Jian-Hui Xiao

Secondary Metabolites from Higher Fungi: Discovery, Bioactivity, and Bioproduction

Medicinal higher fungi such as Cordyceps sinensis and Ganoderma lucidum have been used as an alternative medicine remedy to promote health and longevity for people in China and other regions of the world since ancient times. Nowadays there is an increasing public interest in the secondary metabolites of those higher fungi for discovering new drugs or lead compounds. Current research in drug discovery from medicinal higher fungi involves a multifaceted approach combining mycological, biochemical, pharmacological, metabolic, biosynthetic and molecular techniques. In recent years, many new secondary metabolites from higher fungi have been isolated and are more likely to provide lead compounds for new drug discovery, which may include chemopreventive agents possessing the bioactivity of immunomodulatory, anticancer, etc. However, numerous challenges of secondary metabolites from higher fungi are encountered including bioseparation, identification, biosynthetic metabolism, and screening model issues, etc. Commercial production of secondary metabolites from medicinal mushrooms is still limited mainly due to less information about secondary metabolism and its regulation. Strategies for enhancing secondary metabolite production by medicinal mushroom fermentation include two-stage cultivation combining liquid fermentation and static culture, two-stage dissolved oxygen control, etc. Purification of bioactive secondary metabolites, such as ganoderic acids from G. lucidum, is also very important to pharmacological study and future pharmaceutical application. This review outlines typical examples of the discovery, bioactivity, and bioproduction of secondary metabolites of higher fungi origin.

Optimization of submerged culture requirements for the production of mycelial growth and exopolysaccharide by Cordyceps jiangxiensis JXPJ 0109.

Aims:  The objective of the present study was to investigate the optimal culture requirements for mycelial growth and exopolysaccharide production by Cordyceps jiangxiensis JXPJ 0109 in submerged culture.

Polysaccharides from the Medicinal Mushroom Cordyceps taii Show Antioxidant and Immunoenhancing Activities in a D-Galactose-Induced Aging Mouse Model

Cordyceps taii, an edible medicinal mushroom native to south China, is recognized as an unparalleled resource of healthy foods and drug discovery. In the present study, the antioxidant pharmacological properties of C. taii were systematically investigated. In vitro assays revealed the scavenging activities of the aqueous extract and polysaccharides of C. taii against various free radicals, that is, 1,1-diphenyl-2-picrylhydrazyl radical, hydroxyl radical, and superoxide anion radical. The EC50 values for superoxide anion-free radical ranged from 2.04 mg/mL to 2.49 mg/mL, which was at least 2.6-fold stronger than that of antioxidant thiourea. The polysaccharides also significantly enhanced the antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) and markedly decreased the malondialdehyde production of lipid peroxidation in a D-galactose-induced aging mouse model. Interestingly, the immune function of the administration group was significantly boosted compared with the D-galactose-induced aging model group. Therefore, the C. taii polysaccharides possessed potent antioxidant activity closely associated with immune function enhancement and free radical scavenging. These findings suggest that the polysaccharides are a promising source of natural antioxidants and antiaging drugs. Consequently, a preliminary chemical investigation was performed using gas chromatography-mass spectroscopy and revealed that the polysaccharides studied were mainly composed of glucose, mannose, and galactose. Fourier-transform infrared spectra also showed characteristic polysaccharide absorption bands.

Secondary metabolites from Cordyceps species and their antitumor activity studies.

Cordyceps, an entomopathogenic mushroom, is a famous traditional Chinese medicinal herb (TCM). This higher fungus contains various known and untapped bioactive metabolites, and is looked at as an important source of natural drugs while simultaneously provides good opportunities for discovering new drugs with immunomodulatory, antitumor, hypoglycemic and hypocholesterolemic functions. Therefore, the Cordyceps spp. has been receiving an increasing interest around the world as an interesting natural drug resource. Various secondary metabolites from Cordyceps fungi were reported to have antitumor activities, and antitumor mechanism of those bioactive compounds possesses multi-target, multi-level and multi-pathway characteristics. Challenges in investigations on Cordyceps fungi include the further elucidation of antitumor molecular mechanism and relationship between structure and function of their secondary metabolites.

Jiangxienone, a New Compound with Potent Cytotoxicity against Tumor Cells from Traditional Chinese Medicinal Mushroom Cordyceps jiangxiensis

A new compound, named jiangxienone, has been isolated from a culture of the traditional Chinese medicinal mushroom Cordyceps jiangxiensis, and its chemical structure was established on the basis of spectroscopic and chemical techniques. Jiangxienone showed potent cytotoxic effects against human gastric adenocarcinoma SGC‐7901 cell and human lung carcinoma A549 cell with IC50 values ranging from 1.38 to 2.93 μM, i.e., with at least approximately six‐fold stronger cytotoxicity than cisplatin, a first‐line chemotherapy drug for cancer patients.

