Design, synthesis, and biological activity studies of a new class of sulfonated aurones: First synthesis of acidoaurone isolated from Phyllanthus acidus

Abstract A novel series of aurones were designed by introducing sulfonic acid group on ring‐A and ring‐B of known natural aurones such as hispidol, sulfuretin, maritimetin, and aureusidin. These sulfonated aurones were synthesized by a unique approach. Sulfonation on ring‐A or ring‐B converts water‐insoluble aurones into highly water‐soluble aurones. The sulfonated aurones were tested for their antioxidant, antiinflammatory, and AChE inhibition activities along with their natural aurones. Ring‐A sulfonated aurones displayed higher antioxidant activity, 5‐LOX, and AChE inhibition in comparison with their corresponding natural aurones. Ring‐B sulfonated aurones exhibited potent 5‐LOX inhibitory activity and significant antioxidant activity. Acidoaurone, a first sulfonated aurone isolated from Phyllanthus acidus was synthesized for the first time and was well characterized using NMR, LC–MS, and further confirmed by HMBC.