M.M. Nipunika¹, D.C. Abeysinghe¹, R.M. Dharmadasa^2,

Justicia adhatoda L is a well-known medicinal plant used in traditional systems of medicine globally. Different parts of J. adhatoda have been used for treatment of various ailments, mainly for the respiratory tract-based ailments. The present study was conducted to quantify the total antioxidant capacity (TAC), total phenolic content (TPC) and total flavonoid content (TFC) of different parts (mature leaves, immature leaves, flowers, bracts, soft stems, bark of mature stem and roots) of J. adhatoda using ferric reducing antioxidant power (FRAP) assay, modified Folin-Ciocalteu method and colorimetric method respectively. The results revealed that all tested parts of J. adhatoda contained marked amounts of TAC, TPC and TFC. Among tested parts, immature leaves showed a significantly higher TAC (19.28 ± 1.96 mg/TE g DW) followed by flowers (16.97 ± 0.99 mg/TE g DW) and bracts (14.19 ± 1.85 mg/TE g DW). Significantly the highest TPC (11.33 ± 0.14 mg/GAE g DW) and TFC (16.66 ± 3.06 mg/RE g DW) were observed in flowers followed by bracts and immature leaves. Moreover, there were positive correlations of TAC with TPC (R2 = 0.5411) and TFC (R2 = 0.5209). According to the results, it can be concluded that immature leaves, flowers and bracts of J. adhatoda contain marked amounts of bioactive compounds and hence could be effectively used for pharmaceutical industries.

Acanthaceae, Justicia adhatoda, bioactive compounds, plant parts, total antioxidant capacity