By Baby Sabulal, Varughese George, Mathew Dan and Nediyaparambu Sukumaran Pradeep

Abstract: Abstract: The chemical composition of the essential oils from the rhizomes of four South Indian Hedychium species, viz. H. venustum Wight, H. spicatum Ham. ex Smith var. acuminatum (Roscoe) Wall., H. coronarium Koenig and H. flavescens Carey ex Roscoe was investigated by GC and GC/MS. 1,8-Cineole was the most abundant constituent in the first three oils, present at concentrations of 45.4%, 44.3% and 48.7%, respectively. β-Pinene (43.6%) was the major constituent in the oil from H. flavescens. The percentages of sesquiterpenes were the highest in the rhizome oil of H. venustum (24.0%) followed by H. spicatum var. acuminatum (22.2%), H. flavescens (0.6%) and H. coronarium (0.5%). The antimicrobial activities of all four rhizome oils were tested by the disc diffusion method against three Gram-positive and seven Gram-negative bacteria and two fungi. The strongest activities were observed for the rhizome oil from H. flavescens, especially against Salmonella typhi (23 mm inhibition zone), Escherichia coli (18 mm), Proteus vulgaris (15 mm) and the fungi Candida albicans (13 mm) and C. glabrata (14 mm). Key Word Index: Hedychium venustum, Hedychium spicatum var. acuminatum, Hedychium coronarium, Hedychium flavescens, Zingiberaceae, essential oil composition, 1,8-cineole, β-pinene, antimicrobial activity.

Introduction
Hedychium belonging to the family Zingiberaceae is commonly known as ginger lilies and is a genus of herbs with thick, fleshy and branched rhizomes. In South Asia, the genus Hedychium has over 80 species. Recent studies reported 41 species and four varieties in India, of which 17 species are endemic to India (1,2). Hedychium spicatum is used as a bactericide and fungicide and for the treatment of pain, stomach ailments and inflammation in Indian traditional medicine (3,4). Hedychium coronarium is used for the treatment of swelling, sore throat, tonsillitis and tumor (3). Hedychium spicatum rhizomes are used in perfumery in Tropical Asia. Hedychium spp. are widely cultivated for ornamental purposes especially for their sweet scented flowers (5).

The chemical composition of the rhizome oils from H. spicatum var. acuminatum (Nainital, India), H. aurantiacum (Nainital, India), H. coronarium (Tahiti Island, French Polynesia), H. acuminatum (Darjeeling, India), H. gardenarium (Darjeeling, India) and H. cylindricum (Sabah, Malaysia) were previously studied (4,6–14). Monoterpenes constituted major portions of these rhizome oils, with 1,8-cineole as the single major constituent in H. spicatum var. acuminatum, H. coronarium and H. acuminatum; β-pinene in H. gardenarium; linalool in H. aurantiacum and terpinen-4-ol in H. cylindricum (4, 6–14). Flower oils of H. coronarium (Chiba, Japan and China) and H. flavum (China); leaf and flower oils of H. coronarium (Madagascar) and H. gardenarium (San Miguel Island, Azores) and oil from the aerial parts of H. flavum (Madagascar) were also investigated (15–21). The leaf and flower oils of H. gardenarium from San Miguel Island, Azores were subjected to antimicrobial studies (20).

Genus Hedychium is poorly represented in South India with only four species: H. venustum Wight, H. spicatum Ham. ex Smith var. acuminatum (Roscoe) Wall., H. coronarium Koenig and H. flavescens Carey ex Roscoe (1,2). In this article, we report the chemical characterization, antibacterial and antifungal activities of the oils from the rhizomes of these four Hedychium species. This is the first report on the oils from H. flavescens and endemic H. venustum. Essential oils from the rhizomes of H. coronarium (8–11) and H. spicatum var. acuminatum (4,6,9) have been previously studied, but this is the first report on the South Indian accessions of these two species.