Search system

Abstract

The purpose of the present invention is to provide a technology that enables effective searching for candidate compounds, such as promoters / inhibitors, that have favorable biochemical properties. This search system searches for highly promising inhibitors and promoters based on the degree of structural and polarity similarity between the adsorption site and the substrate-related structure, as well as the polarity and steric bulk of the barrier site. Also, the search system efficiently searches, from among existing compounds similar to the candidate compounds, for highly water-soluble candidates based on the polar surface area per unit difference in solvation free energy of the entire molecule and the bond length.

Description

Exploration System

[0001] The present invention relates to a technique for searching for candidate compounds such as promoters / inhibitors.

[0002] According to Non-Patent Documents 1 and 2, systems for searching for candidate compounds with biological activity are called virtual screening and are classified into methods based on similarity to existing compounds such as inhibitors and ligands, and methods that use structural and polarity information to perform 3D simulations of docking with target proteins. The accuracy of methods for determining similarity to existing compounds tends to improve the more data there is on biologically active compounds. 3D simulations of binding with target proteins make it easier to search for unknown compounds with novel structures.

[0003] A well-known technique for calculating similarity to existing compounds is called fingerprinting. This technique represents the presence or absence of structural features as 1 or 0, and determines the degree of similarity based on the number of ANDs between these. Non-Patent Document 3 describes a "screening method using 2D fingerprints to measure structural similarity." Non-Patent Document 4 describes "3D pharmacophoric triplet (PDTs) fingerprint." Lipinski's rule of five is often used as a structural feature.

[0004] The following Patent Document 1 aims to provide a search system that searches with high accuracy for compounds that are highly similar in terms of both the number of structural features and physicochemical properties, and describes the following technology (see abstract): "In a system for searching for compounds with biological activity, a compound searcher calculates the distance between the feature vectors of a specified compound recorded in a model table and the feature vectors of each compound recorded in a search table, and acquires similar compounds based on the distance between the feature vectors. A GUI displays similar compounds and information indicating the biological activity of the similar compounds."

[0005] Japanese Patent Application Laid-Open No. 2021-108108

[0006] Scior T, Bender A, Tresadern G, et al., "Recognizing Pitfalls in Virtual Screening: A Critical Review", Journal of Chemical Information and Modeling 2012 52 (4), 867-881David K. Johnson and John Karanicolas, "Ultra-High-Throughput Structure-Based Virtual Screening for Small-Molecule Inhibitors of Protein-Protein Interactions", Journal of Chemical Information and Modeling 2016 56 (2), 399-411Peter Willett, "Similarity-based virtual screening using 2D fingerprints", Drug Discovery Today, Volume 11, Issues 23-24, December 2006, Pages 1046-1053Hans Matter and Thorsten Potter, "Comparing 3D Pharmacophore Triplets and 2D Fingerprints for Selecting Diverse Compound Subsets", Journal of Chemical Information and Computer Sciences 1999 39 (6), 1211-1225

[0007] Examples of targets for searching for candidate compounds include promoters / inhibitors that promote / inhibit the adsorption of substrates to enzymes. While structural features that improve the biochemical properties of promoters / inhibitors are well-known, such as "Lipinski's rule of five," these alone are insufficient. Furthermore, in simulation-based 3D docking analysis of target proteins and substrates, focusing solely on the magnitude of adsorption energy often does not lead to the effective discovery of candidate compounds with favorable biochemical properties as promoters / inhibitors.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a technique that can effectively search for candidate compounds such as promoters / inhibitors that have good biochemical properties.

[0009] The screening system of the present invention searches for promising inhibitors and promoters based on the degree of structural and polar similarity between the adsorption site and the substrate-related structure, and the polarity and bulkiness of the barrier site. It also searches for highly water-soluble candidates from existing compounds similar to the candidate compound based on the polar area per solvation free energy difference of the whole molecule and the bond distance.

[0010] The screening system according to the present invention can effectively screen for candidate compounds such as promoters / inhibitors with favorable biochemical properties. Problems, configurations, effects, etc. other than those described above will become clear from the following description of the embodiments.

