Synthesis and cancer cell growth inhibitory activity of icaritin derivatives

Simultaneous quantification of icaritin and its novel 3-methylcarbamate prodrug in rat plasma using HPLC-MS/MS and its application to pharmacokinetic study

A sensitive, rapid, and simple HPLC-MS/MS method was first developed and fully validated to determine the icaritin (ICT) and its novel 3-methylcarbamate prodrug (3N) simultaneously in rat plasma. Analytes were extracted from rat plasma using a liquid-liquid extraction (LLE) method. Chromatographic separation was performed on ACE Excel 2 C18-Amide column. Quantitation of analytes was conducted on an LCMS-8060 triple-quadrupole tandem mass spectrometer. The quantitation mode was the multiple reaction monitoring via positive electrospray ionization. The calibration curve was linear over the concentration range of 1 to 200 ng/ml for ICT with a correlation coefficient of r = 0.9950 and 1 to 400 ng/ml for 3N with a correlation coefficient of r = 0.9956. The intra-precision RSDs were ≤12% for ICT and 3N. The inter-day precision RSDs were ≤10% for ICT and 3N. The accuracy RE was between -2.6% and 7.8% for ICT and 3N. The average ICT, 3N and IS recoveries were 87.9%, 83.6%, and 84.3%. The plasma matrix of ICT and 3N complied with the guidelines. ICT and 3N were stable in rat plasma under various tested conditions. This work has been successfully applied to studying the pharmacokinetics of ICT and 3N.

New insights into the anticancer therapeutic potential of icaritin and its synthetic derivatives

Icaritin is a natural prenylated flavonoid derived from the Chinese herb Epimedium. The compound has shown antitumor effects in various cancers, especially hepatocellular carcinoma (HCC). Icaritin exerts its anticancer activity by modulating multiple signaling pathways, such as IL-6/JAK/STAT3, ER-α36, and NF-κB, affecting the tumor microenvironment and immune system. Several clinical trials have evaluated the safety and efficacy of icaritin in advanced HCC patients with poor prognoses, who are unsuitable for conventional therapies. The results have demonstrated that icaritin can improve survival, delay progression, and produce clinical benefits in these patients, with a favorable safety profile and minimal adverse events. Moreover, icaritin can enhance the antitumor immune response by regulating the function and phenotype of various immune cells, such as CD8+ T cells, MDSCs, neutrophils, and macrophages. These findings suggest that icaritin is a promising candidate for immunotherapy in HCC and other cancers. However, further studies are needed to elucidate the molecular mechanisms and optimal dosing regimens of icaritin and its potential synergistic effects with other agents. Therefore, this comprehensive review of the scientific literature aims to summarize advances in the knowledge of icaritin in preclinical and clinical studies as well as the pharmacokinetic, metabolism, toxicity, and mechanisms action to recognize the main challenge, gaps, and opportunities to develop a medication that cancer patients can use. Thus, our main objective was to clarify the current state of icaritin for use as an anticancer drug.

Nucleolin recognizing silica nanoparticles inhibit cell proliferation by activating the Bax/Bcl-2/caspase-3 signalling pathway to induce apoptosis in liver cancer

Multifunctional nanocarrier platforms have shown great potential for the diagnosis and treatment of liver cancer. Here, a novel nucleolin-responsive nanoparticle platform was constructed for the concurrent detection of nucleolin and treatment of liver cancer. The incorporation of AS1411 aptamer, icaritin (ICT) and FITC into mesoporous silica nanoparticles, labelled as Atp-MSN (ICT@FITC) NPs, was the key to offer functionalities. The specific combination of the target nucleolin and AS1411 aptamer caused AS1411 to separate from mesoporous silica nanoparticles surface, allowing FITC and ICT to be released. Subsequently, nucleolin could be detected by monitoring the fluorescence intensity. In addition, Atp-MSN (ICT@FITC) NPs can not only inhibit cell proliferation but also improve the level of ROS while activating the Bax/Bcl-2/caspase-3 signalling pathway to induce apoptosis in vitro and in vivo. Moreover, our results demonstrated that Atp-MSN (ICT@FITC) NPs had low toxicity and could induce CD3⁺ T-cell infiltration. As a result, Atp-MSN (ICT@FITC) NPs may provide a reliable and secure platform for the simultaneous identification and treatment of liver cancer.

