Antioxidant Activity and Phenolic Content of Chinese Balsam (Impatiens chinensis)

Abstract

Plants of the Impatiens genus includes more than 1,000 species. Several of the species are used as medicinal plants and are known to contain the anti‐inflammatory 2‐methoxy‐1,4‐naphthoquinone. Herbal remedies are used to treat insect bites, rashes, and poison ivy contact dermatitis, as well as management of anxiety and stress. Chinese Balsam (Impatiens chinensis) is found in North‐East India, where it is used medicinally for pain relief, promoting blood circulation, and treating urinary infections. However, very little research has been conducted to analyze the phytochemistry of I. chinensis. Here, is described the first report of antioxidant capacity and phenolic content of the seeds, leaves, stems, roots and flowers of I. chinensis.Impatiens chinensis plants were separated into seeds, leaves, stems, roots and flowers, freeze‐dried, and ground into a powder. For antioxidant assays, ground plant powder was extracted using 1% HCl, 90% aqueous methanol for 2 h under shaking. The 2,2‐diphenly‐1picryl‐hydrazyl‐hydrate (DPPH) and (ABTS) assays were used to determine the antioxidant capacity of each extract. Briefly, 10 μL extract was incubated with 10 μM DPPH for 10 min, after which the absorbance was measured spectrophotometrically at 517 nm. For the ABTS assay, 10 μL extract was incubated with 3.5 mM ABTS radical for 30 s. The absorbance at 734 nm was then measured spectrophotometrically. Results from both assays were compared to a trolox standard and calculated as 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (trolox) equivalents (TE; μmol/g dry weight). Results from the ABTS assay showed antioxidant activities of 189.5±26.7, 7462±286.3, 195.3±31.6, 85.03±19.7, and 484.1±29.3 TE (mean±SEM) for stems, flowers, leaves, roots, and seeds, respectively. In correlation, the DPPH assay revealed the same pattern of radical scavenging ability in the various tissues, with the flowers exhibiting the highest amount of antioxidant capacity. The stems, flowers, leaves, roots, and seeds exhibited 150.1±6.128, 910.8±31.62, 188.8±10.72, 118.2±13.27, and 486.9±17.81 TE (mean±SEM), respectively.The phenolic content of I. chinensis extracts was determined using the Folin‐Ciocalteu assay. 20 μL extract was incubated with 2N 10 μL extract reagent, ddH2O, and 12.56% sodium carbonate. After 30 min, the absorbance at 750 nm was measured spectrophotometrically. Results were compared to gallic acid as a standard, and the phenolic content was calculated as gallic acid equivalents (GAE; μmol/g dry weight). The phenolic content was 1127±42.6, 5046±151.0, 1206±49.3, 662.2±24.5, and 1270±70.5 GAE (mean±SEM).