# Antimicrobial and Odour Qualities of Alkylpyrazines Occurring in Chocolate and Cocoa Products
## 3 Antimicrobial Activity of Pyrazines
### AntiBac-Pred and PASS Testing
The highly credible predictions for more than 500 biological activities are provided by the PASS program (Version 2.0) [61], which is based on a regression approach applied to noncongeneric chemical series. In leave-one-out cross-validation, the average prediction accuracy is over 85%. The PASS method is based on the study of SARs for the training set, which presently consists of around 46,000 medicines, drug candidates and lead compounds with experimentally determined biological activity. In PASS chemical descriptors, the so-called Multilevel Neighbourhoods of Atoms (MNA) are employed. The structural formula given in the MOL-file (SDF-file) form serves as the foundation for the creation of the collection of MNA descriptors [62; 63]. The testing in PASS against Picomavirus, which can cause a number of diseases such as the common cold, poliomyelitis, meningitisitis, hepatitis and paralysis [64], revealed excellent findings in terms of biological activity from a wide range of pyrazine derivatives. Pyrazine, 2,3-dimethylpyrazine, tetramethylpyrazine and 2-methylpyrazine showed the most likely antiviral (Picornavirus) efficacy. When evaluating the compounds' hypothesized antibacterial activity, results with a Pa greater than 0.5 were deemed relevant and are presented in Table 4. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & & **AntiBac-Pred** & & **PASS** \\ \cline{3-6}
**CIN** & **Compound Name** & \multirow{3}{*}{_Yersinia pestis_} & **Resistant My-** & **Corynebacterium** & \multirow{3}{*}{_Picornavirus_} \\  & & & _tuberculosis_ & & & 0.674 \\ \hline
1 & pyrazine & 0.7689 & & & 0.632 \\
7 & tetramethylpyrazine & 0.7431 & & & 0.635 \\
3 & 2,3-dimethylpyrazine & 0.7010 & & & 0.591 \\
4 & 2,5-dimethylpyrazine & 0.7010 & & 0.6459 & & 0.587 \\
5 & 2,6-dimethylpyrazine & 0.6560 & & & 0.601 \\
2 & 2-methylpyrazine & 0.6050 & & & 0.522 \\
6 & trimethylpyrazine & 0.5018 & & & 0.564 \\
15 & 2,3-diethylpyrazine & 0.5018 & & & 0.539 \\
9 & 2-ethyl-3-methylpyrazine & & & & 0.536 \\
19 & 2,3,5-trimethyl-6-ethylpyrazine & & & & 0.6632 \\
30 & 2-isobutyl-3-methoxypyrazine & & & 0.6910 & \\
28 & 2,3,5-trimethyl-6-isobutylpyrazine & & & 0.5910 & \\
27 & 2,3,5-trimethyl-6-isopentylpyrazine & & & 0.5910 & \\
33 & 2-isobutyl-3-methylpyrazine & & & 0.5242 & 0.535 \\
8 & 2-ethylpyrazine & & & 0.523 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The probability (Pa) for the compounds to produce biological activity related to antibacterial action as predicted by the AntiBac-Pred application, and the probability to be active (Pa) for the compounds to produce biological activity related to antiviral (Picornavirus) action as predicted by the PASS application. Summarizing all of the above, the alkylpyrazines present in chocolate and cocoa may be used as effective antibacterial agents in food, for plants and perhaps even as a supplement to current treatments for humans with microbial diseases. Their widespread dispersion in nature and extensive use over a long period of time all across the world determine the safety of their use. There should be more investigations into their antibacterial capabilities.