DIFFERENTIAL ANTIPROLIFERATIVE ACTIONS OF 2′,5′ OLIGO A TRIMER CORE AND ITS CORDYCEPIN ANALOGUE ON HUMAN TUMOR CELLS

Cordycepin: A review of strategies to improve the bioavailability and efficacy

Cordycepin is a bioactive compound extracted from Cordyceps militaris. As a natural antibiotic, cordycepin has a wide variety of pharmacological effects. Unfortunately, this highly effective natural antibiotic is proved to undergo rapid deamination by adenosine deaminase (ADA) in vivo and, as a consequence, its half-life is shortened and bioavailability is decreased. Therefore, it is of critical importance to work out ways to slow down the deamination so as to increase its bioavailability and efficacy. This study reviews recent researches on a series of aspects of cordycepin such as the bioactive molecule's pharmacological action, metabolism and transformation as well as the underlying mechanism, pharmacokinetics and, particularly, the methods for reducing the degradation to improve the bioavailability and efficacy. It is drawn that there are three methods that can be applied to improve the bioavailability and efficacy: to co-administrate an ADA inhibitor and cordycepin, to develop more effective derivatives via structural modification, and to apply new drug delivery systems. The new knowledge can help optimize the application of the highly potent natural antibiotic-cordycepin and develop novel therapeutic strategies.

Cordycepin prevented IL-β-induced expression of inflammatory mediators in human osteoarthritis chondrocytes

PURPOSE

Cordycepin, a nucleoside derivative isolated from Cordyceps, has been reported to exert anti-inflammatory, antitumor, antidiabetic and renoprotective effects. Osteoarthritis (OA) is a degenerative joint disease with an inflammatory component that drives the degradation of cartilage extracellular matrix. This study aimed to assess the effects of cordycepin on human OA chondrocytes.

METHODS

In this study, human OA chondrocytes were pretreated with cordycepin at 10, 50 or 100 μM and subsequently stimulated with interleukin-1β (IL-1β) (5 ng/ml) for 24 h. Production of prostaglandin E2 (PGE2) and nitric oxide (NO) were evaluated by the Griess reaction and an enzyme-linked immunosorbent assay (ELISA). Gene expression of matrix metalloproteinase (MMP)-13, IL-6, inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX-2) was measured by real-time polymerase chain reaction (PCR). MMP-13 and IL-6 proteins in culture medium were determined using cytokine-specific ELISA. Western immunoblotting was used to analyse the iNOS and COX-2 protein production in culture medium. Nuclear factor kappa-B (NF-κB) activity regulation was explored using Western immunoblotting.

RESULTS

Pretreatment with cordycepin significantly inhibited the production of PGE2 and NO induced by IL-1β. Cordycepin also significantly decreased the IL-1β-stimulated gene expression and production of MMP-13, IL-6, iNOS and COX-2 in OA chondrocytes. Pretreatment with cordycepin attenuated IL-1β-induced activation of NF-κB by suppressing degradation of its inhibitory protein nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκB-α) in the cytoplasm.

CONCLUSIONS

We show for the first time the anti-inflammatory activity of cordycepin in human OA chondrocytes. Thus, with this unique profile of actions, cordycepin may prove to be a potentially attractive and new therapeutic/preventive agent for OA.

Improvement on Lipid Metabolic Disorder by 3′-Deoxyadenosine in High-Fat-Diet-Induced Fatty Mice

This study explores the effects of 3′-deoxyadenosine, a compound from Cordyceps militaris, on lipid metabolic disorder induced by a high-fat-diet in C57BL/6 mice. These mice had an obese body, lipid metabolic disorder and insulin resistance and were treated orally with 100 mg/kg/day 3′-deoxyadenosine (DA), 15 mg/kg/day rosiglitazone and 150 mg/kg/day fenofibrate, respectively. Compared to the model mice, the body weight gain in DA-treated mice were decreased by 66.5%, serum triglyceride and total cholesterol levels were decreased by 20.7% and 16.7%, respectively, and the triglyceride content in the skeletal muscle was reduced by 41.2%. This treatment also had a significant effect on insulin resistance. In DA-treated mice, the serum insulin levels and homeostasis model assessment of the insulin resistance index were decreased by 30% and 46%, respectively, and the areas under the glucose-time curve were depressed by 18% in the insulin tolerance test and by 21.5% in the oral glucose tolerance test. Finally, the value of glucose infusion rates and insulin induced-glucose uptake into the skeletal muscle in the hyperinsulinemic-euglycemic clamp test were increased by 18% and 41%, respectively, compared to those in the model mice. This data suggests that the effects of DA on lipid metabolic disorder induced by a high-fat-diet may be linked to its improvement on insulin resistance, especially concerning the increase of insulin sensitivity in the skeletal muscle.

