Antibacterial activity and chemical analysis of methanolic extracts of Piper sarmentosum Roxb
Piper sarmentosum Roxb. is a cultivated plant that is also found wild in South East Asia. It is well known due to its medicinal properties and a variety of active chemical constituents. The potential of the plant extract against bacterial leaf blight and sheath brown rot of rice caused by Xant...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/67754/1/FP%202015%2088%20IR.pdf |
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| Summary: | Piper sarmentosum Roxb. is a cultivated plant that is also found wild in South East
Asia. It is well known due to its medicinal properties and a variety of active chemical
constituents. The potential of the plant extract against bacterial leaf blight and sheath
brown rot of rice caused by Xanthomonas oryzae pv. oryzae and Pseudomonas
fuscovaginae, respectively, were evaluated in this study. The leaf and fruit of P.
sarmentosum were extracted using aqueous methanol 80% (v/v) and the yield
percentage of crude extracts obtained was 7.5% and 7.1% for the fruit and leaf
extract, respectively. The antibacterial activities of the methanolic leaf extract of P.
sarmentosum were screened for potential use as a biological control agent against
rice pathogenic bacteria by agar well diffusion assay. The concentrations of the
extract tested were 25, 50, 100 and 200 mg/mL. The zone of inhibition produced by
the extract against the strains was measured and compared with standard antibiotic
streptomycin sulfate (30 μg/mL). The leaf extract showed antibacterial activity
against X. oryzae pv. oryzae and P. fuscovaginae with the diameter of the inhibition
zone ranging from 9.00±0.00 to 19.33±1.53 mm. Similarly, the fruit extract also
showed positive inhibition against the tested bacteria with the diameter ranging from
9.33±0.58 to 19.33±1.15 mm. Positive control, streptomycin sulfate, showed
inhibition against all the tested bacterial isolates with the range of 17.67±0.58 to
18.00±1.73 mm for the leaf extract and 15.67±5.13 to 21.00±3.46 mm for the fruit
extract. Negative control, aqueous methanol 80% (v/v), showed no inhibition zone
against any microorganism for both the leaf and fruit extracts. The Minimal
Inhibition Concentration (MIC) and Minimal Bactericidal Concentration (MBC)
were then determined. The MIC was obtained at 12.5 mg/mL for both tested bacteria
while for MBC; it was at 12.5 mg/mL for X. oryzea and 25.0 mg/mL for P.
fuscovaginae. For the fruit extract, the MBC value obtained for both P. fuscovaginae
and X. oryzae were at 25.0 mg/mL. The phenolic compounds present in the leaf and
fruit extracts of P. sarmentosum were further identified using HPLC analysis. Five
standards were used in the analysis – caffeic acid, tannic acid, gallic acid, quercetin
and naringin. The identification of each compound was based on a combination of
retention time and spectral matching. The phenolic compounds were separated and quantified in the analysis to obtain the amount of the phenolic compounds present in
each of the samples. The fraction of the elute containing the purified compound was
collected and further tested for antibacterial activity against the pathogenic bacteria.
All of the collected fractions, which were detected as the phenolic compounds based
on the standard used, showed positive inhibition against the tested bacteria. The
results obtained from this study suggest that the leaf and fruit extracts of P.
sarmentosum have potential to be developed as a novel bactericide. |
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