*3.7.1. General screening of proteins and amino acids*

Experimental: 1 ml aqueous extract reacts with 5–6 drops of Millon's reagent (mixture of mercuric nitrate, mercurous nitrate, concentrated nitric acid, and distilled water) and a white precipitate is formed that changes its color to red upon heating. Millon's test is a non-specific test for detecting proteins and amino acids (tyrosine) and, therefore, it must be confirmed by other qualitative tests.

The results obtained after the two aqueous extracts react with Millon reagent are as follows: an opalescent orange solution in the case of Sea buckthorn and a red-brownish precipitate in the case of Gooseberry, therefore confirming the presence of small amounts of proteins and/ or aminoacids in Gooseberry aqueous extract.

#### *3.7.2. Detection of amino acids*

There are three different standard phytochemical methods used to determine the presence of

**a.** *Wagner test*: 1 ml aqueous extract and 1 ml Wagner's reagent (iodine in potassium iodide solution) react and if a reddish-brown precipitate is formed it indicates a positive reaction. **b.** *Mayer test*: to 1 ml aqueous extract, 2 ml concentrated HCl is added followed by few drops of Mayer's reagent (a solution of mercuric chloride and potassium iodide in water); a green color or white precipitate indicates the presence of alkaloids (the results are presented in **Table 8**). **c.** *Hager test*: 2 ml aqueous extract and 2 ml Hager's reagent (a saturated aqueous solution of picric acid) are mixed together and a yellow precipitate indicates a positive test.

According to the results presented in **Table 8**, alkaloids are absent from all the aqueous

The method used for the qualitative screening of anthraquinone compounds involves the reaction of 1 ml aqueous extract with a few drops of 10% ammonia solution with the forma-

Anthocyanosides are present when a pink color appears after the reaction between 1 ml aqueous extract with 5 ml dilute hydrochloric acid (1%). The results are detailed in **Table 9**.

tannins in aqueous extracts from sea buckthorn and gooseberry:

**Phytochemical test Sea buckthorn Gooseberry**

**Table 7.** Qualitative screening of flavonoids and phenolic flavonoids.

170 Phytochemicals - Source of Antioxidants and Role in Disease Prevention

Flavonoids Green-yellow solution Light brown yellow solution Phenolic flavonoids Light yellow solution Opalescent brown-yellow solution

**3.6. Qualitative screening of anthraquinones and anthocyanosides**

**Phytochemical test Sea buckthorn Gooseberry** Alkaloids—Wagner Red-brown solution Red-brown solution Alkaloids—Mayer Light-yellow solution Red-brown solution Alkaloids—Hager Clear yellow solution Red-brown solution

**Phytochemical test Sea buckthorn Gooseberry**

**Table 9.** Qualitative screening of anthraquinones and anthocyanosides.

Anthraquinones Green-yellow solution Brown-yellow solution Anthocyanosides Light yellow solution Brown-yellow solution

extracts.

tion of a pink precipitate.

**Table 8.** Qualitative screening of alkaloids.

There are two different standard methods used (see results in **Table 10**):


The test for cysteine gives a positive reaction in the case of sea buckthorn, while ninhydrin test is negative for both aqueous extracts.


**Table 10.** Qualitative screening of amino acids.

**Figure 8.** Amino acids in sea buckthorn.
