Kang-Ping Xu

Anticancer potential of Hericium erinaceus extracts against human gastrointestinal cancers

ETHNOPHARMACOLOGICAL RELEVANCE Hericium is a genus of mushrooms (fungus) in the Hericiaceae family. Hericium erinaceus (HE) has been used for the treatment of digestive diseases for over 2000 years in China. HE possesses many beneficial functions such as anticancer, antiulcer, antiinflammation and antimicrobial effects, immunomodulation and other activities. The aim of the studies was to evaluate the anticancer efficacy of two extracts (HTJ5 and HTJ5A) from the culture broth of HE against three gastrointestinal cancers such as liver, colorectal and gastric cancers in both of in vitro of cancer cell lines and in vivo of tumor xenografts and discover the active compounds. MATERIALS AND METHODS Two HE extracts (HTJ5 and HTJ5A) were used for the studies. For the study of chemical constituents, the HTJ5 and HTJ5A were separated using a combination of macroporous resin with silica gel, HW-40 and LH-20 chromatography then purified by semipreparative high-performance liquid chromatography (HPLC) and determined by nuclear magnetic resonance (NMR) spectra. For the in vitro cytotoxicity studies, HepG2 and Huh-7 liver, HT-29 colon, and NCI-87 gastric cancer cell lines were used and MTT assay was performed to determine the in vitro cytotoxicity. For in vivo antitumor efficacy and toxicity studies, tumor xenograft models of SCID mice bearing liver cancer HepG2 and Huh-7, colon cancer HT-29 and gastric cancer NCI-87 subcutaneously were used and the mice were treated with the vehicle control, HTJ5 and HTJ5A orally (500 and 1000 mg/kg/day) and compared to 5-fluorouraci (5-FU) at the maximum tolerated dose (MTD, 25-30 mg/kg/day) intraperitoneally daily for 5 days when the tumors reached about 180-200 mg (mm(3)). Tumor volumes and body weight were measured daily during the first 10 days and 2-3 times a week thereafter to assess the tumor growth inhibition, tumor doubling time, partial and complete tumor response and toxicity. RESULTS Twenty-two compounds were obtained from the fractions of HTJ5/HTJ5A including seven cycli dipeptides, five indole, pyrimidines, amino acids and derivative, three flavones, one anthraquinone, and six small aromatic compounds. HTJ5 and HTJ5A exhibited concentration-dependent cytotoxicity in vitro against liver cancer HepG2 and Huh-7, colon cancer HT-29, and gastric cancer NCI-87 cells with the IC50 in 2.50±0.25 and 2.00±0.25, 0.80±0.08 and 1.50±0.28, 1.25±0.06 and 1.25±0.05, and 5.00±0.22 and 4.50±0.14 mg/ml; respectively. For in vivo tumor xenograft studies, HTJ5 and HTJ5A showed significantly antitumor efficacy against all four xenograft models of HepG2, Huh-7, HT-29 and NCI-87 without toxicity to the host. Furthermore, HTJ5 and HTJ5A are more effective than that of 5-FU against the four tumors with less toxicity. CONCLUSION HE extracts (HTJ5 and HTJ5A) are active against liver cancer HepG2 and Huh-7, colon cancer HT-29 and gastric cancer NCI-87 cells in vitro and tumor xenografts bearing in SCID mice in vivo. They are more effective and less toxic compared to 5-FU in all four in vivo tumor models. The compounds have the potential for development into anticancer agents for the treatment of gastrointestinal cancer used alone and/or in combination with clinical used chemotherapeutic drugs. However, further studies are required to find out the active chemical constituents and understand the mechanism of action associated with the super in vivo anticancer efficacy. In addition, future studies are needed to confirm our preliminary results of in vivo synergistic antitumor efficacy in animal models of tumor xenografts with the combination of HE extracts and clinical used anticancer drugs such as 5-FU, cisplatin and doxurubicin for the treatment of gastrointestinal cancers.

