Table 1.

Classification features

Group	Feature	Definition
1	m	Number of compounds connected to >2 reactions.
	u	Number of unpaired compounds.
	t	Reaction type: 1—unpaired compounds on both sides of the reaction, 2—unpaired compounds on only one side, 3—no unpaired compounds.
	h	Number of chokepoint compounds.
	c	Number of compounds.
		Number of compounds connected to >2 and <10 reactions.
		Number of compounds connected to 10–50 reactions
		Number of compounds connected to >50 reactions.
	R	Number of other reactions sharing a compound with this reaction.
		Mean number of other reactions connected to each compound.
	r1	Number of connections of the least connected compound.
	r2	Number of connections of the second least connected compound.
	r3	Number of connections of the third least connected compound.
	r4	Number of connections of the fourth least connected compound.
2	e	Eccentricity using unweighted edges,
		Normalized eccentricity using unweighted edges.
	ew	Eccentricity using weighted edges
		Normalized eccentricity using weighted edges
	b	Betweenness using unweighted edges
	bw	Betweenness using weighted edges
	N	Number of reactions in the connected component.
3		Fraction of reactions of type 1 or 2 in the network.
4	G	Domain: 1—Bacteria, 2—Eukaryota, 3—Archaea.
	D	1—species is related to disease, 0—species is not related to disease.

Note: The features chosen were divided into four groups as shown: 1—local, 2—semi-local, 3—global and 4—non-topological.