A comprehensive review: Biological activity, modification and synthetic methodologies of prenylated flavonoids

Prenylated flavonoids, a unique class of flavonoids which combine a flavonoid skeleton and a lipophilic prenyl side-chain, possess great potential biological activities including cytotoxicity, anti-inflammation, anti-Alzheimer, anti-microbial, anti-oxidant, anti-diabetes, estrogenic, vasorelaxant and enzyme inhibition. Recently, prenylated flavonoids have become an indispensable anchor for the development of new therapeutic agents, and have received increasing from medicinal chemists. The prenylated flavonoids have been outstanding developed through isolation, semi or fully synthesis in a very short period of time, which proves the great value in medicinal chemistry researches. In this review, research progress of prenylated flavonoids including natural prenylated flavonoids, structural modification, synthetic methodologies and pharmacological activities was summarized comprehensively. Furthermore, the structure-activity relationships (SARs) of prenylated flavonoids were summarized which provided a basis for the selective design and optimization of multifunctional prenylated flavonoid derivatives for the treatment of multi-factorial diseases in clinic.

Design, Synthesis, and Biological Evaluation of Icaritin Derivatives as Novel Putative DEPTOR Inhibitors for Multiple Myeloma Treatment

Icaritin is an active ingredient in Epimedium, which has a variety of pharmacological activities. However, the low activity of Icaritin and the unclear target greatly limit its application. Therefore, based on the structure of Icaritin, we adopted the strategy of replacing toxic groups and introducing active groups to design and synthesize a series of new analogues. The top compound C3 exhibited better antimultiple myeloma activity with an IC₅₀ of 1.09 μM for RPMI 8226 cells, induced RPMI 8226 apoptosis, and blocked the cell cycle in the S phase. Importantly, transcriptome analysis, cellular thermal shift assay, and microscale thermophoresis assay confirmed that DEPTOR was the target of C3. Moreover, we explored its binding mode with C3. Especially, C3 displayed satisfactory inhibition of tumor growth in RPMI 8226 xenografts without obvious side effects. In summary, C3 was discovered as a novel putative inhibitor of DEPTOR for the treatment of multiple myeloma.

Dihydrochalcones from the leaves of Lithocarpus litseifolius

Three new phlorizin derivatives, 6"-O-vanilloylphlorizin (1), 6"-O-(4-hydroxybenzoyl)phlorizin (2), 6"-O-feruloylphlorizin (3), along with four known dihydrochalcones, phlorizin (4), 3-hydroxyphlorizin, trilobatin, and 6"-O-acetylphlorizin were isolated from the leaves of Lithocarpus litseifolius. Their structures were established by analysis of extensive spectroscopic data. The new compounds were shown to be non-cytotoxic when tested against A549, HeLa, HepG2, and MCF-7 cell lines.

Treatment for liver cancer: From sorafenib to natural products

Liver cancer most commonly develops in patients with chronic liver disease, the etiology of which includes viral hepatitis (B and C), alcohol, obesity, dietary carcinogens, and so forth. The current treatment modalities, including surgical resection and liver transplantation, have been found far from effective. Hence, there is an obvious critical need to develop alternative strategies for the treatment of it. In this review, we discuss the formation process and therapeutic targets of liver cancer. Currently, targeted therapy is limited to sorafenib, lenvatinib, regorafenib, ramucirumab and cabozantinib which leads to a survival benefit in patients, but on the other hand is hampered by the occurrence of drug resistance. Pleasingly and importantly, there are multiple natural products undergoing clinical evaluation in liver cancer, such as polyphenols like icaritin, resveratrol, and silybin, saponins including ginsenoside Rg3 and glycyrrhizinate, alkaloid containing irinotecan and berberine and inorganic compound arsenic trioxide at present. Preclinical and clinical studies have shown that these compounds inhibit liver cancer formation owing to the influence on the anti-viral, anti-inflammation, anti-oxidant, anti-angiogenesis and anti-metastasis activity. Furthermore, a series of small molecule derivatives inspired by the aforementioned compounds are designed and synthesized according to structure-activity relationship studies. Drug combination and novel type of drug-targeted delivery system thereof have been well developed. This article is ended by a perspective remark of futuristic development of natural product-based therapeutic regimen for liver cancer treatment. We expect that this review is an account for current status of natural products as promising anti-liver cancer treatments and should contribute to its understanding.

