Prenylated isoflavones from Cudrania tricuspidata inhibit NO production in RAW 264.7 macrophages and suppress HL-60 cells proliferation

Phytochemistry and pharmacology of natural prenylated flavonoids

Prenylated flavonoids are a special kind of flavonoid derivative possessing one or more prenyl groups in the parent nucleus of the flavonoid. The presence of the prenyl side chain enriched the structural diversity of flavonoids and increased their bioactivity and bioavailability. Prenylated flavonoids show a wide range of biological activities, such as anti-cancer, anti-inflammatory, neuroprotective, anti-diabetic, anti-obesity, cardioprotective effects, and anti-osteoclastogenic activities. In recent years, many compounds with significant activity have been discovered with the continuous excavation of the medicinal value of prenylated flavonoids, and have attracted the extensive attention of pharmacologists. This review summarizes recent progress on research into natural active prenylated flavonoids to promote new discoveries of their medicinal value.

Inhibitory Effects of 6,8-Diprenylorobol on Endometriosis Progression in Humans by Disrupting Calcium Homeostasis and Mitochondrial Function

6,8-Diprenylorobol is a flavonoid compound extracted from Cudrania tricuspidata. It has various biological functions, such as inhibiting melanin synthesis and inducting cell death in cancerous cells. In addition, Cudrania tricuspidata is known to be effective in female diseases, and previous studies have shown anticancer effects in cervical cancer, a female reproductive disease. Outside of that, Cudrania tricuspidata has various physiological effects. However, the effect of 6,8-diprenylorobol is not well known in other benign and chronic diseases, even in endometriosis, which commonly arises in the female reproductive tract. In the present study, we determined the inhibitory effects of 6,8-diprenylorobol on the growth of endometriosis VK2/E6E7 and End1/E6E7 cells. Results indicated that 6,8-diprenylorobol suppressed cellular proliferation and increased the disruption of the cell cycle, mitochondrial membrane potential (MMP), generation of reactive oxygen species, and Ca²⁺ homeostasis in both endometriosis cells. However, the proliferation of normal stromal cells isolated from endometrial tissue was not altered by 6,8-diprenylorobol. The change in Ca²⁺ levels was estimated in fluo-4- or rhod-2-stained VK2/E6E7 and End1/E6E7 cells after the treatment of the intracellular calcium regulators 2-aminoethoxydiphenyl borate (2-APB) and ruthenium red (RUR) with 6,8-diprenylorobol. A combination of 6,8-diprenylorobol with each regulator decreased the calcium accumulation in endometriosis cells. Furthermore, Western blot analysis indicated that 6,8-diprenylorobol inactivated AKT pathways, whereas it activated P38 MAPK pathways. In addition, 6,8-diprenylorobol decreased mitochondrial respiration, leading to the reduction in ATP production in VK2/E6E7 and End1/E6E7 cells. Collectively, our results suggested that 6,8-diprenylorobol might be a potential therapeutic agent or adjuvant therapy for the management of endometriosis.

6,8-Diprenylorobol induces apoptosis in human colon cancer cells via activation of intracellular reactive oxygen species and p53

6,8-Diprenylorobol is a natural compound mainly found in Glycyrrhiza uralensis fisch and Maclura tricuspidata, which has been used traditionally as food and medicine in Asia. So far, the antiproliferative effect of 6,8-diprenylorobol has not been studied yet in colon cancer. In this study, we aimed to evaluate the antiproliferative effects of 6,8-diprenylorobol in LoVo and HCT15, two kinds of human colon cancer cells. 6,8-Diprenylorobol inhibited the proliferation of LoVo and HCT15 cells in a dose- and time-dependent manner. A 40 μM of 6,8-diprenylorobol for 72 h reduced both of cell viability under 50%. After treatment of 6,8-diprenylorobol (40 and 60 μM) for 72 h, late apoptotic cell portion in LoVo and HCT15 cells were 24, 70% and 13, 90%, respectively, which was confirmed by checking DNA fragmentation in both cells. Mechanistically, 6,8-diprenylorobol activated p53 and its phosphorylated form (Ser15, Ser20, and Ser46) expression but suppressed Akt and mitogen-activated protein kinases (MAPKs) phosphorylation in LoVo and HCT15 cells. Interestingly, 6,8-diprenylorobol induced the generation of intracellular reactive oxygen species (ROS), which was attenuated with N-acetyl cysteine (NAC) treatment. Compared to the control, 60 μM of 6,8-diprenylorobol caused to increase ROS level to 210% in LoVo and HCT15, which was reduced into 161% and 124%, respectively with NAC. Furthermore, cell viability and apoptotic cell portion by 6,8-diprenylorobol was recovered by incubation with NAC. Taken together, these results indicate that 6,8-diprenylorobol has the potential antiproliferative effect against LoVo and HCT15 colon cancer cells through activation of p53 and generation of ROS.

