Design, synthesis, and biological evaluation of ligustrazine - betulin amino-acid/dipeptide derivatives as anti-tumor agents

Natural Products-Pyrazine Hybrids: A Review of Developments in Medicinal Chemistry

Pyrazine is a six-membered heterocyclic ring containing nitrogen, and many of its derivatives are biologically active compounds. References have been downloaded through Web of Science, PubMed, Science Direct, and SciFinder Scholar. The structure, biological activity, and mechanism of natural product derivatives containing pyrazine fragments reported from 2000 to September 2023 were reviewed. Publications reporting only the chemistry of pyrazine derivatives are beyond the scope of this review and have not been included. The results of research work show that pyrazine-modified natural product derivatives have a wide range of biological activities, including anti-inflammatory, anticancer, antibacterial, antiparasitic, and antioxidant activities. Many of these derivatives exhibit stronger pharmacodynamic activity and less toxicity than their parent compounds. This review has a certain reference value for the development of heterocyclic compounds, especially pyrazine natural product derivatives.

Ligustrazine alleviates pulmonary arterial hypertension in rats by promoting the formation of myocardin transcription complex in the nucleus of pulmonary artery smooth muscle cells

Pulmonary arterial hypertension (PAH) is a pathophysiological state of abnormally elevated pulmonary arterial pressure caused by drugs, inflammation, toxins, viruses, hypoxia, and other risk factors. We studied the therapeutic effect and target of tetramethylpyrazine (tetramethylpyrazine [TMP]; ligustrazine) in the treatment of PAH and we speculated that dramatic changes in myocardin levels can significantly affect the progression of PAH. In vivo, the results showed that administration of TMP significantly prolonged the survival of PAH rats by reducing the proliferative lesions, right ventricular systolic pressure (RVSP), mean pulmonary arterial pressure (mPAP), and the Fulton index in the heart and lung of PAH rats. In vitro, TMP can regulate the levels of smooth muscle protein 22-alpha (SM22-α), and myocardin as well as intracellular cytokines such as NO, transforming growth factor beta (TGF-β), and connective tissue growth factor (CTGF) in a dose-dependent manner (25, 50, or 100 μM). Transfection of myocardin small interfering RNA (siRNA) aggravated the proliferation of pulmonary artery smooth muscle cells (PSMCs), and the regulatory effect of TMP on α-smooth muscle actin (α-SMA) and osteopontin (OPN) disappeared. The application of 10 nM estrogen receptor alpha (ERα) inhibitor MPP promoted the proliferation of PSMCs, but it does not affect the inhibition of TMP on PSMCs proliferation. Finally, we found that TMP promoted the nucleation of myocardin-related transcription factor-A (MRTF-A) and combined it with myocardin. In conclusion, TMP can inhibit the transformation of PSMCs from the contractile phenotype to the proliferative phenotype by promoting the formation of the nuclear (MRTF-A/myocardin) transcription complex to treat PAH.

Betulin Acid Ester Derivatives Inhibit Cancer Cell Growth by Inducing Apoptosis through Caspase Cascade Activation: A Comprehensive In Vitro and In Silico Study

Betulin, or naturally occurring triterpene, possesses promising antiproliferative activity. To further explore this potential, thirty-eight betulin acid ester derivatives modified at the C-28 position were tested for antitumor activities. Four human cancer cell lines, MV4-11 (leukemia), A549 (lung), PC-3 (prostate), MCF-7 (breast) as well as the normal BALB/3T3 (mouse fibroblasts) cell line were examined using MTT and SRB assays. A few derivatives exhibited strong antiproliferative activity with IC₅₀ values between 2 and 5 µM. Subsequent mechanistic studies revealed that some derivatives induced apoptosis by inducing caspase-3/7 activity. A strong structure-activity correlation of tested compounds has been proposed along with experimental and in silico pharmacokinetic properties.

Tetramethylpyrazine: A Review of Its Antitumor Potential and Mechanisms

Cancer remains a major public health threat. The mitigation of the associated morbidity and mortality remains a major research focus. From a molecular biological perspective, cancer is defined as uncontrolled cell division and abnormal cell growth caused by various gene mutations. Therefore, there remains an urgent need to develop safe and effective antitumor drugs. The antitumor effect of plant extracts, which are characterized by relatively low toxicity and adverse effect, has attracted significant attention. For example, increasing attention has been paid to the antitumor effects of tetramethylpyrazine (TMP), the active component of the Chinese medicine Chuanqiong, which can affect tumor cell proliferation, apoptosis, invasion, metastasis, and angiogenesis, as well as reverse chemotherapeutic resistance in neoplasms, thereby triggering antitumor effects. Moreover, TMP can be used in combination with chemotherapeutic agents to enhance their effects and reduce the side effect associated with chemotherapy. Herein, we review the antitumor effects of TMP to provide a theoretical basis and foundation for the further exploration of its underlying antitumor mechanisms and promoting its clinical application.

Recent progress on betulinic acid and its derivatives as antitumor agents: a mini review

Natural products are one of the important sources for the discovery of new drugs. Betulinic acid (BA), a pentacyclic triterpenoid widely distributed in the plant kingdom, exhibits powerful biological effects, including antitumor activity against various types of cancer cells. A considerable number of BA derivatives have been designed and prepared to remove their disadvantages, such as poor water solubility and low bioavailability. This review summarizes the current studies of the structural diversity of antitumor BA derivatives within the last five years, which provides prospects for further research on the structural modification of betulinic acid.

Synthesis and biological evaluation of novel ligustrazine-chalcone derivatives as potential anti-triple negative breast cancer agents

A series of novel ligustrazine-chalcone hybrids were synthesized and evaluated for their in vitro and in vivo antitumor activities. The results showed that most of these compounds exhibited significant in vitro cytotoxicity against MDA-MB-231, MCF-7, A549 and HepG2 cell lines with IC₅₀ values as low as sub-micromole. Among them, compounds 6c and 6f possessed better comprehensive characteristics for the antiproliferation effects on both MDA-MB-231 (IC₅₀: 6c, 1.60 ± 0.21 μM; 6f, 1.67 ± 1.25 μM) and MCF-7 (IC₅₀: 6c, 1.41 ± 0.23 μM; 6f, 1.54 ± 0.30 μM). They also exhibited the potent colony-formation inhibitory abilities on above two cell lines in both concentration and time dependent manners, as well as the significantly suppression capabilities against the migration of such cell lines in a concentration dependent manner by wound-healing assay. Of note, compound 6c could significantly induce the apoptosis of MDA-MB-231 cells in a concentration dependent manner and inhibited the transformation of the growth cycle of MDA-MB-231 cells and blocked the cell growth cycle in G0/G1 phase. Moreover, the in vivo antiproliferation assay of compound 6c on TNBC model indicated such compound had a remarkable potency against tumor growth with a widely safety window. Further immunohistochemistry analysis illustrated that compound 6c was provided with a potent capacity to significantly reduce the Ki-67 positive rate in a dose dependent manner. All the results suggested that these hybrids presented both in vitro and in vivo proliferation inhibition potency against breast cancer and further development with good therapeutic potential should be of great interest.