Fig. 7. The path designer network of discriminating metabolites (yellow mark) in positive (A) and negative modes (B). There are 7 discriminating metabolites in positive mode such as PI, PE and LPE, in which PI and PE tend to be central of the network; there are 6 discriminating metabolites in positive mode such PC, LPC, SM, carnosine and car, in which PC and SM tend to be central of the network.