독/약 ≫ 천연독 ≫ 식물독 ≫ 식물

천연독 : 저해제 inhibitor

저해제 inhibitor
- 트립신 저해제
- 봉쇄제 : 피트산, 옥살산 oxalic acid

자연독 : 항영양소
- 생콩의 항영양소
- 리치의 독성 : MCPG, 아이들의 의문사

Other various inhibitors are present in a wide variety of food stuffs. Briefly, they include: amylase inhibitor (in wheat, rye, sorghum, beans), plasmin inhibitor which inhibits blood clotting5 (in some beans), cholinesterase inhibitors (in carrots, cabbage, asparagus, broccoli, celery, radishes, raspberries, strawberries, oranges, pumpkin, peppers, tomatoes, turnips, apples, eggplant, and especially potatoes), and kallikrein inhibitor which reduces antibody formation5 (in potatoes).

Amylase inhibitors

Naturally occurring inhibitors of α-amylase are found in aqueous extracts of wheat, rye and kidney beans. The physiological role of α-amylase inhibitors in plants is not well understood, but may protect them against insect infestation. In mammals, some amylase inhibitors have been shown to attenuate the normal increase in blood glucose that occurs after ingestion of starch. However, since α-amylase inhibitors have been shown to be inactivated by gastric acid, pepsin or pancreatic proteinases, their potential as “starch blockers” is limited [67]. α-Amylase inhibitors were once added to foods as “starch blockers” to limit carbohydrate absorption for the purpose of weight loss; however, the FDA later determined that at least this use of α-amylase inhibitors was as drug, and they were consequently taken off the market [68].
α-Amylase inhibitor protein is a major allergen (referred to as Asp o 2) that has been implicated in the development of occupational toxicity known as “baker’s asthma disease” [69]. Although α-amylase inhibitor protein is naturally found in wheat flour, it is also found in flour in which α-amylase from Aspergillus oryzae has been added to enhance carbohydrate fermentation by yeast [70]. Consequently, α-amylase inhibitor protein can be potentially found in baked products that are derived from sources other than wheat. Cases of food allergy have been reported in people ingesting bread containing α-amylase inhibitor protein. Symptoms of allergy include sneezing, rhinorrhea, oropharyngeal itching, hoarseness, cough and dyspnea [71].
High α-amylase inhibitor activity against human salivary α-amylase has been found in wheat flour (590 units/g), whole wheat flour (351 units/g) and whole rye flour (186 units/g). Bread baking reduces the activity by 80–100%, depending on type. The activity in uncooked spaghetti (248 units/g) is reduced more than 98% by 15 minutes of boiling. Boiling of red beans for 1.5 hours reduces activity to undetectable levels [71]. However, α-amylase has been shown to retain some allergenic activity when heated to 200 °C (Baur et al., as cited in Phadia AB 2010 [72], p. 2).

Protease inhibitors  
Protease inhibitors inhibit digestive enzymes and, when present in high levels in the diet, may decrease the avian body's Peasability to digest proteins and lead to pancreatic hypertrophy. Although these enzyme inhibitors are present to a degree in all plants, significant levels are found in all legumes, corn, lettuce, oats, peas, peanuts, barley, beets, buckwheat, wheat, rice, rye, turnips, sweet potatoes and potatoes (in VERY high amounts).5 Luckily protease inhibitors are readily inactivated by cooking,5 so if any of the above-listed food sources are going to constitute a major part of your birds' diet, you should cook them first.

tannins  
Acorns, lettuce, carrots, rape seed, grape seeds, bananas, spinach, onions, milo, grapes, and raisins have high levels of tannins. (Rhubarb, tea, coffee, and chocolate also contain high levels of tannins but these foods should never be fed to birds anyway as they may be harmful or toxic). Tannins can inhibit digestive enzymes, bind protein, and reduce the bioavailability of vitamin B12 and iron.5 Additionally, at high levels, tannins can cause epithelium and liver damage.5 Tannins (tannic acids) are the chemicals that are responsible for the normal browning of fruits and vegetables that have been bruised or cut. If feeding any of the above-listed "safe" foods that contain tannic acid, only feed them in moderation.

Oxalate, phytate  

Oxalate (oxalic acid) is an organic acid makes calcium and other trace minerals unavailable to Grated carrotbirds because it binds them.5 Lower levels of oxalate can cause reduced growth, kidney stones, and poor bone mineralization.5 Peas, beets, beet greens, lettuce, turnips, carrots, and berries have lower levels of oxalates; high levels of oxalates can cause diarrhea, poor blood clotting, vomiting and convulsions.5 Very high levels are found in spinach (tea also contains very high levels of oxalate, but it should not be fed to birds due to its caffeine content).

