Antiproliferative and Apoptosis-Inducing Activities of 4-Isopropyl-2,6-bis(1-phenylethyl)phenol Isolated from Butanol Fraction of Cordyceps bassiana

Cordyceps spp.: A Review on Its Immune-Stimulatory and Other Biological Potentials

In recent decades, interest in the Cordyceps genus has amplified due to its immunostimulatory potential. Cordyceps species, its extracts, and bioactive constituents have been related with cytokine production such as interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor (TNF)-α, phagocytosis stimulation of immune cells, nitric oxide production by increasing inducible nitric oxide synthase activity, and stimulation of inflammatory response via mitogen-activated protein kinase pathway. Other pharmacological activities like antioxidant, anti-cancer, antihyperlipidemic, anti-diabetic, anti-fatigue, anti-aging, hypocholesterolemic, hypotensive, vasorelaxation, anti-depressant, aphrodisiac, and kidney protection, has been reported in pre-clinical studies. These biological activities are correlated with the bioactive compounds present in Cordyceps including nucleosides, sterols, flavonoids, cyclic peptides, phenolic, bioxanthracenes, polyketides, and alkaloids, being the cyclic peptides compounds the most studied. An organized review of the existing literature was executed by surveying several databanks like PubMed, Scopus, etc. using keywords like Cordyceps, cordycepin, immune system, immunostimulation, immunomodulatory, pharmacology, anti-cancer, anti-viral, clinical trials, ethnomedicine, pharmacology, phytochemical analysis, and different species names. This review collects and analyzes state-of-the-art about the properties of Cordyceps species along with ethnopharmacological properties, application in food, chemical compounds, extraction of bioactive compounds, and various pharmacological properties with a special focus on the stimulatory properties of immunity.

4-(Tert-butyl)-2,6-bis(1-phenylethyl)phenol induces pro-apoptotic activity

Previously, we found that KTH-13 isolated from the butanol fraction of Cordyceps bassiana (Cb-BF) displayed anti-cancer activity. To improve its antiproliferative activity and production yield, we employed a total synthetic approach and derivatized KTH-13 to obtain chemical analogs. In this study, one KTH-13 derivative, 4-(tert-butyl)-2,6-bis(1-phenylethyl)phenol (KTH-13-t-Bu), was selected to test its anti-cancer activity. KTH-13-t-Bu diminished the proliferation of C6 glioma, MDA-MB-231, LoVo, and HCT-15 cells. KTH-13-t-Bu induced morphological changes in C6 glioma cells in a dose-dependent manner. KTH-13-t-Bu also increased the level of early apoptotic cells stained with annexin V-FITC. Furthermore, KTH-13-t-Bu increased the levels of cleaved caspase-3 and -9. In contrast, KTH-13-t-Bu upregulated the levels of pro- and cleaved forms of caspase-3, -8, and -9 and Bcl-2. Phospho-STAT3, phospho-Src, and phospho-AKT levels were also diminished by KTH13-t-Bu treatment. Therefore, these results strongly suggest that KTH-13-t-Bu can be considered a novel anti-cancer drug displaying pro-apoptotic activity.

Anti-Proliferative and Pro-Apoptotic Activities of 4-Methyl-2,6-bis(1-phenylethyl)phenol in Cancer Cells

