<![CDATA[ABSTRACT Quantitative Structure-Activity Relationship (QSAR) study have been conducted to antimalarial active compounds of cassane-type diterpenes isolated from seed kernels of Bagore (Caesalpinia crista Linn.), using the atomic net charges data resulted from AM1 method of semi-empirical calculations. The aim of this research is to determine the mathematic equation model of quantitative structure-activity relationship from antimalarial active compounds of cassane-type diterpenes isolated from seed kernels of Bagore (Caesalpinia crista Linn.) using the electronic parameter of AM1 method. The best QSAR equation model was determined by multiple linier regression analysis and tested by leave-one-out type of cross validation methods. The result indicates that the biological activity is represented by a linier function of activity versus atomic net charges of C1, C2, C3, C4, and C6 which is expressed by : Log (1/C) = -7,362(+ 4,251) qC1 +3,258 (+ 4,590) qC2 + 11,038 (+4,485) qC3 + 29,421 (+20,542) qC4 + 19,849 (+6,171) qC6 + 8,541 (+2,256) The equation is significant at 95% level. The cross validation analysis give minimal value of PRESS=64,372 and SEP = 2,93; where Log (1/IC50) = biological activity and q = atomic net charges Key words : QSAR, Atomic Net Charges, Cross Validation Methods ABSTRAK Studi hubungan kuantitatif struktur-aktivitas (HKSA) telah dilakukan terhadap 42 senyawa aktif antimalaria turunan diterpen kassan hasil isolasi dari biji Bagore (Caesalpinia crista Linn.) menggunakan data muatan bersih atom hasil perhitungan semiempiris metode (Austin Model 1) AM1. Tujuan penelitian ini adalah menentukan model persamaan matematis hubungan kuantitatif struktur-aktivitas dari senyawa aktif antimalaria turunan diterpen kassan furano hasil isolasi dari biji Bagore (Caesalpinia crista Linn.) dengan parameter elektronik menggunakan metode AM1. Pemilihan model persamaan HKSA terbaik ditentukan dengan analisis regresi multilinier dan diuji dengan metode validasi silang leave-one-out. Hasil penelitian menunjukkan bahwa aktivitas biologis merupakan fungsi linier dari muatan bersih atom C1, C2, C3, C4, dan C6 yang dinyatakan dalam persamaan : Log (1/C) = -7,362(+ 4,251) qC1 +3,258 (+ 4,590) qC2 + 11,038 (+4,485) qC3 + 29,421 (+20,542) qC4 + 19,849 (+6,171) qC6 + 8,541 (+2,256) Persamaan signifikan pada tingkat kepercayaan 95%. Hasil analisis validasi silang memberikan data parameter pengujian relatif minimal yaitu PRESS = 9,645; dimana Log (1/IC50) = aktivitas biologis dan q = muatan bersih atom Kata kunci : HKSA, Muatan Bersih Atom, Metode Validasi Silang]]>
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