GLS and neoplasm: About 500 compounds from a small in-house database of natural products were screened against the KGA model in silico, as a result, a new withanolide with characteristic δ-lactol side chain, physapubescin K from Physalis pubescens L., was discovered as a new natural KGA inhibitor, which showed potent anticancer activity both in vitro and in vivo and displayed synergistical inhibition of tumor cell growth with benserazide and erlotinib.