Hyaluronic acid enhances proliferation of human amniotic mesenchymal stem cells through activation of Wnt/β-catenin signaling pathway

This study investigated the pro-proliferative effect of hyaluronic acid (HA) on human amniotic mesenchymal stem cells (hAMSCs) and the underlying mechanisms. Treatment with HA increased cell population growth in a dose- and time-dependent manner. Analyses by flow cytometry and immunocytochemistry revealed that HA did not change the cytophenotypes of hAMSCs. Additionally, the osteogenic, chondrogenic, and adipogenic differentiation capabilities of these hAMSCs were retained after HA treatment. Moreover, HA increased the mRNA expressions of wnt1, wnt3a, wnt8a, cyclin D1, Ki-67, and β-catenin as well as the protein level of β-catenin and cyclin D1 in hAMSCs; and the nuclear localization of β-catenin was also enhanced. Furthermore, the pro-proliferative effect of HA and up-regulated expression of Wnt/β-catenin pathway-associated proteins - wnt3a, β-catenin and cyclin D1 in hAMSCs were significantly inhibited upon pre-treatment with Wnt-C59, an inhibitor of the Wnt/β-catenin pathway. These results suggest that HA may positively regulate hAMSCs proliferation through regulation of the Wnt/β-catenin signaling pathway.

New cytochalasins from medicinal macrofungus Crodyceps taii and their inhibitory activities against human cancer cells.

Three new cytochalasins (1-3) together with two known cytochalasin analogues (4 and 5) were isolated from the chloroform fraction of ethanolic extract of a medicinal macrofungus Cordyceps taii. The structures of the new compounds were elucidated on the basis of spectroscopic analysis, including HRESIMS, 1D and 2D NMR experiments. The cytotoxicities of Compounds 1-5 were investigated by the sulforhodamine B (SRB) method in vitro against human highly metastatic lung cancer cell 95-D, human lung cancer cell line A-549 and normal hepatocyte HL-7702. The results revealed that Compounds 4 and 5 showed potent antitumor activities against human lung cancer cell 95-D with IC50 value of 3.67 and 4.04 μM, respectively. In comparison with cisplatin, the first-line chemotherapy drug, they had little or no cytotoxicity on normal cells, but showed stronger cytotoxic effects on cancer cells 95-D.

Synergistic antitumor efficacy of antibacterial helvolic acid from Cordyceps taii and cyclophosphamide in a tumor mouse model

The antibacterial agent helvolic acid, which was isolated from the active antitumor fraction of Cordyceps taii, showed potent cytotoxicity against different human cancer cells. In the present study, the in vivo antitumor effect of helvolic acid was investigated in murine sarcoma S180 tumor-bearing mice. Doses of 10 and 20 mg/kg/day helvolic acid did not exert significant antitumor activity. Interestingly, co-administration of 10 mg/kg/day helvolic acid and 20 mg/kg/day cyclophosphamide (CTX) – a well-known chemotherapy drug – showed promising antitumor activity with a growth inhibitory rate of 70.90%, which was much higher than that of CTX alone (19.5%). Furthermore, the combination markedly prolonged the survival of tumor-bearing mice. In addition, helvolic acid enhanced the immune organ index. The protein expression levels of β-catenin, cyclin D1, and proliferating cell nuclear antigen were significantly suppressed in mice treated with 20 mg/kg/day helvolic acid and in those receiving combination therapy. Taken together, these results indicated that helvolic acid in combination with CTX showed potent in vivo synergistic antitumor efficacy, and its mechanism of action may involve the Wnt/β-catenin signaling pathway.

Cell Factories of Higher Fungi for Useful Metabolite Production.

Higher fungi or called as macro-fungi, consisting of the divisions ascomycetes, basidiomycetes, and imperfect fungi, are receiving great interest around the world, because studies of higher fungi help us not only to find new edible and officinal resources but also to understand their complicated biology. In recent decades, a large number of useful substances from higher fungi have been isolated, identified, and characterized, which have important biological functions, such as reducing blood pressure, enhancing immunity, and possessing anti-cancer and anti-HIV and other pharmacological activities. This chapter will review the genetic manipulation tools for higher fungi, omics analysis of higher-fungus cell factories, and production of useful metabolites by higher fungi, including those of terpenoids, heterocyclics, polysaccharides, and polyketides. Trends in future development of cell factories of higher fungi for useful metabolite production will also be analyzed. Graphical Abstract Strategies for improving cell factories of higher fungi for useful metabolite production.

Editorial Comment: Jiangxienone, a New Compound with Potent Cytotoxicity against Tumor Cells from Traditional Chinese Medicinal Mushroom Cordyceps jiangxiensis.

In one of the recent issues of Chemistry & Biodiversity (Chem. Biodiversity 2012, 9, 1349. DOI: 10.1002/cbdv.201100244), a contribution entitled ÐJiangxienone, a New Compound with Potent Cytotoxicity against Tumor Cells from Traditional Chinese Medicinal Mushroom Cordyceps jiangxiensisÏ by Jian-Hui Xiao (acting as the senior corresponding author), Zhong-Hua Sun, Wei-Dong Pan, Yu-Hong Lî, Dai-Xiong Chen, and Jian-Jiang Zhong (corresponding author) has been published. In May, 2015, we have been informed by Prof. Hirokazu Kawagishi, Shizuoka University, Japan, that the compound Jiangxienone cannot be regarded as a ÐnewÏ compound since it had already been identified and reported (Tetrahedron 2009, 65, 9850). Based on this fact, to which Prof. Kawagishi drew our attention, the published article should be rectified, besides further statements within the text, at least in the title, skipping the adjective ÐnewÏ. Further, a trivially coined new name, Jiangxienone, may not be given to an already known compound. We are deeply grateful to Prof. Kawagishi for his comments, including his ethical concerns we wholeheartedly share, and we apologize for the erroneous statements, unfortunately overseen during the Reviewing, as well as Editorial Process, in the article mentioned above. CHEMISTRY & BIODIVERSITY – Vol. 12 (2015) 1287