Egger, Keith

Mushrooms, the fruiting bodies of fungi, are known to be powerful sources of nutraceuticals and pharmaceuticals but there are limited studies focusing on exploring the medicinal value of mushrooms native to North America. Here, I describe the isolation of two novel bioactive polysaccharides from the aqueous extracts of the fungus Echinodontium tinctorium: an immunostimulatory complex polysaccharide (EtISPFa) of 1354 kDa, and a growth-inhibitory β-glucan of 275 kDa. In addition, six small molecules including a phenol derivative, a new diphenylmethane derivative and three lanostane-type triterpenes were isolated from the organic extracts of E. tinctorium. The molar mass of these isolated small molecules (labelled 1-6) was determined to be 124, 260, 506, 498, 496, and 440 g/mol respectively. Phase separation, Sephadex LH-20 size exclusion, Sephadex DEAE ion exchange chromatography, Sephacryl S-500 HR size exclusion, silica column chromatography, and HPLC were used for bioactivity-guided purification. Chemical structures and linkages of EtISPFa and EtGIPL1a polysaccharides were determined by gas chromatography mass spectrometry (GCMS) and nuclear magnetic resonance (NMR). Final structures of small molecules were determined by Fourier transform infrared spectroscopy (FTIR), electrospray ionization mass spectrometry (ESI-MS), NMR, and X-ray crystallography. Immuno-stimulatory activity of EtISPFa was assessed by immunoassay in Raw 264.7 murine macrophage cells and growth-inhibitory activity of EtGIPL1a and small molecules were assessed by MTT growth-inhibitory assay in cancer cell lines. The mechanism of growth inhibition was assessed via apoptosis and cell cycle assays. EtISPFa stimulated the immune response by inducing TNF-α and other inflammatory cytokines in murine macrophage cells. In contrast, EtGIPL1a showed promising anti-proliferative activity against U251 glioblastoma cells and on ten other cancer cell lines. EtGIPL1a induced apoptosis in U251 cells with an increased cleaved caspase-3 apoptotic marker and significant DNA fragmentation in cell cycle analysis. Amongst the small molecules, compounds (2), (4) and (5) caused growth-inhibition in U251 cells; compound (4) also showed promising effects on multiple other cancer cell lines; all its bioactivities are reported here for the first time. The crystal structures of compounds (2), (4) and (5) have also been reported for the first time. Molecular targets of (1), (2), (4) and (5) by MolTarPred were predicted and warrants further experimental investigation.

Modern science is currently working to characterize the beneficial compounds from mushrooms and their potential as pharmaceutical drugs. In this thesis, eight British Columbian wild mushroom collections (3 species), comprising Fomitopsis pinicola, Phaeolus schweinitzii and Phaeolus sp., were screened for growth-inhibitory potential. Out of 28 crude extracts, 15 exhibited strong growth-inhibitory activity. For the Phaeolus sp. collection, liquid-liquid extraction, sizeexclusion chromatography and high-performance liquid chromatograph-mass spectrometry (HPLCMS) were used to purify the growth-inhibitory compound of interest. NMR analyses confirmed its identity as hispidin, a known potent anti-cancer compound. Another compound with a mass to charge ratio of 283.2 in hexane extract of Phaeolus sp. was detected by HPLC-MS. This study provides the foundational work for further isolation of small molecule(s) from the three mushroom species and shed light on the profile of Phaeolus sp. as a source of growth-inhibitory compounds.

The first part of this thesis investigated the growth-inhibitory and immunomodulatory potential of six wild Canadian mushrooms. Out of 24 crude extracts, six showed strong growth-inhibitory activity, two exhibited strong immuno-stimulatory activity and nine demonstrated potent anti-inflammatory activity. The second part of this thesis involved purification and characterization of growth-inhibitory compounds from Albatrellus flettii. Liquid-liquid extraction, Sephadex LH-20 and HPLC-Mass Spectrometry (HPLC-MS) were used to purify the three compounds of interest. NMR analyses confirmed their identity as grifolin, neogrifolin and confluentin. Grifolin and neogrifolin inhibited IMP1-KRas RNA interaction as demonstrated using an in-vitro fluorescent polarization assay. The three compounds suppressed KRas expression in SW480 and HT-29 human colon cancer cells. Confluentin, shown for the first time, to induce apoptosis and arrest cell cycle in SW480 cells. The third part of this thesis involved the development of methods to purify growth-inhibitory compounds from Sarcodon scabripes. HPLC-MS detected some potential novel compounds.