HKC (at a dose of 0.75 g/kg [i.g.] for 28 days) significantly decreased the levels of BUN, serum creatinine, and urine protein in plasma, and molecular mechanisms demonstrated that HKC notably downregulated the protein expression of NADPH oxidase (NOX)-1, NOX-2, NOX-4, α-smooth muscle actin (α-SMA), and p-extracellular signal-regulated kinase (ERK)1/2 by inhibiting the NADPH oxidase/ROS/ERK signaling pathways in renal tissue in rats with chronic renal failure induced by adenine in vivo (Cai et al., 2017a). Here, FMO5 is linked to chronic kidney disease.