[0011] 1 is an overall diagram of a search system 100. FIG. 2 shows an example format of a compound structure table 200. FIG. 3 shows an example format of a candidate compound feature table 300. FIG. 4 is a flowchart explaining the operation of an overall structure feature calculation module 112. FIG. 5 is a flowchart explaining the operation of a conjugated / branched structure extraction module 113 and a conjugated structure feature calculation module 114. FIG. 6 is a flowchart explaining the operation of an adsorption / barrier site extraction module 115 and an adsorption / barrier site feature calculation module 116. FIG. 7 is a flowchart explaining the operation of a promising degree calculation module 117.

[0012] FIG. 1 is an overall diagram of a search system 100 according to an embodiment of the present invention. The search system 100 is a system for searching for promising compound candidates expected to have desired properties related to inhibitors or fluorescent reagents. The search system 100 includes an information extraction module 110, formatted data 118, a structural feature extraction module 111, a compound structure table 200, a search module 109, a candidate compound feature table 300, an overall structure feature calculation module 112, a conjugated / branched structure extraction module 113, a conjugated structure feature calculation module 114, an adsorption / barrier site extraction module 115, an adsorption / barrier site feature calculation module 116, and a likelihood calculation module 117. The search system 100 is connected to a user's GUI (Graphical User Interface) 101 via the Internet 106 and to a public database 104 via a network 105.

[0013] The public database 104 records the ID (or information identifying the compound), name, structural formula (e.g., InChI: International Chemical Identifier, Smiles: simplified molecular input line entry system, etc.), physicochemical properties, biological activity, etc. of a plurality of compounds. The physicochemical properties include, for example, molar mass, boiling point, freezing point, vapor pressure, density, water solubility, organic solvent solubility, thermal stability, acid-alkalinity, and spectrum. The biological activity may be information called bioassay, and includes biological response and biological effect amount.

[0014] The information extraction module 110 reads data 119 from the public database 104, extracts file data 120 for each compound that describes the ID, compound name, structural formula, physicochemical properties, and biological activity, and stores this in formatted data 118.

[0015] The structural feature extraction module 111 reads file data 121 of the formatted data 118, analyzes structural formulas such as InChI and Smiles, and accumulates, for each compound, data 122 in a compound structure table 200, which are characterized by (a) the number of ring structures classified by the number of members and the number of nitrogen, oxygen, and sulfur contained, etc., (b) the number of chain structures classified by the type of substitution, functionality, and characteristic group, (c) the number of pharmacophores, which are aggregates of combinations of ring and chain structures, (d) physicochemical properties such as molar mass, boiling point, freezing point, vapor pressure, density, water solubility, organic solvent solubility, thermal stability, acidity / alkalinity, and spectrum, and (e) bioassays such as biological response and biological effect amount.

[0016] The structural feature extraction module 111 may store data 122 including a new structure newly generated by slightly changing the feature amount in the compound structure table 200. In addition, the operator 107 may read data 119 from the public database 104 and manually add the data to the formatted data 118 and the compound structure table 200.

[0017] The overall structure feature calculation module 112 analyzes the data 122 characterized by the structural feature extraction module 111 to calculate the solvation free energy difference of the entire molecule, the polar area, the number of fluorine atoms, and the minimum and maximum values ​​of the interatomic bond distance as data related to the water solubility of each compound, and stores the calculated data 130 describing the calculation results in the compound structure table 200.

[0018] The conjugated / branched structure extraction module 113 extracts a conjugated / branched structure 126 in which π electrons are connected for each compound by analyzing the data 122 characterized by the structural feature extraction module 111. The conjugated structure feature calculation module 114 calculates, for the extracted conjugated / branched structure 126, data related to the fluorescence of each compound, such as the number of branches in the conjugated structure and the length of the longest side, the rotational restraint force based on the polarity around the branched structure, the symmetry and coplanarity of the branched structure, the number of strong cathode atoms attached to the conjugated structure and their distance from the center, the number of atoms heavier than carbon, and the number, regularity, and symmetry of fused rings, and stores calculated data 131 describing the results in the compound structure table 200.

