Dear Thanigaivel,

So many factors come to play. There are so many antioxidants available in plants and in this case an uncommon kind of plant (seaweed).  The solubility of different antioxidants in different extraction solvents differs. However, the determination by profiling the antioxidant type/composition is important before an inference/conclusion can be made.

file:///C:/Users/M.%20PC/Downloads/molecules-14-02167.pdf

may be helpful

Hi,

The phenolic compounds exhibit wide range of solubility (hydrophillic, lipophillic, amphiphillic). As a results, they show different extractability depending upon the nature of extracting solvent. In most of the cases, the polyphenols are better solubilized and extracted in polar solvents. A quick check of phenolic profiling helps to understand the exact nature of polyphenols in your test system. 

I suggest you to perform extraction using hydro-alcoholic mix (80: 20 ethanol: water) and other combinations, you may observe even better activity!

Additionally, try the activity test in oil and (or) oil-water emulsion system to gain better insights into the nature and functionality of extracts.

Rohit

I concur with Rohit's answer. Phenolic are powerful antioxidants and highly soluble in ethanol (polar solvents). Have you tried water extract of the same plant for the antioxidant activity?

Thank you all for ur answers..By the way Rohitash i have performed water extraction also, but the activity is significantly lower than the ethanolic extract. My worry is wen the ethanolic yield is obtained for the further study, will it be feasible for the invivo studies, since slightly toxic in nature, it is also having effective radical scavenging property. whether the polyphenolics are only responsible for these activities ?

Hi

I hope that following article will be useful.

Regards

Mr.Thanigaivel

Many Phenols and flavonoids are not in free state that in plants ,they are highly impact with glycosides, tannins ,terpenoids and with saponins sometime,bez of its nature .

My suggestion is check the solubility test with the solvents you use, perform simple test tube test ( find the inference either ppt or colour intensity)

Next u try for any validated either UV-Visible  method or HPTLC methods for dried or pre quantifed LOD concentrated sample .

You come to know the actual picture before u go for any INVITRO AND INVIVO ANTIOXIDANT activity

This will not only saves time ,but actually reports the best solvents and try to correlate with the reported phytoconstituents from any reference

Hope all got cleared with my explanation ,

Still required please write my name in Google scholar and check the article based of punarnava,RJPT JOURNAL I THINK 

Thank you Badmanaban sir

Dear.

The radical scavenging properties of phenolic compounds is referred to their hydrogen donation properties, and their resonance stable structure, which oxygen can donate with its perelectron. Alcohol water mixture with ratio 70 to 80 was found to give high amounts of phenolic substances. Regarding to antioxidant, the in vitro tests can be interfered with fake antioxidant compounds, so the IC50 results is more acceptable than the inhibition percentage. DPPH, ABTS, methods is more acceptable than reducing power an hydrogen peroxide methods.

The extraction yield and antioxidant activity not only depend on the extraction method but also on the solvent used for extraction. The presence of various antioxidant compounds with different chemical characteristics and polarities may or may not be soluble in a particular solvent. Polar solvents are frequently used for recovering polyphenols from plant matrices. The most suitable solvents are aqueous mixtures containing ethanol, methanol, acetone, and ethyl acetate. Ethanol has been known as a good solvent for polyphenol extraction and is safe for human consumption. Pertoleum ether, chloroform, and dichloromethane are nonpolar and therefore don't have the ability to extract those antioxidants you are interested in.

Hi Thanigaivel,

Antioxydant compounds in particular polyphenols are highly soluble in polar solvents. Ethanol has been known as a good solvent for these bioactive compounds extraction. I suggest you to use other polar solvents or (water-ethanol) mixture and to determine the total polyphenols contents and total antioxydant activity for each obtained crude extract in order to choose the suitable solvent for further study.

