Background: Khella (Ammi visnaga Lam.) fruits (Apiaceae) are rich in furanochromones, mainly khellin and visnagin, and are thus incorporated in several pharmaceutical products used mainly for treatment of renal stones. Methods: The objective of this study was to compare the yield of khellin and visnagin obtained using different conventional solvents and supercritical fluid extraction (SCFE) with carbon dioxide (containing 5% methanol as co-solvent). Water, acetone and ethanol (30% and 95%) were selected as conventional solvents. Results: Highest extract yield was obtained from 30% ethanol (15.44%), while SCFE gave the lowest yield (4.50%). However, the percentage of furanochromones were highest in SCFE (30.1%), and lowest in boiling water extract (5.95%). HPLC analysis of conventional solvent extracts showed other coumarins that did not appear in supercritical fluid extraction chromatogram due to non-selectivity of solvent extraction. Ammi visnaga extracts as well as standard khellin and visnagin were tested for their cytotoxic activity using sulforhodamine B assay on breast cancer (MCF-7) and hepatocellular carcinoma (Hep G2) cell lines. Results revealed a strong cytotoxic activity (IC₅₀ < 20 µg/mL) for the SCFE and standard compounds (khellin and visnagin) (IC₅₀ ranging between 12.54 ± 0.57 and 17.53 ± 1.03 µg/mL). However, ethanol and acetone extracts had moderate cytotoxic activity (IC₅₀ 20–90 µg/mL) and aqueous extract had a weak activity (IC₅₀ > 90 µg/mL). Conclusions: Thus, supercritical fluid extraction is an efficient, relatively safe, and cheap technique that yielded a more selective purified extract with better cytotoxic activity.

Background/Objectives: This study aimed to develop botanical nanofibers loaded with Psidium guajava leaf extract to heal wounds effectively. Methods: A 2³ factorial design was conducted to study the impact of freeze-drying parameters—freezing time, vacuum, and lyophilization time—on the total phenolic and flavonoid content in the lyophilized extract. Then, a polyurethane-based nanofiber dressing loaded with Psidium guajava leaf extract was fabricated using a one-step electrospinning technique. The nanofiber was evaluated considering total polyphenol and flavonoid content, surface roughness, and morphological assessment by scanning electron microscopy. Finally, the nanofiber was evaluated using in vivo wound-healing studies, histopathological analyses, and assessments of tissue levels of tumor necrosis factor-alpha, interleukin-6, matrix metalloproteinase, and growth factors. Results: The optimal conditions for freeze-drying the aqueous extract of Psidium guajava leaves were a freezing time of 24 h, a vacuum adjusted to 0.02 bar, and a lyophilization time of 48 h. The total polyphenol and flavonoid content within the nanofiber was 96 ± 1.2% and 91.83 ± 2.4%, respectively. Incorporating lyophilized extract in the nanofiber led to a decreased roughness average and root mean square roughness of the nanofiber. The nanofiber was continuous and had a smooth, uniform surface. The in vivo wound-healing assay showed superior wound-healing compared to the commercial Panthenol cream. These results were confirmed with histopathological studies. Conclusions: The extraction technique and lyophilization parameters significantly affect the bioactive content of Psidium guajava leaf extract. The botanical-loaded nanofiber showed greater wound-healing potential than a commercial cream, confirming its potential in regenerative medicine and wound repair applications.