[0019] A user 102 sends a command 124 via GUI 101 to a search module 109 of the search system 100, specifying candidate compounds, substrates that bind to target proteins / enzymes, their structural formulas, target fields, etc.

[0020] The search module 109 extracts existing compounds and new structures (134) that are highly similar to the candidate compound designated by the user from the compound structure table 200 by using the distance between feature vectors consisting of (a) the amount of various structural features such as ring structure, chain structure, and pharmacophore, (b) physical and chemical properties such as molar mass, boiling point, freezing point, vapor pressure, density, water solubility, organic solvent solubility, thermal stability, acidity / alkalinity, and spectrum, and (c) bioassays such as biological response and biological effect amount.

[0021] The adsorption / barrier site extraction module 115 extracts adsorption / barrier sites 127 for each of existing compounds and novel structures that are highly similar to a user-specified candidate compound and the extracted candidate compound, based on the degree of similarity with the structure of the user-specified substrate. The adsorption / barrier site feature calculation module 116 calculates feature quantities 138 of the extracted adsorption / barrier sites 127 and stores them in a candidate compound feature table 300. The promise calculation module 117 determines the promise of the compounds as inhibitors, promoters, strong fluorescent materials, long-wavelength fluorescent materials, or reagents based on data 139 stored in the candidate compound feature table 300, and returns a determination result 136.

[0022] The search module 109 transmits the determination result 123 (which may be the same as the determination result 136 or may be a result that has been processed in some way) to the GUI 101 of the user 102. This enables the user 102 to efficiently search for promising candidates for inhibitors and fluorescent reagents.

[0023] FIG. 2 shows an example format of a compound structure table 200. The compound structure table 200 has records 201 describing the characteristics of each compound, the number of which is equal to the number of compounds. For convenience, a branch number is assigned to each record, and M records 201 (201-1 to 201-M) are shown. Each record 201 has the following: an ID number 202; a compound name 203; InChI Smiles 204; a feature quantity 205 consisting of multiple features 208-1 to n, such as ring structure, chain structure, physical / chemical properties, pharmacophore, biological response, biological effect amount, and bioassay, which are characterized by the structural feature extraction module 111; and a solvation free energy difference 209 of the entire molecule, a polar area 210, the number of fluorine atoms 211, and interatomic bonds, which are calculated and accumulated by the overall structural feature calculation module 112. A feature quantity 206 relating to water solubility consisting of the maximum and minimum values ​​212 and 213 of the fusion distance; and a feature quantity 207 relating to the conjugated structure consisting of the number of branches 214 and the length of the longest side 215 in the conjugated structure, the rotational restraint force 216 based on the polarity around the branched structure, the symmetry 217 and coplanarity 218 of the branched structure, the number 219 of strong cathode atoms attached to the conjugated structure and the distance from the center 229, the number of atoms heavier than carbon 220, the number 221 of fused rings, symmetry 222, and regularity 223, calculated and accumulated by the conjugated structure feature calculation module 114.

[0024] The symmetry 217 and coplanarity 218 of the branched structure may be limited to the branched structure of the nitrogen ion. The number of branches 214 and the length 215 of the longest side in the conjugated structure, and the rotational restraining force 216 based on the polarity around the branched structure may be limited to the conjugated structure connecting the nitrogen atom and the nitrogen ion.

[0025] 3 shows an example of the format of the candidate compound characteristic table 300. The candidate compound characteristic table 300 temporarily stores characteristic data of existing compounds and new structures that are highly similar to the user-specified candidate compound extracted by the search module 109 from the compound structure table 200, as well as characteristic data of adsorption / barrier sites extracted and calculated by the adsorption / barrier site extraction module 115 and the adsorption / barrier site characteristic calculation module 116.

