Natural compounds are rich in pharmacological properties that are a hot topic in pharmaceutical research. The quinoline ring plays important roles in many biological processes in heterocycles. Many pharmacological compounds, including saquinavir and chloroquine, have been marketed as quinoline molecules with good anti-viral and anti-parasitic properties. Therefore, in this review, we summarize the medicinal chemistry of quinoline-modified natural product quinoline derivatives that were developed by several research teams in the past 10 years and find that these compounds have inhibitory effects on bacteria, viruses, parasites, inflammation, cancer, Alzheimer’s disease, and others.

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.

Ursolic acid (UA), a plant-derived compound, has many properties beneficial to health. In the present study, we synthesised three series of novel UA derivatives and evaluated their anti-Toxoplasma gondii activity both in vitro and in vivo. Most derivatives exhibited an improved anti-T. gondii activity in vitro when compared with UA (parent compound), whereas compound 3d exhibited the most potent anti-T. gondii activity in vivo. Spiramycin served as the positive control. Additionally, determination of biochemical parameters, including the liver and spleen indexes, indicated compound 3d to effectively reduce hepatotoxicity and significantly enhance anti-oxidative effects, as compared with UA. Furthermore, our molecular docking study indicated compound 3d to possess a strong binding affinity for T. gondii calcium-dependent protein kinase 1 (TgCDPK1). Based on these findings, we conclude that compound 3d, a derivative of UA, could act as a potential inhibitor of TgCDPK1.

The emergence of natural products has provided extremely valuable references for the treatment of various diseases. Cucurbitacin B, a tetracyclic triterpenoid compound isolated from cucurbitaceae and other plants, is the most abundant member of the cucurbitin family and exhibits a wide range of biological activities, including anti-inflammatory, anti-cancer, and even agricultural applications. Due to its high toxicity and narrow therapeutic window, structural modification and dosage form development are necessary to address these issues with cucurbitacin B. This paper reviews recent research progress in the pharmacological action, structural modification, and application of cucurbitacin B. This review aims to enhance understanding of advancements in this field and provide constructive suggestions for further research on cucurbitacin B.