DPPH radical scavenging activity

Liu JK, Hu L, Dong ZJ and Hu Q. 2004. DPPH radical scavenging activity of ten natural p-terphenyl derivatives obtained from three edible mushrooms indigenous to China. Chem Biodiv 1 (4) 601—605. 

Nakajima, K., Yoshie-Stark, Y., and Ogushi, M. (2009). Comparison of ACE inhibitory and DPPH radical scavenging activities of fish muscle hydrolysates. Food Chem. 114,844—851. 

The hybrid molecules, comprised of sydnones and other heterocyclic compounds, constitute one of the more promising approaches for the design of bioactive compounds. 3-Aryl-4-formylsydnones (22) are attractive starting compounds for several 4-heterocycle-substituted sydnones, such as thiazo-lidinone (23) and thiazoline (24, 25) [14,15], imidazoles (26) [16], thiadia-zolines (27), thiadiazoles (28) [17], and indoles (29) [18]. Some sydnonyl-substituted thiazolidinone (23) and thiazoline (30) derivatives exhibited a potent l,l-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, comparable to that of vitamin E [14,15]. 

Kang, H.M., and M.E. Saltveit. 2002a. Antioxidant enzymes and DPPH-radical scavenging activity in chilled and heat-shocked rice (Oryza sativa L.) seedlings radicles. J. Agri. Food Chem. 50 513-518. 

The DPPH radical scavenging activity was determined according to the method of Kim et al, (2002). The DPPH radical (100 jiM) was dissolved in 80% of aqueous methanol. The plant extract solutions, 0.1 mL, were added to 2.9 mL of the methanolic DPPH solution and the mixture was vigorously shaken and was kept at 23 °C in the dark for 30 min. The decrease of the absorbance of the resulting solution was monitored at 517 nm (Cary 50 Scan UV-Visible apparatus) after 30 min. A control, which consists of 0.1 mL of 50% aqueous methanol and 2.9 mL of DPPH solution, was prepared. The DPPH radical scavenging activity of plant extracts is expressed as mg/ g of dry weight of vitamin C equivalents (VCEAC). This measure was taken after 30 min reaction time. The radical stock solution had to be daily prepared and the tests were repeated at least three times. 

Table 2. Total phenolic and total flavonoid contents of the plant parts 3.2 ABTS and DPPH radical-scavenging activity...

Fiedler and collaborators isolated three new pigmented phenazine compounds, dermacozines li-J (94—96), from Dermacoccus abyssi sp. nov. strains MTl.l and MT1.2 (Figure 14) (14JNP416).When these compounds were tested for l,l-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, it was found that dermacozine li (94) was the most active with an IC50 value of 18.8 pM. 

IC50 value of 3326 g/mL, while the T. marschallianus essential oil had a slightly lower IC50. Thymol showed the best DPPH radical scavenging activity better than BHT (Jia et al 2010). Ichrak et al. (2011) investigated the antioxidant and antibacterial activities of T. pallidus Coss. ex Batt. and T. satureioides Coss. essential oils obtained by steam HD. T. pallidus essential oil revealed to have camphor (29.8%) as a major compound, followed by dihydrocarvone (17.6%), borneol (7.6%), and camphene (7.5%), respectively. T. satureioides contains borneol, carvacrol, and p caryophyllene as most content (29.5%, 9.1%, and 8.2%, respectively). T. pallidus and T. satureioides essential oils exhibited strong antioxidant activity (Ichrak et al., 2011). 

As for the acid-catalyzed cyclization products 2, 13-15, 19 and 21, there was no correlation with the absorbance of UV light and the DPPH radical scavenging activities of a variety of additive compounds (Table III). 

Figure 6. The yield of oxidation products from citral (10 and 12) vs. DPPH radical scavenging activity of each additive compound at pH 3.5.

Sisodia et al. (2013) evaluated antioxidant activity for different extract of Ramalina roesleri species and found that the DPPH radical scavenging activity of extracts ranged from 29.42 to 87.90 %. Sharma et al. (2012) examined the antioxidant activity of two common hchens, namely, Parmotrema reticulatum and Usnea... 

Atranorin, protolichesterinic acid, usnic acid, 2-hydroxy-4-methoxy-6-propyl benzoic acid, homosekikaic acid, sekikaic acid, benzoic acid, 2,4-dihydroxy-6-propyl and 2,4-dihydroxy-3,6-dimethyl benzoate isolated from the hexane extract from Ramalina roesleri were assayed for antioxidant activity by l,l-diphenyl-2-picrylhydrazyl (Sisodia et al. 2013). Maximum DPPH radical scavenging activity was exhibited by sekikaic acid followed by homosekikaic acid. 

Al-Dabbas, M. M., K. Al-Ismail, K. Kitahara, N. Chishaki, F. Hashinaga, T. Suganuma, and K. Tadera. 2007. The effects of different inorganic salts, buffer systems, and desalting of Varthemia crude water extract on DPPH radical scavenging activity. Food Chemistry 104(2) 734-739. 

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