[0026] The candidate compound characteristic table 300 has records 301 that describe the characteristics of each of the candidate compounds designated by the user, existing compounds that are highly similar to the candidate compounds designated by the user, and novel structures. For convenience, a subnumber is assigned to each record, and X records 301 (301-1 to 301-X) are shown. Each record 301 has the following: ID number 302; compound name 303; InChI Smiles 304; feature quantities 305 consisting of multiple features 308-1 to n, such as ring structure, chain structure, physical / chemical properties, pharmacophore, biological response, biological effect amount, and bioassay, characterized by the structural feature extraction module 111; feature quantities 306 relating to water solubility, consisting of a solvation free energy difference 309 of the entire molecule, a polar area 310, the number of fluorine atoms 311, and maximum and minimum interatomic bond distances 312 and 313, calculated and accumulated by the overall structural feature calculation module 112; and branching within the conjugated structure calculated and accumulated by the conjugated structure feature calculation module 114. a feature quantity 307 relating to the conjugated structure, which includes the number of atoms 314, the length of the longest side 315, the rotational inhibition force 316 based on the polarity around the branched structure, the symmetry 317 and coplanarity 318 of the branched structure, the number of strong cathode atoms attached to the conjugated structure 319 and the distance from the center 329, the number of atoms heavier than carbon 320, the number of fused rings 321, symmetry 322, and regularity 323; and a feature quantity 324 relating to the adsorption / barrier site, which includes the structure / polarity vector 325 of the adsorption site extracted and calculated by the adsorption / barrier site extraction module 115 and the adsorption / barrier site feature calculation module 116, the structure / polarity similarity 326 of the adsorption site with the substrate-related structure, the polarity 327 of the barrier site, and the bulkiness 328 of the barrier site.

[0027] FIG. 4 is a flowchart illustrating the operation of the global structural feature calculation module 112. The global structural feature calculation module 112 calculates the solvation free energy difference (logp) and the polar area from the structural formula InChi / Smiles in the data 122 characterized by the structural feature extraction module 111 (step 401). Next, the number of fluorine atoms and the minimum and maximum atomic bond distances are calculated from the structural formula InChi / Smiles (step 402). Finally, the solvation free energy difference (logp) and the polar area are corrected using the minimum and maximum values ​​of the number of fluorine atoms and the atomic bond distances (step 403). Specifically, the solvation free energy difference (logp) is corrected to be smaller and the polar area is corrected to be larger depending on the number of fluorine atoms. Furthermore, the solvation free energy difference (logp) is corrected to be larger depending on the atomic bond distance. The corrected values ​​are entered in the water solubility feature 206 in the compound structure table 200, and the process ends.

[0028] 5 is a flowchart illustrating the operation of the conjugated / branched structure extraction module 113 and the conjugated structure characteristic calculation module 114. The conjugated structure characteristic calculation module 114 extracts conjugated / branched structures with linked π electrons from the structural formulas InChi / Smiles in the data 122 characterized by the structural characteristic extraction module 111 (step 501). The conjugated structure characteristic calculation module 114 calculates the number of branches and the length of the longest side from the extracted conjugated / branched structures with linked π electrons, particularly from the conjugated structures connecting nitrogen atoms and nitrogen ions (step 502). The conjugated structure characteristic calculation module 114 calculates the rotational inhibition force based on the polarity around the branched structures of the nitrogen ions, and the symmetry and coplanarity of the branched structures from the extracted conjugated / branched structures with linked π electrons (step 503). The conjugated structure feature calculation module 114 calculates the number of strongly polar atoms attached to the conjugated structure, the distance from the center, and the number of atoms heavier than carbon from the conjugated structure in which the extracted π electrons are linked (step 504). The conjugated structure feature calculation module 114 calculates the number of fused rings, regularity, and symmetry of the conjugated structure from the conjugated structure in which the extracted π electrons are linked (step 505). The conjugated structure feature calculation module 114 enters the calculated value in the feature amount 207 related to the conjugated structure in the compound structure table 200, and ends the processing. Regarding the strength of polarity, for example, if the polarity is equal to or greater than carbon, it can be considered to be strongly cathodic, and if it is less than carbon, it can be considered to be strongly anodic.

