MSc

Costus pictus D.Don is a Mexican plant brought to India during 2002-2003. Due to the spiral appearance of stems, it is called as spiral ginger/ stepladder plant. Costus pictus is commonly known as insulin plant in the central part of Kerala. Diabetic patients used to take raw leaves of the plant as a folk remedy for hyperglycemia. The studies of Benny et al. (2004)., Balaji (2005) and Jothivel et al.(2007) are in agreement with its hypoglycaemic property.

Insulin is taking through injection for treating hyperglycemia. An antidiabetic plant protein could exert a beneficial effect in the diabetic situation by enhancing insulin secretion and / or by mimicking insulin action. As insulin is a protein, comparison of its characters to proteins of a hypoglycaemic plant may open new doors to the field of diabetic treatment.

The project entitled ‘Characterization of proteins in Costus pictus D.Don’ was taken up at CPBMB, College of Horticulture, Kerala Agricultural University, Vellanikkara. The objective of the experiment was the isolation, purification and characterization of proteins in Costus pictus and comparison with insulin.

Effect of extraction buffers, percentage acrylamide and quantification of protein were studied. Use of 0.2 M Tris buffer at pH 7.2 and 10% acrylamide in the electrophoresis were found to be the most suitable condition for studying the proteins in Costus plant.

The study revealed the presence of acidic and basic proteins in this plant. Proteins of basic nature in the Costus pictus are precipitated with ammonium sulphate in the range of 30-50 per cent saturation which were stained with Coomassie dye and acidic proteins were precipitated at high saturation of ammonium sulphate which were expressed in silver staining.

Salting out of Costus protein was efficiently carried out with 80 per cent ammonium sulphate saturation. Aggregation of small proteins and the ability to regulate the breakage of long proteins were observed in the sequential saturation of ammonium sulphate. The hydrophobicity of the proteins in the sample was evident in the ammonium sulphate precipitation. Same pattern was observed in the electrophoretic pattern of fractions from DEAE cellulose with NaCl gradient. Hydrophobic patches were obtained for small and large proteins of Costus plant. Aggregation of proteins in Costus can be considered as its characteristics. pH was one of the major factor contributed aggregation and elution of proteins.

On comparing with insulin, 70-80 per cent sequential precipitation gave a protein of similar range of molecular weight of insulin available in the market by Recombinant DNA Technology. The present study revealed that the gradient application of salt and pH can be efficiently utilized for isolating single protein from Costus. Purification, sequencing and further studies are to be conducted for establishing the antidiabetic property of Costus plant.

Costus protein may provide signals in the body fluid that may recognize by the cells in the pancreas for the production of insulin. It may also be possible to function as receptor that conveys information to produce insulin within the body. Plant protein may serve as intracellular signaling component that mediate the effect of insulin production and as a key component of the machinery that determines which genes are to be expressed and whether mRNA is translating in to insulin.