show that there are over 600 efficient TCM formulations comprising Aconitum medicinal materials. But high toxicity limits their clinical application. Clinically, the Aconitum medicinal materials must undergo a complex processing process that includes soaking, steaming, and boiling with pharmaceutical excipients, which makes highly toxic ester diterpenoid alkaloids are hydrolyzed to form less toxic aminoalcohol-diterpenoid alkaloids (ADAs).

AIM OF THE STUDY

This review aims to summarize the pharmacokinetic and pharmacological activities of low-toxicity ADAs, providing a reference for future ADAs research and drug development.

MATERIALS AND METHODS

Accessible literature on ADAs published between 1984 and 2022 were screened and obtained from available electronic databases such as PubMed, Web of Science, Springer, Science Direct and Google Scholar, followed by systematic analysis.

RESULTS

ADAs are secondary products of plant metabolism, widely distributed in the Aconitum species and Delphinium species. The toxicity of ADAs as pharmacodynamic components of Aconitum medicinal materials is much lower than that of other diterpenoid alkaloids due to the absence of ester bonds. On the one hand, the pharmacokinetics of ADAs have received little attention compared to other toxic alkaloids. The research primarily focuses on aconine and mesaconine. According to existing studies, ADAs absorption in the gastrointestinal tract is primarily passive with a short T_max. Simultaneously, efflux transporters have less impact on ADAs absorption than non-ADAs. After entering the body, ADAs are widely distributed in the heart, liver, lungs, and kidney, but less in the brain. Notably, aconine is not well metabolized by liver microsomes. Aconine and mesaconine are excreted in urine and feces, respectively. ADAs, on the other hand, have been shown to have a variety of pharmacological activities, including cardiac, analgesic, anti-inflammatory, anti-tumor, antioxidant, and regenerative effects via regulating multiple signaling pathways, including Nrf2/ARE, PERK/eIF2α/ATF4/Chop, ERK/CREB, NF-κB, Bcl-2/Bax, and GSK3β/β-catenin signaling pathways.

CONCLUSIONS

ADAs have been shown to have beneficial effects on heart disease, neurological disease, and other systemic diseases. Moreover, ADAs have low toxicity and a wide range of safe doses. All of these suggest that ADAs have great potential for drug development.

Divergent Total Syntheses of Napelline-Type C20-Diterpenoid Alkaloids: (-)-Napelline, (+)-Dehydronapelline, (-)-Songorine, (-)-Songoramine, (-)-Acoapetaldine D, and (-)-Liangshanone

The napelline-type alkaloids possess an azabicyclo[3.2.1]octane moiety and an ent-kaurane-type tetracyclic skeleton (6/6/6/5) along with varied oxidation patterns embedded in the compact hexacyclic framework. Herein, we disclose a divergent entry to napelline-type alkaloids that hinges on convergent assembly of the ent-kaurane core using a diastereoselective intermolecular Cu-mediated conjugate addition and subsequent intramolecular Michael addition reaction as well as rapid construction of the azabicyclo[3.2.1]octane motif via an intramolecular Mannich cyclization. The power of this strategy has been demonstrated through efficient asymmetric total syntheses of eight napelline-type alkaloids, including (-)-napelline, (-)-12-epi-napelline, (+)-dehydronapelline, (+)-12-epi-dehydronapelline, (-)-songorine, (-)-songoramine, (-)-acoapetaldine D, and (-)-liangshanone.

Daphnetin, a Coumarin in Genus Stellera Chamaejasme Linn: Chemistry, Bioactivity and Therapeutic Potential

Coumarins is a huge family of phenolic compounds containing a common structure of 2 H -1-benzopyran-2-one. Nowadays, more than 1,300 natural-based coumarins have been identified in a variety of plants, bacteria and fungi, many of them exhibited promising biomedical performance. Daphnetin (7,8-dihydroxycoumarin) is a typical coumarin associated with a couple of bioactivities such as anti-cancer, antibacterial, anti-inflammatory and anti-arthritis. In the treatment of diseases, it has been verified that daphnetin has outstanding therapeutic effects on diabetes, arthritis, transplant rejection, cancer and even on central nervous system diseases. Herein, we summarized the chemical synthetic methodologies, bioactivities, therapeutic potentials and structure-activity relationships of daphnetin and its derivatives. Hopefully, this review would be beneficial for the discovery of new coumarin-based biomedicine in the near future.

