Nanoencapsulation of a combined extract from Kleinhovia hospita L. and Eleutherine bulbosa (Mill.) Urb.: Antioxidant, antimicrobial activity, and phytochemical characterization
Abstract
The global restriction of antibiotic growth promoters (AGPs) in poultry production necessitates efficacious plant-based alternatives. This study developed and characterized a nanoencapsulated co-extract of Tahongai leaves (Kleinhovia hospita L.) and Tiwai onions (Eleutherine bulbosa (Mill.) Urb.) using maltodextrin–xanthan as wall materials and freeze-drying as the drying step. Physicochemical characterization by FTIR showed bands attributable to O–H, aromatic C=C, C–N, and C–O/C–O–C vibrations, indicating retention of key functional groups and intermolecular interactions within the polymeric matrix. Scanning electron microscopy imaging revealed irregular, porous particles typical of lyophilized systems, consistent with effective size reduction and high surface area. Functionally, the nanoencapsulated formulation exhibited strong antioxidant activity with a 2,2-diphenyl-1-picrylhydrazyl IC₅₀ of 62.22 μg/mL. Phytochemical screening confirmed the presence of alkaloids, phenolics, flavonoids, tannins, saponins, and terpenoids/steroids, and quantitative colorimetry (Folin–Ciocalteu, AlCl₃, and vanillin–HCl) verified phenolic, flavonoid, and tannin content. Antimicrobial testing against Escherichia coli and Salmonella typhimurium showed a dose-dependent response. At 6–8%, the formulation produced larger inhibition zones against Escherichia coli (4.22–4.37 mm) than the zinc bacitracin positive control, while activity against Salmonella typhimurium increased with dose but remained below the positive control. These data indicate that nanoencapsulation preserved bioactive functionality and yielded a formulation with relevant antioxidant and selective antibacterial properties. The nanoencapsulated Tahongai–Tiwai co-extract, therefore, represents a promising natural candidate to support gut health and microbial control in poultry, warranting further in vivo validation and process optimization to enhance oxidative stability and gastrointestinal delivery.