Antioxidant activity of ethanolic extract of inflorescence of Ormenis Africana in vitro and in cell cultures

Riadh Ben Mansour, 1 Bochra Gargouri,1 Mohamed Bouaziz,2 Nésrine Elloumi,1 Imtinène Belhadj Jilani,3 Zaineb Ghrabi,3 and Saloua Lassoued1

Abstract

Background

The antioxidant potency of the hydroethanolic extract of Ormenis Africana (HEOA), Asteraceae was evaluated with regards to total polyphenol, flavonoid and anthocyanins content. Antioxidant activity has been assessed chemically and biologically. First, the free radical scavenging ability of HEOA was evaluated using two commonly in vitro tests: ABTS and DPPH radicals. Then, the protection effect of this extract against oxidative stress was conducted in HeLa cells treated with Fe2+ or H2O2. Oxidative stress was evaluated by measuring the lipid peroxidation levels (TBARs and DC) and the antioxidant enzymes activities (catalase and Superoxide dismutase). Cytotoxic effect of HEOA was prealably determined against HeLa cell line by MTT assay.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3115891/

Dear Thanigaivel,

the reason of your results is that ethanol known as polar solvent for extraction which gives the advantage of extraction polar phytochemicals especially polyphenols. the latter ones are knowing as the most potent antioxidants. there many methods for extracting natural products and each method gives different results especially on the chemical composition which play an important role on the biological effects of these extracts.

the other mentioned solvents are used for extracting specific phytochemical classes with different polarity, for example, petroleum ether is knowing for the extraction of nonpolar constituents, chloroform is knowing for extracting terpenoids  and some nonpolar polyphenols (aglycones). for water which is knowing as the polar solvent for extraction, the aqueous extract will contain all the constituents which play an role in the decrease and the increase of some biological activities basing on the phytochemical classes.

When the extract contains flavones it shows better anti-oxidant activity.Conjugated compds. show better radical capture (anti-oxidant) activity.

Phenolic contents and antioxidant activity of ethanolic extract of Capparis spinosa

Abstract

Caper plant (Capparis spinosa) extracts have been associated with diverse biological activities including anti-oxidant properties. In this work, we characterized the hydro-ethanolic extract obtained from C. spinosa leaves [hydroethanolic extract of C. spinosa (HECS)] by analyzing the content in anti-oxidant compounds such as polyphenols, flavonoids and anthocyanins. Further, we evaluated HECS antioxidant activities in vitro using bleaching of 1,1-diphenyl-2-picrylhydrazyl radical and ABTS test as well as by pretreatment of HeLa cells exposed to Fe2+ or H2O2. Our findings indicate that HECS contains high amount of total phenolic compounds and high levels of flavonoids and anthocyanins. Furthermore, HECS exhibited antioxidant activity in both chemical and biological tests. Specially, pretreatment of HeLa cells with different concentrations of the extract conferred protection against lipid peroxidation and modulated activities of two antioxidant enzymes, SOD and catalase. These results revealed HECS antioxidant effects and suggest that C. spinosa leaves are a potential source of natural antioxidant molecules with possible applications in industry and medicine.

http://link.springer.com/article/10.1007/s10616-014-9764-6

Which protocol have you used for you assay? In which solvent have you dissolved your extracts? have you use the same protocol for all the extracts? I ask all these questions because there are many parameters that can influence the antioxidant activity of a sample and among this parameters are the solvent used for the assay...And it is known that Ethanol has a great influence on antioxidant activity on a sample. 

It is not the solvent, it is the nature of compounds which shows activity. In this particular plant may be the antioxidant compounds will be in the ethanolic extract and may be in some other solvent in another plant

Normal according to the principle of "like dissolve like" because it is the only polar protic solvent of the list outside water. However, what would happen if he also used the MeOH?

Dear S. Thanigaivel,

As we know like dissolve like, most of the antioxidant are polar in nature and extracted better in polar solvents as compared to non polar and medium polar ones. As the ethanol is more polar as compared to the other solvent used due to which it extracts more amount of antioxidant compounds as compared to other solvent used. Dear you may go for Acetone and Methanol, which may even give you better results than ethanol and water. due to their protic polar nature and intermediate polarity which help in the extraction of large number of secondary metabolites which known for their antioxidant potential.