Elettaria cardamomum leaves, an underutilized resource: chemical profile of its essential oil and insecticidal activity

Elettaria cardamomum is known as the 'Queen of spices'; its leaf essential oil (EO) is least investigated and barely utilized. Here we report the chemical composition of E. cardamomum leaf EOs collected from five locations in the southern Western Ghats in India. EOs of fresh and dry capsules were also analyzed for comparison of their chemical profiles. The major constituents in cardamom leaf EOs were beta-pinene (35.6-51.9%) and coronarin E (17.7-34.2%). In fumigant toxicity assays against two stored product pests, lowest LC50 against Tribolium castaneum was recorded in EO of fresh capsules (124.05 mu L/L), followed by dry capsules (LC50 128.21 mu L/L) and leaves (LC50 148.00 mu L/L); LC(50)s of fresh, dry capsule and leaf EOs against Sitophilus oryzae were 30.24, 35.33 and 89.42 mu L/L, respectively. This study demonstrates cardamom leaves as a source of untapped bioactive principles which can be viably utilized for the production of botanical pesticides.

Automated summary

Elettaria cardamomum leaf essential oil has been poorly studied and utilized. This research analyzed the chemical composition of cardamom leaf essential oils from different locations in southern Western Ghats, India, and compared them with fresh and dry capsules. The major constituents were beta-pinene and coronarin E. Fumigant toxicity assays revealed that the essential oil from fresh capsules had the lowest LC50 against Tribolium castaneum, followed by dry capsules and leaves, and the LC50s against Sitophilus oryzae were significantly lower for fresh capsules compared to dry capsules and leaves. This study demonstrates the potential of cardamom leaves as a source of bioactive compounds for botanical pesticides.