[0029] 6 is a flowchart illustrating the operation of the adsorption / barrier site extraction module 115 and the adsorption / barrier site characteristic calculation module 116. The adsorption / barrier site extraction module 115 creates vectors that quantify the polarity of consecutive atoms connected starting from the polar atom at the end of the chain structure for each of the candidate compounds entered by the user and the existing compounds and new structures highly similar to the user-specified candidate compound extracted by the search module 109 from the compound structure table 200, and the substrate-related structure, and calculates the similarity between the substrate-related structure and each candidate substance (existing compound, new structure) based on the distance between the vectors (step 601). The adsorption / barrier site extraction module 115 extracts the adsorption site with the most similar structure / polarity arrangement to the substrate-related structure, and extracts other structures as barrier sites (step 602). The adsorption / barrier site characteristic calculation module 116 corrects the polarity and bulkiness of the barrier site by weighting the polarity and bulkiness of the barrier site according to the number of atoms connected to the adsorption site (step 603). Specifically, the weight is increased for barrier sites whose distance (number of atoms connected to the adsorption site) is closer than a threshold, and similarly, the weight is increased for barrier sites whose distance is farther than the threshold (increasing the weight means that the inhibitory effect is considered to be high). The adsorption / barrier site characteristic calculation module 116 enters the calculated value in the characteristic amount 324 related to the adsorption / barrier site in the candidate compound characteristic table 300, and then ends the process.

[0030] FIG. 7 is a flowchart illustrating the operation of the likelihood calculation module 117 .

[0031] Step 701: The likelihood calculation module 117 outputs the following records listed in the candidate compound feature table 300 to the search module 109: (a) Records in which the structural / polarity similarity 325 between the adsorption site and the substrate-related structure is high (above the first threshold) and the polarity / bulkness 327 / 328 of the barrier site is large (above the second threshold) are output as highly promising inhibitors; records in which the structural / polarity similarity 325 between the adsorption site and the substrate-related structure is high (above the third threshold) and the polarity / bulkness 327 / 328 of the barrier site is small (below the fourth threshold) are output as highly promising promoters.

[0032] Step 702: The likelihood calculation module 117 outputs to the search module 109, as candidates with high water solubility, records in the candidate compound feature table 300 that have a high polar area 310 per solvation free energy difference 309 of the entire molecule (above the fifth threshold) and a small interatomic bond distance (below the sixth threshold).

[0033] Step 703: The promising degree calculation module 117 lists the candidate compound characteristic table 300. Records with a small number of branches 314 of the conjugated structure (less than the seventh threshold), a short length 315 of the longest side (less than the eighth threshold), a large rotational restraint force 316 of the branched structure (greater than the ninth threshold), a high symmetry 317 of the branched structure (greater than the tenth threshold) and a high coplanarity 318 (greater than the eleventh threshold), a small number 319 of cathode atoms with stronger cathode polarity than the carbon atoms attached to the conjugated structure (less than the twelfth threshold), and a large distance 329 from the center (greater than the thirteenth threshold) are output as promising phosphors likely to have high quantum yields. In particular, phosphors with high rotational restraint force, symmetry, and coplanarity around the branched structure of the nitrogen cation (considered to be high if they are greater than the twentieth threshold, greater than the twenty-first threshold, or greater than the twenty-second threshold, respectively), and small conjugated branches connecting the nitrogen atom and nitrogen ion (less than the twenty-third threshold) are output as promising phosphors with high quantum yields.

[0034] Step 704: The likelihood calculation module 117 outputs, as promising fluorophores likely to have long wavelengths, records in the candidate compound feature table 300 in which the length 315 of the longest side of the conjugated region is long (above the 14th threshold), the distance 329 from the center of the conjugated structure is large (e.g., attached to the outer edge of the conjugated structure), the number 319 of cathode atoms with stronger cathode polarity than carbon atoms is large (above the 15th threshold), and the number 320 of atoms heavier than carbon atoms in the conjugated structure is large (above the 16th threshold).