6,8-Diprenylorobol Induces Apoptosis in Human Hepatocellular Carcinoma Cells via Activation of FOXO3 and Inhibition of CYP2J2

6,8-Diprenylorobol is a phytochemical derived from the roots of Glycyrrhiza uralensis Fisch. 6,8-Diprenylorobol exhibits several biological activities, but the effects of 6,8-diprenylorobol on cancers have been hardly investigated. This study is aimed at elucidating the anticancer effect and working mechanism of 6,8-diprenylorobol in HepG2 and Huh-7, two kinds of human hepatocellular carcinoma (HCC) cell lines. WST-1, cell counting, and colony formation assays and morphological change analysis showed that 6,8-diprenylorobol treatment decreased the cell viability and proliferation rate. Cell cycle analysis indicated that 6,8-diprenylorobol treatment increased the population of the G1/0 stage. Annexin V/PI double staining and TUNEL analysis showed that 6,8-diprenylorobol treatment increased the apoptotic cell population and DNA fragmentation. Western blot analysis showed that 6,8-diprenylorobol treatment increased the expression of cleaved PARP1, cleaved caspase-3, FOXO3, Bax, Bim, p21, and p27 but decreased the expression of Bcl2 and BclXL. Interestingly, 6,8-diprenylorobol inhibited CYP2J2-mediated astemizole O-demethylation and ebastine hydroxylase activities with K_i values of 9.46 and 2.61 μM, respectively. CYP2J2 siRNA transfection enhanced the anticancer effect of 6,8-diprenylorobol in HepG2 and Huh-7 cells through the downregulation of CYP2J2 protein expression and upregulation of FOXO3. Taken together, this study proposes that 6,8-diprenylorobol treatment may be a useful therapeutic option against HCC by targeting CYP2J2 and FOXO3.

Potent Cytotoxic Natural Flavonoids: The Limits of Perspective

BACKGROUND

Besides the numerous biologic and pharmacologic functions in the human body that act as potent antioxidants, flavonoids (flavones, flavanones, flavonols, flavanols and isoflavones) are noted as cancer preventive or therapeutic agents.

METHODS

This review summarizes the published data using PubMed, Science Direct, and Scopus.

RESULTS

In this context, recognition and introduction of the most active cytotoxic flavonoids as promising agents for cancer therapy gives insight for further evaluations. However, there are some critical points that may affect the entering of flavonoids as active cytotoxic phytochemicals in the clinical phase. Issues such as the abundance of active species in nature, the methods of extraction and purification, solubility, pharmacokinetic profile, presence of the chiral moieties, method of synthesis, and structure modification may limit the entry of a selected compound for use in humans. Although plenty of basic evidence exists for cytotoxic/antitumor activity of the versatility of flavonoids for entry into clinical trials, the above-mentioned concerns must be considered.

CONCLUSION

This review is an effort to introduce cytotoxic natural flavonoids (IC50< 10 µM) that may have the potential to be used against various tumor cells. Also, active constituents, molecular mechanisms, and related clinical trials have been discussed as well as the limitations and challenges of using flavonoids in clinic.

Furowanin A Exhibits Antiproliferative and Pro-Apoptotic Activities by Targeting Sphingosine Kinase 1 in Osteosarcoma

Osteosarcoma (OS) is one of the most common malignant bone tumors among children and young adults. Furowanin A (Fur A), one of the active ingredients of Millettia pachycarpa Benth, has been found to exert pro-apoptotic activity in human leukemia cells. This study is designed to evaluate the efficacy of Fur A against OS. The effect of Fur A on cell viability was assessed by Cell Counting Kit-8 (CCK-8) assay. Western blotting and quantitative real-time PCR (qRT-PCR) were performed to determine the protein and mRNA level of sphingosine kinase 1 (SphK1), respectively. To validate the role of SphK1 in the pro-apoptotic activity of Fur A, overexpressing SphK1 vector and siRNA targeting SphK1 were utilized to transfect OS cells. Moreover, an OS xenograft murine model was used to analyze the therapeutic efficacy of Fur A in vivo. Fur A treatment led to a dose-dependent decrease in the number of viable cells. It also exhibited antiproliferative activity and significantly promoted apoptotic cell death in OS cell lines. Our results showed that the anticancer activity of Fur A was associated with downregulation of SphK1 and inactivation of its downstream signaling. The mediatory role of SphK1 was validated when the pro-apoptotic activity of Fur A was significantly blocked by SphK1 overexpression, while SphK1 knockdown sensitized the OS cells to Fur A. We concluded that Fur A can exhibit anti-growth and pro-apoptotic activities in vitro and in vivo in OS by downregulating SphK1. Our study highlights the possibility of utilizing Fur A as a chemotherapeutic agent in the treatment of OS. Anat Rec, 302:1941-1949, 2019. © 2019 American Association for Anatomy.