Synthesis of Coumarin Derivatives: A New Class of Coumarin-Based G Protein-Coupled Receptor Activators and Inhibitors

To expand the range of daphnetin-based inhibitors/activators used for targeting G protein-coupled receptors (GPCRs) in disease treatment, twenty-five coumarin derivatives 1–25, including 7,8-dihydroxycoumarin and 7-hydroxycoumarin derivatives with various substitution patterns/groups at C3-/4- positions, were synthesized via mild Pechmann condensation and hydroxyl modification. The structures were characterized by ¹H NMR, ¹³C NMR and ESI-MS. Their inhibition or activation activities relative to GPCRs were evaluated by double-antibody sandwich ELISA (DAS–ELISA) in vitro. The results showed that most of the coumarin derivatives possessed a moderate GPCR activation or inhibitory potency. Among them, derivatives 14, 17, 18, and 21 showed a remarkable GPCR activation potency, with EC₅₀ values of 0.03, 0.03, 0.03, and 0.02 nM, respectively. Meanwhile, derivatives 4, 7, and 23 had significant GPCR inhibitory potencies against GPCRs with IC₅₀ values of 0.15, 0.02, and 0.76 nM, respectively. Notably, the acylation of hydroxyl groups at the C-7 and C-8 positions of 7,8-dihydroxycoumarin skeleton or the etherification of the hydroxyl group at the C-7 position of the 7-hydroxycoumarin skeleton could successfully change GPCRs activators into inhibitors. This work demonstrated a simple and efficient approach to developing coumarin derivatives as remarkable GPCRs activators and inhibitors via molecular diversity-based synthesis.

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1-F7) were synthesized via chemical modification at C-2 and C-2' phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1-F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 μM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

Simultaneous determination of five bioactive components of XiaoJin Capsule in normal and mammary gland hyperplasia rat plasma using LC-MS/MS and its application to a pharmacokinetic study

XiaoJin Capsule (XJC) is a classic Traditional Chinese Medicine formula for clinical treatment of thyroid nodules, mammary gland hyperplasia and breast cancer. For the specification and rational application of XJC in the future, an accurate and specific LC-MS/MS method was developed and validated for quantitative determination of five components in rat plasma after oral administration of XJC. The collected plasma samples were extracted by protein precipitation with methanol-acetonitrile (1:3, v/v) mixture solvent and separated on a C₁₈ column using a gradient elution system. Mass spectrometry was performed on a triple quadrupole mass spectrometer, and samples were detected in positive ionization and multiple reactions monitoring mode. The method was properly validated in terms of linearity, precision, accuracy, recovery, matrix effect and stability. All calibration curves showed good linearity (r²  > 0.9910) over their concentration ranges. The intra- and inter-day precisions (RSD) were within 11.0%, and the LLOQ was 0.1, 0.2, 0.5, 7.5 and 7.5 ng/ml for aconine, songorine, neoline, 3-acetyl-11-keto-β-boswellic acid and 11-keto-β-boswellic acid, respectively. Extraction recovery, matrix effect and stability were satisfactory in rat plasma. This established method was successfully applied to a pharmacokinetics study of five compounds after oral administration of XJC to normal and mammary gland hyperplasia model rats.

Syntheses and evaluation of daphnetin derivatives as novel G protein-coupled receptor inhibitors and activators

A series of daphnetin (7,8-dihydroxycoumarin) derivatives 1-22 were synthesized including sixteen new compounds (1-5, 7-14, 18, 21 and 22) and six known compounds (6, 15-17, 19 and 20). Their pharmacological activities on G protein-coupled receptors (GPCRs) were evaluated by double antibody sandwich ELISA (DAS-ELISA) in vitro. Daphnetin derivatives with various substitution patterns/groups were obtained from inhibitors to activators on GPCRs. Derivatives 2-5, 8, 15, 16 and 18-20 possessed moderate activation potency on GPCRs. Among them, derivatives 3-5, 16 and 19 presented significant activation potency on GPCRs with EC₅₀ values in the range of 1.18-1.91 nM. Derivatives 6, 11, 14 and 18 showed significant inhibitory potency on GPCRs with IC₅₀ values in the range of 1.26-1.38 nM. Moreover, the structure-activity relationships (SARs) of daphnetin derivatives were discussed in detail. The new daphnetic-based GPCRs activators and inhibitors have potentials as future drug candidates for the treatment of metabolic diseases.