Cordycepin inhibits IL-1beta-induced MMP-1 and MMP-3 expression in rheumatoid arthritis synovial fibroblasts

OBJECTIVE

MMP is a key enzyme in the degradation of extracellular matrices, and its expression plays important roles in inflammatory diseases. Cordycepin (3'-deoxyadenosine), a bioactive compound of Cordyceps militaris, has been shown to exhibit many pharmacological activities, such as anti-cancer, anti-inflammatory and anti-infection activities. In this study, we aimed at the inhibitory effect of cordycepin on IL-1beta-induced MMP-1 and MMP-3 expression as well as the molecular basis using RA synovial fibroblasts (RASFs).

METHODS

RASFs were isolated from synovial tissue obtained from 12 patients with RA and cultured in monolayer. Expression of MMP-1 and MMP-3 was evaluated using western blotting and real-time PCR. Chemokines were analysed by ELISA. The phosphorylation of mitogen-activated protein kinase was measured by western blotting. Electrophoretic mobility shift assay was performed to evaluate binding activities of DNA to nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1).

RESULTS

Cordycepin inhibited IL-1beta-induced MMP-1 and MMP-3 expressions in RASFs in a dose-dependent manner. Among various chemokines [such as monocyte chemoattractant protein-1 (MCP-1), GRO-alpha, regulated upon activation, normal T-cell expressed and presumably secreted (RANTES) and epithelial neutrophil activating peptide 78 (ENA-78)], cordycepin specifically blocked IL-1beta-induced ENA-78 production in RASF. Moreover, cordycepin significantly inhibited IL-1beta-induced p38/JNK and AP-1 activation, but not extracellular signal-regulated kinase (ERK) and NF-kappaB activation.

CONCLUSIONS

Cordycepin is a potent inhibitor of IL-1beta-induced chemokine production and MMP expression and strongly blocks the p38/JNK/AP-1 signalling pathway in RASFs.

Cordycepin (3'-deoxyadenosine) inhibits human platelet aggregation in a cyclic AMP- and cyclic GMP-dependent manner

Cordycepin (3'-deoxyadenosine) is isolated from Cordyceps militaris, a species of the fungal genus Cordyceps. Cordycepin is an ingredient used in traditional Chinese medicine and is prescribed for various diseases, such as cancer and chronic inflammation. In this study, we investigated the novel effect of cordycepin (3'-deoxyadenosine) on collagen-induced human platelet aggregation. Cordycepin inhibited dose-dependently collagen-induced platelet aggregation in the presence of various concentrations of exogenous CaCl(2). Of two aggregation-inducing molecules, cytosolic free Ca(2+) ([Ca(2+)](i)) and thromboxane A(2) (TXA(2)), cordycepin (500 microM) blocked the up-regulation of [Ca(2+)](i), by up to 74%, but suppressed TXA(2) production by 46%. Subsequently, Ca(2+)-dependent phosphorylation of both 47-kDa and 20-kDa proteins in collagen-treated platelets was potently diminished by cordycepin. However, upstream pathways for producing these two inducers, such as the activation of phospholipase C-gamma2 (PLC-gamma2) (assessed by the phosphotyrosine level) and the formation of inositol 1,4,5-trisphosphate (IP(3)), were not altered by cordycepin. Cordycepin increased the level of second messengers adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) in collagen-stimulated platelets. Whereas the NO-sensitive guanylyl cyclase inhibitor ODQ did not alter the cordycepin-induced up-regulation of cGMP, the adenylyl cyclase inhibitor SQ22536 completely blocked the cAMP enhancement mediated by cordycepin, indicating that cordycepin had different modes of action. Therefore, our data suggest that the inhibitory effect of cordycepin on platelet aggregation might be associated with the down-regulation of [Ca(2+)](i) and the elevation of cAMP/cGMP production.

