Abstract:
Pekepekekiore is the Māori name for a New Zealand native edible mushroom now known as Hericium novae-zealandiae. There is little to no published scientific data available on this mushroom. The aim of this study was to investigate the chemical constituents in H. novaezealandiae and their biological activities. Normal column chromatography combined with preparative HPLC was used to isolate compounds, which were then characterized by spectroscopic methods, namely UV, MS, NMR and single crystal X-ray diffraction. The HPLC-DAD method was subsequently applied for the quantification of the identified compounds. In addition, the bioactivities of the extracts and the compounds were evaluated in relation to anti-proliferation of three prostate cancer (PCa) cell lines (DU145, LNCaP, and PC3), AChE inhibition and antioxidant activities. Four nucleoside substitutes, namely cytidine, uridine, adenosine, and guanosine were identified from the aqueous extract. The total content was as high as 10.67 mg/g dry weight. A compound unique to Hericium, hericenone C, was identified from the ethanol extract of H. novae-zealandiae. In addition, three other compounds were isolated, and their structures were characterized as hericene B (another compound unique to Hericium), ergosterol and ergosterol peroxide. The contents of hericene B and ergosterol were determined as 28.53 and 2.09 mg/g dry weight, respectively. The polysaccharides possessed anti-proliferative activity on PCa cell lines. Subsequently, it was determined through RT-qPCR assays that apoptosis was one of the possible mechanisms responsible for the anti-proliferative activity in the LNCaP cell line. This was supported by the upregulation of CASP3, CASP8, and CASP9 gene expression. An alternative mechanism, discovered in PC3, was revealed to be anti-inflammation, which was supported by the down-regulation of IL6 and up-regulation of IL24. The polysaccharides also exhibited antioxidant and weak AChE inhibitory activities. Both the ethanol extract and ergosterol peroxide possessed anti-proliferative activities to the three prostate cancer cell lines tested. Ergosterol peroxide was considered likely to be one of the major compounds responsible for the anti-proliferative effect of the ethanol extract. The RT-qPCR assay showed two possible mechanisms for these anti-proliferative activities. One was apoptosis, supported by the up-regulation of CASP3, CASP8, CASP9, and an increase in the ratio of Bax/Bcl2. The other was anti-inflammation, indicated by the down-regulation of IL6 and up-regulation of IL24. The ethanol extract also exhibited antioxidant and AChE inhibitory (though weak) activities. However, none of the four compounds, namely hericenone C, hericene B, ergosterol peroxide, and ergosterol alone, were found to account for these latter two activities. This is the first report of the chemical components and their bioactivities of H. novae-zealandiae. The high content of nucleosides (over 1% dry weight) and hericene B (nearly 3% dry weight) indicates the potential of this New Zealand Hericium sp. as a useful natural source of these compounds. In addition, the polysaccharide and ethanol extracts (and its constituent ergosterol peroxide) exhibited promising anti-proliferation effects in three PCa cell lines. Current findings suggest that the lipophilic constituents from H. novae-zealandiae may have potential health benefits and enhance cancer treatments.