The essential oil obtained from the fresh leaves of Zanthoxylum alatum was analysed by gas chromatography/mass spectrometry (GC/MS). Fourteen components were identified, and linalool (30.58%), 2-decanone (20.85%), β-fenchol (9.43%), 2-tridecanone (8.86%), β-phellandrene (5.99%), Sabinene (4.82%), and α-pinene (4.11%) were the main components. The EO and methanolic extract of Z. alatum exhibited potent antifungal activity against Alternaria alternata, Alternaria brassicae, and Curvularia lunata. The EO also showed significant antibacterial activity against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, and Escherichia coli. Further, antimicrobial constituents of the EO were isolated by bioautography and preparative thin layer chromatography (PTLC) and identified as β-fenchol and linalool using GC/MS analysis. In addition to this, the free radical scavenging activity and antioxidant potential of EO and methanolic extract/fractions of Z. alatum were also investigated using in vitro assays including scavenging ability against DPPH•, reducing power and chelating ability on Fe2+ ions. Our results demonstrate that Z. alatum could be used as a resource of antioxidant and antimicrobial compounds which may find applications in food and pesticide industries.

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The essential oil obtained from fresh leaves of Eucalyptus teretecornis (family Myrtaceae) was analysed by gas chromatography/mass spectrometry (GC/MS). Twenty eight compounds were identified and β-pinene (22.55%), α-pinene (22.50%), 1,8-cineole (19.84%), limonene (5.62%), β-fenchol (3.10%), α-phellandrene (2.90%), α-eudesmol (2.66%) and 4-(2-methylcyclohex-1-enyl)-but-2-enal (2.34%) were the main components. The antifungal activity of the essential oil was assayed against Alternaria alternata using bioautography. Two main bioactive components namely a 1 (R f =0.27) and a 2 (R f =0.33) were observed that produced inhibition zone of 4 mm and 8 mm in diameter respectively. The minimum inhibitory amount (MIA) of a 1 and a 2 against A. alternata was determined as 28 μg and 10 μg, respectively using bioautography assay. Components corresponding to a 1 and a 2 were determined as β-fenchol (oxygenated monoterpene) and α-eudesmol (oxygenated sesquiterpene) respectively using GC/MS analysis. The antioxidant activity of the essential oil and its bioactive fraction was evaluated by DPPH radical scavenging assay, β-carotene/linoleic acid bleaching assay, reducing power assay and metal chelating assay. In addition fraction of the essential oil that showed antioxidant activity was analyzed using GC/MS and α-fenchol, 4-terpineol and carvacrol were the main components.

The present investigation suggests that the three organs of A. catechu differ significantly in their antioxidant potential as seen in the DPPH radical scavenging assay, reducing power assay, metal ion chelating assay, superoxide radical scavenging assay and hydroxyl radical scavenging assay. Further, our results showed that crude methanol extract and ethyl acetate fraction of heartwood of A. catechu might have a good potential as a source for natural health products due to its antioxidant and DNA protective activities.

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