Variability of antioxidative quercetin content in Siamese neem tree leaves in Thailand by TLC-densitometry

• Main Authors: P. Sithisarn, W. Gritsanapan
• Other Authors: Mahidol University
• Format: Conference or Workshop Item
• Published: 2018
• Subjects: Agricultural and Biological Sciences
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/18658

Siamese neem tree (Azadirachta indica var. siamensis) is a Thai medicinal plant of which young leaves and flowers are used as a bitter tonic. Siamese neem tree leaves exhibited antioxidant activity according to flavonoids including quercetin, rutin and rhynchosin-O-β-D)-glucoside. Quercetin is reported to be the major antioxidative component. There has been no report about the content of antioxidant in Siamese neem tree leaves before. Therefore, the quantitative analysis of quercetin content in Siamese neem tree leaves collected from different locations in Thailand was performed. Leaf aqueous extracts of Siamese neem tree collected from 12 provinces in Thailand were quantitatively analyzed for quercetin content using a TLC-densitometric method. Quercetin content in the leaf aqueous extracts and in the dried leaf samples were in the range of 6.19 ± 0.16 to 48.11± 1.50 mg% w/w and 1.55 ± 0.04 to 19.30 ± 0.60 mg% w/w, respectively. The average high quercetin content was found in samples from Prachin Buri, Songkhla, and Phetchabun Provinces. Comparing between areas, it was found that samples from the East and the South of Thailand significantly contain high quercetin content while the samples from the Northeast and the West exhibited low content. These results would be useful as basic information for finding good sources of Siamese neem tree leaf as raw material with high active antioxidant content and also useful as a guide for standardization of Siamese neem tree leaf extract used for medicinal and health supplement purposes.