A new UV-LC method for estimation of a - Tomatine and a -Solanine in Tomato

A rapid and reliable High Pressure Liquid Chromatographic (HPLC) method was developed for simultaneous detection and estimation of two major tomato glycoalkaloids (GA) a -tomatine and a - solanine deployed in defense of tomato plants against phytopathogens. The technique involved methanol extraction of 1–5 g sample of tomato tissues, ammonia precipitaion and subsequent detection and quantification by HPLC. Aliquots of 20 11.1 each were separated on a 200 x 4.6 mm. Hypersil APS 5μm NH2 reverse phase column using a mobile phase of methanol: acetonitrile:0.01M potassium dihydrogen orthophosphate buffer in the ratio of 3:2:1 in isocratic mode at a flow rate of 0.3 mVmin. Under these conditions, the retention time of a -tomatine and a -solanine were approximately 14.6 and 169 min, respectively. The peak areas were found to be linear in the test concentration range of 25 to 300 μg GA/g tomato tissues. The recoveries of the spiked a -tomatine and a-solanine ranged from 85 to 93% and the method could satisfactorily detect as low as 25 μg a -tomatine and 5 μg a-solaninelg tomato. The technique was used for analysis of a-tomatine and a-solanine in fruits of 3 tomato cultivars, two resistant (PAU-7 and SL-120) and one susceptible (Pusa Ruby) to Meloidogyne incognita. The concentration of a -tomatine was 3 times higher in green fruits of resistant than the susceptible cultivars, but it declined rapidly when fruits ripened.