Synthesis Of Silver Nanoparticles and Screening Antioxidant and Anticancer Activity of Philippine Mahogany

Cancer is one of the leading causes of mortality worldwide and remains a major public health challenge [1]. Oxidative stress caused by excessive free radical generation contributes significantly to carcinogenesis and disease progression [2]. Antioxidants can neutralize reactive oxygen species and reduce oxidative cellular damage [3].

Nanotechnology has attracted significant attention in biomedical research due to the unique physicochemical properties of nanoparticles [4]. Silver nanoparticles (AgNPs) possess remarkable antimicrobial, antioxidant, anti-inflammatory, and anticancer activities [5]. Green synthesis of nanoparticles using plant extracts offers advantages such as eco-friendliness, low toxicity, simplicity, and biocompatibility [6].

Philippine Mahogany (Swietenia macrophylla), belonging to the family Meliaceae, is traditionally used for various medicinal purposes [7]. The plant contains biologically active phytochemicals including flavonoids, alkaloids, tannins, terpenoids, and phenolic compounds which may contribute to therapeutic activity [8].

The present investigation focused on the green synthesis of silver nanoparticles using Swietenia macrophylla leaf extract and evaluation of their antioxidant and anticancer potential.

2. MATERIALS AND METHODS

2.1 Materials

Silver nitrate (AgNO3), DPPH, ABTS, MTT reagent, and analytical grade solvents were procured from certified suppliers. Human cancer cell lines MCF-7 and HeLa were obtained from a recognized cell repository.

2.2 Collection and Preparation of Plant Extract

Fresh leaves of Swietenia macrophylla were collected, washed thoroughly with distilled water, shade dried, and powdered.

Preparation of Aqueous Extract

Twenty grams of powdered leaves were boiled in 100 mL distilled water for 20 min and filtered using Whatman No.1 filter paper. The filtrate was stored at 4°C for further use.

2.3 Phytochemical Screening

Preliminary phytochemical analysis was performed to identify flavonoids, alkaloids, tannins, phenolics, saponins, glycosides, and terpenoids using standard procedures [9].

2.4 Synthesis of Silver Nanoparticles

Silver nanoparticles were synthesized using green synthesis method [10].

Procedure

Ten milliliters of plant extract was added to 90 mL of 1 mM silver nitrate solution under continuous stirring at room temperature. Formation of dark brown color indicated synthesis of silver nanoparticles.

The reaction mixture was incubated for 24 h and centrifuged at 12,000 rpm for 20 min. The obtained nanoparticles were washed and dried.

Reaction Equation

Ag++Plant phytochemicals→AgNPsAg^+ + Plant\ phytochemicals \rightarrow AgNPsAg++Plant phytochemicals→AgNPs

2.5 Characterization of Silver Nanoparticles

2.5.1 UV–Visible Spectroscopy

Formation of AgNPs was confirmed by measuring absorbance between 300–700 nm.

2.5.2 Fourier Transform Infrared Spectroscopy (FTIR)

FTIR analysis was performed to identify functional groups involved in reduction and stabilization of nanoparticles.

2.5.3 X-ray Diffraction (XRD)

XRD analysis was carried out to determine crystalline nature of AgNPs.

2.5.4 Scanning Electron Microscopy (SEM)

SEM analysis was used to examine morphology and surface characteristics.

2.5.5 Transmission Electron Microscopy (TEM)

TEM was used to determine nanoparticle size and shape.

2.5.6 Zeta Potential Analysis

Zeta potential was measured to determine stability of nanoparticles.

2.6 Antioxidant Activity

2.6.1 DPPH Radical Scavenging Assay

DPPH assay was performed at different concentrations of AgNPs [11].

Percentage Inhibition Formula

Inhibition (%)=A0−A1A0×100Inhibition\ (\%) = \frac{A_0 - A_1}{A_0} \times 100Inhibition (%)=A0?A0?−A1??×100

Where:

• A0A_0A0? = Control absorbance
• A1A_1A1? = Sample absorbance

2.6.2 ABTS Radical Scavenging Assay

ABTS assay was performed to evaluate antioxidant potential of synthesized nanoparticles.

2.7 Anticancer Activity

2.7.1 Cell Culture

MCF-7 and HeLa cancer cell lines were cultured in DMEM supplemented with fetal bovine serum and antibiotics.

2.7.2 MTT Cytotoxicity Assay

Cytotoxicity of AgNPs was evaluated using MTT assay [12].

Cell Viability Formula

Cell Viability (%)=Absorbance of treated cellsAbsorbance of control cells×100Cell\ Viability\ (\%) = \frac{Absorbance\ of\ treated\ cells}{Absorbance\ of\ control\ cells} \times 100Cell Viability (%)=Absorbance of control cellsAbsorbance of treated cells?×100

2.8 Apoptosis Assay

Apoptotic activity was assessed using Annexin V-FITC staining and flow cytometry.

2.9 Statistical Analysis

All experiments were conducted in triplicate. Data were expressed as mean ± standard deviation. Statistical analysis was performed using one-way ANOVA followed by Tukey’s test. Values of p < 0.05 were considered statistically significant.

3. RESULTS

3.1 Phytochemical Screening

Preliminary phytochemical analysis confirmed the presence of major bioactive compounds.

3.2 Visual Observation and UV–Visible Analysis

Formation of dark brown color confirmed synthesis of silver nanoparticles.

UV–Visible spectroscopy showed a characteristic surface plasmon resonance peak at 432 nm indicating formation of AgNPs.

3.3 FTIR Analysis

FTIR spectra confirmed involvement of phytochemicals in nanoparticle stabilization.

3.4 XRD Analysis

XRD patterns demonstrated crystalline nature of silver nanoparticles with characteristic peaks corresponding to face-centered cubic silver.

3.5 SEM and TEM Analysis

SEM and TEM images revealed spherical nanoparticles with uniform distribution.

The negative zeta potential indicated good nanoparticle stability.

3.6 DPPH Antioxidant Activity

The antioxidant activity increased with concentration.

3.7 ABTS Antioxidant Activity

The nanoparticles exhibited strong ABTS radical scavenging activity.

3.8 Anticancer Activity

MCF-7 Breast Cancer Cell Line

HeLa Cervical Cancer Cell Line

The synthesized AgNPs demonstrated dose-dependent cytotoxicity against cancer cells.

3.9 Apoptosis Assay

Flow cytometry analysis indicated significant apoptosis induction in nanoparticle-treated cancer cells.