In vitro antioxidant activities and an investigation of neuroprotection by six Salvia species from Iran: A comparative study Sareh Asadi a , Abolhassan Ahmadiani a , Mohammad Ali Esmaeili b , Ali Sonboli b , Niloufar Ansari a , Fariba Khodagholi a, * a Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran b Department of Biology, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C. Tehran, Iran article info Article history: Received 23 November 2009 Accepted 24 February 2010 Keywords: Antioxidant activity Flavonoids Neuroprotection Radical DNA damage Salvia Total phenolic content abstract Methanolic extracts of six species of Salvia (S. hydrangea, S. lachnocalyx, S. macilenta, S. multicalis, S. sclarea and S. xanthocheila) were analyzed for their antioxidant properties, ability to prevent DNA damage by free radicals, and neuroprotective effects. Several biochemical assays were used to evaluate their antioxidant properties: DPPH Å , FRAP, b-carotene bleaching and TEAC assays. The amounts of phenolics and flavonoids were also determined. Comparison study of Salvia species showed that extracts from S. hydrangea and S. macilenta are strong antioxidants and that from S. lachnocalyx is a weak one. Furthermore, extracts from all of these species can at high concentrations (P50 lg/ml) inhibit DNA damage by free radicals. Further- more, these species not only showed no cytotoxic effects in nerve growth factor (NGF)-differentiated PC12 cells, they also protected them against H 2 O 2 -induced cell death. Thus these plants may be candi- dates for treating neurodegenerative diseases. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Free radicals, chemical species with one or more unpaired elec- trons, are produced in normal or pathological cell metabolism in different circumstances. Environmental stresses cause generation of free radicals faster than their degradation in the cell (Wen-Chi et al., 2000). This imbalance leads to oxidative stress, which has been suggested as the root cause of aging and various other human disorders like atherosclerosis, stroke, diabetes, cancer and neuro- degenerative diseases such as Alzheimer’s disease (AD) and Parkin- sonism (Tiwari, 2004). Although humans and other organisms possess antioxidant defenses (enzymes, such as superoxide dismu- tase and catalase, or compounds such as ascorbic acid, tocopherols and glutathione) and repair systems that protect them against oxi- dative damage, these systems are insufficient to totally prevent damages (Simic, 1998). Antioxidants can interfere with the oxida- tion process by reacting with free radicals, chelating free catalytic metals and by acting as oxygen scavengers (Shahidi and Wanas- undara, 1992). For several years, many researchers have been searching for powerful but non-toxic antioxidants from natural sources, especially edible or medicinal plants. Such natural antiox- idants could prevent the formation of reactive-species-related disorders in human beings without using synthetic compounds, which may be carcinogenic and harmful to the lungs and liver (Branen, 1975). A great number of natural medicinal plants have been tested for their antioxidant activities, showing that the raw extracts or isolated pure compounds from them were more effec- tive antioxidants in vitro than BHT or vitamin E (Gordon and Weng, 1992; Pyo et al., 2004), so medicinal plants can be a potential source of natural antioxidants (Cosquini et al., 2003). The genus Salvia (Laminaceae) includes nearly 900 species spread throughout the world, of which 17 are endemic to Iran (Mozafarian, 1996). Plants belonging to this genus are pharmaco- logically active and have been used in folk medicine all around the world. Many Salvia species and their isolated constituents pos- sess significant antioxidant activities in enzyme-dependent and enzyme-independent systems (Hohmann et al., 1999; Zupko et al., 2001). The phytochemical analysis of Salvia species show the presence of many compounds belonging mainly to the group of phenolic acids, phenolic glycosides, flavonoids, anthocyanins, coumarins, polysaccharides, sterols, terpenoids and essential oils (Lu and Foo, 2002; Ghannadi et al., 1999). 0278-6915/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2010.02.035 Abbreviations: ABTS Å+ , 2,2 0 -azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; AEAC, ascorbic acid equivalent capacity; ANOVA, analysis of variances; AOA, antioxidant activity; BHT, butylated hydroxyltoluene; DMEM, Dulbecco’s modified Eagle’s medium; DMSO, dimethyl sulfoxide; DPPH, 2,2- diphenyl-1-picrylhydrazyl; FCR, Folin–Ciocalteu reagent; FRAP, ferric reducing antioxidant power; LPO, lipid peroxidation; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyl tetrazolium bromide; TEAC, Trolox equivalent antioxidant capacity; TPTZ, 2,4,6-tris(2 0 -pyridyl)-1,3,5-triazine; PBS, phosphate buffer saline. * Corresponding author. Tel.: +98 21 22429768; fax: +98 21 22432047. E-mail address: khodagholi@sbmu.ac.ir (F. Khodagholi). Food and Chemical Toxicology 48 (2010) 1341–1349 Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox