Riccardin D, a Macrocyclic Bisbibenzy, Inhibits Human Breast Cancer Growth through the Suppression of Telomerase Activity

Synthesis and evaluation of folate-mediated targeting and poly (β-amino ester)-mediated pH-responsive delivery system of riccardin D based on the O-carboxymethylated chitosan micelles

This study aimed to combine the active targeting function of folate (FA) receptor-mediated endocytosis with the pH-responsive drug delivery of poly (ethylene glycol)-grafted-poly (-amino ester) copolymers (PEG-PAE) in cancer targeting therapy. Herein, O-carboxymethylated chitosan (OCMC) was grafted with hydrophobic deoxycholic acid (DOCA). Further, PEG-PAE and FA-conjugated DOCA modified OCMC were synthesized to develop the potential cancer-targeted carrier (PEG-PAE-DOMC-FA), for which the structure was investigated by 1H NMR and FTIR. Then riccardin D (RD) was successfully loaded for tumor-targeted drug delivery. The particle size, zeta potential, encapsulating efficiencies, and loading content profiles of PEG-PAE-DOMC-FA/RD showed a strong dependence on the environmental pH values. The cumulative release of PEG-PAE-DOMC-FA/RD at pH 5.0 (90.63 %) was higher than pH 7.4 (51.12 %), which also indicated the pH sensitivity. Moreover, a lower IC50 and higher coumarin-6 uptake were found because of the folate-receptor-mediated endocytosis. In pharmacokinetic study, PEG-PAE-DOMC-FA/RD significantly improved the mean retention time (MRT) and AUC(0-∞) from 7.89 h and 36.1 mg/L·h of control group to 10.03 h and 123.8 mg/L·h. In the xenograft mice model, stronger antitumor efficacy and lower toxicity were confirmed. In conclusion, the multi-functional micelles could be considered as a promising vehicle for delivering hydrophobic drugs to tumors.

Determination of the in vitro metabolic stability and metabolites of the anticancer derivative riccardin D-N in human and mouse hepatic S9 fractions using HPLC-Q-LIT-MS

Riccardin D-N (RD-N) is an aminomethylated derivative of the macrocyclic bisbibenzyl compound riccardin D (RD), which has shown stronger activity against cancer cells than RD. However, there has been no research on the metabolism of RD-N. The present study aimed to characterize the in vitro metabolism and metabolic stability of RD-N after incubation with mouse and human hepatic S9 fractions using high performance liquid chromatography-hybrid triple quadrupole/linear ion trap mass spectrometry (HPLC-Q-LIT-MS). Multiple ion monitoring (MIM) and multiple reaction monitoring (MRM)-information dependent acquisition-enhanced product ion (MIM/MRM-IDA-EPI) scans were used to identify the metabolites formed. MRM scans were also used to quantify the changes in the amount of RD-N and to semi-quantify the main metabolites. Twenty-eight metabolic products were detected and 25 structures were predicted. Hydroxylation, dehydrogenation, glucuronidation, and methylation were proposed to be the principle metabolic pathways in the in vitro incubation with human and mouse hepatic S9 fractions. There were differences in the number and abundance of RD-N metabolites between the human and mouse hepatic S9 fractions. RD-N was shown to have good metabolic stability. After 2 h of incubation, 44% of the original RD-N remained in the human hepatic S9 fraction compared with 22% in the mouse. The major metabolites of RD-N, M4, M8, M20 and M21, were monitored semi-quantitatively using the typical transitions. Finally, HPLC-Q-LIT-MS was used for the identification and quantitation of the metabolites of R D-N, which is a simple and efficient method to rapidly screen potential drug candidates.

Cytotoxic Activity of Riccardin and Perrottetin Derivatives from the Liverwort Lunularia cruciata

Seven new bisbibenzyls (1-7) were isolated from the methanol extract of the liverwort Lunularia cruciata along with one previously known bibenzyl and five known bisbibenzyls. The structures of compounds 1-7 were elucidated on the basis of the spectroscopic data. These newly isolated bisbibenzyls may be divided into two groups, the acyclic bisbibenzyls, perrottetins (1-3), and the cyclic analogues, riccardins (4-7). Besides standard perrottetin and riccardin structures (1 and 4, respectively), they contain phenanthrene (3 and 5), dihydrophenanthrene (2), and quinone moieties (6 and 7), rarely found in natural products. The new compounds 3 and 5, as well as the known riccardin G, exhibited cytotoxic activity against the A549 lung cancer cell line with IC₅₀ values of 5.0, 5.0, and 2.5 μM, respectively.

