Plants synthesize numerous secondary metabolites viz. terpenoids, alkaloids, glycosides, anthocyanins, flavonoids, lignans, tannins, phenolics, caretenoids, steroids and saponins, for diverse applications. Different plants parts (leaves, stem, root, rhizome, flowers, and seeds) of medicinal and aromatic plants accumulate these secondary metabolites of medicinal value and the composition was controlled by genetic factors, geographic and climatic conditions, developmental stage of the plant, extraction methods, etc [1Ramakrishna A, Ravishankar GA. Influence of abiotic stress signals on secondary metabolites in plants. Plant Signal Behav 2011; 6(11): 1720-31.
[http://dx.doi.org/10.4161/psb.6.11.17613] [PMID: 22041989] -5Bukvički D, Stojković D, Soković M, et al. Satureja horvatii essential oil: in vitro antimicrobial and antiradical properties and in situ control of Listeria monocytogenes in pork meat. Meat Sci 2014; 96(3): 1355-60.
[http://dx.doi.org/10.1016/j.meatsci.2013.11.024] [PMID: 24342186] ]. Zingiberaceae, the largest monocotyledonous family in India, includes 52 genera and 1400 species distributed in the Indo-Malaysian region of Asia. Among them, 22 genera and 178 species were reported in the north eastern and peninsular regions of India. Various members of this family are of economic importance for food-flavour, spice, medicine and source of essential oils and oleoresins of medicinal and export value [6Burkill HI. Dictionary of the economic products of the malay peninsula 1966.-9Tripathi S, Goel AK. Ethnobotanical Diversity of Zingiberaceae in North-Eastern India. Ethnobotany 2001; 13: 67-9.]. The genus Alpinia, consist ca. 230 species worldwide with major distribution in China, India, East Indies, and Polynesia and are used as spices and food additives agent and in the traditional medicine for the treatment of dyspepsia, gastralgia, and sea-sickness and for abdominal colic pains and as digestive, spleen and liver tonic. These are accredited with various pharmacological activities such as antispasmodic, myorelaxant, anti-oxidant, anti-inflammatory, anti-emetic, antiulcer, anti-inflammatory, anti-parasitic, anti-allergic and spasmolytic properties for their use in various indigenous medicinal formulations [10Chopra RN, Nayar SL. Chopra IC Glossary of Indian Medicinal Plants 1956; 13.-14Kaul PN, Rao BR, Singh K, Bhattacharya AK, Ramesh GR. Volatile constituents of essential oils isolated from different parts of A. calcarata Rosc. J Essent Oil Res 2005; 17: 7-9.
[http://dx.doi.org/10.1080/10412905.2005.9698814] ]. Numerous studies on leaf, flower and rhizome essential oil of A. calcarata and A. zerumbet have been carried out on its uses and applications in many common and rare health problems. Alpinia spp. are characterized by a wide range of volatile compounds in numerous phytochemical studies and mainly found to be dominated by monoterpenoids such as 1,8-cineole, camphor, (E)-methyl cinnamate, terpinene-4-ol, and pinenes, ocimenes, and fenchyl acetate as the major constituent distributed in their essential oils [11Padalia RC, Chanotiya CS, Sundaresan V. Compositional variability in essential oil from different parts of Alpinia speciosa from India. Nat Prod Commun 2010; 5(2): 279-82.
[http://dx.doi.org/10.1177/1934578X1000500223] [PMID: 20334144] -22Prudent D, Perineau F, Bessiere JM, Michel G, Bravo R. Chemical analysis, bacteriostatic and fungistatic properties of the essential oil of the Atomau from Martinique (Alpiniaspeciosa K. Schum.). J Essent Oil Res 1993; 5: 255-64.
[http://dx.doi.org/10.1080/10412905.1993.9698218] ]. The chemical composition of the rhizome essential oil of A. calcarataand A. zerumbet revealed the presence of oxygenated monoterpene endo-fenchyl acetate as the distinctive marker constituents along with other commonly distributed monoterpenoids [12Padalia RC, Verma RS, Sundaresan V, Chanotiya CS. Chemical diversity in the genus Alpinia (Zingiberaceae): comparative composition of four Alpinia species grown in Northern India. Chem Biodivers 2010; 7(8): 2076-87.
[http://dx.doi.org/10.1002/cbdv.201000013] [PMID: 20730971] ]. The present experiment focuses on the chemical evaluation & biological activity of two Alpinia species viz. A. calcarata and A. zerumbet grown in tarai regions at CIMAP resource center Pantnagar, Uttarakhand, India.

