The effect of solvent type in antioxidant compounds extraction from banana tissues was studied. The solvent system used was pure methanol, ethanol, acetone and their aqueous solution at 50% and 70% concentrations. Comparison among three common cultivars of banana in Malaysia (Berangan, Mas and Raja) had been done and their antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging system, ferric reducing ability in plasma (FRAP)
assays and total phenolic content (TPC) assays. Acetone 70% had the strongest antioxidant compounds extraction power as compared to other solvent. All banana samples were found to be low in primary antioxidant but powerful secondary antioxidant source of fruit. The ascending order of banana cultivars in term of their antioxidant activities in all antioxidant assays carried out were Berangan < Mas < Raja. FRAP-TPC assays were highly correlated (R2>0.70) than FRAP-DPPH
and TPC-DPPH assays due to the same mechanism that occurred in the reaction of FRAP and TPC assays.
In this paper, antioxidant properties of Aegle marmelos (stem bark, leaves) and Murraya koenigii (stem bark, root) were
evaluated by 2,2-diphenyl-1-picrylhydrazy (DPPH) free radical scavenging, 2,2’-Azino-bis(3-ethylbenzthiozoline-6-sulfonic
acid) (ABTS) decolourisation, cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP)
and linoleic acid/β-carotene assays. The chloroform extract of Murraya koenigii stem bark was found to possess the
highest antioxidant activity in CUPRAC (1490.89 mgTE/g extract). In contrary, the hexane extract from Aegle marmelos
leaves exhibited the weakest antioxidant activity in the DPPH assay (81.06 mgTE/g extract). The bioactive compound
mahanimbine (7) isolated from the stem bark of Murraya koenigii was found to be the most active antioxidant agent
with TEAC of 927.73 and 1649.31 mgTE/g corresponding to the ABTS and CUPRAC assays, respectively, as well as a good
lipid peroxidation inhibitor with an inhibitory percentage of 70.95%. These CUPRAC and ABTS assays are the first report
for Malaysian Murraya koenigii species.