Synthesis and Characterization of Silver Nanoparticles from Rhizophora apiculata and Studies on Their Wound Healing, Antioxidant, Anti-Inflammatory, and Cytotoxic Activity

Silver nanoparticles (AgNPs) have recently gained interest in the medical field because of their biological features. The present study aimed at screening Rhizophora apiculata secondary metabolites, quantifying their flavonoids and total phenolics content, green synthesis and characterization of R. apiculata silver nanoparticles. In addition, an assessment of in vitro cytotoxic, antioxidant, anti-inflammatory and wound healing activity of R. apiculata and its synthesized AgNPs was carried out. The powdered plant material (leaves) was subjected to Soxhlet extraction to obtain R. apiculata aqueous extract. The R. apiculata extract was used as a reducing agent in synthesizing AgNPs from silver nitrate. The synthesized AgNPs were characterized by UV-Vis, SEM-EDX, XRD, FTIR, particle size analyzer and zeta potential. Further aqueous leaf extract of R. apiculata and AgNPs was subjected for in vitro antioxidant, anti-inflammatory, wound healing and cytotoxic activity against A375 (Skin cancer), A549 (Lung cancer), and KB-3-1 (Oral cancer) cell lines. All experiments were repeated three times (n = 3), and the results were given as the mean ± SEM. The flavonoids and total phenolics content in R. apiculata extract were 44.18 ± 0.086 mg/g of quercetin and 53.24 ± 0.028 mg/g of gallic acid, respectively. SEM analysis revealed R. apiculata AgNPs with diameters ranging from 35 to 100 nm. XRD confirmed that the synthesized silver nanoparticles were crystalline in nature. The cytotoxicity cell viability assay revealed that the AgNPs were less toxic (IC₅₀ 105.5 µg/mL) compared to the R. apiculata extract (IC₅₀ 47.47 µg/mL) against the non-cancerous fibroblast L929 cell line. Antioxidant, anti-inflammatory, and cytotoxicity tests revealed that AgNPs had significantly more activity than the plant extract. The AgNPs inhibited protein denaturation by a mean percentage of 71.65%, which was equivalent to the standard anti-inflammatory medication diclofenac (94.24%). The AgNPs showed considerable cytotoxic effect, and the percentage of cell viability against skin cancer, lung cancer, and oral cancer cell lines was 31.84%, 56.09% and 22.59%, respectively. R. apiculata AgNPs demonstrated stronger cell migration and percentage of wound closure (82.79%) compared to the plant extract (75.23%). The overall results revealed that R. apiculata AgNPs exhibited potential antioxidant, anti-inflammatory, wound healing, and cytotoxic properties. In future, R. apiculata should be further explored to unmask its therapeutic potential and the mechanistic pathways of AgNPs should be studied in detail in in vivo animal models.