The complex of phosphoric acid and sugar is called phytate or phytic acid. This complex effectively forms a heterocyclic ring with metal atoms (minerals such as iron, zinc, and calcium), making the minerals unavailable.5 Phytates are found in nuts, cereal grains (germ and bran), and legumes. Phytic acid is also present in green beans, berries, carrots, broccoli, potatoes, and sweet potatoes, but at lower levels.

Lectins in legumes

Lectins are a group of glycoproteins that are present in high levels in legumes (e.g., black beans, soybeans, lima beans, kidney beans and lentils) and grain products [73,74]. Lectins can reversibly bind to carbohydrates without altering their covalent structure [73]. The ability of lectins to bind to and agglutinate red blood cells is well known and used for blood typing—hence the lectins are commonly called hemagglutinins. Lectins also can bind avidly to mucosal cells and interfere with nutrient absorption from the intestine [75]. Because the ability of the lectins to cause intestinal malabsorption is dependent on the presence of enteric bacteria, it has been hypothesized that lectins may also produce toxicity by facilitating bacterial growth in the GI tract [76].

Lectins isolated from black beans can produce growth retardation when fed to rats at 0.5% of the diet, and lectin from kidney beans causes death within two weeks when fed to rats at 0.5% of the diet. Soybean lectin produces growth retardation when fed to rats at 1% of the diet. The castor bean lectin ricin (one of the most toxic natural substances known) is notorious for causing deaths of children, and has been used as an instrument of bioterrorism [75].

Phytohaemagglutinin (PHA) is a lectin found in significant quantities (as much as 2.4–5% of total protein) in legumes such as red or white kidney beans, green beans and fava beans. PHA has a number of different properties, including the ability to induce mitosis, affect membrane transport and permeability to proteins, and agglutinate red blood cells. Rats fed a diet containing 6% PHA exhibit weight loss, associated with malabsorption of lipid, nitrogen and vitamin B12 [76]. PHA from red kidney beans inhibits sodium and chloride absorption in the rabbit ileum, indicating that PHA can affect electrolyte transport in the gut [77]. Symptoms of toxicity to PHA in humans such as nausea, vomiting, or diarrhea occur within three hours of ingestion. Recovery generally occurs within four or five hours of onset [78].

There are no FDA regulations or guidelines restricting the presence of lectins in food, but the FDA does provide recommended cooking practices prior to consuming legumes. Concentrations of PHA (and other lectins) are higher in uncooked than cooked beans. A raw, red kidney bean can contain up to 70,000 hemagluttinating units (hau). Most lectins are reduced by moist, but not dry heat. Therefore, steaming or boiling causes a significant reduction in concentrations of lectins in beans. Boiling for at least ten minutes has been shown to reduce hau in beans by 200-fold. Because cooking temperatures under 176 °F do not destroy lectin, use of slow cooking and/or a crockpot is not advised for cooking beans [79].

Thiaminase  
Thiaminase destroys thiamin;5 it is in raw fish, red cabbage, beets, Brussels sprouts, and berries, and is produced by some microorganisms that can inhabit that GI tract. Flax seed (and therefore linseed meal) should not be fed in high quantities because a compound present in it may inhibit pyridoxine (vitamin B6).5 Diarrhea and vomiting can be the result of a bird consuming high amounts of saponins5 which are present in alfalfa, spinach, soy beans, broccoli, asparagus, apples, eggplant, and potatoes. Lastly, goitrogens have anti-thyroid effects;5 they are present in soybean, peanuts, pine nuts, all of the brassica family (turnips, rutabaga, broccoli, Brussels sprouts, cabbage, kohlrabi, mustard, cauliflower, kale), and somewhat occur in carrots, peaches, strawberries, pears, radishes, and millet.

Anti-thiamine compounds

Substances that act on the availability of vitamins are commonly referred to as antivitamins. These include materials that can cause a deficiency of vitamins by competing with vitamins in various metabolic reactions as the result of similar chemical structure or destroying or decreasing the effects of a vitamin by modifying the molecular conformation or by forming a complex [67].
Thiaminase cleaves thiamine (vitamin B1) at the methylene linkage, rendering it biologically inactive. Activity of thiaminase requires a cosubstrate—usually an amine or sulfhydryl-containing protein such as proline or cysteine. Thiaminase is found in fish, crab, clams and in some fruits and vegetables such as blueberries, black currants, red beets, Brussels sprouts and red cabbage [67].
Thiamine is an essential vitamin involved in energy production. Thiamine deficiency is associated with impaired pyruvate utilization, resulting in a shortage of cellular ATP. In humans, thiamine deficiency may lead to weakness and weight loss. Severe thiamine deficiency produces “beri-beri”, a disease characterized by anorexia, cardiac enlargement, and muscular weakness leading to ataxia [80]. Cooking destroys thiaminases in fish and other sources. There are no FDA regulations or guidelines specific to the presence of thiaminase in food.