Influence of N-substituted Amino Group on the Insecticidal Activity of 2-(n-Octyl)-3-(n-propyl)isothiourea Derivatives

2-(n-Octyl)-3-(n-propyl)isothiourea 유도체의 살충활성에 미치는 N-치환 Amino group의 영향

New twenty 2-(n-octyl)-3-(n-propyl)isothiourea derivatives(S) were synthesized which is modified from the insecticidal Buprofezine (Applaud) in the selective insecticidal activities in-vitro against Diamond-Back moth (Plutella Xylostella Linnaeus). The structure activity relationships(SAR) between the insecticidal activity$(pI_{50})$ and a various physicochemical parameters of the substituent(Z) of S were analyzed by the multiple regression technique. The activities would depend largely on the MR, ${\pi}$ and $L_1$ parameters. The SAR was rationalized by parabolic function of MR, ${\pi}$ and $L_1$ constant, where the optimal values of the constants were $L_1=5.22{{\AA}}$, $MR=15.70\;Cm^3/mol$ and ${\pi}=1.60$, respectively. The steric effects play an important role in determining insecticidal activity. The SAR suggest that the S derivatives having a substituents with a small breadth and an appropriate length as Z group showed potent activity. From the results, the iso-propyl group(Z) substituent (5) with three carbon atom was the most effective compound.

살충성Buprofezine분자의 구조를 변형한 20종의 새로운 isothiourea유도체(S)를 합성하고 N-치환(Z)amino기의 변화에 따르는 6종의 해충에 대한 살충활성을 검토한 바, 배추 좀나방(Plutella Xylostella Linnaeus)에 대하여 현저하게 선택적인 살충성을 나타내었다. N-치환(Z) amino기의 치환기(Z)가 변화함에 따른 물리-화학적 파라미터와 배추 좀나방에 대한 살충활성값 (Obs. $pI_{50}$)과의 구조-활성 관계(SAR)식으로부터 살충활성에 미치는 물리-화학적 파라미터의 영향은 MR>${\pi}$>$L_1$의 순이었으며, 이들 파라미터의 적정값(optimal value)은 각각 $L_1=5.22{{\AA}}$, $MR=15.70(Cm^3/mol)$ 및 ${\pi}=1.60$이었다. 이 값을 만족하는 치환기(Z)로는 탄소 원자수가 3개로 구성된 iso-propyl 치환체(5)로써 가장 큰 살충성(Obs. $pI_{50}=3.00$)을 나타내었다.