The essential oil composition, antimicrobial activity and antioxidant assay of the extracts from aerial parts of Dicliptera roxburghiana Nees.

Dicliptera roxburghiana Nees. is a shrub belonging to the family Acanthaceae. The present study was undertaken because of the medicinal importance of this genus and the need for a report on its essential oil composition and antibacterial activity. Essential oil from the whole aerial part, including flowers, of the plant was extracted by steam distillation method and analysed by GC-FID and GC-MS. In all, sixty-nine compounds constituting 85.5% of the total oil composition have been identified. The essential oil contained high concentrations of non-terpenic compounds (33.5%), while the terpenoid compounds had a higher concentration still (52.0%). The unidentified portion contained several minor constituents with ambiguous Mass Spectra. The major constituents of the essential oil were identified as beta-panasinsene (11.2%), phytol (10.0%), pentadecanal (8.6%), cis, cis, cis-7,10,13-hexadecatrienal (7.6%), linalool (4.2%) and cameroonan -7-alpha-ol (4.2%). The antioxidant activity of four different extracts (whole aerial parts)was performed by two methods, namely, DPPH assay and metal chelating assay. Significant results were obtained in each case at 100 mu g/mL concentration. For antibacterial screening, the essential oil exhibited the highest activity against Gram-negative Pasteurella multocida (15.66 +/- 0.57 mm) and Gram-positive Bacillus subtilis (13.00 +/- 1.00 mm). The highest activity of ethyl acetate extract was recorded against Gram-negative Pasteurella multocida (12.00 +/- 0.00 mm). The hexane extract of the plant was found to be most active against Gram-positive Enterococcus faecalis (13.33 +/- 0.57 mm). The chloroform extract showed the highest activity against Gram-negative Xanthomonas phaseoli (16.33 +/- 1.15 mm) and Gram-positive Enterococcus faecalis (12.00 +/- 1.00 mm). For methanol extract, the highest activity was observed against Gram-negative Agrobacterium tumefaciens (10.66 +/- 0.57 mm) and Gram-positive Enterococcus faecalis (10.33 +/- 0.57 mm). The essential oil exhibited the highest antifungal activity against the fungal strains, namely, Aspergillus niger (17.66 +/- 0.57 mm), followed by Aspergillus flavus (16.66 +/- 0.57 mm) and Candida albicans (16.33 +/- 0.57 mm). The essential oil and extracts from this plant species may be utilised to control various microbial infectious diseases and serve as an antioxidant supplement.