A comparative study on the in vitro and in vivo antitumor efficacy of icaritin and hydrous icaritin nanorods

Icaritin (ICT) and hydrous icaritin (HICT) are two similar flavonoids compounds isolated from Epimedium Genus. This is the first comparative study on their in vitro and in vivo antitumor effects. Nanorods (NRs) were prepared for ICT and HICT by anti-solvent precipitation method using D-alpha tocopherol acid polyethylene glycol succinate (TPGS) as a stabilizer. The prepared ICT-NRs and HICT-NRs had similar diameter (155.5 nm and 201.7 nm), high drug loading content (43.30 ± 0.22% and 41.08 ± 0.19%), excellent stability and a similar sustaining drug release manner. Nanorods improved the in vitro toxicity against 4 different cancer cells in contrast to free ICT or free HICT; however, no significant difference was observed in this regard between ICT-NRs and HICT NRs. In the in vivo study on the anticancer efficacy on MCF-7 and PLC/PRE/5 tumor-bearing mice model, HICR-NRs displayed certain advantage over ICT NRs with higher tumor inhibition rate.

Selective alkylation of β-anhydroicaritine and their biological evaluation on anticancer

A convenient and selective alkylation of icaritin has been developed. The methodology involved initial formation of β-anhydroicaritine (3) under acidic conditions followed by selective methylation at the C-3 position and then alkylation at C-5 position. Several alkylated β-anhydroicaritine derivatives were synthesised using this methodology. These newly synthesised derivatives, especially the compounds 5b, 5c and 5j, significantly suppressed cell proliferation when tested against cancer cell lines in vitro. Compound 5j (R = Bn) exhibited a competitive inhibition against MCF7 in vivo compared to tamoxifen.

Molecular and cellular basis of the anticancer activity of the prenylated flavonoid icaritin in hepatocellular carcinoma

The prenylated flavonoid icaritin (ICT) is currently undergoing phase 3 clinical trial for the treatment of advanced hepatocellular carcinoma (HCC), based on a solid array of preclinical and clinical data. The antitumor activity originates from the capacity of the drug to modulate several signaling effectors in cancer cells, mainly the estrogen receptor splice variant ERα36, the transcription factors STAT3 and NFκB, and the chemokine receptor CXCR4. Recent studies have implicated additional components, including different microRNAs, the generation of reactive oxygen species and the targeting of sphingosine kinase-1. ICT also engages the RAGE-HMGB1 signaling route and modulates the apoptosis/autophagy crosstalk to promote its anticancer activity. In addition, ICT exerts profound changes on the tumor microenvironment to favor an immune-response. Collectively, these multiple biochemical and cellular characteristics confer to ICT a robust activity profile which can be exploited to treat HCC, as well as other cancers, including glioblastoma and onco-hematological diseases such as chronic myeloid leukemia. This review provides an update of the pharmacological properties of ICT and its metabolic characteristics. It also addresses the design of derivatives, including both natural products and synthetic molecules, such as SNG1153 also in clinical trial. The prenylated flavonoid ICT deserves attention as a multifunctional natural product potentially useful to improve the treatment of advanced hepatocellular carcinoma.

