HPLC simultaneous analysis for quality assessment of Stemona curtisii roots and determination of their insecticidal activities

Stemona spp. have been traditionally used as natural pesticides and medicinal plants. S. curtisii, a dominant species of south and southwest Thailand, attracted attention for its insecticidal properties caused by specific alkaloids. A HPLC analytical method for quantitative determination of the major derivatives oxystemokerrine, stemocurtisine, stemocurtisinol, and stemofoline in root extracts of S. curtisii was developed. The method was validated for its linearity, precision, accuracy, limit of detection (LOD) and limit of quantitation (LOQ). Ten root samples were collected from various localities in Thailand and investigated for their insecticidal activities against neonate larvae of Spodoptera littoralis. Stemofoline was shown to possess the highest insecticidal activity with a LC50 value at 2.4ppm and EC50 at 0.98ppm. The present work provides a simultaneous HPLC analysis for quality assessment and standardization of S. curtisii raw materials, extracts and final products with regard to active Stemona alkaloids for further development as high quality natural insecticidal products.