The essential oil composition of leaves and rhizomes of A. calcarata and A. zerumbet, cultivated in Tarai regions of Pantnagar, Uttarakhand, India, were analyzed and compared using capillary GC and GC-MS. The identified constituents with their relative percentage composition are given in Table 1. The essential oil analysis results in the identification of 31 compounds forming 89.26-94.32% of total identified from the leaves and rhizome of the A. calcarata and A. zerumbet. The leaf and rhizome oil of A. calcarata were mainly characterized by oxygenated monoterpenes (51.49 and 70.94% resp.) represented by1, 8-cineole (36.07 and 43.63% resp.),camphor (11.60 and 4.31% resp.), terpinen-4-ol (1.64 and 1.00% resp.), and monoterpene hydrocarbons (39.60 and 15.4% resp.) with β-pinene (23.52 and 5.02% resp.), α-pinene (7.73 and 3.42% resp.) and camphene (6.49 and 4.97% resp.) as major constituents. In addition to these, other compounds found in significant content in leaf and rhizome oil of A. calcarata were viridiflorol (1.92 and 3.36% resp.) and (E)-methyl cinnamate (1.03 and 1.54% resp.). Moreover, theleaf and rhizome essential oil of A. zerumbet oil were also characterized mainly by oxygenated monoterpenes (55.25 and 58.46% resp.) with 1,8-cineole (26.51 and 15.61% resp.), terpinen-4-ol (20.87 and 6.42% resp.), camphor (1.94 and 3.21% resp.) as major constituents along with monoterpene hydrocarbons viz., β-pinene (14.81 and 8.83% resp.), (Z)-β-ocimene (11.86 and 2.84% resp.), α-pinene (5.96 and 3.22% resp.). Other compounds found in significant amount were linalool (2.26 and 1.65% resp.), (E)-β-ocimene (2.19 and 1.17% resp.), and α-terpineol (2.08 and 1.06% resp.), myrcene (0.49 and 3.49% resp.), and bornyl acetate (0.32 and 5.61% resp.). The results showed that presence of endo-fenchyl acetate (13.12 and 24.39% resp.) and exo-fenchyl acetate (0.10 and 0.16% resp.) as marker constituents of rhizome essential oil of both A. calcarata and A. zerumbet, whereas these compounds were absent in the leaf oil of A. calcarata and A. zerumbet. The present results on composition of the leaf and rhizome essential oils of A. calcarata and A. zerumbet were very close to the earlier reports, showing presence of oxygenated monoterpenoids (1,8-cineole, terpinen-4-ol, endo-fenchyl acetate) and monoterpenoid hydrocarbons (α-pinene, β-pinenes, ocimenes) as characteristics constituents [11Padalia RC, Chanotiya CS, Sundaresan V. Compositional variability in essential oil from different parts of Alpinia speciosa from India. Nat Prod Commun 2010; 5(2): 279-82.
[http://dx.doi.org/10.1177/1934578X1000500223] [PMID: 20334144] , 12Padalia RC, Verma RS, Sundaresan V, Chanotiya CS. Chemical diversity in the genus Alpinia (Zingiberaceae): comparative composition of four Alpinia species grown in Northern India. Chem Biodivers 2010; 7(8): 2076-87.
[http://dx.doi.org/10.1002/cbdv.201000013] [PMID: 20730971] ]. In one study, the samples collected from southern India of A. calcarata showed two different compositions, in one, endo-fenchyl acetate was the major constituent of rhizome essential oil, while in the second geraniol was reported as a major constituent with no endo-fenchyl acetate [13Rout PK, Sahoo S, Rath SP, Rao YR. Analysis of the leaf, rhizome and root oils of two accessions of AlpiniacalcarataRosc. cultivated at Bhubaneswar. J Essent Oil Res 2005; 17: 398-400.
[http://dx.doi.org/10.1080/10412905.2005.9698941] , 14Kaul PN, Rao BR, Singh K, Bhattacharya AK, Ramesh GR. Volatile constituents of essential oils isolated from different parts of A. calcarata Rosc. J Essent Oil Res 2005; 17: 7-9.
[http://dx.doi.org/10.1080/10412905.2005.9698814] , 18Choudhary JU, Yusuf M, Hussein MM. Composition of the rhizome oil of Alpinia calcarata. Indian Perfumer 2003; 47: 355-7.].The presence of monoterpenoids 1,8-cineole, terpinen-4-ol, α-pinene, β-pinene, ocimenes and fenchyl acetate are responsible for their sweet smell and may be utilized for perfumery and fragrance purposes.

