Semustine

For centuries, the aerial parts of Sideritis species have been known for their medicinal properties as herbal teas. Although the antioxidant and anti-inflammatory properties of the genus have been widely documented, the underlying mechanisms are yet to be sufficiently clarified.

We investigated the anti-inflammatory and anticancer activities of phytochemicals of the Sideritis genus.

Through literature mining, a chemical library containing 657 components of the Sideritis genus was formed. We studied these compounds for binding to NLRP3 and NF-κB proteins in silico by virtual drug screening and molecular docking, and in vitro by microscale thermophoresis (MST). Liquid chromatography-high-resolution mass spectrometry analysis (LC-HRMS) was performed in the Sideritis extracts. One of the identified compounds, verbascoside, was investigated for its cytotoxic activity by mining a panel of 49 tumor cell lines in the data repository of the National Cancer Institute (NCI, USA).

Virtual screening and molecular docking results highlighted two compounds targeting both proteins of interest, i.e., verbascoside (acteoside) and apigenin 7,4'-bis(trans-p-coumarate), as both had lowest binding energies of less than -10 kcal/mol. Using MST, we then verified that both compounds bound to the target proteins. Verbascoside bound to NLRP3 and NF-κB with K_d values of 0.67 ± 0.18 μM and 0.01 ± 0.08 μM, while apigenin 7,4'-bis(trans-p-coumarate) had K_d values of 4.60 ± 1.66 μM and 0.27 ± 0.75 μM, respectively. Verbascoside was abundant in the Sideritis extracts, according to LC-HRMS analysis. Since inflammation is strongly related to carcinogenesis, we investigated the anticancer activity of verbascoside in the second part of this study. We investigated the activity of verbascoside in 49 tumor cell lines of the NCI. Comparing its activity with 81 standard anticancer drugs revealed numerous interactions with DNA-damaging agents (alkylators, topoisomerase I/II inhibitors, antimetabolites), indicating that verbascoside may also affect the DNA of tumor cells. We further investigated the involvement of verbascoside in several main drug resistance mechanisms, i.e., ABC transporters, oncogenes, tumor suppressors, cellular proliferation rates, and other parameters. Except for the correlation to the mutational status of NRAS, no other significant relationships were found, indicating that verbascoside is not involved in most of the common drug resistance mechanisms. Two-dimensional cluster analysis-based heatmap generation of a proteomic profile from 40 out of 3171 proteins revealed a significant correlation between the expression of these proteins in 49 tumor cell lines, and the cellular response to verbascoside. This indicates that the presence of these proteins is a determinant for sensitivity or resistance to this natural product.

The database established here represents a valuable resource for the screening of bioactivites of the Sideritis genus. The experimental validation of the anti-inflammatory and cytotoxic activities of selected compounds proved that virtual drug screening and molecular docking are suitable tools for the identification of putative drug candidates. Verbascoside was among the top 10 compounds binding to two key anti-inflammatory proteins, NLRP3 and NF-kB. Additionally, data from the NCI indicate that verbascoside is not linked to main drug resistance mechanisms.

Autologous stem cell transplantation (ASCT) is a salvage therapy for relapsed or refractory diffuse large B-cell lymphoma (DLBCL). We have developed a novel conditioning regimen called CEAC (oral semustine 250 mg/m² d-6, etoposide 300 mg/m² d-5 ~ d-2, cytarabine 500 mg/m² d-5 ~ d-2, and cyclophosphamide 1200 mg/m² d-5 ~ d-2) In lymphoma patients in China. Here, we conducted a study to compare the conventional BEAM regimen with the CEAC regimen in 110 DLBCL patients. Propensity-score matching was performed in a 1:4 ratio (22 patients received BEAM and 88 received CEAC). Our results showed no significant difference in the overall response rate (95% vs 97%, P = 1.000) and complete response rate (66% vs 73%, P = 0.580) between the two cohorts. The 5-year progression-free survival (PFS), 5-year overall survival (OS), and 5-year cumulative incidence of relapse (CIR) for all patients were 72% (95% CI 62%-82%), 92% (95% CI 86%-97%), and 29% (95% CI 17%-38%), respectively. There was no significant difference in the 5-year PFS (80% vs 70%, P = 0.637), 5-year OS (95% vs 91%, P = 0.496), and 5-year CIR (20% vs 30%, P = 0.733) between cohorts. In terms of safety, the CEAC cohort had a lower incidence rate of grade 1-2 gastrointestinal hemorrhage (P = 0.023) and severe nausea (P = 0.007) compared with the BEAM cohort. In conclusion, the CEAC regimen seems to be a suitable alternative to the BEAM regimen for ASCT in DLBCL patients.