Tentoxin is a natural cyclic

tetrapeptide A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors ...

produced by phytopathogenic

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

Alternaria alternata ''Alternaria alternata'' is a fungus causing leaf spots, rots, and blights on many plant parts, and other diseases. It is an opportunistic pathogen on over 380 host species of plant. It can also cause upper respiratory tract infections and a ...

''. It selectively induces

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

in several germinating seedling plants. Therefore, tentoxin may be used as a potential natural

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

, and is a lactam. Tentoxin was first isolated from ''Alternaria alternata'' (syn. ''tenuis'') and characterized by George Templeton ''et al.'' in 1967. Tentoxin has also been used in recent research to eliminate the

polyphenol oxidase Polyphenol oxidase (PPO; also polyphenol oxidase i, chloroplastic), an enzyme involved in fruit browning, is a tetramer that contains four atoms of copper per molecule. PPO may accept monophenols and/or ''o''-diphenols as substrates. The ...

(PPO) activity from seedlings of higher plants.Duke, S.O. & Vaughn, K.C. 1982. Lack of involvement of polyphenol oxidase in ortho-hydroxylation of phenolic compounds in mung bean seedlings. ''Physiol. Plant. 54:'' 381-385.

References

{{reflist Cyclic peptides Tetrapeptides Twelve-membered rings