The sphingosine kinase-1/sphingosine-1-phosphate axis in cancer: Potential target for anticancer therapy

Sphingolipid metabolites, such as ceramide, sphingosine and sphingosine-1-phosphate (S1P), play many important roles in cellular activities. Ceramide and sphingosine inhibit cell proliferation and induce cell apoptosis while S1P has the opposite effect. Maintaining a metabolic balance of sphingolipids is essential for growth and development of cells. Sphingosine kinase (SPHK) is an important regulator for keeping this balance. It controls the level of S1P and plays important roles in proliferation, migration, and invasion of cancer cells and tumor angiogenesis. There are two isoenzymes of sphingosine kinase, SPHK1 and SPHK2. SPHK1 is ubiquitously expressed in most cancers where it promotes survival and proliferation, while SPHK2 is restricted to only certain tissues and its functions are not well characterized. SPHK1 is currently considered as a novel target for the treatment of cancers. Targeting SPHK1 would provide new strategies for cancer treatment and improve the prognosis of cancer patients. Here we review and summarize the current research findings on the SPHK1-S1P axis in cancer from many aspects including structure, expression, regulation, mechanism, and potential inhibitors.

Synthesis and Biological Evaluation of Novel Alkyl Amine Substituted Icariside II Derivatives as Potential Anticancer Agents

A series of novel alkyl amine-substituted icariside II (ICA II) derivatives were synthesized by Mannich reactions at the 6-C position (compounds 4a–d) and changing the carbon chain length at the 7-OH position (compounds 7a–h), and their in vitro antitumor activity towards human breast cancer lines (MCF-7 and MDA-MB-231) and human hepatoma cell lines (HepG2 and HCCLM3-LUC) were evaluated by the MTT assay. Compared with ICA II, most of the twelve derivatives showed good micromole level activity and a preliminary structure-activity relationship (SAR) for the anticancer activity was obtained. Compound 7g showed the most potent inhibitory activity for the four cancer cell lines (13.28 μM for HCCLM3-LUC, 3.96 μM for HepG2, 2.44 μM for MCF-7 and 4.21 μM for MDA-MB-231), which was 2.94, 5.54, 12.56 and 7.72-fold stronger than that of ICA II. The preliminary SAR showed that the introduction of a alkyl amine substituent at 6-C was not favorable for the anticancer activity, while most of the 7-O-alkylamino derivatives exhibited good antitumor activity and the anticancer activity 7-O-alkylamino derivatives were influenced by the alkyl chain length and the different terminal amine substituents. Furthermore, the effects of compound 7g on apoptosis and cell cycle of MCF-7 cells were further investigated, which showed that compound 7g triggered apoptosis and arrested the cell cycle at the G0/G1 phase in MCF-7 cells. Our findings indicate that compound 7g may be a promising anticancer drug candidate lead.

Acremotins A-D, peptaibiotics produced by the soil-derived fungus Acremonium persicinum SC0105

Four new peptaibiotics, acremotins A-D (1-4) featuring three α,α-dialkylated amino acid-imino acid motifs and an unreduced C-terminal residue, along with the known peptaibiotic XR586 (5) were isolated from the solid cultures of the soil-derived fungus Acremonium persicinum SC0105. Their primary structures were characterized by detailed analysis of the HRESIMS/MS fragmentation pattern combined with comprehensive interpretation of the 1D and 2D NMR spectroscopic data. The absolute configurations of amino acid residues were determined by the advanced Marfey's method. Sequence alignment result shows that 1-4 are closely related to zervamicin IIB and emerimicin IIA, thus belong to peptaibiotic subfamily-3 (SF3). The three-dimensional (3D) structure of 4 was established by theoretical conformational analysis using the ab initio density functional theory (DFT) method, which, together with the CD spectrum, indicated an amphiphilic and helical structure for 4. 1-5 actively inhibited the growth of gram-positive bacterial pathogens, and amongst them 4 was the most potent compound showing MIC of 12.5 and 6.25 µg/ml against S. aureu and MRSA strains, respectively. 1-5 were also cytotoxic against three human cancer cell lines with IC₅₀ ranging from 1.2 to 21.6 μM.

Design, synthesis and structure–activity relationships of mangostin analogs as cytotoxic agents

A series xanthone derivatives were synthesized and cytotoxicity results indicated that the isopentene group at C-8 is essential.

Icaritin induces MC3T3-E1 subclone14 cell differentiation through estrogen receptor-mediated ERK1/2 and p38 signaling activation

Icaritin (ICT), a hydrolytic product of icariin from the genus Epimedium, has many indicated pharmacological and biological activities. Several studies have shown that ICT has potential osteoprotective effects, including stimulation of osteoblast differentiation and inhibition of osteoclast differentiation. However, the molecular mechanism for this anabolic action of ICT remains largely unknown. Here, we found that ICT could enhance MC3T3-E1 subclone 14 preosteoblastic cell differentiation associated with increased mRNA levels and protein expression of the differentiation markers alkaline phosphatase (ALP), type 1 collagen (COL1), osteocalcin (OC), osteoponin (OPN) and runt-related transcription factor 2 (RUNX2), and improved mineralization, confirmed by bone nodule formation and collagen synthesis. To characterize the underlying mechanisms, we examined the effect of ICT on estrogen receptor (ER) and mitogen-activated protein kinase (MAPK) signaling. ICT treatment induced p38 kinase and extracellular signal-regulated kinase 1/2 (ERK1/2) activation, but it demonstrated at the same time point no effect on activation of c-Jun N-terminal kinase (JNK). ER antagonist ICI182780, p38 antagonist SB203580 and ERK1/2 antagonist PD98059 markedly inhibited the ICT-induced the mRNA expression of ALP, COL1, OC and OPN. ICI182780 attenuated the ICT-induced phosphorylation of p38 and ERK1/2. These observations indicate a potential mechanism of osteogenic effects of ICT involving the ERK1/2 and p38 pathway activation through the ER.

Bioactive Pentacyclic Triterpenoids from the Leaves of Cleistocalyx operculatus

Thirteen new pentacyclic triterpenoids, cleistocalyxic acids A-K (1, 2, 4, 5, and 7-13) and cleistocalyxolides A (3) and B (6), and 15 known analogues (14-28), based on taraxastane, oleanane, ursane, multiflorane, and lupane skeletons, were isolated from the leaves of Cleistocalyx operculatus. The structures of 1-13 were elucidated by analysis of their spectroscopic data and ECD/TDDFT computations. Cleistocalyxolide A (3), presumed to be derived from the known taraxastane-type compound 14, has a rare rearranged triterpenoid backbone. Cleistocalyxic acid B (2) displayed cytotoxicity against HepG2, NCI-N87, and MCF-7 cancer cell lines with IC₅₀ values ranging from 3.2 to 6.5 μM, and cleistocalyxic acid D (5) was active against HepG2 and NCI-N87 cells with values around 5.0 μM. The noncytotoxic cleistocalyxic acid E (7) inhibited production of IL-6 by 68.1% and TNF-α by 53.7% in LPS-induced RAW 264.7 macrophages at a concentration of 2 μM.

Anti-Cancer Properties of the Naturally Occurring Aphrodisiacs: Icariin and Its Derivatives

Epimedium (family Berberidaceae), commonly known as Horny Goat Weed or Yin Yang Huo, is commonly used as a tonic, aphrodisiac, anti-rheumatic and anti-cancer agent in traditional herbal formulations in Asian countries such as China, Japan, and Korea. The major bioactive compounds present within this plant include icariin, icaritin and icariside II. Although it is best known for its aphrodisiac properties, scientific and pharmacological studies suggest it possesses broad therapeutic capabilities, especially for enhancing reproductive function and osteoprotective, neuroprotective, cardioprotective, anti-inflammatory and immunoprotective effects. In recent years, there has been great interest in scientific investigation of the purported anti-cancer properties of icariin and its derivatives. Data from in vitro and in vivo studies suggests these compounds demonstrate anti-cancer activity against a wide range of cancer cells which occurs through various mechanisms such as apoptosis, cell cycle modulation, anti-angiogenesis, anti-metastasis and immunomodulation. Of note, they are efficient at targeting cancer stem cells and drug-resistant cancer cells. These are highly desirable properties to be emulated in the development of novel anti-cancer drugs in combatting the emergence of drug resistance and overcoming the limited efficacy of current standard treatment. This review aims to summarize the anti-cancer mechanisms of icariin and its derivatives with reference to the published literature. The currently utilized applications of icariin and its derivatives in cancer treatment are explored with reference to existing patents. Based on the data compiled, icariin and its derivatives are shown to be compounds with tremendous potential for the development of new anti-cancer drugs.