Table 1
Comparative leaf and rhizome essential oil composition of two Alpinia spp.

Table 2
Antibacterial potential of the essential oils of leaves and rhizome of Alpinia spp.

The antibacterial potential of the leaf and rhizome essential oil of A. calcarata and A. zerumbet was tested for antibacterial potential activity against eight bacterial strains viz. S. aureus-96, S. aureus-2940, B. subtilis, S. epidermidis, S. mutans, K. pneumoniae, E. coliand S. typhimurium. The leaf and rhizome essential oils of A. calcarata and A. zerumbet showed varying degree of activities against tested pathogens (Table 2). The leaf oil of A. calcarata shows maximum antibacterial potential activity against S. mutans (ZOI: 14 mm, MIC: 500 μg/mL) followed by on S. aureus-96 (ZOI: 7 mm, MIC: 500 μg/mL), S. typhimurium (ZOI: 7 mm, MIC: 500 μg/mL), B. subtilis (ZOI: 6 mm, MIC: 1000 μg/mL), and S. aureus-2940 (ZOI: 5 mm, MIC: 1000 μg/mL). However, the rhizome oil of A. calcarata shows maximum antibacterial activity against the bacteria K. pneumoniae (ZOI: 14 mm, MIC: 125 μg/mL) and significant antibacterial activity against E. coli (ZOI: 12 mm, MIC: 250 μg/mL), S. aureus-96 (ZOI: 10 mm, MIC: 250 μg/mL), S. epidermidis (ZOI: 11mm, MIC: 125 μg/mL), and S. aureus-2940 (ZOI: 8 mm, MIC: 250 μg/mL). Moreover, the leaf oil of A. zerumbet shows maximumantibacterial potential activity against S. epidermidis (ZOI: 10 mm, MIC: 500 μg/mL) followed byB. subtilis (ZOI: 7 mm, MIC: 1000 μg/mL), S. typhimurium (ZOI: 7 mm, MIC: 500 μg/mL), S. aureus-96 (ZOI: 6 mm, MIC: 500 μg/mL), S. aureus-2940 (ZOI: 5 mm, MIC: 1000 μg/mL), andS. mutans (ZOI: 5 mm, MIC: 1000 μg/mL). However, the rhizome oil of A. zerumbet showed maximum antibacterial activity against S. mutans (ZOI: 14 mm, MIC: 250 μg/mL) and B. subtilis (ZOI: 14 mm, MIC: 250 μg/mL), followed by S. aureus-2940 (ZOI: 12 mm MIC: 250 μg/mL),S. epidermidis (ZOI: 11 mm, MIC: 500 μg/mL), S. aureus-96 (ZOI: 9 mm, MIC: 500 μg/mL), K. pneumoniae (ZOI: 8 mm, MIC: 500 μg/Ml), E. coli (ZOI: 6 mm, MIC: 1000 μg/mL) and S. typhimurium (ZOI:5, MIC: 1000 μg/mL). Results showed that the leaf oil of A. calcarata shows very good antibacterial potential activity againstS. mutans whereas its rhizome oil of significant antibacterial activity against the bacteria Klebsiella pneumoniae, E. coli, S. aureus-96, and S. epidermidis. The rhizome essential oil of A. zerumbet showed potent antibacterial activity against S. mutans, B. subtilis S. aureus-2940 and S. epidermidis; however its leaf oil showed maximumactivity against S. epidermidis.

The genus Alpinia is presently considered as an augmented source of medication in traditional medicine for various health problems. Numerous studies have been carried out on the utility of different parts of the Alpinia species viz. leaves, roots, rhizomes and flowers. Of all the species, A. calcarata and A. zerumbet have been widely studied. The study revealed that the essential oils from leaves and rhizomes of A. calcarata and A. zerumbet possess aroma chemicals viz. 1,8-cineole, ocimenes, terpinen-4-ol, α-pinene, β-pinene and fenchyl acetate for utilization in perfumery and fragrance related formulation. In the southern part of India, these species are in cultivation and used as raw material for phytochemicals and traditional medicine. The antibacterial activity assay also showed that their essential oils possess significant activities against some of the tested pathogenic bacterial strains. The results showed that the future prospect needs to be carried out in these plants for utilizing different plant parts as a prominent source of essential oils and aroma chemicals for product formulation.