[0035] Step 705: The promising degree calculation module 117 outputs records in the candidate compound feature table 300 that have a large number of fused rings 321 in the conjugated structure (above the 17th threshold), a high regularity 323 (above the 18th threshold), and a high symmetry 322 (above the 19th threshold) as promising optical materials with high refractive index and transmittance.

[0036] The search module 109 outputs highly water-soluble compounds and highly promising inhibitors, promoters, fluorescent materials, and optical materials output from the likelihood calculation module 117 to the GUI 101 of the user 102. This enables the user 102 to efficiently search for promising candidates for inhibitors and fluorescent reagents.

[0037] Summary of the Invention The search system 100 according to the present invention, by simply inputting a compound candidate and a substrate-related structure, can efficiently search for promising inhibitors or promoters from existing compounds and novel structures similar to the compound candidate, based on the degree of structural and polar similarity of the adsorption site with the substrate-related structure and the polarity and bulkiness of the barrier site. Furthermore, it can efficiently search for highly water-soluble candidates from existing compounds and novel structures similar to the compound candidate, based on the polar area per solvation free energy difference of the entire molecule and the length of the bond distance. Furthermore, it can efficiently search for promising fluorophores likely to have high quantum yields, long wavelengths, or optical properties such as refractive index and transmittance from existing compounds and novel structures similar to the compound candidate, based on the number of branches and the length of the longest side of the conjugated structure, the rotational inhibition force of the branched structure based on the polarity around the branched structure, the symmetry and coplanarity of the branched structure, the number of strongly polar atoms and the number of atoms heavier than carbon attached to the conjugated structure, and the number, regularity, and symmetry of the fused rings of the conjugated structure.

[0038] In the above embodiment, the thresholds (first to twenty-third thresholds) used by the promising degree calculation module 117 when identifying promising compound candidates can be arbitrarily set to appropriate values ​​depending on the properties of the values ​​to be compared. The values ​​of each threshold may be stored in advance in the search system 100, for example, or may be input / updated by the user via a GUI.

[0039] In the above embodiments, each module provided in the search system 100 can be configured by hardware such as a circuit device that implements these functions, or by software that implements these functions being executed by a computing device such as a CPU (Central Processing Unit).

[0040] 100: Search system 109: Search module 110: Information extraction module 111: Structural feature extraction module 112: Overall structure feature calculation module 113: Conjugate / branched structure extraction module 114: Conjugate structure feature calculation module 115: Adsorption / barrier site extraction module 116: Adsorption / barrier site feature calculation module 117: Promise calculation module 200: Compound structure table 300: Candidate compound feature table

Claims

1. A search system for searching for compounds, comprising: a memory unit for storing a compound structure table that accumulates compound data describing the structures of existing compounds; an overall structure feature calculation module that calculates features of the overall structure of a molecule; an adsorption / barrier site extraction module that extracts adsorption sites and barrier sites of compound candidates; an adsorption / barrier site feature calculation module that calculates the features of each of the adsorption sites and the barrier sites; and a likelihood calculation module that searches the compound structure table for compound candidates having specific properties based on the features of each of the adsorption sites and the barrier sites, wherein the overall structure feature calculation module calculates the polar area per solvation free energy difference and the minimum and maximum bond distances for the entire compound molecule and stores the results in the compound structure table; and the adsorption / barrier site extraction module extracts, for the compound candidates described in the compound structure table, a site having a structure / polar configuration most similar to a substrate-related structure as the adsorption site, and extracts other structures as the barrier sites, the adsorption / barrier site feature calculation module calculates the structural / polarity similarity between the adsorption site and the substrate-related structure for the compound candidate described in the compound structure table, and calculates the polarity / bulkness of the barrier site; the likelihood calculation module identifies a compound candidate whose structural / polarity similarity is equal to or greater than a first threshold and whose polarity / bulkness is equal to or greater than a second threshold as a highly promising inhibitor; the likelihood calculation module identifies a compound candidate whose structural / polarity similarity is equal to or greater than a third threshold and whose polarity / bulkness is less than a fourth threshold as a highly promising accelerator; and the likelihood calculation module identifies a compound candidate whose polarity area per solvation free energy difference is equal to or greater than a fifth threshold and whose bond distance is less than a sixth threshold as a highly water-soluble compound candidate.