Discovery and Characterization of 4-Hydroxy-2-pyridone Derivative Sambutoxin as a Potent and Promising Anticancer Drug Candidate: Activity and Molecular Mechanism

Sambutoxin, a representative derivative of 4-hydroxy-2-pyridone, was isolated from Hericium alpestre for the first time in this study. The possible correlation between the sambutoxin-induced suppression of tumor growth and its influence on cell-cycle arrest and apoptosis was investigated. The effects of sambutoxin on reactive oxygen species (ROS) production, DNA damage, mitochondrial transmembrane potential, cell apoptosis, and the expression of related proteins were evaluated. An in vitro cell viability study demonstrated that sambutoxin could inhibit the proliferation of various cancer cells. Treatment with sambutoxin induced the production of ROS, which caused DNA damage. Furthermore, the subsequent sambutoxin-induced activation of ATM and Chk2 resulted in G2/M arrest, accompanied by decreased expression of cdc25C, cdc2, and cyclin B1. Sambutoxin induced apoptosis by activating the mitochondrial apoptosis pathway through an increased Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), cytochrome (Cyt) c release, caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) degradation. The ROS elevation induced the sustained phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125, a JNK inhibitor, nearly completely reversed sambutoxin-induced apoptosis. Accordingly, an in vivo study showed that sambutoxin exhibited potential antitumor activity in a BALB/c nude mouse xenograft model without significant systemic toxicity. Moreover, the expression changes in proteins related to the G2/M phase, DNA damage, and apoptosis in vivo were consistent with those in vitro. Importantly, sambutoxin has remarkable antiproliferative effects and is a promising anticarcinogen candidate for cancer treatment.

Suppression of the NF‑κB signaling pathway in colon cancer cells by the natural compound Riccardin D from Dumortierahirsute

Colorectal cancer (CRC) is a major cause of mortality and morbidity. Chronic inflammation is closely associated with the development, progression and prognosis of the majority of intestinal malignancies. In recent years, targeting the nuclear factor (NF)‑κB signaling pathway for CRC therapy has become an attractive strategy. Riccardin D, a novel macrocyclicbis (bibenzyl) compound, was isolated from the Chinese liverwort plant. Previous studies have suggested that Riccardin D exerted chemo‑preventative effects against the intestinal malignancy formation. In the present study, cell counting kit‑8, Hochest 33258 staining, mitochondria membrane permeability assay, western blotting analysis, reverse transcription‑polymerase chain reaction, luciferase reporter gene assay and molecular modeling analysis were performed to detect the effect and mechanisms of Riccardin D on human colon cancer cells. The results demonstrated that Riccardin D significantly inhibited the growth of HT‑29 cells. In addition, the cDNA expression of cyclooxygenase‑2, and the protein expression and activity of NF‑κB and tumor necrosis factor‑α were downregulated; however, the protein expression of cleaved caspase‑3 and ‑9, and cleaved poly (adenosine diphosphate‑ribose) polymerase, and the B‑cell lymphoma (Bcl)‑2: Bcl‑2‑associated X protein ratio were upregulated. Furthermore, Auto Dock analysis identified binding sites between Riccardin D and NF‑κB. These results indicated that Riccardin D may inhibit cell proliferation and induce apoptosis in HT‑29 cells, which may be associated with the blocking of the NF‑κB signaling pathway. Thus, Riccardin D should be investigated as an NF‑κB inhibitor in cancer therapy.

Anti-cancer effects of Piper nigrum via inducing multiple molecular signaling in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Piper nigrum is widely used as a folk medicine including usage for pain relief, fevers, as well as an anti-cancer agent. However the crude extract of piperine free P. nigrum (PFPE), which inhibits breast cancer, and its mechanisms are still being kept secret. This research aims to elucidate the anti-cancer effects of PFPE and its mechanisms.

MATERIALS AND METHODS

Anti-cancer effects of PFPE were investigated in N-nitroso-N-methylurea (NMU)-induced mammary tumorigenesis rats and breast cancer cell lines MCF-7 and ZR-75-1. Furthermore, the cancer prevention effects of PFPE were investigated in rats. Western blotting was employed to study protein levels induced by PFPE.

RESULTS

PFPE was found to up-regulate p53, and down-regulate estrogen receptor (ER), E-cadherin (E-cad), matrix metalloproteinase 9 (MMP-9), matrix metalloproteinase 2 (MMP-2), c-Myc, and vascular endothelial growth factor (VEGF) levels in breast cancer rats. Moreover, PFPE decreased protein levels of E-cad, c-Myc, and VEGF in MCF-7 cells. These results suggest that PFPE can enhance breast cancer cell response to phytochemicals, then induce cell cycle arrest, and inhibit cancer cell proliferation resulting in tumor size decrease in the PFPE treated group. It further suggests that PFPE may suppress tumor cell invasion, migration, and angiogenesis. In addition, PFPE possessed cancer prevention effects through generation of reactive oxygen species (ROS) to higher cancer cell cellular stress.

CONCLUSIONS

PFPE may possess anti-cancer and cancer prevention effects; hence, it deserves further investigation as a novel candidate for breast cancer treatment.