New natural inhibitors of hexokinase 2 (HK2): Steroids from Ganoderma sinense.

Hexokinase 2 (HK2), a rate-limiting enzyme in the first step of glycolysis pathway, expresses at high level in cancer cells compared with normal cells. HK2 provides a new target for cancer therapy due to its pivotal role in tumor tumourigenic and metastatic process. The structure-based virtual ligand screening in a small in-house database of natural products predicted that a new steroid, (22E,24R)-6β-methoxyergosta-7,9(11),22-triene-3β,5α-diol (2) from Ganoderma sinense has high binding affinity to HK2 with significant calculated binding free energy. Based on this prediction, compound 2, together with the other 12 steroid analogues (1, 3-13) from this plant were selected for further in vitro microscale thermophoresis (MST), enzyme inhibition, and cell-based assays based on the HK2 target. And compound 2 was finally identified as an HK2 inhibitor. As the first natural HK2 inhibitor, compound 2 can be considered as a potential drug candidate targeting at HK2 for cancer therapy.