In this model, n represents the number jest christian cupid za darmo of compounds contributed to build the model. The R value is the correlation coefficient; the closer R is to 1, the better the goodness of fit of the equation. 39 The Fcalc/Fdining table value represents the ratio between the variance of the calculated and tabulated values and, therefore, indicates that the regression relationships were statistically significant and did not occur by chance. Q2 serves as a criterion of robustness and predictive ability of the regression equation. The high Q2 value (>0.5) suggests the model’s ability to give an accurate prediction. The low s (the standard error of estimates) and SPRESS values suggest that the model is statistically significant for activity prediction. 39
New r worth of 0.976 off model six displayed that there are an effective correlation amongst the independent details (descriptors) and you may cytotoxic affairs of your xanthones. I verified you to definitely 97.6% of your own altered cytotoxic interest of your own studied xanthones is brought about by amendment from qC1, qC2, qC3, second dipole, and logP. These types of results was basically highly relevant to an earlier investigation one to indicated that architectural amendment of one’s aromatic band C, especially on C1 and you may C2 ranks, predict upgrade of your own cytotoxic pastime of your own xanthone compounds. Hence, architectural modification is recommended to your band An excellent or C. 41
Model 6 has been used to predict the activity of the compounds to enable comparison with experimental results (observed activity). Observed versus predicted log 1/ICfifty values based on the selected model 6 are presented in Table 6, and its scatter plot is presented in Figure 1. The correlation result showed that model 6 could predict the cytotoxic activity of 10 xanthone compounds very well, with a slope and correlation coefficient (R 2 ) of 0.976 and 0.951, respectively.
The fundamental construction from xanthone (Desk step 1) demonstrates phenyl ring B cannot be replaced. Customization of one’s web charges out-of adjoining atoms (qO11, qC9, qC9a, qC4a, qO10, qC10a, and you will qC8) will only be purchased through electronic density induction out-of charges modification away from atoms in phenyl rings A beneficial and you may C. In line with the framework off compound 5 (whilst encountered the ideal cytotoxic interest), it adjustment could well be achieved by modifications within qC5, qC7, and you will qC8 (ring Good) and also at qC1 and you may qC2 (band C). Hence, these two phenyl groups have to be believed within the designing a separate xanthone which have greatest cytotoxic activity. 41
Modification of new xanthones in line with the chosen model six are performed by using the construction regarding compound 5 (step three,4,6-trihydroxyxanthone) while the design by the high worth of new cytotoxic hobby
The best selected QSAR model is used to predict the cytotoxic activities of new synthetic xanthone compounds. The better cytotoxic activities of xanthones as IC50 values are given by the more positive value of log 1/IC50. 50. Efforts such as substitution of electron-donating groups, such as R, OH, OR, NH2, NR2, NHCOR, OCOR, or CHCR2 groups, at the C1 and C2 positions (C3 position remained unchanged as the previous structure of compound 5) could be made. Structural modifications of compound 5 generated some formulas of new xanthones with better predicted cytotoxic activities, as listed in Table 7.
Table 7 The newly designed xanthone derivatives and their predicted cytotoxic activities calculated by using the best QSAR modelAbbreviations: IC50, inhibitory concentration 50%; QSAR, quantitative structure–activity relationship.