MICROSCOPIC, MOLECULAR AND CROCINS CONTENT EVALUATIONS OF SELECTED GARDENIA SPECIES IN THAILAND

Abstract

Gardenia species have been used worldwide for ornamentation and medicinal purpose. Additionally, the fruit of Gardenia jasminoides is also used in traditional health systems. Crocin is the major constituent found in the fruit of G. jasminoides. Due to the scientific data of microscopic, molecular characteristics including the crocin content have never been reported, this study aimed to evaluate microscopic, molecular characteristics as well as the crocin content of selected Gardenia species in Thailand. Midrib transverse section and the constant values of leaves (stomatal number, stomatal index, palisade ratio, epidermal cell area and trichome number) from eleven Gardenia species were evaluated under microscope. RAPD fingerprint was also performed for their genetic assessment. Pharmacognostic parameters and crocin content were evaluated from G. jasminoides fruits. The results indicated that leaf measurement showed individual microscopic characteristics. RAPD fingerprint obtained from 20 primers generated 573 reproducible bands of which 99.5% were polymorphism bands. Similarity index ranged from 0.089 to 0.332. A dendogram was constructed using the unweighted pair-group method with arithmetic averages (UPGMA) and can be divided into 2 distinct clusters. Moreover, RAPD fingerprint developed by selected primers can be used to identify eleven Gardenia species. Pharmacognostic parameters of G. jasminoides fruit revealed that the total ash, acid insoluble ash, loss on drying and moisture content should be not more than 4.9, 0.7, 8.8 and 10.0 % while water and ethanol soluble extractive values should be not less than 26.9 and 22.5 % of dry weight respectively. UV/Visible spectrophotometric method was developed and validated for determination of crocin content based on International Conference of Harmonization (ICH) guideline. This method was linear in the range between 5 and 100 µg/ml and exhibited suitable accuracy, precision and robustness. The crocin content in G. jasminoides fruits was 7.55 mg/g of dried crude drug. In conclusion, microscopic, molecular characteristics including the crocin content evaluation from this study could be applied for assessing the identification and standardization of Gardenia species and G. jasminoides fruits as well.