Salvia Extract Antioxidant Activity In Vitro Study

The synthetic antioxidants such as butylated hydroxyltoluene(BHT) and butylated hydroxyanisole (BHA) have antioxidant activities.However,the synthetic antioxidants have the problem with their mutagenic activity.The development of effective and safe natural antioxidants becomes one of the main topics in the field of food chemistry.There are many Chinese herbs available in China and it has been verified that many of them are full of natural antioxidants.Salvia plebeia R.Br.which was screened out of 719 species of Chinese herbs grows indigenously in wet places almost throughout China and India,belonging to the Labiateae.It was traditionally used in folk medicine for its effects such as relieving cough and asthma,antihistamine,antimicrobial property and antioxidant activity on lipid peroxidation.But the reports about its free radical scavenging activity and antioxidant effect in mitochondria are even less.This experiment aims to evaluate the antioxidant activity of Salvia plebeia R.Br extract(SE),in order to understand the usefulness of this plant as a foodstuff as well as in medicine.First,SE is extracted by 70%ethanol three times under reflux condition,then remove the ethanol,the remaining aqueous solution of the extraction was eluted with petroleum(v:v=1:1) and ethyl acetate(v:v=1:1), respectively.The aqueous solution fraction(SE1) and ethyl acetate solution fraction(SE2) were evaporated to dryness,giving for the next analyses.Second,we examined the antioxidant activity of SE,employing various in vitro assay systems,including DPPH·/O₂^-·/·OH radical-scavenging, reducing power assay system,peroxidation of polyunsaturated fatty acid from yolk lipoprotein induced by Fe²⁺ method,andβ-carotene/linoleic acid assay system.Third,we have investigated the effects of SE on damaged rat liver mitochondria induced by Fe²⁺-Vc.Malondialdehyde(MDA), mitochondrial swelling,ATPase activity and protein carbonyl content along with superoxide anion generation were measured.The results showed that both the extracts exposed strong antioxidant capability in a dose-dependent manner,but the results were different for each species depending on the applied test. IC₅₀ values in scavenging abilities on DPPH·and O₂^- of SE2 were 0.79 mg/mL and 0.26 mg/mL, whereas for SE1 they were 1.40 mg/mL and 0.39 mg/mL.The hydroxyl radical scavenging ability of SE1 and SE2 were 62.27%and 17.23%at 1.0 mg/mL.Effectiveness in reducing powers was in a descending order of SE2>SE1.In lipid peroxidation assay,the maximum inhibition of SE1 and SE2 were 55.55%and 66.36%respectively.The total antioxidant activities of SE1 and SE2 were lower than BHT onβ-carotene/linoleic acid assay system.SE2 has been shown to inhibit the rat liver mitochondrial swelling and the lipid peroxidation stronger than SE1.The two extracts were found to be effective in inhibiting the oxidation of thiol groups and maintaining ATPase activity.IC₅₀ values in scavenging O₂^- of SE1 and SE2 were 0.36 mg/mL and 0.29 mg/mL respectively.The results of this text indicated that SE had high antioxidant capacities.It exhibited remarkable free radicals(DPPH·,O₂^- and·OH) scavenging abilities and effective reducing power.SE also showed powerful inhibitory effects on peroxidation of polyunsaturated fatty acid from yolk lipoprotein induced by Fe²⁺ and onβ-carotene/linoleic acid assay system.Furthermore,SE showed to inhibit the rat liver mitochondrial swelling and the oxidation of thiol groups.It also protected mitochondria membranes by scavenging superoxide anions and scavenging lipid free radicals as well as maintaining ATPase(one of membrane-bound enzymes) activity obviously.The higher efficiency of SE2,as compared to SE1,should be due to the presence of the more flavonoids in SE2.Whether there is more evident antioxidant activity of SE in vivo,it still needs further study.