It has been found that 4-isopropyl-2,6-bis(1-phenylethyl)phenol (KTH-13), a novel compound isolated from Cordyceps bassiana, is able to suppress tumor cell proliferation by inducing apoptosis. To mass-produce this compound, we established a total synthesis method. Using those conditions, we further synthesized various analogs with structural similarity to KTH-13. In this study, we aimed to test their anti-cancer activity by measuring anti-proliferative and pro-apoptotic activities. Of 8 compounds tested, 4-methyl-2,6-bis(1-phenylethyl)phenol (KTH-13-Me) exhibited the strongest anti-proliferative activity toward MDA-MB 231 cells. KTH-13-Me also similarly suppressed the survival of various cancer cell lines, including C6 glioma, HCT-15, and LoVo cells. Treatment of KTH-13-Me induced several apoptotic signs in C6 glioma cells, such as morphological changes, induction of apoptotic bodies, and nuclear fragmentation and chromatin condensation. Concordantly, early-apoptotic cells were also identified by staining with FITC-Annexin V/PI. Moreover, KTH-13-Me highly enhanced the activation of caspase-3 and caspase-9, and decreased the protein level of Bcl-2. In addition, the phosphorylation levels of Src and STAT3 were diminished in KTH-13-Me-treated C6 cells. Therefore, these results suggest that KTH-13-Me can be developed as a novel anti-cancer drug capable of blocking proliferation, inducing apoptosis, and blocking cell survival signaling in cancer cells.

4-Isopropyl-2,6-bis(1-phenylethyl)aniline 1, an Analogue of KTH-13 Isolated from Cordyceps bassiana, Inhibits the NF-κB-Mediated Inflammatory Response

The Cordyceps species has been a good source of compounds with anticancer and anti-inflammatory activities. Recently, we reported a novel compound (4-isopropyl-2,6-bis(1-phenylethyl)phenol, KTH-13) with anticancer activity isolated from Cordyceps bassiana and created several derivatives to increase its pharmacological activity. In this study, we tested one of the KTH-013 derivatives, 4-isopropyl-2,6-bis(1-phenylethyl)aniline 1 (KTH-13-AD1), with regard to anti-inflammatory activity under macrophage-mediated inflammatory conditions. KTH-13-AD1 clearly suppressed the production of nitric oxide (NO) and reactive oxygen species (ROS) in lipopolysaccharide (LPS) and sodium nitroprusside- (SNP-) treated macrophage-like cells (RAW264.7 cells). Similarly, this compound also reduced mRNA expression of inducible NO synthase (iNOS) and tumor necrosis factor-α (TNF-α), as analyzed by RT-PCR and real-time PCR. Interestingly, KTH-13-AD1 strongly diminished NF-κB-mediated luciferase activities and nuclear translocation of NF-κB family proteins. In accordance, KTH-13-AD1 suppressed the upstream signaling pathway of NF-κB activation, including IκBα, IKKα/β, AKT, p85/PI3K, and Src in a time- and dose-dependent manner. The autophosphorylation of Src and NF-κB observed during the overexpression of Src was also suppressed by KTH-13-AD1. These results strongly suggest that KTH-13-AD1 has strong anti-inflammatory features mediated by suppression of the Src/NF-κB regulatory loop.

Pro-Apoptotic Activity of 4-Isopropyl-2-(1-Phenylethyl) Aniline Isolated from Cordyceps bassiana

Cordyceps species including Cordyceps bassiana are a notable anti-cancer dietary supplement. Previously, we identified several compounds with anti-cancer activity from the butanol fraction (Cb-BF) of Cordyceps bassiana. To expand the structural value of Cb-BF-derived anti-cancer drugs, we employed various chemical moieties to produce a novel Cb-BF-derived chemical derivative, KTH-13-amine-monophenyl [4-isopropyl-2-(1-phenylethyl) aniline (KTH-13-AMP)], which we tested for anti-cancer activity. KTH-13-AMP suppressed the proliferation of MDA-MB-231, HeLa, and C6 glioma cells. KTH-13-AMP also dose-dependently induced morphological changes in C6 glioma cells and time-dependently increased the level of early apoptotic cells stained with annexin V-FITC. Furthermore, the levels of the active full-length forms of caspase-3 and caspase-9 were increased. In contrast, the levels of total forms of caspases-3, caspase-8, caspase-9, and Bcl-2 were decreased in KTH-13-AMP treated-cells. We also confirmed that the phosphorylation of STAT3, Src, and PI3K/p85, which is linked to cell survival, was diminished by treatment with KTH-13-AMP. Therefore, these results strongly suggest that this compound can be used to guide the development of an anti-cancer drug or serve as a lead compound in forming another strong anti-proliferative agent.