Chemo-divergence in essential oil composition among germplasm collection of fiveOcimumspecies from eastern coastal plains of India

The present work was aimed to study chemical diversity among Ocimum species collected from Eastern Coastal Plains of India. Seventeen accessions representing five Ocimum species namely; O. basilicum L., O. tenuiflorum, O. gratissimum L., O. americanum L. and O. citriodorum Vis. were investigated for essential oil content and oil composition by GC/FID and GC/MS. Essential oil content isolated from aerial parts of Ocimum species varied from 0.27% to 0.47% on fresh weight basis. A total of eighty-three compounds, constituting 95.2–99.9% of total oil were identified in five Ocimum species. Major volatile constituents identified were monoterpenoids (camphor, linalool, neral, nerol, geraniol, 1,8-cineole, ocimenes) and phenylpropanoids (methyl chavicol, eugenol, methyl eugenol, methyl cinnamate). Ocimum species germplasm was classified into different chemotypes. O. americanum accessions belonged to camphor-rich chemotype (38.7–51.4%); while O. gratissimum belonged to eugenol-rich chemotype (59.7–71.8%). A unique high (E)-methyl cinnamate-rich chemotype (61.3–69.0%) was identified in O. basilicum whereas eugenol and methyl eugenol-rich two chemotypes were identified in O. tenuiflorum germplasm. Essential oil profiling of O. citriodorum showed two distinct chemotypes rich in geranial/neral and methyl chavicol.