Abstract The aim of the work was to estimate the quality of some compositions in turmeric volatile oil and quantity of individual and total curcuminoids in turmeric powder dried under different conditions. Effect of convection time (0–30 min) and microwave time (20–60 min) on quality of volatile oil compositions and quantity of curcuminoids were investigated using computer software. Quality of volatile oil obtained from the hydrodistillation of dried turmeric was analyzed by gas chromatography–mass spectrometry. The quantity of individual curcuminoids (bisdemethoxycurcumin, demethoxycurcumin, and curcumin) and total curcuminoids were analyzed by high performance liquid chromatography. Ten volatile compounds in turmeric volatile oil were used to estimate the variation of their quality. Results showed that ar-turmerone, turmerone, and curlone were the three major compounds found in turmeric volatile oil. The quality of the ten volatile compounds varied depending on convection time and microwave time. The three principal curcuminoids were found in turmeric dried at long convection time and medium microwave time. However, curcumin was also found in high amount in turmeric dried at short convection time and long microwave time. Total curcuminoids in dried turmeric were equal to or greater than 5% (w/w) as stated in the Thai Herbal Pharmacopoeia. It was found that almost all of the drying procedure achieved the standard of the Thai Herbal Pharmacopoeia except at short convection time and short microwave time. In summary, convection combined with microwave drying affected the quality of volatile oil compositions and quantity of curcuminoids of turmeric raw material.

ABSTRACT Centella asiatica (L.) Urb., Apiaceae, is commonly used as food, food supplement, and medicine. Development of the extraction process to obtain the high extent of the active compound is necessary. So, the response surface methodology was used in this work to optimize the dynamic maceration of C. asiatica to obtain the highest content of the four centelloids including asiatic acid, madecassic acid, asiaticoside, and madecassoside. Two factors: extraction temperature and extraction time, were studied. The content of four centelloids was observed. After the extraction of C. asiatica using ethanol, the content of four centelloids was analyzed using validated high performance liquid chromatography. The optimization result showed that madecassoside and asiaticoside had a similar pattern of the contour plots and response surfaces. These two centelloids were highly extracted at a high extraction time and high extraction temperature. The other two centelloids had the same pattern, they had a high content at a high temperature and time as well as at a low temperature and time. The simultaneous highest content of four centelloids was achieved when extracted at 60 °C for 120 min. The optimal condition could be used as standard condition for extraction of C. asiatica to provide the highest content of four centelloids.

ABSTRACT The objective of the work was to validate the high performance liquid chromatography for simultaneous determination of stability of madecassoside and asiaticoside in Centella asiatica (L.) Urb., Apiaceae, extract-loaded film forming polymeric dispersions. High performance liquid chromatography method was validated in five topics: linearity and range, limit of detection and limit of quantitation, specificity, precision, and accuracy. Results showed the method had a good linearity (R2 > 0.9990) in the range of 5–150 µg/ml and specific. The limit of detection and limit of quantitation of madecassoside were 81 and 245 ng/ml and asiaticoside were 21 and 64 ng/ml, respectively. The percent relative standard deviation of intraday and interday precision were less than 1 and 3%, respectively. The accuracy presented as percent recovery was 101.54–103.29% for madecassoside and 100.39–102.58% for asiaticoside. This validated high performance liquid chromatography method was used to determine the stability of the formulation containing Centella asiatica extract. Centella asiatica extract-loaded film forming polymeric dispersions used Eudragit® RS 30D and Eudragit® RL 30D as film former, glycerin as plasticizer, and absolute ethanol as solvent and penetration enhancer. Three formulations with different ratio of Eudragit® RS 30D and Eudragit® RL 30D were prepared and stored for 90 days at 4 ºC, 25 ºC, and 40 ºC. Stability results showed that almost all of the formulations were unstable at 25 ºC and 40 ºC. Except, two of three formulations were stable at 4 ºC. However, the formulation was further developed to improve the stability of madecassoside and asiaticoside in the formulation.