Bruceine D Acts as a Potential Insecticide by Antagonizing 20E-EcR/USP Signal Transduction

The quassinoids bruceines A-M: pharmacology, mechanism of action, synthetic advance, and pharmacokinetics-a review

Bruceines A-L are among the quassinoid representatives found in the medicinal plant Brucea javanica (L.). An overview of their pharmacological activities is still unknown. The given research deals with highlights in their pharmacological result, molecular mechanism of action, synthetic progress, and pharmacokinetics. From previous evidence, bruceine derivatives are potential agents for anticancer treatments, as well as they are appropriate to treat inflammation, diabetes, and parasitic infections, and protect the neurons, kidneys, and lungs. Cytokine inhibitions, oxidative stress responses, and various signaling pathways, such as MAPK (mitogen-activated protein kinase) and NF-κB (nuclear factor-kappa B), have been proposed as the underlying mechanisms of action. Synthetic approaches to synthesize new derivatives with enhancement activities are based on free hydroxyl group modifications. Bruceines seem to be promptly absorbed by both oral and intravenous administrations, but their bioavailability is not high (less than 6%). Pre-clinical and clinical studies to prove their anticancer potential and other activities are urgent. Structural modifications, nano-combinations, and synergistic effects are necessary.

Bruceine D inhibits the growth of Spodoptera litura by inducing cell apoptosis in the midgut via an oxidative burst

BACKGROUND

Spodoptera litura is one of the most harmful lepidoptera pests in China, and is difficult to control due to its strong resistance to the current frequently used insecticide species. The requirement to develop pesticides with novel toxicology mechanisms to control S. litura is urgent. The quassinoid of bruceine D display outstanding systemic properties and strong insecticidal activity against S. litura, which possess notable application potential for integrative management of S. litura, but the mechanism of toxicity remains unclear.

RESULTS

In this study, we found that bruceine D exerts potent growth inhibitory activity against S. litura, disrupting the ecdysone and juvenile hormone titers, and causing long-term adverse effects. Association analysis between transcriptomics and metabolomics suggested that bruceine D affected the digestion and absorption capacity of S. litura larvae by inducing a strong oxidative stress response and cell apoptosis in the intestine. Further analysis demonstrated that bruceine D can inhibit the activities of digestive and antioxidant enzymes and induce malondialdehyde (MDA) and reactive oxygen species (ROS) overaccumulation in the midgut. Moreover, the protein level of Bax, cleavage caspase 3, and cytochrome c expressed in cytoplasm (cyto) were up-regulated by bruceine D, while Bcl-2 and cytochrome c expressed in mitochondria (mito) were down-regulated. In addition, there was a noticeable increase in caspase-3 protease activity. Histopathological observations revealed that bruceine D damages the structure of midgut epithelial cells and activates lysosomes, which subsequently disrupts the midgut tissue.

CONCLUSION

Overall, our findings suggested that bruceine D induced excessive ROS accumulation in midgut epithelial cells. The resulting cell apoptosis disrupted midgut tissue, leading ultimately to reduced nutrient digestion and absorption in the midgut and the inhibition of larval growth. © 2024 Society of Chemical Industry.

Effect of Brucea javanica Oil on the Toxicity of β-Cypermethrin Emulsifiable Concentrate Formulation

Enhancing the performance of traditional pesticide formulations by improving their leaf surface wetting capabilities is a crucial approach for maximizing the pesticide efficiency. This study develops an emulsifiable concentrate (EC) of 4.5% β-cypermethrin containing Brucea javanica oil (BJO). The incorporation of BJO aims to improve the leaf-wetting properties of the EC formulation and enhance its insecticidal effectiveness. The droplet size and emulsion characteristics of β-CYP EC emulsion with varying concentrations of the emulsifier were evaluated, and changes after incorporating BJO were assessed to develop the optimal formulation. A comprehensive comparison was conducted among commercial 4.5% β-cypermethrin EC (β-CYP EC-1), 4.5% β-cypermethrin EC with BJO (β-CYP EC-2), and 4.5% β-cypermethrin EC without BJO (β-CYP EC-3). This comparison encompassed various factors including storage stability, insecticidal activity, cytotoxicity, and wetting performance on cabbage leaves. The results indicated that the ideal emulsifier concentration was 15% emulsifier 0201B. β-CYP EC-2 demonstrated superior wetting properties on cabbage leaves (the wetting performance of β-CYP EC-2 emulsion on cabbage leaves is 2.60 times that of the β-CYP EC-1 emulsion), heightened insecticidal activity against the third larvae of Plutella xylostella [diamondback moth (DBM)] [the insecticidal activity of the β-CYP EC-2 emulsion against the third larvae of DBM is 1.93 times that of the β-CYP EC-1 emulsion (12 h)], and more obvious inhibitory effects on the proliferation of DBM embryo cells than the other tested formulations. These findings have significant implications for advancing pest control strategies and promoting sustainable and effective agricultural practices.

Bruceine B Displays Potent Antimyeloma Activity by Inducing the Degradation of the Transcription Factor c-Maf

The oncogenic transcription factor c-Maf has been proposed as an ideal therapeutic target for multiple myeloma (MM), a not-yet-curable malignancy of plasma cells. In the present study, we establish a c-Maf-based luciferase screen system and apply it to screen a homemade library composed of natural products from which bruceine B (BB) is identified to display potent antimyeloma activity. BB is a key ingredient isolated from the Chinese traditional medicinal plant Brucea javanica (L.) Merr. (Simaroubaceae). BB inhibits MM cell proliferation and induces MM cell apoptosis in a caspase-3-dependent manner. The mechanism studies showed that BB inhibits c-Maf transcriptional activity and downregulates the expression of CCND2 and ITGB7, the downstream genes typically modulated by c-Maf. Moreover, BB induces c-Maf degradation via proteasomes by inducing c-Maf for K48-linked polyubiquitination in association with downregulated Otub1 and USP5, two proven deubiquitinases of c-Maf. We also found that c-Maf activates STAT3 and BB suppresses the STAT3 signaling. In the in vivo study, BB displays potent antimyeloma activity and almost suppresses the growth of myeloma xenografts in 7 days but shows no overt toxicity to mice. In conclusion, this study identifies BB as a novel inhibitor of c-Maf by promoting its degradation via the ubiquitin-proteasomal pathway. Given the safety and the successful clinical application of bruceine products in traditional medicine, BB is ensured for further investigation for the treatment of patients with MM.