| Ginger, Zingiber officinale Rosc. is a medicinal plant found to have varities of pharmacological effect. Ginger capsules is one of the most popular dosage form of ginger that has been used widely as anti-emetic. The main active ingredients responsible for that indication are 6-gingerol and 6-shogaol. There was limited study of the stability of these two compounds in ginger capsules. This research aims to investigate the stability of 6-gingerol and 6-shogaol in ginger capsules stored at different temperatures (4 0C, room temperature and 450C). Samples were determined for the percentage remaining of 6-gingerol and 6-shogaol at 0, 1, 3 and 6 months by HPLC. The HPLC conditions included= reverse phase column (C18= 250x4.60 mm 150 micron), flow rate 1.0 ml/min, 282 nm UV-detector, mobile phase of water= methanol in gradient system. The results of method validation showed that this method was reliable in terms of linearity (correlation coefficient (R2) > 0.999), intra-day precision (% RSD< 2%), inter-day precision (% RSD average = 5.10 and 5.50%) and accuracy (%recovery = 93-103%). HPLC Chromatograms of 6-gingerol and 6-shogaol had an average retention time of 11.93 and 28.89 minutes, respectively.
Stability studies of 6-gingerol and 6-shogaol in ginger capsules showed that the amount of 6-gingerol decreased gradually as a function of time and temperature. After storage at 4 0C, room temperature and 45 0C for 6 months, the percentage remaining of 6-gingerol were 88.05, 68.29 and 36.38, respectively. In contrast, the percentage remaining of 6-shoghaol stored at 4 0C, room temperature and 45 0C for 6 months were 112.22, 222.50 and 378.33, respectively.
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