A Comparative Study of Two Oroxylum indicum (L.) Kurz. Phenotypes Based on Phytochemicals and Antioxidant Effects, and the Anti-Inflammatory Activity of Leaf and Pod Extracts

Abstract

Indian trumpet tree Oroxylum indicum (L.) Kurz exhibits a wide range of biological activities in all plant parts, including anti-inflammation, antioxidant, and wound-healing activities. In Thailand, there are tall- and short-stem phenotypes. The latter are preferred for commercial cultivation due to their fast growth and lower harvesting cost. This study aimed to compare the chemical profiles and antioxidant effects of leaves and young pods between two phenotypes using principal component analysis (PCA) and then to evaluate the anti-inflammatory potential of the selected phenotype’s plant parts. The biomarker contents were quantified by HPLC. The antioxidants were determined using the DPPH, ABTS, and FRAP models. Nitric oxide (NO) production assays in LPS-induced RAW264.7 macrophages were performed to determine the anti-inflammatory property of the extracts. The PCA revealed that there were no differences in total phenolic content, total flavonoid content, or antioxidant activities between short- and tall-stem phenotypes. Higher potency of the NO-inhibitory effect was achieved from the leaf extract than the pod extract. These results support using the short-stem phenotypes for utilizing the leaf and pod of O. indicum, and suggest choosing the leaf part for further anti-inflammatory product development.