Structural modification and biological activity studies of tagitinin C and its derivatives

Research on the anti-hepatic fibrosis effects and active components of the medicinal plant Tithonia diversifolia

BACKGROUND

The medicinal folk plant Tithonia diversifolia A. Gray has traditionally been used to treat hepatitis and liver cancer. However, the anti-fibrotic effect of this plant extract and its main active substances remain unclear.

OBJECTIVE

This study aims to elucidate the anti-fibrotic effect of T. diversifolia ethanol extract, identify the main active substances, and explore their possible molecular mechanisms.

METHODS

Firstly, carbon tetrachloride (CCl4) was injected intraperitoneally to induce liver fibrosis in mice to investigate the protective effect of T. diversifolia ethanol extract. Then, thirty compounds in this extract were identified through liquid chromatography-mass spectrometry (LC-MS/MS) analysis, column chromatography, and spectroscopic analysis. In addition, the anti-fibrotic effect of sesquiterpene lactone compounds were investigated on TGF-β-induced hepatic stellate cell activation.

RESULTS

The T. diversifolia ethanol extract significantly inhibits symptoms of carbon tetrachloride-induced liver fibrosis and the collagen deposition in pathological tissues by suppressing the protein expression of various pro-fibrotic factors. A comprehensive profile of thirty-one compounds was established, including nine sesquiterpenes, six phenolic acids, six fatty acids, five phenylpropanoids, and three flavonoids. Notably, one previously unreported sesquiterpene lactone, namely 1β-ethoxydiversifolin 3-O-methyl ether (1), together with twenty-nine known compounds were obatined. Sesquiterpene Tagitinin C shows significant anti-fibrotic effects on TGFβ1-induced HSC-T6 activation by inducing cell apoptosis and regulating the TGF-β1/Smad pathway.

CONCLUSION

The above results indicate that the T. diversifolia extract can effectively alleviate liver fibrosis, with sesquiterpene lactones being a major component. In the future, the germacranolides-type of sesquiterpene lactone Tagitinin C can be developed as a precursor compound for anti-fibrotic therapy.

Sesquiterpene lactones from Tithonia diversifolia with ferroptosis-inducing activities

Eight previously undescribed sesquiterpene lactones (1-8), together with six known ones (9-14) were isolated from the aerial parts of Tithonia diversifolia (Hemsl.) A. Gray. The absolute configurations of these compounds were elucidated using HRMS, NMR spectroscopy, optical rotation measurements, X-ray crystallography, and ECD. Among them, sesquiterpene lactones 2-4 share a unique carbon skeleton with a rare C-3/C-4 ring-opened structure. Compounds 1 and 8 showed moderate inhibitory effects toward CT26 murine colon carcinoma cells by promoting lipid ROS production, highlighting their potential as ferroptosis inducers.

Sesquiterpene Lactones as Promising Candidates for Cancer Therapy: Focus on Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease which confers to patients a poor prognosis at short term. PDAC is the fourth leading cause of death among cancers in the Western world. The rate of new cases of pancreatic cancer (incidence) is 10 per 100,000 but present a 5-year survival of less than 10%, highlighting the poor prognosis of this pathology. Furthermore, 90% of advanced PDAC tumor present KRAS mutations impacting in several oncogenic signaling pathways, many of them associated with cell proliferation and tumor progression. Different combinations of chemotherapeutic agents have been tested over the years without an improvement of significance in its treatment. PDAC remains as one the more challenging biomedical topics thus far. The lack of a proper early diagnosis, the notable mortality statistics and the poor outcome with the available therapies urge the entire scientific community to find novel approaches against PDAC with real improvements in patients' survival and life quality. Natural compounds have played an important role in the process of discovery and development of new drugs. Among them, terpenoids, such as sesquiterpene lactones, stand out due to their biological activities and pharmacological potential as antitumor agents. In this review, we will describe the sesquiterpene lactones with in vitro and in vivo activity against pancreatic tumor cells. We will also discuss the mechanism of action of the compounds as well as the signaling pathways associated with their activity.