Figure 5

Six natural products of the flavonoids with good inhibitory activity on the Mtb proteasome. Inhibitory activities of six flavonoids (each 200 μM) were as follows: baicalein 84.30%, pectolinarin 88.69%, hispidulin 82.06%, myricetin 84.50%, quercetin 74.40% and kaempferol 68.29%. The common structural features are the hydroxyl at the C ring C-3 (myricetin, quercetin and kaempferol), or the hydroxyl (baicalein) or the methoxyl (pectolinarin and hispidulin) at the A ring C-6.