1 OAJMAP (2012) Essential oil constituents and their biological activities from the leaves of Cassia fistula growing in Nepal Prabodh Satyal 1 , Noura S. Dosoky 2 , Ambika Poudel 3 and William N. Setzer 1 * 1 Department of Chemistry, University of Alabama in Huntsville, Huntsville, AL 35899, USA 2 Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA 3 Department of Chemistry, MMAMC Campus, Tribhuvan University, Biratnagar, Nepal * Corresponding author. E-mail: wsetzer@chemistry.uah.edu Open Access Journal of Medicinal and Aromatic Plants Vol. 3 (2): 1-4 Introduction The genus Cassia is comprised of ten species of yel- low, flowering ornamental trees of the Fabaceae (Press et al., 2000). Cassia fistula L., locally known as “ra- jbriksha” in Nepal, is a deciduous tree native to East India, Nepal, Burma, and Malaysia (Press et al., 2000). Traditionally in Nepal, the plant’s fruit pulp is used as an antipyretic (Gewali, 2008), it is also used to treat habitual constipation (Mabberly, 1997). The leaf is used to treat jaundice, piles, rheumatism, ulcers, insect bites, facial paralysis and skin eruptions (Wealth of India, 2007), the leaf is also one of the most important in- gredients in preparing Ayurvedic medicine (Agrawal et al., 2005). C. fistula can attain 6-10 m in height and it has compound leaves of 5-12 cm length (Gupta, 2010). Various pharmacological activities (antitussive, CNS, clastogenic, antipyretic, antioxidant, laxative, anti-in- flammatory, hepatoprotective, larvicidal, antitumor, an- tiparasitic, antifertility, and anti-leishmanial) have been reported for this plant (Danish et al., 2011). Phytochem- ically, the leaf of the C. fistula contains mainly oxalic acid, flavonoids, tannins, and anthraquinones, while the fruits contain anthraquinones, flavonoids, and waxes (Bahorun et al., 2005). Materials and methods Plant Material The plant materials of Cassia fistula were collected from the city of Biratnagar (26°28” N, 87°16” E, 72 m above sea level) in the Morang district in the Koshi Zone of Nepal in May 2011. The plant was identified by Tilak Gautam and a voucher specimen (1703) has been deposited in the herbarium of the Tribhuvan University, Post Graduate Campus, Botany Department, Biratnagar. The fresh leaves (100 g) were crushed and hydrodistilled using a Clevenger-type apparatus for 4 hours, which gave a clear, pale yellow essential oil (0.012 g) that was stored at 4ºC until analysis. Gas chromatographic – mass spectral analysis The essential oil of C. fistula was analyzed by GC- MS using an Agilent 6890 GC with Agilent 5973 mass selective detector as described previously (Satyal et al., 2012). Identification of the oil components was based on their retention indices determined by reference to a homologous series of n-alkanes and by comparison Abstract: Cassia fistula L. (Fabaceae) fruit is used traditionally in Nepal as an antipyretic and to treat constipation, while the leaves are used to treat jaundice, piles, rheumatism, ulcers, insect bites, facial paralysis and skin eruptions. C. fistula leaves are important ingredients in Ayurvedic medicine. This study was undertaken to characterize the volatile constituents of C. fistula leaves and to evaluate their antimicrobial and cytotoxic properties. The essential oil from the leaves of Cassia fistula collected from Biratnagar, Nepal, was obtained by hydrodistillation and analyzed by GC-MS. Antimicrobial activities (minimum inhibitory concentration) against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, and Candida albicans, were determined using the microbroth dilution technique, in-vitro cytotoxic activity against MCF-7 human adenocarcinoma cells was determined using the MTT method. C. fistula leaf oil was composed of only seven components, all of which were identified: eugenol (25.0%), (E)-phytol (21.5%), camphor (13.5%), limonene (11.0%), salicyl alcohol (10.4%), linalool (9.9%), and 4-hydroxybenzyl alcohol (8.7%). The leaf oil showed antifungal activity against A. niger (MIC = 78 μg/mL) and C. albicans (MIC = 313 μg/mL), but only marginal cytotoxicity against MCF-7 cells (19.63 ± 11.89% kill at 100 μg/ mL). All of the individual essential oil components were screened for activity. Eugenol exhibited antifungal properties (MIC on A. niger = 78 μg/mL) and limonene and phytol were cytotoxic (IC 50 = 74.7 and 54.3 μg/mL, respectively). Key words: essential oil composition, eugenol, phytol, camphor, limonene, salicyl alcohol, linalool, 4-hydroxybenzyl alcohol Manuscript received : 22 June, 2012 Manuscript accepted : January 20, 2013