Inhibitory effect of selaginellin on high glucose-induced apoptosis in differentiated PC12 cells: Role of NADPH oxidase and LOX-1

Hyperglycemia clearly plays a key role in the development and progression of diabetic neuropathy. Hyperglycemia induces oxidative stress to generate reactive oxygen species in diabetic neurons resulting in neuronal damage and dysfunction. Apoptosis has been proposed as a possible mechanism for high glucose-induced neural dysfunction and neuronal cell injury. High glucose per se enhances lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) expression via activation of NADPH oxidase/reactive oxygen species pathway in endothelial cells. Selaginellin, a component extracted from Saussurea pulvinata (Hook. et Grev.) Maxim, was assessed for its ability to protect rat pheochromocytoma (PC12) cells against oxidative toxicity induced by high glucose. The differentiated PC12 cells were pretreated with various concentrations (10(-7), 3×10(-7) or 10(-6) M) of selaginellin for 1 h and then co-treated with selaginellin and D-glucose (75 mM) for 72 h. Selaginellin was shown to protect differentiated PC12 cells against high glucose toxicity, as determined by characteristic morphological features, cell viability, and apoptosis as evaluated by Hoechst 33,258 staining assay, annexin V-propidium iodide double staining assay and caspase-3 activity. In addition, the increase in NADPH oxidase activity, mRNA expression of NADPH oxidase subunits (NOX-1 and NOX-2) and LOX-1, and reactive oxygen species production induced by high glucose were significantly inhibited by selaginellin or by anti-LOX-1 antibody. The present study demonstrated that inhibitory effect of selaginellin on high glucose-induced cell injury and apoptosis in differentiated PC12 cells is related to inhibition of LOX-1/NADPH oxidase-reactive oxygen species/caspase-3 signaling pathway.

Two new selaginellin derivatives from Selaginella tamariscina (Beauv.) Spring

Two new selaginellin derivatives, selaginellins K (1) and L (2), were isolated from Selaginella tamariscina (Beauv.) Spring and characterized as 2-formyl-4,4′-dihydroxy-3-[(4-hydroxyphenyl)ethynyl]biphene and 4,4′-dihydroxy-2-methyl-3-[(4-hydroxyphenyl)ethynyl]biphene on the basis of their spectroscopic data including UV, IR, 1D, and 2D NMR as well as HR-ESI-MS spectroscopic analysis.

Selaginellin C, a new natural pigment from Selaginella pulvinata Maxim (Hook et Grev.)

A novel compound, selaginellin C (1), was isolated from Selaginella pulvinata Maxim (Hook et Grev.) as (R,S)-4-((1,2-dihydroxyethyl)-2′,4′-dihydroxy-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)((4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone, along with two known compounds, selaginellin (2) and selaginellin A (3). The structure of the new compound was elucidated on the basis of 1D and 2D NMR as well as HR-ESI-MS spectroscopic analysis.

Selaginellins I and J, two new alkynyl phenols, from Selaginella tamariscina (Beauv.) Spring

Selaginellins I (1) and J (2), two new compounds, were isolated from Selaginella tamariscina (Beauv.) Spring and were characterized as (R,S)-4-((2′,4′-dihydroxy-4-(hydroxymethyl)-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone (1) and (R,S)-4-((3-((3,4-dihydroxyphenyl)ethynyl)-4′-hydroxy-4-(hydroxymethyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone (2) on the basis of UV, IR, 1D and 2D NMR, and HR-ESI-MS spectroscopic analysis.

Cyclooxygenase-2 inhibitors in lung cancer treatment: Bench to bed.

