Volatile chemistry of a plant: mono-sesquiterpenoid pattern in the growth cycle of Curcuma haritha

Volatile molecules, mostly terpenoids, play a significant role in plant defence. The growth pattern-terpenoid interrelationship of Curcuma haritha, a perennial herb in the ginger family, is tracked by probing the contents of individual mono/sesquiterpenoids throughout its growth cycle by GC-based techniques (GC-FID, GC-MS, Co-GC, LRI determination, database and literature search), supported by NMR/mass spectroscopy. Forty to sixty-four volatile compounds were identified in various growth stages. Major monoterpenes in C. haritha volatile oils were camphor (35.3 ± 0.89%/15.3 ± 0.16%), 1,8-cineole (13.9 ± 0.27%/7.1 ± 0.09%), isoborneol (9.4 ± 0.27%/4.6 ± 0.10%) and borneol (4.4 ± 0.12%/2.3 ± 0.07%). Total monoterpene (C₁₀) content in C. haritha was highest (69.7-67.0%) in its early growth stages (sprouting/leaf development) and gradually declined towards underground dormancy (lowest 36.9%). Major sesquiterpenes were germacrane-type compounds: curdione (19.8 ± 0.37%/11.1 ± 0.11%), furanogermenone (18.8 ± 0.16%/trace), neocurdione (6.2 ± 0.14%/2.6 ± 0.04%) and germacrone (5.7 ± 0.12%/1.5 ± 0.06%). Total sesquiterpene (C₁₅) content showed an opposite trend, i.e. 29.9% in sprouting stage to a maximum of 60.9% in dormancy. Guaiane-type sesquiterpene lactones zedoarondiol, isozedoarondiol, zedoarolide B and zedoalactone B were also isolated from the acetone extract/ethyl acetate fraction of C. haritha rhizomes. The reverse progression of mono- and sesquiterpene levels from sprouting/leaf development/leaf-withering stage to dormancy reveals an energetically feasible biosynthetic/defence plan in C. haritha. Copyright © 2009 John Wiley & Sons, Ltd.