Role of phenolics as antioxidants, biomolecule protectors and as anti–diabetic factors – Evaluation on bark and empty pods of Acacia auriculiformis

ObjectiveTo search for an efficient and inexpensive source of phytoconstituents with antioxidant potential and health promoting traits from bark and empty pods of Acacia auriculiformis (A. auriculiformis).MethodsSamples of bark and empty pod extracts were analyzed for bioactives (phenolics, flavonoids and proanthocyanidins) and subjected to free radical scavenging activity on DPPH˙, ABTS˙+, OH˙, O2•− and NO along with the determination of reducing power, iron chelating activity and peroxidation inhibition. Defensive action of extracts on biomolecules and cell membranes were evaluated by DNA nicking assay and haemolysis inhibition assay respectively. α-amylase and α-glucosidase inhibitory potentials were also determined.ResultsAll the bioactives analyzed were higher in bark (B) than empty pods (EP) [TPC: B (574.51±16.11); EP (96.80±3.45) mg GAE/g. TFC: B (94.71±7.65); EP (247.87±20.45) mg RE/g. Proanthocyanidins: B (2.81±0.31); EP (1.25±0.01) mg LE/100 g DM] except flavonoids. Both the extracts showed higher quenching capacity on DPPH and ABTS (DPPH: B (0.21±0.01); EP (1.51±0.17) g extract/g DPPH. ABTS: B (111 519.14±79 340.91); EP (80 232.55±32 894.12) mmol TE/g) with the FRAP of B (84 515.63±3 350.69) and EP (47 940.79±1 257.60) mmol Fe (II)/g. Iron chelation was not observed. In addition, they showed lower quenching activity on OH˙ (B (48.95±1.72); EP (34.94±1.62)%) and equivalent quenching on O2•− (B (53.47±3.92); EP (24.41±2.61)%), NO (B (49.04±5.04); EP (51.00±5.13)%), peroxidation inhibition (B (67.50±5.50); EP (55.1±2.3)%) and antihaemolytic potential (B (87.60±6.84)%) towards authentic antioxidant standards. Interestingly, Empty pod extracts are devoid of antihaemolytic activity. Both the extracts showed dose dependent DNA protection. Besides this, bark and empty pod extracts exhibited dual inhibiting potential against α -amylase and α-glucosidase enzymes.ConclusionsOn summarization, it insinuated that both bark and empty pods can be used for the preparation of antioxidant/nutraceutical supplements and in anti–diabetic formulations.