Interferon-induced proteins are elevated in blood samples of patients with chemically or virally induced chronic fatigue syndrome

Overlapping symptomatologies between Chronic Fatigue Syndrome (CFS) and Chemical Sensitivity have been observed by different investigators. Therefore, it is of great importance to develop biomarker(s) for possible differentiation between viral induced CFS (without sensitivity to chemicals) versus chemically induced CFS. Since interferon induced proteins 2-5A Synthetase and Protein Kinase RNA (PKR) have been implicated in the viral induction of CFS, the objective of this study was to utilize 2-5A and PKR activity for differentiation between CFS induced by either viruses or chemicals. Based on the CDC definition and criteria, twenty CFS patients who were positive for viral genome(s) (mainly HHV6; HTLVII, EBV, and CMV) and did not have any history of exposure to toxic chemicals were included in this study. As a comparison, the second group of patients consisted of twenty individuals from the same geographical area who were negative for viral genomes but had been exposed to methyl tertiary-butyl ether concentration of up to 70 ppb and benzene concentration up to 14 ppb. All patients complained of fatigue and other symptoms overlapping between the two groups. From all 40 patients, blood was drawn, leukocyte extract was prepared and assayed for 2-5A Synthetase and PKR activity. Clinical specimens which were positive for viral genomes showed from 2.2-38.7 fold increase in 2-5A activity and 1.3-13.5 fold increase in PKR activities over the background of the healthy controls. Similarly, the second group (negative for viral genomes, but exposed to chemicals) showed a 1.1-29.2 fold increase for 2-5A Synthetase and a 1.3-11.6 fold increase for PKR when they were compared to healthy subjects. To elucidate mechanisms involved in viral versus chemical induction of 2-5A Synthetase and PKR, MDBK cell lines were cultured either in the presence or absence of HHV6, MTBE, or Benzene, heat shock proteins and interferon-beta. 2-5A and PKR activities were measured in all the above conditions. A clear induction of 2-5A and PKR was observed when MDBK cells were exposed to HHV6, MTBE, and Benzene. This induction was more significant with HSP90, HSP70, and IFN-beta indicating their involvement in the mechanism of action. However, when MDBK cells were incubated either with MTBE + Benzene or HHV6 in the presence or absence of anti IFN-beta or anti-HSP-70, the activities of both 2-5A and PKR in HHV6 infected cells were inhibited by more than 90% due to addition of anti IFN-beta, and only 20% by addition of anti-HSP70. While in MTBE + Benzene exposed cells anti IFN-beta reduced the activity of these enzymes by 40% and anti-HSP70 by more than 90%. This variation in the induction of 2-5A and PKR by anti-HSP70 or IFN-beta indicates involvement of IFN-beta in viral induction 2-5A and PKR, and HSP involvement in chemical induction of these enzymes. We conclude that 2-5A and PKR are not only biomarkers for viral induction of CFS, but biomarkers to other stressors that include MTBE and Benzene.

Growth inhibitors against tumor cells in Cordyceps sinensis other than cordycepin and polysaccharides

Cordyceps sinensis is a parasitic fungus that has been used as a Chinese medicine for a long time. In the present study, inhibitory effects of crude methanolic extracts of C. sinensis fruiting bodies on various tumor cell lines were demonstrated. The crude methanolic extracts were fractionated into 15 fractions by silica gel column chromatography. Two of the 15 fractions (CS-36-39 and CS-48-51) significantly inhibited the growth of K562, Vero, Wish, Calu-1, and Raji tumor cell lines. The inhibitory activities were not due to the polysaccharides, which have been removed in the extracting process. The polarities of these two fractions indicated that they were different from that of cordycepin. Therefore, it is suggested that tumor cell growth inhibitors, other than cordycepin and polysaccharides, are contained in C. sinensis.

Antiviral effects of 2',5'oligoadenylates (2-5As), and related compounds

Dephosphorylated "core" of 2',5'-oligoadenylate (2-5A) dimer (A2'p5'A), exogenously added to nonpermeabilized FL cells, inhibited the multiplication of Sindbis virus and vesicular stomatitis virus (VSV). The compound was shown to inhibit viral protein synthesis. The addition of A2'p5'A at the early stage of viral replication was more effective than that at the late stage. In contrast with the core, phosphorylated 2-5A (p5'A2'p5'A and ppp5'A2'p5'A) and 2-5A analogs containing cordycepin (3'-deoxyadenosine) did not show such antiviral effects. The rate of uptake of [3H]ppp5'A 2'p5'A into acid-soluble and acid-insoluble fractions, especially into the acid-insoluble fraction, was faster than that of [3H]A2'p5'A. These results suggest that the difference of antiviral activity between A2'p5'A and ppp5'A2'p5'A does not result from the different rate of uptake by cells, but from the different rate of from acid-soluble to acid-insoluble fractions.