Isolation of naturally occurring novel isoflavonoids: an update

This review covers the literature concerning the isolation and identification of new naturally occurring isoflavonoids from Leguminosae and non-Leguminous species between 2012–2017.

Bioactive compounds from Cudrania tricuspidata: A natural anticancer source

The tumor is becoming a critical threat to our lives in these years. Searching for antitumor substances from natural products is a great interest of scientists. Cudrania tricuspidata (C. tricuspidata) is a regional plant containing 158 flavonoids and 99 xanthones, and others ingredients with favorable bioactivity. This review comprehensively analyzes the antitumor compounds from C. tricuspidata against different tumors, and 78 flavonoids plus xanthones are considered as underlying antineoplastic. Importantly, the structure of preylation groups is the primary source of antitumor activity among 45 flavonoids plus xanthones, which could be a direction of structural modification for a better antitumor ability. Additionally, the fruits are also preferable sources of antitumor compounds compared to the roots and barks due to the abundant isoflavones and sustainability. However, many studies only focused on the cells viability inhibition of the compounds, the underlying molecular mechanisms, and the intracellular targets remain ambiguous. In conclusion, C. tricuspidata has a great potential for anti-tumor prevention or therapy, but more attention should be paid to deeper research in vitro and in vivo models.

Anti-neuroinflammatory effects of cudraflavanone A isolated from the chloroform fraction of Cudrania tricuspidata root bark

CONTEXT

Cudrania tricuspidata Bureau (Moraceae) is an important source of traditional Korean and Chinese medicines used to treat neuritis and inflammation.

OBJECTIVE

The anti-neuroinflammatory effects of cudraflavanone A isolated from a chloroform fraction of C. tricuspidata were investigated in LPS-induced BV2 cells.

MATERIALS AND METHODS

Cudraflavanone A was isolated from the root of C. tricuspidata, and its structure was determined by MS and NMR data. Cytotoxicity of the compound was examined by MTT assay, indicating no cytotoxicity at 5-40 μM of cudraflavanone A. NO concentration was measured by the Griess reaction, and the levels of PGE2, cytokines and COX-2 enzyme activity were measured by each ELISA kit. The mRNA levels of cytokines were analysed by quantitative-PCR. The expression of iNOS, COX-2, HO-1, NF-κB, MAPKs and Nrf2 was detected by Western blot.

RESULTS

Cudraflavanone A had no major effect on cell viability at 40 μM indicating 91.5% viability. It reduced the production of NO (IC50 = 22.2 μM), PGE2 (IC50 = 20.6 μM), IL-1β (IC50 = 24.7 μM) and TNF-α (IC50 = 33.0 μM) in LPS-stimulated BV2 cells. It also suppressed iNOS protein, IL-1β and TNF-α mRNA expression. These effects were associated with the inactivation of NF-κB, JNK and p38 MAPK pathways. This compound mediated its anti-neuroinflammatory effects by inducing HO-1 protein expression via increased nuclear translocation of Nrf2.

DISCUSSION AND CONCLUSIONS

The present study suggests a potent effect of cudraflavanone A to prevent neuroinflammatory diseases. Further investigation is necessary to elucidate specific molecular mechanism of cudraflavanone A.

Polysubstituted Isoflavonoids from Spatholobus suberectus, Flemingia macrophylla, and Cudrania cochinchinensis

Four hitherto unknown polysubstituted isoflavonoids, including three isoflavans: 7,4'-dihydroxy-8,2',3'-trimethoxyisoflavan (1), 7,2',4'-trihydroxy-8,3'-dimethoxyisoflavan (2), and 7,2',4'-trihydroxy-5-methoxyisoflavan (3), and one prenylated isoflavone cudraisoflavone M (4) were isolated from the ethanol extracts of Spatholobus suberectus (for 1 and 2), Flemingia macrophylla (for 3), and Cudrania cochinchinensis (for 4), respectively. Their structures were established on the basis of extensive spectroscopic analysis. Compounds 1 and 4 exhibited weak cytotoxic activity against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480).