Table 1 The detailed description of SMILES attributes and graph invariants for constructed models of pIC₅₀

SMILES attribute

Sk

SMILES atom, i.e., one symbol (e.g. ‘C’, ‘N’, ‘=’, etc.) or a group of symbols that cannot be examined separately (e.g., ‘Cl’, ‘Br’, Si’, etc.)

SSk

a mixture of two SMILES-atoms

BOND

Presence or absence of chemical bonds: double (=), triple (#), and stereochemical (@) or @@)

PAIR

Association two of BOND, NOSP, and HALO

HARD

Association of BOND, NOSP, and HALO in the united

structural code

NOSP

Presence or absence of different chemical elements:

nitrogen (N), oxygen (O), sulfur (S), and phosphorus (P);

C_max

Maximum number of rings

N_max

Maximum number of nitrogen atoms in a molecule

O_max

Maximum number of oxygen atoms in a molecule structure

Graph invariant

e2k

Morgan extended connectivity of first order

e3k

Morgan extended connectivity of second-order

pt2k

Number of paths of lengths 2 and 3 starting from a given vertex in the graph

pt3k

Number of paths of length 3 starting from a given vertex in the graph

S2_k

Valence shells of the second orders

S3_k

Valence shells of the third orders

C5 and C6

Codes of rings (five-member and six-member rings, with the data on the presence or absence of heteroatoms, aromaticity, and the total number of given rings in the molecule)