Acid Water-ground Nano-realgar Is Superior to Crude Realgar in Promoting Apoptosis of MCF-7 Breast Cancer Cells.

OBJECTIVE: Realgar is a traditional mineral Chinese medicine with antitumor effects, but it has high toxicity and low efficacy in its crude form. The purpose of this study was to optimize realgar to increase its efficacy and therapeutic potential. METHODS: Crude realgar (CR) was mechanically ground to obtain nano-realgar (NR), and then nano-realgar processed products (NRPPs) were obtained using three different traditional Chinese medicine processing methods: grinding in water, acid water, and alkali water, respectively. RESULTS: By analyzing the size distribution of nanoparticles and the content of arsenic trioxide (As2O3; ATO), we found that acid water-ground NRPPs had the characteristics of high purity and low toxicity. The effects of CR, NR, and NRPPs on proliferation, cell cycle, and apoptosis of MCF-7 cells were detected, and the ability of NRPPs to induce apoptosis in MCF-7 cells was analyzed. The results showed that the average particle size of acid water-ground NRPPs was 137.7 nm, and the content of ATO was 2.83 mg/g. Acid water-ground NRPPs showed better effects on inhibiting proliferation, cell cycle, and apoptosis of MCF-7 cells than CR and NR. Western blot assays further confirmed that acid water-ground NRPPs upregulated the protein expression of TP53, Bax, cytochrome c, caspase-9, and caspase-3 in MCF-7 cells (P<0.05) and inhibited the expression of Bcl-2 (P<0.05). CONCLUSION: These results suggest that acid water-ground NRPPs can induce apoptosis of MCF-7 cells through regulating mitochondrial-mediated apoptosis, providing evidence for the clinical application of realgar.

Rubesanolides F and G: Two Novel Lactone-Type Norditerpenoids from Isodon rubescens.

A phytochemical investigation of the leaves of the medicinal plant Isodon rubescens led to the isolation of the two new degraded abietane lactone diterpenoids rubesanolides F (1) and G (2). Their structures were elucidated based on the analyses of the HRESIMS and 1D/2D NMR spectral data, and their absolute configurations were determined by ECD spectrum calculations and X-ray single crystal diffraction methods. Compounds 1 and 2, with a unique γ-lactone subgroup between C-8 and C-20, were found to form a carbonyl carbon at C-13 by removal of the isopropyl group in an abietane diterpene skeleton. Rubesanolide G (2) is a rare case of abietane that possesses a cis-fused configuration between rings B and C. The two isolates were evaluated for their biological activities against two cancer cell lines (A549 and HL60), three fungal strains (Candida alba, Aspergillus niger and Rhizopus nigricans) and three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis).