 As homoserine dehydrogenase is found mainly in plants, bacteria, and yeast, but not mammals, it is a strong target for antifungal drug development.Recently, 5-hydroxy-4-oxonorvaline (HON) was discovered to target and inhibit HSD activity irreversibly.HON is structurally similar to aspartate semialdehyde, so it is postulated that it serves as a competitive inhibitor for HSD.