1. Background
2. Objectives
3. Methods
3.1. Chemical Materials
3.2. Preparation of the Plant Extracts
3.3. Bacterial Strains
3.4. Evaluation of Antibacterial Activity Using the Agar Well Diffusion Assay
3.5. Determination of the MIC and MBC Using the Serial Dilution Method
3.6. Determination of the Total Flavonoid and Phenolic Contents
3.7. Anti-radical Activity by the DPPH Assay
3.8. Investigation of the Phytochemical Compounds
3.9. Statistical Analysis
4. Results
| Bacteria | Colored Skin | White Skin | Gentamicin | Ciprofloxacin | ||||
|---|---|---|---|---|---|---|---|---|
| Methanolaa, b | Ethanolba, b | Aqueousca, b | Methanolaa, b | Ethanolba, b | Aqueousca, b | |||
| B. subtilis | 13 ± 0.88M | 17.67 ± 0.33IJ | 13.33 ± 0.33ML | 14.5 ± 1.73KL | 11.67 ± 0.88NO | 9.33 ± 0.33PQ | 29 ± 0.57D | 29.5 ± 0.33D |
| B. cereus | 20 ± 0.58H | 17.33 ± 1.33IJ | 12.67 ± 1.2MN | 8.33 ± 0.88QR | 11 ± 1.53O | 9.67 ± 0.33PQ | 19.66 ± 0.33I | 28.5 ± 0.66D |
| S. aureus | 20.33 ± 0.33H | 16.67 ± 0.88J | 12.67 ± 0.33MN | 17.67 ± 0.33IJ | 15 ± 2.4K | 10 ± 0.58P | 20 ± 1H | 28.5 ± 0.66D |
| S. pyogenes | 8 ± 0.67R | 12.33 ± 0.33MN | 10 ± 1P | 16.8 ± 0.66J | 14.5 ± 0.00KL | 0 ± 0U | 20 ± 0.57H | 31.5 ± 0.33C |
| M. luteus | 20 ± 0.58H | 14 ± 0.58L | 9.33 ± 0.88PQ | 26.67 ± 1.76E | 13.67 ± 0.33ML | 0 ± 0.00U | 22 ± 0.33G | 30 ± 1C |
| S. typhi | 12 ± 0.58N | 12.67 ± 0.33MN | 13.33 ± 0.33ML | 13 ± 0.58M | 14 ± 1L | 15.67 ± 0.88JK | 29.5 ± 1D | 33 ± 0.57B |
| S. boydii | 11.67 ± 0.33NO | 7.67 ± 0.33S | 7.33 ± 0.33S | 13.33 ± 0.33ML | 10.33 ± 0.88OP | 0 ± 0.00U | 19 ± 0.57I | 37.5 ± 0.66A |
| P. aeruginosa | 5.33 ± 2.67T | 12 ± 0.58N | 0 ± 0U | 15.33 ± 1.2JK | 14.7 ± 0.67KL | 0 ± 0.00U | 20 ± 0.33H | 24.5 ± 0.66F |
| E. coli | 12.33 ± 0.33MN | 12.33 ± 0.33MN | 9 ± 0.33Q | 19.67 ± 0.88HI | 15.67 ± 1.2JK | 12.33 ± 0.33MN | 19.5 ± 1HI | 24.5 ± 0.57F |
| E. aerogenes | 14 ± 0.33l | 13 ± 0.58M | 12.33 ± 1.2MN | 22 ± 0.58G | 20.67 ± 0.88GH | 9.33 ± 1.33PQ | 11 ± 0.33O | 28 ± 0.33D |
aValues are expressed as mean ± SD.
bSame letters shows non-significant difference at P < 0.05.
4.1. MIC and MBC
| Organ | Con. | Bacteria | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| B. subtilis | B. cereus | S. aureus | M. luteus | E. aerogenes | S. typhi | P. aeruginosa | E. coli | S. pyogenes | S. boydii | |||
| Colored skin | M | MIC | 25 | 6.25 | 12.5 | 12.5 | 50 | 12.5 | - | 50 | - | - |
| MBC | 50 | 50 | 50 | 100 | - | 25 | - | 100 | - | - | ||
| E | MIC | 50 | 25 | 25 | 50 | 25 | 25 | 100 | 25 | - | - | |
| MBC | - | 50 | 100 | 100 | 50 | 50 | - | 100 | - | - | ||
| A | MIC | 50 | 100 | 50 | - | 50 | 100 | - | - | - | - | |
| MBC | - | - | - | - | 100 | 200 | - | - | - | - | ||
| White skin | M | MIC | 25 | 50 | 6.25 | 12.5 | 50 | - | 100 | 12.5 | - | - |
| MBC | 50 | 100 | 25 | 50 | 100 | - | 100 | 50 | - | - | ||
| E | MIC | 50 | 25 | 25 | 25 | 25 | 50 | - | 50 | - | - | |
| MBC | 100 | 50 | 50 | 100 | 50 | 100 | - | - | - | - | ||
| A | MIC | - | - | 100 | 50 | - | 50 | - | 50 | - | - | |
| MBC | - | - | - | 100 | - | - | - | |||||
Abbreviations: A, aqueous; Con., concentration (mg/mL); E, ethanol; M, methanol; -, lack of bacterial growth.
4.2. Evaluation of Antioxidant Properties
4.2.1. Total Phenolic and Flavonoid Content
| Organ | Extract | Colored Skin | White Skin |
|---|---|---|---|
| Phenols, mgGA/g | Methanol | 79.71A | 71.63A |
| Flavonoids, mgQ/g | Methanol | 3.63B | 4.06A |
aSame letters show non-significant difference at P < 0.05.
4.3. Anti-Radical Activity by DPPH
| Organ | Inhibition Rate of DPPH at Various Concentrations, mg.mL-1 | IC50 | ||||
|---|---|---|---|---|---|---|
| 0.2 | 0.4 | 0.6 | 0.8 | 1 | ||
| Colored skin | 79.92 | 86.13 | 93.81 | 96.4 | 98.47 | 0.1251A |
| White skin | 72.7 | 74.44 | 78.16 | 82.85 | 85.31 | 0.1376A |
| Ascorbic acid | 91.3 | 92.43 | 97.41 | 98.56 | 99.67 | 0.1095A |
aSame letters show non-significant difference at P < 0.05.
4.4. Identification of Phytochemical Compounds
| Organ | C. grandis | ||
|---|---|---|---|
| Alkaloid | Saponin | Tannin | |
| Colored skin | + | - | - |
| White skin | + | + | - |
Abbreviations: +, presence; -, absence.
