In vitro regeneration of gamma irradiated callus of artemisia annua and evaluation of increase artemisinin content by HPLC analysis

Artemisia annua is a aromatic annual herb also referred as sweet wormwood and called as ginghaosu which belongs to the family Asteraceae.1 According to published reports artemisinin content in A. annua vary in different parts and it has been detected in aerial parts such as leaves inflorescence, seeds and stem of plants. In leaves more artemisinin content is observed but ten fold higher is observed in flowers at full blooming stage.2,3 A. annua leaf contains peltate gland where high amount of artemisinin concentration is reported by many scientists.4 Professor You you Tu and coworker discovered artemisinin, the effective antimalerial drug in 1971 and got the nobel prize in Physiology or Medicine in 2015.5 A. annua contains sesquiterpenes lactone with endoperoxide bridge (C-OC-O) which is one of the most important drug in the treatment of chloroquine-resistant and cerebral malarias.6,7 .Artemisinin and its derivatives (ARTs) are highly specific which can only be synthesized by A. annua. Other non volatile compounds which are sesquiterpene lactones origine are arteannuin B, artemisinic acid, artemisia methyl ester, artemisinol, artemisilactone, dihydroartemisinin, artesunate, artemether, and arteether. Among these, artemether and arteether get rapidly metabolized to dihydroartemisinin when enters the body and show strong anticancer activity.8 Mutational breeding involves high energy radiation such as X, β and γ-rays, which are electromagnetic radiations that initiate or inhibit the growth and differentiation of plant cells and organs.9 Gamma rays are the efficient ionizing radiations which induces high mutation in plants. They could also modify physiological characteristics of plant to create new mutants for production of high amounts of commercially important metabolites.10 Gamma rays interact with cells internal components and release free radicals. These free radicals either damage or modify the differentiation process, morphology, physiology and bioactive components depending on applied dose.11 Gamma irradiation are reported to enhanced the production of antioxidant defence enzymes and reduces ascorbic acid, total soluble protein, amino acids and sugars in callus cultures of Rosmarinus officinalis L.12 Low gamma dose gamma rays enhanced the growth of callus in Cucumis melo while higher dose reduced the growth.13The gamma irradiation significantly stimulate the shikonin biosynthesis in Lithospermum erythrorhizon cell cultures.14 Artemisinin has very poor extinction coefficient.15,16 and poor staining characteristics also its analysis from natural sources has become a challenging task. The absence of specific chromophore in the molecule makes detection more difficult.17 Artemisinin shows the UV-Visible spectra at 254nm. Detection of artemisinin can be