Fig. 4. 13C in Triterpenoids from Uncaria macrophylla as ferroptosis inhibitors

Fig. 4. 13C NMR calculation results of 5 and 6. (A) Linear regression analysis of calculated 13C NMR shifts of 2′R (left) and 2′S (right) against the experimental shifts of 5 and the sDP4 probability for assignment of 5 to the candidate stereoisomers. (B) Linear regression analysis of calculated 13C NMR shifts of 2′R (left) and 2′S + (right) against the experimental shifts of 6 and the sDP4+ probability for assignment of 6 to the candidate stereoisomers.