The fresh new picture out-of design 6 try statistically an educated; hence, all of the pursuing the conversations are derived from design six

These types of conclusions were strongly related a previous data you to definitely revealed that structural modification of your own fragrant ring C, particularly within C1 and you may C2 ranks, forecast improvement of the cytotoxic hobby of xanthone ingredients

In this model, n represents the number 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 F_calc/F_{dining 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

The brand new roentgen value of 0.976 away from design six displayed there is an effective correlation within separate parameters (descriptors) and you can cytotoxic products of one’s xanthones. I affirmed one 97.6% of changed cytotoxic activity of the analyzed xanthones is caused from the amendment of qC1, qC2, qC3, minute dipole, and logP. Ergo, structural amendment is suggested toward band A great otherwise C. 41

This new relationship effect revealed that model six you will definitely anticipate the new cytotoxic craft out of ten xanthone compounds very well, that have a mountain and you will relationship coefficient (Roentgen dos ) off 0

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/IC_fifty values based on the selected model 6 are presented in Table 6, and its scatter plot is presented in Figure 1. 976 and 0.951, respectively.

The essential design from xanthone (Desk 1) demonstrates phenyl band B cannot be replaced. Alteration of internet fees from adjacent atoms (qO11, qC9, qC9a, qC4a, qO10, qC10a, and qC8) is only going to be obtained as a result of digital thickness induction of costs amendment off atoms from inside the phenyl rings A and you can C. Based on the build off compound 5 (whilst had the finest cytotoxic interest), which customization could be achieved by modifications at the qC5, qC7, and you may qC8 (ring A beneficial) as well as qC1 and qC2 (band C). Thus, both of these phenyl bands must be thought within the designing a new xanthone having most useful cytotoxic hobby. 41

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. Modification of new xanthones on the basis of the selected model 6 was performed by using the structure of compound 5 (3,4,6-trihydroxyxanthone) as the model because of the highest value of the cytotoxic activity. The more negative net atomic charge of qC1, qC2, and qC3, along with the more positive value of the dipole moment and logP, was recommended to increase the more positive value of log 1/IC₅₀. 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.