Ruchi Acharya

Microwave-Assisted Mild Conversion of Natural Dihydrotagetone into 5-Isobutyl-3-methyl-4,5-dihydro- 2(3H)-furanone, an Analogue of Whisky Lactone*

A microwave-assisted mild protocol is developed for the synthesis of 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone, an analogue of whisky lactone, from dihydrotagetone, an acyclic monoterpenoid obtained from Tagetes minuta. The methodology involved oxidation of dihydrotagetone in the presence of sodium metaperiodate/potassium permanganate/alumina to give 2,6-dimethyl-4-oxo-heptanoic acid, which upon reduction and subsequent lactonization provided 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone. The reaction is also conducted under conventional conditions and is compared with the microwave method.

Toxicity of pure compounds isolated from Tagetes minuta oil to Meloidogyne incognita

Essential oils are natural volatile substances found in a variety of plants. The toxicity of z-β-ocimene and dihydrotagetone (isolated from the oil of Tagetes minuta) to eggs and juveniles of Meloidogyne incognita was investigated in vitro. Tagetes minuta oil at 4%, 3%, 2% and 1% was strongly toxic to eggs and juveniles of M. incognita. Further studies revealed that dihydrotagetone and z-β-ocimene isolated from the oil showed strong nematicidal activity against M. incognita, with dihydrotagetone showing a higher level of toxicity than z-β-ocimene. The results of this study suggest that dihydrotagetone and z-β-ocimene isolated from T. minuta oil are potential sources of botanicals for control of the root-knot nematode M. incognita.