Plant acid toxicology

1. Toxicology of Plant Acids
Nabeela Jabeen
Mphil Pharmacognosy

2. Plant Acids
 Plant acids. Plants contain organic acids.
 According to chemical classification the acids may belong to different groups,
they may be divided into two classes, the volatile and nonvolatile ones.
 Volatile acids are the ones that volatilize and pass from the liquid as vapor. The
odor of acetic acid or vinegar during cooking is well known.
 The following acids of the CnH1nO2 series are volatile, the first ones being more
volatile than the last ones:

3. CLASSIFICATION OF PLANT ACIDS
1. VOLATILE OILS
 Formic acid H. COOH
 Acetic acid CH3.COOH
 Propionic acid CH3 . CH1 . COOH
 Butyric acid CH3 . CH1 . CH1 . COOH
 Valeric acid CH3.CH1.CH1CH1COOH
 Caproic acid CH3 . CH1 . CH1 . CH1 . CH1 . COOH
 Formic and acetic acids have been obtained from plants during distillation. Onslow
states that propionic acid has only rarely been found in plants.

4. NON-VOLATILE OILS
 Non-volatile acids. The following are some of the more common non-volatile
ones found in foods:
 Dicarboxylic acids
 Oxalic acid COOH. COOH
 Malonic acid COOH . CH1 . COOH
 Succinic acid COOH . CH1 . CH1 . COOH
 Glutaric acid COOH . (CH1)3 . COOH
 Adipic acid COOH . (CH1)4 . COOH
 Hydroxydicarboxylic acids
 M alic acid COOH . CHOH . CH1 . COOH
 Tartaric acid COOH . CHOH . CHOH . COOH
 Hydroxytricarboxylic acids

5. Oxalic acid (purpose in plant)
 Oxalic acid, or oxalate, is primarily found in leafy green vegetables, rhubarb and
beets.
 Oxalic acid and oxalates are produced and present in plants in different
amounts. Insoluble calcium oxalate plays a key role in regulating calcium
concentration, which is important in the functioning of guard cells.
 Oxalates provide tolerance to aluminium toxicity to plants growing in acid soils.

6.  Both oxalic acid and calcium oxalate provide self-defence against insect pests
and grazing animals.
 Oxalates are involved in phytoremediation of soils rendered toxic by heavy
metals, like lead, cadmium, zinc, etc.

7. Toxicity of oxalic acid
 There is a possible risk of congenital malformation in the fetus
 Cause Destruction of tissues of
 Respiratory tract
 Skin
 Eye

8. Symptoms
 burning sensation, cough, wheezing,
 laryngitis, shortness of breath, spasm, inflammation and edema of the larynx
 inflammation and edema of the
 bronchi,
 pneumonitis
 pulmonary edema

9. Lethal Dose
 In humans, ingested oxalic acid has an oral LDLo (lowest published lethal dose) of
600 mg/kg.
 It has been reported that the lethal oral dose is 15 to 30 grams.
 The toxicity of oxalic acid is due to kidney failure caused by precipitation of
solid calcium oxalate, the main component of kidney stones.

10. Treatment of oxalic acid toxicity
 If the chemical was swallowed, immediately give the person water or milk, unless
instructed otherwise by a health care provider.
 DO NOT give water or milk if the person is having symptoms (such as vomiting,
convulsions, or a decreased level of alertness) that make it hard to swallow.

11. Amino acid
 Amino Acids are fundamental ingredients in the process of Protein Synthesis.
 About 20 important Amino Acids are involved in the process of each function. ...
 Proteins have a structural function, metabolic function (enzymes), a transport
function and a stock of Amino Acids function.

12. Toxicity of amino acid
 Those nonprotein amino acids found in food and fodder plants and known to be
toxic to man and domestic animals are described.
 These include toxins from many legume genera including Lathyrus, from other
higher plant families, from seaweeds, and from fungi.
 Some inhibit protein synthesis, while others are incorporated into proteins with
toxic effects.
 Basic processes such as urea synthesis and neurotransmission may be disrupted.

13.  The probable roles of nonprotein amino acids in protecting plants against
 predators,
 pathogens,
 competing plant species
 Alfalfa (Medicago sativa), which contains canavanine, and lentil (Lens culinaris), which
which contains homoarginine.

14. Resin acids
 They are often mixtures of organic compounds , principally terpenes.
 Many plants, particularly woody plants, produce resin in response to injury.
 The resin acts as a bandage protecting the plant from invading insects and
pathogens.