In the present study, the antibacterial activity of Cornus macrophylla was examined. Organic solvent extracts of leaves were prepared using methanol, n-hexane, chloroform, and ethyl acetate. Antibacterial activity was examined by using a 100 mg/mL extract concentration. Penicillin was kept as a positive control while dimethyl sulfoxide was taken as a negative control. Methanolic extract exhibited a 21.5, 36.3, 25.3, and 23.7 mm inhibition zone diameter (IZD); n-hexane showed a 33, 40, 32.8, and 28.7 mm IZD; chloroform showed a 18.8, 29, 22.3, and 21.6 mm IZD; and ethyl acetate showed a 23.5, 30.2, 30, and 22.3 mm IZD against Erwinia carotovora, Pseudomonas syringae, Ralstonia solanacearum, and Xanthomonas axonopodis, respectively. The n-hexane extract revealed high antibacterial activity against all bacterial species as compared with methanolic, chloroform, and ethyl acetate extract. Gas Chromatography Mass Spectrometry (GC/MS) analysis of n-hexane extract depicted the presence of 55 compounds. Out of these compounds, one compound, identified as α-amyrin (Mol. wt = 426), exhibited the maximum peak area (32.64%), followed by A’-Neogammacer-22(29)-en-3-ol, acetate, (3.beta.,21.beta.)- (Mol. wt = 468) and β-amyrin (Mol. wt = 426) having peak areas of 25.97 and 6.77%, respectively. It was concluded that the antibacterial activity observed during the present investigation may be due to these compounds.

Background: Antifungal activity of slender amaranth (Amaranthus viridis L.) is well documented but such studies are scarce in Pakistan, especially against plant pathogens. It was hypothesized that A. viridis has antifungal activity against fungal phyto-pathogens also. Objective: Identification of antifungal constituents from leaf extracts of A. viridis. Methods: Different organic solvent extracts of A. viridis leaves were evaluated against 5 plant pathogenic fungal species viz. Alternaria alternata, Aspergillus flavus, Drechslera australiensis, Fusarium oxysporum and Macrophomina phaseolina. Antifungal activity of A. viridis was determined by serial dilution method. Six levels (0, 5, 10, 15, 20 and 25 mg mL-1) of treatments of each n-hexane, chloroform and ethyl acetate were employed against all fungal species in a Completely Randomised Design (CRD). Results: Generally, all organic solvent extracts reduced the fungal biomass significantly with the increase in extract concentration but ethyl acetate leaf fraction exhibited pronounced activity and reduced the fungal growth up to 44% in A. alternata, 39% in A. flavus, 48% in D. australiensis, 48% in F. oxysporum and 45% in M. phaseolina. Gas Chromatography Mass Spectrometry (GCMS) analysis of ethyl acetate leaf fraction revealed 09 compounds. Out of these 9 compounds, one compound identified as 1,2- Benzenedicarboxylic acid, mono (2-ethylhexyl) ester) showed 58.5% peak value. Conclusions: It was concluded that 1,2- Benzenedicarboxylic acid, mono (2-ethylhexyl) ester) being in the highest concentration in the ethyl acetate leaf fraction of A. viridis may be responsible for antifungal activity. This compound can serve as structural analog to develop ecofriendly fungicides.

In the present study, antibacterial and antioxidant [1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity] activities of a weed, slender amaranth (Amaranthus viridis L.) were investigated. Extracts of different plant parts were prepared in n-hexane, chloroform and ethyl acetate. Antibacterial activity was measured by using 100 mg mL-1 concentration extracts against 4 deadly phytopathogenic bacterial species viz. Pseudomonas syringae Van Hall, Ralstonia solanacearum Smith, Erwinia carotovora (Jones), Holland and Xanthomonas axonopodis Hasse. In antioxidants assays, 10, 20 and 30 mg mL-1 extracts were used keeping DPPH as control. In these bioassays, ethyl acetate fraction of A. viridis leaf exhibited the best antibacterial and antioxidants activity. Ethyl acetate leaf fraction showed the highest inhibition zone diameter (IZD) where it caused 21 mm IZD against P. syringae and 19 mm IZD against E. carotovora. This extract also showed 22, 52 and 84% antioxidant activity at 10, 20 and 30 mg mL-1 concentrations, respectively. Previously there is no report available that describes antibacterial activity of root extract of A. viridis against P. syringae. Moreover, antioxidant activity of stem and root extracts in n-hexane, chloroform and ethyl acetate was investigated first time in the world. It was concluded that the biological activities observed during the present investigation may be due to the presence of bioactive constituents that can be harnessed as natural antibacterials and antioxidants.