2
in the appearance of “DNA laddering” when the DNA is analyzed by agarose gel electrophoresis Arends, et. al 1990. Principle of this assay is apoptotic DNA binds quickly to glass fiber fleece in
the presence of a chaotropic salt, guanidine hydrochloride guanidine HCl. After cellular impurities are washed off the fleece, the DNA is released from the fleece with a low salt buffer
Wyllie, et. al 1998.
B. OBJECTIVE
The objective of this research was to analyze apoptotic DNA fragments of HCT-116 human colon cancer cell incubated with cell free supernatant contained short chain fatty acids SCFA
derived from fermentation of type 3 resistant starch RS3 of sweet potato Ipomoea batatas by C. Butyricum BCC B2571 using DNA ladder assay.
3
II. LITERATURE REVIEW
A. RESISTANT STARCH RS
Resistant starch RS has been defined as t otal amount of starch, and the products of starch
degradation that resists digestion in the small intestine of healthy people then enter the large
bowel. It occurs for various reasons including chemical structure, cooking of food, chemical modification, and food mastication Topping and Clifton 2001.
There are four types of resistant starch. Starch found in plant cell walls that is inaccessible to amylase activity is one type of
resistant starch, designated type 1 resistant starch RS1. Food sources of RS1 include partially milled grains and seeds. Resistant starch also may be formed during food processing.
Ungelatinized granules of starch are typically resistant to enzymatic digestion and are designated type 2 resistant starch RS2. This type of starch can be found in potatoes and unripe green
bananas. Cooking and cooling starchy foods by moist heat or extrude starchy foods, for example, generates retrogade starch called type 3 resistant starch RS3. Chemical modifications of starch,
such as formation of starch esters, or cross-bonded starches, also result in resistant starch, called type 4 resistant starch RS4. RS3 and RS4 may be partially fermented by colonic bacteria
Gropper, et. al 2009 . Interestingly, if RS2 granules are heated to over 100ºC, the granularity is
lost and starch is gelatinized or the granules swell thereby increasing the availability of the starch to amylase. However, when the starch cools, there is some recrystallization of the starch. This is
called retrogradation, which is resistant to α–amylase hydrolysis Medeiros and Wildman 2012. Starch that is trapped within whole plant cells or within the food matrix, and some starch
granules that have not been fully gelatinized, are hydrolysed only very slowly by a-amylase and therefore may escape complete digestion in the small intestine. The energy yield to the body from
this source is less than that provided if starch is digested and absorbed in the small intestine Englyst, et. al 1996. The glycemic effects of starch is therefore lowered, which decreases insulin
secretion. In addition to glycemic management resistant starches may play role in weight management as well Medeiros and Wildman 2012.
The material included in the definition of RS reaches the human large intestine and thus becomes a substrate for microbial fermentation. The end-products are H
2
and CO
2
, CH
4
in about half the population, and short-chain fatty acids.
SCFA consist primarily of butyrate, propionate and acetate
Englyst, et. al 1996. SCFA contribute to normal large bowel function and prevent pathology through their actions in the lumen and on the colonic musculature and vasculature,
through their metabolism by colonocytes Topping and Clifton 2001.
B. SHORT CHAIN FATTY ACID SCFA