The most common and leading cause of cancer-related death in men is lung cancer. Despite the recent advances in chemotherapy, advanced lung cancer still remains incurable. For this, the understanding of molecular mechanisms involved in lung carcinogenesis is necessary to provide potentially effective therapeutic targets for the treatment of lung cancer, and thus the therapeutic limitations can be overcome. Cyclooxygenase-2 (COX-2) is an important inflammation factor that is reported to be up-regulated in different cancers. A number of COX-2 inhibitors have been developed, but most of them are restricted due to the different risk factors. Currently, the FDA has allowed celecoxib to remain on the market but advised physicians to apply this drug with alternative therapies or to use at a low dosage. Some other COX-2 inhibitors, such as, apricoxib and etoricoxib are under critical investigation currently. Celecoxib is being tested in clinical trials against lung cancer, as a single agent or in combination with other agents. Recent studies have suggested celecoxib as a feasible and clinically active regimen in the treatment of patients with lung cancer. However, more clinical trials are necessary for the better understanding of the role of selective COX-2 inhibitors in the prevention and treatment of lung cancer along with their assessment of toxicity. In this review, we have discussed the mechanism of actions of COX-2 in cancer progression and the therapeutic use of COX-2 inhibitors in the treatment of lung cancer with subsequent clinical studies and future management.

Selaginellin M, a new selaginellin derivative from Selaginella pulvinata

A new selaginellin derivative, selaginellin M (1), together with one known compound, selaginellin E (2), was isolated from Selaginella pulvinata. The structure of the new compound was elucidated and named as (R,S)-4-((4′-hydroxy-4-((2-hydroxyethoxy)methyl))-3-((4-hydroxyphenyl)ethynyl)biphenyl-2-yl)(4-hydroxyphenyl)methylene)cyclohexa-2,5-dienone on the basis of the spectroscopic data including UV, IR, 1D, and 2D NMR as well as HR-ESI-MS analysis.

Effects of selaginellin on homocysteine-induced senescence in human umbilical vein endothelial cells.

Homocysteine plays a key role in endothelial cell senescence associated with atherosclerosis-based cardiovascular diseases. Selaginellin, a component extracted from Selaginella pulvinata (Hook. et Grev.) Maximo, was assessed for its ability to protect human umbilical vein endothelial cells against homocysteine-induced senescence. The endothelial cells were pretreated with various concentrations (10−7, 3 × 10−7, or 10−6 M) of selaginellin for 1 hour before exposure to homocysteine. Selaginellin was shown to protect endothelial cells against homocysteine-induced senescence, as determined by senescence-associated β-galactosidase activity, telomerase activity, and cell cycle distribution. In addition, the increase in levels of intracellular reactive oxygen species and downregulation of SIRT1 gene expression induced by homocysteine were significantly reversed by selaginellin. Our study suggests that selaginellin has a protective effect against homocysteine-induced senescence through mechanisms related to antioxidation via scavenging reactive oxygen species and upregulating the expression of SIRT1 gene.

Unciflavones A–F, six novel flavonoids from Selaginella uncinata (Desv.) Spring

Six new flavonoids, unciflavones A-F (1-6), have been isolated from medicinal plant Selaginella uncinata (Desv.) Spring. Their structures were established on the basis of extensive NMR analysis including 1D NMR ((1)H, (13)C and DEPT) and 2D NMR (COSY, HSQC, HMBC) experiments as well as HRESIMS analysis. All compounds possess exceptional structural features with an aryl substituent at the C-8 position, which are uncommonly encountered in natural resources and firstly reported in genus Selaginella.

Uncinataflavone, a new flavonoid with a methyl benzoate substituent from Selaginella uncinata

Uncinataflavone (1), a new flavonoid, together with four known compounds (2–5), was isolated from Selaginella uncinata (Desv.) Spring. Compounds 2 and 3 were isolated from the genus selaginella for the first time. The structure of the new compound was determined as methyl 3-(5,7-dihydroxy-2-(4-hydroxyphenyl)-4-oxo-4H-chromen-6-yl)-4-methoxybenzoate by means of spectroscopic evidence, including UV, IR, 1D and 2D NMR analyses as well as HR-ESI-MS. These compounds (1–5) were evaluated for the antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl assay system.