Spectrophotometric Analysis of Vitamin A and Vitamin E in Different Species of Dioscorea Tuber

1Department of Physical Sciences, College of Science, 2University Research and Development Services, 1,2University of Eastern Philippines, University Town, Northern Samar, Philippines 3University Research and Development Services, University of Eastern Philippines 3University Town, Catarman N. Samar, Philippines 3Office of the President, University of Eastern Philippines, Catarman N. Samar, Philippines


INTRODUCTION
Yam, a term usually applied to a plant of the genus Dioscorea (family Dioscorea), including several tropical species cultivated for food. There are plant with thick annual, climbing stems bearing alternate or opposite entire or lobed leaves and unisexual in long clusters. The flowers generally small and individually conspicuous, though collectively slow. Each consists of greenish, build shape or flat perianth six species, enclosing stamens of the male flowers or surmounting a three-celled, tree winged ovary in the female. The ovary ripens into a membranous capsule, bursting by three values liberates numerous flattish or globosely seeds. The species are native of the warmer region of both hemispheres. The plant grows freely in deep sandy soil, moderately enriched (Morisawa, 1999).
Everywhere and not all of us get the courage to take. There are risks that are worthy to be taken and some are not. When it comes to the food we are eating we choose to have consumed the ordinary ones and not something that is extraordinary. But, for us Filipinos we let our minds travel and let our creativity spill through the foods we serve to our family. One of the foods that really need our creativity is Dioscorea hispida dennst this root crop is now becoming or considered to be one of the Philippines alternative staple foods for rice. Many of us still don't know what this root crop is.
D.hispida can also have benefits if not taken as food. In some country, it is considered as medicinal plant. It is capable of relieving abdominal contraction and stomach pain. In addition, Dioscorea hispida dennst can help women in optimal breast enlargement because it is excellent source of beta-carotene and diosgenin, a powerful that is capable of doing diseases like diabetes, leprosy, heart burn library pain menstrual pain, inflammation of gall bladder, rheumatism or joint pain and callus.
Hence, this study was conducted to determine the vitamin A and vitamin E content of different species of Dioscorea tuber extract.

METHODOLOGY Collection and Preparation of the Plant Extracts
The Dioscorea species of tuber extracts were weighed separately and grinded using electric blender. About 200g of each species tubers were finely cut into a small pieces then squeezed through clean cheesecloth to separate the tubers extracts to a beaker. The extracts was poured in a clean bottle in preparation for the physical characterization and determination of vitamin A and E content.

Determination of Physical Properties
The physical properties of the Dioscorea species tuber extracts were determined using the following procedures.

Boiling point
About 2 mL of each species of Dioscorea tuber extract was placed in a test tube. The test tube was heated in an oil bath and the temperature where the tuber extract started to boil was recorded. The process were repeated thrice.

Color
The color was observed by five evaluators using the sense of sight. About 5 mL of different Dioscorea species of tuber extracts was poured into a transparent beaker. Then, using the sense of sight, the evaluators was ask to described the color of the different Dioscorea species tuber extracts contained in the transparent beaker.

Density
The extract used in determination was poured into a previously weighed graduated cylinder. The volume was recorded. Then it was weighed on the triple analytical balance. The mass of the extract was obtained by subtracting the mass of the empty graduated cylinder from the mass of the cylinder with the plant extract. Density was calculated using the formula.

Density = Mass (of the Dioscorea species extracts) Volume (of the Dioscorea species extracts)
Odor The odor were observed by five evaluators using the olfactory sense. About 5 mL of different Dioscorea species of tuber extracts was poured into a transparent beaker. Then, using the sense of smell, the evaluators was described the odor of the different Dioscorea species tuber extracts contained in the transparent beaker.

pH
The pH was tested on the different Dioscorea species using a digital pH meter. About 20 mL of different Dioscorea tuber extract was placed in a beaker. Then, a digital pH meter was placed to record. The procedure was repeated thrice.

Solubility
The three (3) solvents were used, namely; hexane, water and ethanol. About 2 mL of each species of Dioscorea tuber extracts was placed into nine (9) clear test tubes. Then, three test tubes was poured with two (2) mL each of hexane, same goes to another three test tubes, but was poured with two (2) mL each of water, and lastly, the remaining three test tubes with tuber extracts was poured with two (2) mL each of ethanol solvent. The nine test tubes were observed to determine the solubility of the different Dioscorea tuber extracts in three (3) solvents. The results were recorded as miscible or immiscible. Miscible if only one phase was formed and immiscible if more than one phase was formed. Three trials were done for solubility determination.

Determination of vitamin A and vitamin E
The plant sample of 4mg in ethanol were mixed with 2.5 oleic acid in 99.5% ethanol (4.1mL), 0.05 M phosphate buffer, pH 7 (8mL) and kept in cap containers under the dark conditions at 40˚C. To 0.1 mL of this solution, 9.7 mL of 99.5% of ethanol and 0.1 mL of 30% ammonium thiocyanate were added. After 3 min, 0.1mL of 2M ferrous chloride in 3.5% HCL was added to the reaction mixture and the absorbance of the red color was measured at 500 nm each 1 hour until the absorbance control reached maximum. The control and the standard were subjected to the same procedure ass the sample except for the control, where there was no addition of sample, and for the standard 4 mg of sample were replaced with 4mg of ἀ-tocopherol or vitamin E and retinol for vitamin A.

RESULTS AND DISCUSSSION
This study focused on two different Dioscorea species tuber extract such as korot (Dioscorea hispida dennst), and tinampay (Dioscora alata var.clava Linn). The physical properties of the Dioscorea were determined and spectrophotometer was used to determine the vitamin A and vitamin E content of each different species of tuber extracts.
To be able to determine vitamin A and vitamin E a way of determination like spectrophotometry was chosen. This is due to a good precision of the method. As a result, spectrophotometric methods are widely used, among others in food analytics for determination of natural compounds including vitamins.

Physical Properties
The physical properties of the two different dioscorea species tuber extracts separately were determined in terms of boiling point, color, odor, pH, and solubility. of Dioscorea can be a good source of natural vitamins A and E.

CONCLUSIONS
Based on the findings of this study, the researcher formulated the following conclusions. The two different species Dioscorea tuber extracts both has a lower boiling point, the color of korot has milky white and the tinampay is brown, unpleasant in odor, the tubers extracts are both a polar substance. Also, Dioscorea species known as a toxic plant have a good source of natural vitamins A and E.