Qinghaosu modification

Study on the reactions of qinghaosu is heuristic, not only for determination of its structure, but also especially for understanding chemical properties and hence for the modification and utilization of the qinghaosu molecule to develop a new medicinal apphcation. Among them, reduction and acidic degradation have been paid the most attention and have received more practical application. 

The 4-methyl is located near the peroxy group, so the modification on C-4 may offer the important information about the SAR. Some compounds (Structure 5-16) were therefore synthesized These compounds showed more activity than qinghaosu. It was noteworthy that deoxoartemisinin was also more active than qinghaosu in vitro and in vivo. ... 

A series of qinghaosu analogs of C-3 or/and C-13 modification were prepared from artemisinic acid by Lee et al. (Scheme 5-19). Among these analogs, only 13-nitromethyl qinghaosu had antimalarial activity comparable with qinghaosu. 

Among the various natural products, which have been found to possess antiprotozoal activity in humans, quinine (2) and qinghaosu (7) have undergone extensive molecular modifications to obtain better antimalarial drugs. The salient results of these studies are described below. 

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