Antioxidant properties of plants can help thwart a plethora of conditions including cancer, bronchitis, asthma, ulcers, coronary heart diseases, scabies, insomnia, senile debility, diabetes, dysentery, etc. In this study, Andrographis paniculata (Family: Acanthaceae) was investigated for antioxidant activity. 1, 1-Diphenyl-2-picryl hydrazyl (DPPH), reducing power assay, total antioxidant capacity, 2,2'-azino-bis (3ethylbenzothiazoline-6-sulfonic acid) (ABTS), nitric oxide test, total phenolic and flavonoid from methanol, acetone, and water extracts were investigated employing various established in-vitro system. The results divulged that methanol extract had significant activity in quenching of DPPH, reducing power, ABTS, nitric oxide, antioxidant capacity when compared to other extracts. All extracts were correlated with two specific standard antioxidants ascorbic acid and butylated hydroxyanisole. The methanol extract at 500 µg/ml showed the highest scavenging activity of DPPH (91.78 ± 0.02%), ABTS (99.76 ± 0.05%). Total antioxidant capacity was 83.35 ± 0.13 AAE/mg. Reducing the power of methanol extract was significant compared to all other fractions. Nitric oxide scavenging activity was maximum in acetone extract (80.73 ± 0.05%). The quantitative estimation of the extract revealed a considerable amount of flavonoids and conversely, the amount of phenolic compounds was poor. The flavonoid content (592.34 ± 0.13 mg QE/g of dry extract) was maximum in methanol extract but phenolic content of methanol and acetone extract was very similar. This study strongly suggests that methanol extract exhibits more potent antioxidant activity than other extracts of acetone and water.
