Antimicrobial Prospects of Domesticated Ornamental Leaf Extracts Against Skin Pathogens

The increasing popularity of natural plant-based treatments offers an alternative to conventional therapies for various cutaneous infections due to their potential efficacy and lower side effects. Thus, the present study aimed to investigate the antimicrobial and cytotoxic properties of leaf extracts from five selected domesticated ornamental plants against pathogens implicated in acne vulgaris and dermatophytosis. The selected plant leaves were successively macerated with solvents of increasing polarity and the extracts were underwent qualitative phytochemical analysis. The antimicrobial activities were evaluated using the broth microdilution method. Extracts with high antimicrobial activity (MIC≤128µg/mL) were subsequently tested for cytotoxicity on BJ fibroblast cells, and the selectivity index (SI) was calculated. Extraction yields were highest in Bougainvilea glabra (72.04%) and lowest in Plumeria obtusa (21.6%). Phytochemical screening revealed the presence of alkaloids, flavonoids, terpenoids, tannins, phenols, quinolones, saponins, and coumarins, with phenols found in all extracts. The aqueous extract of Alamanda cathartica (AC-Aq) and the methanol extract of Ixora coccinea (IC-Met) showed the most potent antibacterial activities against P. acnes and S. epidermidis, with MIC values of 128μg/mL and 64μg/mL, respectively. Antifungal activity was most pronounced in AC-Aq against T. mentagrophytes and T. rubrum, with MIC values of 32μg/mL. The six active extracts revealed varying degrees of toxicity, with the aqueous extract of P. obtusa (PO-Aq) exhibited the least cytotoxicity (CC50: 713.31±3.71 μg/mL), while IC-Aq was the most cytotoxic (CC50: 116.72±2.28 μg/mL). AC-Aq demonstrated the highest SI values, indicating effective antimicrobial activity at non-toxic concentrations.