2. The search system according to claim 1, further comprising: a conjugated / branched structure extraction module that extracts, from the structures of the compound, conjugated structures in which π electrons are connected and branched structures within the conjugated structures; and a conjugated structure feature calculation module that calculates the number of branches and the length of the longest side of the conjugated structure, the rotational inhibition force of the branched structure based on the polarity around the branched structure, the symmetry and coplanarity of the branched structure, and the number of strongly polar atoms attached to the conjugated structure, wherein the promising degree calculation module identifies, as promising phosphors with high quantum yields, compound candidates in which the number of branches of the conjugated structure is less than a seventh threshold, the length of the longest side of the conjugated region is less than an eighth threshold, the rotational inhibition force of the branched structure is not less than a ninth threshold, the symmetry of the branched structure is not less than a tenth threshold and the coplanarity is not less than an eleventh threshold, the number of cathode atoms attached to the conjugated structure that have stronger polarity than the carbon atoms is less than a twelfth threshold and the distance from the center is not less than a thirteenth threshold.

3. The search system according to claim 1, further comprising: a conjugated / branched structure extraction module that extracts, from the structures of a compound, conjugated structures in which π electrons are connected and branched structures within the conjugated structures; and a conjugated structure feature calculation module that calculates the number of branches and the length of the longest side of the conjugated structure, the number of polar atoms having stronger negative polarity than the carbon atoms attached to the conjugated structure, and the number of atoms heavier than the carbon atoms in the conjugated structure; wherein the likelihood calculation module identifies, as promising long-wavelength phosphors, compound candidates in which the length of the longest side of the conjugated structure is equal to or greater than a 14th threshold, the number of negative atoms attached to the outer edge of the conjugated structure is equal to or greater than a 15th threshold, and the number of atoms heavier than the carbon atoms in the conjugated structure is equal to or greater than a 16th threshold.

4. The search system according to claim 1, further comprising: a conjugated / branched structure extraction module that extracts, from the structures of a compound, conjugated structures in which π electrons are connected and branched structures within the conjugated structures; and a conjugated structure feature calculation module that calculates the number of fused rings in the conjugated structure, the regularity of the conjugated structure, and the symmetry of the conjugated structure, wherein the promising degree calculation module identifies, as promising optical materials with high refractive index and transmittance, candidate compounds in which the number of fused rings in the conjugated structure is equal to or greater than a 17th threshold, the regularity of the conjugated structure is equal to or greater than an 18th threshold, and the symmetry is equal to or greater than a 19th threshold.

5. The search system described in claim 1, characterized in that the overall structural feature calculation module corrects the solvation free energy difference to be smaller and corrects the polar area to be larger depending on the number of fluorine atoms the compound has.

6. The search system described in claim 1, characterized in that the adsorption / barrier site extraction module extracts polar atoms at the ends of chain structures for sites possessed by compound candidates described in the compound structure table, and calculates the similarity between the substrate-related structure and the site based on a vector that quantifies the polarities of the atoms connected in succession starting from that point.

7. The search system described in claim 1, characterized in that the adsorption / barrier site characteristic calculation module calculates the polarity and bulkiness of the barrier site after weighting by weighting the polarity and bulkiness of the barrier site according to the number of atoms connected to the adsorption site so that those with a number of atoms greater than or less than a threshold value are given more weight.

8. The search system described in claim 2, characterized in that the promising degree calculation module identifies, as promising fluorescent substances with high quantum yields, compound candidates in which the rotational restraint force of the nitrogen cation in the conjugated structure around the branched structure is equal to or greater than a 20th threshold, the symmetry of the branched structure is equal to or greater than a 21st threshold, the coplanarity of the branched structure is equal to or greater than a 22nd threshold, and the branching of the conjugation connecting the nitrogen atom and the nitrogen ion is less than a 23rd threshold.

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