New lathyrane diterpenoids with anti-inflammatory activity isolated from the roots of Jatropha curcas L

Ethnopharmacological relevance: Jatropha curcas L. (Euphorbiaceae), as a drought resistant shrub mainly cultivated in tropical and subtropical areas worldwide, is widely used as traditional medicine to cure arthritis, dysentery, abscess and pneumonia in Asian, African and South American folklores. The methanolic extracts of the roots have been revealed the anti-inflammatory activity in vivo and vitro. Aim of study: This research aimed to provide promising anti-inflammatory candidates from the roots of J. curcas. In addition, RNA-Seq was conducted to give targeted genes involved in the anti-inflammatory action. Materials and methods: The diterpenoids were isolated from the CH2Cl2 fraction of the methanolic extract from the roots of J. curcas by column chromatography (CC): silica gel, Sephadex LH-20, ODS, semi-preparative reversed-phase high-performance liquid chromatography (HPLC). The structures were identified based on HRESI-MS and 1D, 2D-NMR spectroscopic analysis. Their anti-inflammatory effects were tested on lipopolysaccharide (LPS, 500 ng/mL)-stimulated murine RAW264.7 macrophages. Furthermore, we conducted transcriptome-wide RNA sequencing to profile gene expression alterations in LPS-induced RAW264.7 cells upon treatment with jatrocurcasenone I (4) and analyzed the underlying genes targeted by this compound. Results: Six diterpenoids were obtained from J. curcas, and four of them were identified to be new lathyrane diterpenoids: jatrocurcasenones F-I (1-4). Compounds 3 and 4 exhibited potent inhibitory activities against LPSinduced nitric oxide (NO) production in RAW264.7 cells with IC50 values of 11.28 mu M and 7.71 mu M, respectively. Western blotting analysis showed that the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were suppressed with the supplementation of 3 and 4. The results of RNA-seq showed that 4 (20 mu M) exhibited regulation on the 587 differentially expressed genes (DEGs) induced by LPS (500 ng/ mL). Transcriptome-wide RNA sequencing indicated that the protective activity of 4 supplementation was most likely driven by modulating expression levels of IL-1 alpha, IL-1 beta, IL-1f6, IL-6, IL-1rn, IL-27, Ccl2, Ccl5, Ccl7, Ccl9, Ccl22, Cxcl10, Tnfsf12, Tnfsf15, Lta, Trim25, Bcl2a1a, Dusp1, Dusp2, Ptgs2, Edn1 and Nr4a1. Conclusions: This study offered four new lathyrane diterpenoids, of them, jatrocurcasenone I (4) showed significant anti-inflammatory activity. RNA-Seq suggested that jatrocurcasenone I (4) could be a candidate drug for the prevention inflammation-mediated diseases by modulating 24 candidate DEGs.

Automated summary

This study identified and isolated new diterpenoids with anti-inflammatory activity from the roots of Jatropha curcas, particularly jatrocurcasenone I (4) which showed potent inhibition of nitric oxide production induced by LPS. RNA-Seq analysis revealed that jatrocurcasenone I (4) may act as a candidate drug for inflammation-mediated diseases by modulating the expression of multiple candidate DEGs.