1. Background & Objective
Peperomia pellucida (L.) Kunth, commonly known as "shiny bush" or "rau càng cua" in Vietnam, is a widely distributed annual herbaceous plant with significant use in traditional medicine. It is known for its therapeutic potential due to its richness in alkaloids, flavonoids, phenolic compounds, and other bioactive constituents. This study aimed to evaluate the chemical composition and biological activities (including antioxidant, antibacterial, antifungal, anti-inflammatory, and antidiabetic effects) of different solvent-extracted fractions from P. pellucida collected in Can Tho City, Vietnam.
2. Materials and Methods
Four fractions were obtained from the ethanol extract of P. pellucida using solvents with increasing polarity: hexane, dichloromethane, ethyl acetate, and aqueous (water). Each fraction was analyzed for its total content of phenolics, flavonoids, and alkaloids, and was subjected to a series of bioactivity assays, including:
- Antioxidant assays: DPPH, ABTS, iron-reducing power, and total antioxidant capacity (TAC)
- Antibacterial assays: MIC and MBC against 5 bacterial strains
- Antifungal activity: Inhibition of Candida albicans
- Anti-inflammatory activity: Protein denaturation inhibition (using BSA)
- Antidiabetic activity: Inhibition of α-amylase and α-glucosidase enzymes
3. Chemical Composition Results
| Compound Type | Hexane | Dichloromethane | Ethyl Acetate | Aqueous |
|---|---|---|---|---|
| Phenolics | 112 ± 3.34 mg GAE/g | 141 ± 1.77 mg GAE/g | 234 ± 2.95 mg GAE/g | 123 ± 5.04 mg GAE/g |
| Flavonoids | 423 ± 22.6 mg QE/g | 169 ± 6.30 mg QE/g | 1839 ± 18.8 mg QE/g | 173 ± 22.6 mg QE/g |
| Alkaloids | 219 ± 6.55 mg AE/g | 221 ± 6.23 mg AE/g | 157 ± 14.0 mg AE/g | 255 ± 23.8 mg AE/g |
The ethyl acetate fraction was particularly rich in phenolics and flavonoids, while the aqueous fraction contained the highest alkaloid content.
4. Antioxidant Activity
Ethyl acetate showed the strongest antioxidant performance across all four assays:
| Assay | Hexane | DCM | Ethyl Acetate | Aqueous | Standard (Gallic acid) |
|---|---|---|---|---|---|
| DPPH | 2319 µg/mL | 1525 µg/mL | 334 µg/mL | 1806 µg/mL | 3.6 µg/mL |
| ABTS | 297 µg/mL | 213 µg/mL | 51.4 µg/mL | 348 µg/mL | 0.47 µg/mL |
| Fe-Reducing | 264 µg/mL | 140 µg/mL | 79.1 µg/mL | 429 µg/mL | 10.44 µg/mL |
| TAC | 97.6 µg/mL | 114 µg/mL | 83.0 µg/mL | 175 µg/mL | 19.20 µg/mL |
These results correlated with the high flavonoid and phenolic content in the ethyl acetate extract.
5. Antibacterial Activity
Five pathogenic bacterial strains were tested:
Bacillus cereus, Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa.
| Bacteria | Best MIC (Fraction) | MIC Range (mg/mL) |
|---|---|---|
| B. cereus | Dichloromethane | 0.5 – 1 |
| E. coli | Dichloromethane | 0.5 – 1 |
| S. aureus | DCM & EA | 4 – 8 |
| S. typhimurium | Hexane & DCM | 4 – 8 |
| P. aeruginosa | Dichloromethane | 2 – 4 |
The dichloromethane fraction showed the best MIC and MBC results across most strains. Ethyl acetate also showed good inhibition. Hexane showed minimal antibacterial activity.
6. Antifungal Activity
Tested on Candida albicans using agar well diffusion:
- All fractions showed antifungal activity.
- Ethyl acetate had the largest inhibition zone (up to 5.33 mm) at 100 mg/mL.
- Hexane showed the weakest effect.
7. Anti-inflammatory Activity
Tested using the albumin denaturation method (BSA) with Diclofenac as reference:
| Fraction | IC50 (µg/mL) |
|---|---|
| Hexane | 2788.6 ± 53.4 |
| Dichloromethane | 452.8 ± 9.8 |
| Ethyl Acetate | 216.7 ± 7.2 |
| Aqueous | 8389.7 ± 75.1 |
| Diclofenac | 205.4 ± 0.5 |
Ethyl acetate had anti-inflammatory activity close to Diclofenac, indicating strong therapeutic potential.
8. Antidiabetic Activity
The inhibition of α-amylase and α-glucosidase was evaluated, comparing to acarbose as the standard:
| Fraction | α-Amylase IC50 | α-Glucosidase IC50 |
|---|---|---|
| Hexane | 208.83 µg/mL | 1218.40 µg/mL |
| Dichloromethane | 191.60 µg/mL | 312.14 µg/mL |
| Ethyl Acetate | 951.84 µg/mL | 157.04 µg/mL |
| Aqueous | 758.76 µg/mL | 399.18 µg/mL |
| Acarbose | 155.68 µg/mL | 116.45 µg/mL |
- Ethyl acetate: Best α-glucosidase inhibitor.
- Dichloromethane & Hexane: Best α-amylase inhibitors.
- Aqueous was moderate; all showed dose-dependent inhibition.
9. Conclusion
This comprehensive study demonstrates that Peperomia pellucida contains diverse bioactive compounds that vary depending on the extraction solvent:
- The ethyl acetate fraction is the most promising, showing high antioxidant, antifungal, anti-inflammatory, and α-glucosidase inhibitory activities.
- The dichloromethane fraction is notably effective against bacteria and α-amylase.
- These findings support the ethnomedicinal use of P. pellucida and highlight its potential for development into natural pharmaceuticals or functional food ingredients.
Ngày đăng: 18-08-2025
Tác giả: NGUYỄN THỊ BÍCH NHƯ
