Variation in DPPH scavenging activity and major volatile oil components of cassumunar ginger, Zingiber montanum (Koenig), in response to water deficit and light intensity

Cassumunar ginger, Zingiber montanum (Koenig) Link ex Dietr. (Zingiberaceae), is called Phlai in Thailand. The current study investigates the levels of antioxidant activity and major volatile oil components in cassumunar ginger exposed to varying water deficits (0, 30, 60, 90 and 120 days before harvest) and light intensities (100%, 50% and 25% sunlight). A 120-day water deficit resulted in high volatile oil content and increased sabinene content, but DPPH scavenging activity was not affected. The quantity of volatile oil in the cassumunar ginger exposed to a 120-day water deficit was almost twice that of both the control and the sample exposed to a 30-day deficit. The highest terpinen-4-ol content was obtained after a 60-day water deficit, and (E)-1-(3′,4′-dimethoxyphenyl) butadiene content tended to decrease with prolonged water deficiency. The antioxidant activities of cassumunar ginger were 52.98%, 41.75% and 42.93% in plants grown at 100%, 50%, and 25% sunlight, respectively. Light intensity of 50% or 25% increased the biomass of cassumunar ginger but decreased the volatile oil content; antioxidant activity was not significantly affected.

Research highlights▶ Antioxidant activity and volatile oil in cassumunar ginger were investigated during growth. ▶ Water deficit has no effect on antioxidant activity or DMPBD content. ▶ Water deficit affect the volatile oil content of sabinene and terpinen-4-ol. ▶ Light intensity has no effect on antioxidant activity. ▶ Lower light intensity decreased volatile oil content.