QESAR study tripeptide analogues as antioxidation agents

A database consisting of 23 tripeptides was used to study the quantitative relationships between electric surface potential descriptors and antioxidant activity QESARs. The important structural descriptors SaaNH_acnt, SsOH_acnt, SaaN, SaaN_acnt, SsssCH, SaaaC, SsNH3p, SdO, SdO_acnt were selected for constructing the linear models QESARs with genetic algorithm. The best 4-variable linear model QESARlinear including the structural descriptors SaaN, SdO, SdO_acnt and SsOH_acnt was constructed. The quality QESARlinear was exhibited in statistical values R2 fitness of 97.5660, standard error of estimation SE of 0.0378, F-stat of 130.2731, R2 test of 93.3851. The non-linear model as neural network model QESARneural I(4)-HL(3)-O(1) with R2 fitness of 98.2296 was built by using structural descriptors in QESARlinear model. The antioxidation activities of tripeptides resulting from QESARlinear and QESARneural model were pointed out in values MARE, % of 27.4282 and 20.0672, respectively.
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QESAR study tripeptide analogues as antioxidation agentsTạp chí Đại học Thủ Dầu Một, số 3(5) – 2012 QESAR STUDY OF TRIPEPTIDE ANALOGUES AS ANTIOXIDATION AGENTS Nong Thi Hong Duyen(1) – Pham Van Tat(2) (1) Hue University of Science; (2) Thu Dau Mot University ABSTRACT A database consisting of 23 tripeptides was used to study the quantitativerelationships between electric surface potential descriptors and antioxidant activityQESARs. The important structural descriptors SaaNH_acnt, SsOH_acnt, SaaN,SaaN_acnt, SsssCH, SaaaC, SsNH3p, SdO, SdO_acnt were selected for constructing thelinear models QESARs with genetic algorithm. The best 4-variable linear modelQESARlinear including the structural descriptors SaaN, SdO, SdO_acnt and SsOH_acntwas constructed. The quality QESARlinear was exhibited in statistical values R2fitness of97.5660, standard error of estimation SE of 0.0378, F-stat of 130.2731, R2test of 93.3851.The non-linear model as neural network model QESARneural I(4)-HL(3)-O(1) with R2fitness of98.2296 was built by using structural descriptors in QESARlinear model. The antioxidationactivities of tripeptides resulting from QESARlinear and QESARneural model were pointedout in values MARE, % of 27.4282 and 20.0672, respectively. Keywords: QESARs model, multiple regression, neural network and antioxidation tripeptides *1. Introduction xidation activities QESAR may indicate The antioxidation compounds prevent quantitatively change of biological activitythe biological and chemical substances from or physicochemical properties corres-radical-induced oxidation damage [4]. The ponding to composition of amino acids inhydrolysis from various proteins, such as peptide chain [2], [3].soybean, casein, bullfrog, royal jelly, venison, This work reports the use ofr-lactalbumin, myofibrillar, rice endosperm, multivariate regression and neuro-fuzzyhave been shown to have antioxidant technique with genetic algorithm toactivities against the peroxidation of lipids construct the quantitative relationshipsor radical scavenging activities [1]. between electric surface potential Relationships between structural desc- descriptors and antioxidation activities forriptors (electric surface potential) and antio- tripeptides. The electric surface potential 11Journal of Thu Dau Mot university, No3(5) – 2012descriptors of tripeptides are calculated by adjusting the control 1.0) were taken fromincorporating molecular mechanics MM+ a source of Li Yao Wang [1]. Theand semiempirical quantum chemical experimental data were divided into thecalculation SCF PM3. The linear model training set as calibration group and theQESARlinear and non-linear model test set as external validation set. TheQESARneural are founded by those validation set of 5 tripeptides was derivedstructural descriptors. The antioxidant randomly from original data. Theactivities of tripeptides resulting from remaining tripeptides were constituted thethese models QESARs are compared to training set. This set includes 18those from literature. tripeptides with values of experimental activities, as listed in Table 1. The ACexp2. Methodology values in range 0.0441 – 0.6369 were used 2.1. Antioxidant data to fit for the adjustable parameters of The experimental data of 23 QESAR models. The test set consisting ofantioxidation tripeptides used in this study 5 tripeptides in Table 5 with ACexp values(ACexp: antioxidant activities of peptides in range 0.3170 – 0.6369 was used towere measured by the ferric thiocyanate evaluate its predictability.methods which are relative activities by Table 1. The tripeptide structures and experimental antioxidant values ACexp , respectively [1] No Tripeptide ACexp No Tripeptide ACexp 1 CYY 0.4699 13 HHR 0.0635 2 HHA 0.0680 14 HHS 0.0862 3 HHC 0.1277 15 HHT 0.0862 4 HHD 0.1877 16 HKH 0.0441 5 HHE 0.1877 17 HRH 0.0441 6 HHG 0.3170 18 LWL 0.6061 7 HHI 0.0680 19 PWK 0.4066 8 HHK 0.0635 20 RWK 0.6061 9 HHL 0.0680 21 RWQ 0.6061 10 HHM ...