Insight into the antiviral activity of synthesized schizonepetin derivatives: A theoretical investigation

The antiviral activity of schizonepetin derivatives 1A-1C were investigated via theoretical methods and results are compared with experimental results. The derivatives 1 A and 1 C have the highest and the lowest antiviral activity, respectively. The interactions of derivatives 1A-1C and BN-nanotube are examined. Results show that, derivatives 1A-1C can effectively interact with BN-nanotube (9, 9) and their adsorptions are favorable. The energy of derivative 1 A is higher than derivatives 1B and 1 C. The derivative 1 A has highest absolute µ, ω and ∆N values and it has lowest absolute ƞ value. Results show that, theoretical and experimental trends of antiviral activity of derivatives 1A-1C were similar, successfully.


Results and discussion
calculated ∆e ad and ∆G ad of schizonepetin derivatives 1A-1C on nanotube. The F, Br and CF 3 synthesized derivatives of schizonepetin have high antiviral activity than other derivatives. The experimental researchers confirmed that F, Br and CF 3 synthesized derivatives of schizonepetin can be synthesized more  www.nature.com/scientificreports www.nature.com/scientificreports/ comfortable than other derivatives. The experimental researchers shown that F, Br and CF 3 synthesized derivatives of schizonepetin have most antiviral active against HSV-1 virus and influenza virus H3N2 [20][21][22][23][24][25] .
The ∆E ad and ∆G ad of schizonepetin derivatives 1A-1C on nanotubes are stated in Table 2. The ∆E ad and ∆G ad are negative and the adsorption of derivatives 1A-1C on studied BN-nanotube (9,9) are favorable processes. The ∆E ad of derivatives 1 A and 1B are higher than derivative 1 C. The ∆G ad of derivatives 1 A on BN-nanotube (9,9) are higher than derivatives 1B and 1 C ca 0.10 and 0.17 eV. The ∆G ad value of derivative 1B on BN-nanotube (9,9) are more negative than derivative 1 C ca 0.07 eV. The derivative 1 A has the best ability to nanotube adsorption. These results can be interpret based on this fact that the electrons of orbitals of F and Br groups have higher interactions with unoccupied orbitals of BN-nanotube (9,9). The electrons of C atoms of CF 3 group have lower potential to interaction with orbitals of BN-nanotube (9,9). Therefore, the ∆E ad and ∆G ad of derivatives 1 A and 1B are more negative than derivative 1 C and the most interactions are obtained for derivatives 1 A and BN-nanotube (9,9).
Calculated quantum molecular descriptors of schizonepetin derivatives 1A-1C and BN-nanotube (9,9). The calculated energy parameters for schizonepetin derivatives 1A-1C and BN-nanotube (9,9) are reported in Table 3. The calculated µ value of BN-nanotube (9,9) is −0.56 eV. The calculated µ value of derivatives 1A-1C ranges from −0.45 to −0.47 eV and absolute µ values of them decreases in the order: 1 A > 1B > 1 C. Therefore, obtained absolute µ values show that derivative 1 A has highest electron and derivative 1 C has lowest electron.
In Table 3, the ƞ of BN-nanotube (9,9) is 0.09 eV. The obtained ƞ values of derivatives 1A-1C decrease in the order: 1 A < 1B < 1 C. As the minimum of the ƞ value within the derivatives 1A-1C is for derivative 1 A. Therefore, ƞ values show that 1 A has lowest stability and high reactivity and 1 C has lowest reactivity. These results can be interpret based on this fact that the F and Br atoms of derivatives 1 A and 1B are shared electrons to unsaturated ring and they have high potential to stable the schizonepetin. In the derivative 1 C the CF 3 substituent can decrease the stability of schizonepetin and C atoms of CF 3 do not transfer the electrons to ring of schizonepetin. Therefore, it can be concluded the derivative 1 C has lower activity than derivatives 1 A and 1B.
Calculated ω value of BN-nanotube (9, 9) is 1.81 eV. The calculated ω value of derivatives 1A-1C ranges from 0.60 to 1.44 eV. Among the derivatives 1A-1C the ω value decreases in the order: 1 A > 1B > 1 C. Therefore, obtained ω values show that derivative 1 A has highest capacity to accept electrons and derivative 1 C has lowest capacity to accept electrons.
The calculated ∆N value of complexes of derivatives 1A-1C with BN-nanotube (9,9) are reported in Table 3. The all of the calculated ∆N values are negative and derivatives 1A-1C can act as electron donors and BN-nanotube (9,9) can act as electron acceptors. Results show that derivative 1 A has highest absolute ∆N value and it has highest interaction with BN-nanotube (9,9). The derivative 1 C has lowest absolute ∆N value and it has lowest interaction with BN-nanotube (9,9).
Comparison of experimental and theoretical trends of antiviral activity of schizonepetin derivatives 1A-1C. The antiviral activity of derivatives is decreased as follow: 1 C < 1B < 1 A. The adsorption ability of derivatives 1A-1C via adsorption parameters (∆E ad and ∆G ad ) is: 1 A > 1B > 1 C. The obtained µ, ƞ and ω values show that derivative 1 A has highest absolute µ and ω values and it has lowest absolute ƞ values. Also derivative 1 C has lowest absolute µ and ω values and it has highest ƞ value.