On pauciflorum var. pauciflorum (leaves); Millettia pinnata (inner bark); and Grewia mesomischa (root bark) for antiglycation and inhibitoryWe first examined the extracts to determine their content of phenolics and flavonoids. Phenolic and flavonoid compounds are secondary metabolites ubiquitously found in different parts of plants that commonly exhibit antioxidant activities. The total phenolic content of the tested plant extracts ranged from 72.36 ?15.84 to 347.87 ?14.90 g GAE/mg (Table 2). Among PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/16233097 the leaves, fruits and bark extracts, the highest total phenol content was in P. banksii fruits, whereas M. pinnata inner bark extracts had the lowest (Table 2). The extracts contained Sodium dichloroacetate flavonoids in the range from 3.36 ?0.87 to 26.30 ?2.75 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/19118039 g QE/mg (Table 2). Interestingly, P. pubescens fruits had the lowest flavonoid content, while the leaves of the same plant had the second highest flavonoid content among the selected medicinal plants. Antioxidant activity of the extracts was then assessed using two different methods, the FRAP and DPPH assays. The effect of selected extracts on FRAP and DPPH measured in this study are shown in Table 2 and Fig. 1, respectively. FRAP, a measure of antioxidant power, determines the reducing ability of an antioxidant reacting with a ferric-tripyridyltriazine (Fe3+-TPTZ) complex to form coloured ferrous-tripyridyltriazine (Fe2+TPTZ). Test samples that favour reduction of the complex fromTable 2 Total phenolic, flavonoid and FRAP contents in the selected Australian medicinal plant extractsPlant name Total phenolic (g GAE/mg) 333.70 ?11.95e 347.87 ?14.90e 323.53 ?12.eFlavonoid content (g QE/mg) 14.66 ?3.25b 7.02 ?4.49ab 19.38 ?5.bcFRAP (g AAE/mg) 449.98 ?41.74d 453.14 ?38.19d 235.68 ?9.36bc 453.30 ?51.79d 193.34 ?7.01b 311.42 ?23.16c 26.46 ?1.73a 214.52 ?21.79bPetalostigma banksii Leaves Fruits RootsPetalostigma pubescens Leaves Fruits 276.96 ?13.84d 112.29 ?5.34b 140.24 ?5.28b 72.36 ?15.84a 200.71 ?5.52c 22.64 ?4.32c 3.36 ?0.87a 26.30 ?2.75c 10.01 ?4.05ab 10.61 ?3.83abMemecylon pauciflorum var. pauciflorum Leaves Millettia pinnata Inner bark Grewia mesomischa Root barkValues are expressed as mean ?SD, n = 3 GAE Gallic acid equivalence, QE Quercetin equivalence, FRAP ferric reducing antioxidant potential, AAE ascorbic acid equivalence Data in the same column marked with different letters were significantly different (p < 0.05)Deo et al. BMC Complementary and Alternative Medicine (2016) 16:Page 6 ofFig. 1 DPPH radical scavenging activity ( ) of selected Australian medicinal plant extracts tested at 0.5 mg/mL. Values are expressed as means ?SD, n = 3. Data marked with different letters were significantly different (p < 0.05). BHT = butyl hydroxyl toluene (positive control)Fe3+-TPTZ to Fe2+-TPTZ, with indication of an intense blue colour development confirms the presence of a reductant ie., antioxidant [38]. FRAP values in the selected sample extracts ranged from 26.46 ?1.73 to 453.30 ?51.79 g AAE/mg (Table 2). P. banksii leaf and fruit extracts and the P. pubescens leaf extract were significantly higher (p < 0.05) whereas the M. pinnata inner bark extract had the lowest FRAP values. The DPPH assay is a measure of the reduction of alcoholic DPPH solution in the presence of a hydrogen-donating antioxidant due to the formation of a non-radical form, DPPH-H. In this assay, the purple colour is reduced to a yellow coloured diphenylpicrylhydrazine by the test sample containing antioxidant [39]. For the tested extracts, all.