Protective effects of Stephania pierrei tuber-derived oxocrebanine against LPS-induced acute lung injury in mice

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) have high mortality rates. Though corticosteroids are commonly used for the treatment of these conditions, their efficacy has not been conclusively demonstrated and their use can induce various adverse reactions. Hence, the application of corticosteroids as therapeutic modalities for ALI/ARDS is limited. Meanwhile, the aporphine alkaloid oxocrebanine isolated from Stephania pierrei tubers has demonstrated anti-inflammatory efficacy in murine/human macrophage cell lines stimulated by lipopolysaccharide (LPS). Accordingly, the primary objectives of the present study are to investigate the anti-inflammatory effects of oxocrebanine on LPS-induced murine alveolar epithelial (MLE-12) cells and its efficacy against LPS-induced murine ALI. Results show that oxocrebanine downregulates the abundance of interleukin (IL)-1beta, IL-6, and inducible nitric oxide synthase, as well as the phosphorylation of nuclear factor-kappaB (NF-κB), stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), p38, protein kinase B (Akt), and glycogen synthase kinase-3beta signalling proteins in LPS-induced MLE-12 cells. Moreover, in a murine ALI model, oxocrebanine lowers lung injury scores and lung wet/dry weight ratios while reducing inflammatory cell infiltration. It also suppresses LPS-induced tumour necrosis factor-alpha and IL-6 in the bronchoalveolar lavage fluid and plasma. Moreover, oxocrebanine downregulates NF-κB, SAPK/JNK, p38, and Akt phosphorylation in the lung tissues of LPS-treated mice. Taken together, the foregoing results show that oxocrebanine provides significant protection against LPS-induced ALI in mice primarily by suppressing various inflammatory signalling pathways in alveolar epithelial cells and lung tissues. Hence, oxocrebanine might prove effective as an anti-inflammatory agent for the treatment of lung inflammation.

Oxocrebanine from Stephania pierrei exerts macrophage anti-inflammatory effects by downregulating the NF-κB, MAPK, and PI3K/Akt signalling pathways

Plant-derived medicinal compounds are increasingly being used to treat acute and chronic inflammatory diseases, which are generally caused by aberrant inflammatory responses. Stephania pierrei Diels, also known as Sabu-lueat in Thai, is a traditional medicinal plant that is used as a remedy for several inflammatory disorders. Since aporphine alkaloids isolated from S. pierrei tubers exhibit diverse pharmacological characteristics, we aimed to determine the anti-inflammatory effects of crude extracts and alkaloids isolated from S. pierrei tubers against lipopolysaccharide (LPS)-activated RAW264.7 macrophages. Notably, the n-hexane extract strongly suppressed nitric oxide (NO) while exhibiting reduced cytotoxicity. Among the five alkaloids isolated from the n-hexane extract, the aporphine alkaloid oxocrebanine exerted considerable anti-inflammatory effects by inhibiting NO secretion. Oxocrebanine also significantly suppressed prostaglandin E₂, tumour necrosis factor-α, interleukin (IL)-1β, IL-6, inducible nitric oxide synthase, and cyclooxygenase (COX)-2 protein expression by inactivating the nuclear factor κB, c-Jun NH₂-terminal kinase, extracellular signal-regulated kinase 1/2, and phosphatidylinositol 3-kinase/Akt inflammatory signalling pathways. Molecular docking analysis further revealed that oxocrebanine has a higher affinity for toll-like receptor 4/myeloid differentiation primary response 88 signalling targets and the COX-2 protein than native ligands. Thus, our findings highlight the potential anti-inflammatory effects of oxocrebanine and suggest that certain alkaloids of S. pierrei could be used to treat inflammatory diseases.

Oxocrebanine: A Novel Dual Topoisomerase inhibitor, Suppressed the Proliferation of Breast Cancer Cells MCF-7 by Inducing DNA Damage and Mitotic Arrest

BACKGROUND

DNA topoisomerase (Topo) inhibition plays key role in breast cancer treatment. Stephania hainanensis H. S. Lo et Y. Tsoong (S. hainanensis), a Li nationality plant that has abundant aporphine alkaloids, can inhibit Topo.

PURPOSE

To identify a dual Topo inhibitor, a deep and systematic study of active aporphine alkaloids in S. hainanensis and their mechanisms of inhibiting breast cancer proliferation and Topo activity are essential.

STUDY DESIGN

This study aimed to assess the anti-breast cancer and Topo inhibitory activities of oxocrebanine and explore the underlying mechanisms.

METHODS

The growth inhibitory activities of 12 compounds in S. hainanensis were screened by MTT assay in MCF-7, SGC-7901, HepG-2 cells, and compared with the effects on human normal mammary epithelial MCF-10A cells as non cancer control cells. The Topo inhibitory activity was assessed by DNA relaxation and unwinding assays, kDNA decatenation assay and western blot. Cell cycle and autophagy analyses were carried out with flow cytometry and staining. Acridine orange staining and α-tubulin morphology were observed by fluorescence microscopy. Western blot was used to examine microtubule assembly dynamics and the expression levels of key proteins associated with DNA damage, autophagy and mitotic arrest.

RESULTS

Oxocrebanine was the anti-breast cancer active alkaloid in S. hainanensis. It exhibited the best inhibitory effect on MCF-7 cells with an IC₅₀ of 16.66 μmol/l, and had only weak effect on the proliferation of MCF-10A cells. Oxocrebanine inhibited Topo I and II α in a cell-free system and in MCF-7 cells. The DNA unwinding assay suggested that oxocrebanine intercalated with DNA as a catalytic inhibitor. Oxocrebanine regulated the levels of Topo I and IIα and DNA damage-related proteins. Oxocrebanine led to the mitotic arrest, and these effects occurred through both p53-dependent and p53-independent pathways. Oxocrebanine induced autophagy, abnormal α-tubulin morphology and stimulated enhanced microtubule dynamics.

CONCLUSION

Oxocrebanine was the anti-breast cancer active aporphine alkaloid in S. hainanensis. Oxocrebanine was a Topo I/IIα dual inhibitor, catalytic inhibitor and DNA intercalator. Oxocrebanine caused DNA damage, autophagy, and mitotic arrest in MCF-7 cells. Oxocrebanine also disrupted tubulin polymerization. Accordingly, oxocrebanine held a great potential for development as a novel dual Topo inhibitor for effective breast cancer treatment.