Pharmacognostic evaluation and chrysazin Quantitation of Xyris indica flowering heads

Abstract

Flowering heads of Xyris indica L. have been used as crude drug in Traditional Thai medicine for a long time. It has traditionally been used to treat ringworm, constipation and flatulence. The aim of this study was to investigate the pharmacognostic specification and analysed the content of chrysazin in X. indica flowering heads. The flowering heads were collected from 15 different sources in Thailand. The drawing of whole plant of X. indica was illustrated in detail. The crude drug was dried in hot air oven and ground to powders. The macroscopic characteristics were dried flowering heads with brown bract, yellow flowers, variable in sizes, slightly characteristic odour and slightly bitter, astringent taste. The histological characteristics were fragment of corolla, seeds, pollen grain and staminode. The loss on drying, total ash, acid-insoluble ash, water soluble extractive matter and ethanol soluble extractive matter and water content were 6.899 ± 0.165, 2.497 ± 0.033, 0.409 ± 0.027 , 6.592 ± 0.474, 4.030 ± 0.486 and 11.121 ± 1.132 % dry weight, respectively. TLC fingerprint of ethanolic extracts of X. indica flowering heads were performed using silica gel as stationary phase and petroleum ether and ethyl acetate (8:1) as mobile phase. Detection under ultraviolet light (254 nm and 365 nm) as well as under visual light after with 5% potassium hydroxide solution showed chrysazin yellow fluorescent band under UV 365 nm at hRf = 59. The chrysazin content in of X. indica flowering heads was determined by TLC-densitometry and TLC image analysis using aforementioned mobile phase. The linearity of chrysazin by TLC-densitometry was 15.0-75.0 µg/ml with R2=0.9997, % recovery was in range of 90.67-99.16 %, the precision was between 0.76 -14.28 % RSD, LOD and LOQ were 5.48 and 16.62 µg, respectively and % RSD of robustness was 4.44 %. The linearity of chrysazin by TLC image analysis was 15.0-75.0 µg/ml with R2=0.9986, % recovery was in range of 91.87-96.00 %, the precision was between 0.78-3.95 % RSD, LOD and LOQ were 5.90 and 17.89 µg, respectively and % RSD of robustness was 3.60 %. The quantitative analysis showed that chrysazin content of X. indica flowering heads by TLC-densitometry was 0.0223 ± 0.0011 g/100 g of dried crude drug whereas chrysazin content by TLC image analysis was 0.0219 ± 0.0007 g/100 g of dried crude drug. Both methods were compared statistically using paired t-test statistical analysis. It was indicated that the chrysazin content from both methods were not significantly different. Antimicrobial activities of benzene extract of X. indica flowering heads and standard chrysazin were tested by agar-overlay bioautography. The benzene extract on TLC plate inhibited the growth of 4 tested gram positive bacteria, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus. The chrysazin in benzene extract and standard chrysazin inhibited the growth of Bacillus subtilis. This study is useful for identification, authentication and standardization of X. indica crude drug. Besides, it provides scientific evidences in antimicrobial potential of X. indica flowering heads.