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ABSTRACT: The present study was conducted at the plant biotechnology laboratory in S. Thangapazham Agricultural College, Vasudevanallur, Tenkasi District by the Department of Crop Improvement. The aim of this study wasto analyze 25 plant species with potential medicinal values based on traditional knowledge for presence of secondary metabolites.We analyzed and screened the presence of secondary metabolites in most grown weed crops in our region. The weed crops that used to analyze were Phyllanthus niruri, Andrographis paniculata, Centratherum punctatum, Andrographis paniculate, Euphorbia heterophylla, Calotropis procera, Cyperus rotundus, Acmella oleracea, Echinochloa colona, Lantana camara, Tridax procumbens, Chloris barbata. From this, we concluded that these weeds can be used for the medicinal purposes.

KEYWORDS: Secondary metabolites, Medicinal plants, Qualitative analysis

INTRODUCTION Medicinal Plants and secondary metabolites A Medicinal Plant is any plant which, in one or more of its organs, contains substances that can be used for therapeutic purposes or which are precursors for the synthesis of useful drugs. The term “Medicinal Plants” includes various types of plants used in herbalism. According to WHO, around 21,000 plant species have the potential for being used as medicinal plant. More than 30% of the entire plant species, at one time or other were used for medicinal purposes.

MATERIALS AND METHODS: The present research work was undertaken with the aim of qualitative analysis of secondary metabolites for 25 plant samples using aqueous and alcoholic extractions, and establishing tissue culture in five selected plant species among the 25 species. The experiments of the present studies were carried out at the plant biotechnology laboratory at S. Thangapazham Agricultural College, Vasudevanallur. Details of materials and methods used were as follows.

Plant samples: Totally 25 plant samples were selected from mini-orchard medicinal garden, some from Nursery garden and some of the weeds from fields of S.Thangapazham Agricultural College Campus.

Aqueous extraction of plant sample: Weight of fresh leaves were taken and washed thoroughly and left for drying. Later after complete drying. Dried samples were completely dried in incubator at 60˚c for 8 hours and then the dried leaves were made into fine powder in mechanical grinder, powdered leaf sample of plant taken into a butter paper cover (Kumari and Bhatnagar 2016). And some modification are done from the known procedure after several trials, For 5g of sample 50ml of distilled water added in the ratio of 1:10.Boil it under 600 c for 30 minutes for secondary metabolite content in the leaf powder dissolve into the aqueous, then filtrate through whattman no.1 filter paper to getting clear extract. After filtering, the extracts were centrifuge at 2500 rpm for 15 minutes and store it in sterile bottle at 50 c for further use. Ethanolic extraction of plant sample: 250 g of fresh leaves were taken washed thoroughly and transferred into a round bottomed flask and it was added 500ml of ethanol and 500 ml of distilled water and was preserved carefully until 10 days, the extraction was taken and was filtered using whattman filter paper and feature pure sample was obtained using the Soxhlet apparatus (Das 2016). And modification taken are, For 10g of air dried powder macerated with 100 ml of ethanol, kept in the shaker for 72 hours, then kept at reduced pressure concentrated to 100 ml, Redissolve with alcohol and store it for further use.

Qualitative analysis of secondary metabolites: Alkaloids (Stochmal et al., 2022): 1ml of 1% HCl was added to 3 ml of extract in a test tube and was treated with few drops of Meyer’s reagent. If the creamy white precipitation occur which indicate the presence of alkaloid. (Mayer’s reagent: Freshly prepared by dissolving a mixture of mercuric chloride (1.36 g) and of potassium iodide (5.00 g) in water (100.0 ml).

Saponins (Kumari and Bhatnagar 2016): 5 ml of extract was shaken vigorously to obtain a stable persistent froth. The frothing was then mixed with 3 drops of olive oil and formation of emulsion which indicated the presence of saponins.

Flavonoids (Kumari and Bhatnagar 2016): A few drops of 1% NH3 solution was added to the extract in a test tubes. If a yellow coloration was noticed for presence of flavonoids.

Tannins (Kumari and Bhatnagar 2016): To 0.5 ml of extract solution, 1 ml of distilled water and 1 to 2 drops of ferric chloride solution were added. If the extract color change into bluish black or brownish green indicates presence of tannins.

Glycosides (Kumari and Bhatnagar 2016): 10 ml of 50% H2SO4 was added to 1 ml of extract in a boiling tube. The mixture was heated in a boiling water for 5 minutes. 10 ml of Fehling’s solution( 5 ml of each solution A&B) was added and boiled. Formation of brick red precipitation indicates the presence of glycosides.

Phenols (Kumari and Bhatnagar 2016): 3-4 drops of 1% ferric chloride was added to extract. If the extract color change into bluish black indication of phenols.

Steroids (Kumari and Bhatnagar 2016): Add 1 ml of crude extract with 2ml of chloroform. Add few drops of conc. H2SO4. Presence of red color upper layer indicate the presence of steroids.

Terpenoids (Kumari and Bhatnagar 2016): 5 ml of extract was mixed with 2 ml of CHCl3 in a test tube. 3 ml of conc. H2SO4 was carefully added to the mixture to form a layer. If the formation of interface with a reddish brown coloration for the presence of terpenoids.

CONCLUSION We analyzed and screened the presence of secondary metabolites in most grown weed crops in our region. The weed crops that used to analyze were Phyllanthus niruri, Andrographis paniculata, Centratherum punctatum, Andrographis paniculate, Euphorbia heterophylla, Calotropis procera, Cyperus rotundus, Acmella oleracea, Echinochloa colona, Lantana camara, Tridax procumbens, Chloris barbata.

We got positive results for all the tests like Alkaloids, Terpenoids, Saponins, Flavonoids, Tannins, Glycosides, Phenols and steroids in the plant species such as Cissus quadrangularis, Calotropis procera, Cyperus rotundus, Acmella oleracea, Ocimum sanctum in aqueous extract. From this, we concluded that these weeds can be used for the medicinal purposes.