Guava (Psidium Guajava L.) Leaf Bioactives: From Phytochemical Characterization to Therapeutic and Technological Applications

Guava leaves (Psidium guajava L.) are rich in bioactive compounds such as flavonoids, phenolic acids, tannins, terpenes, alkaloids, essential oils, minerals, and vitamins, which contribute to their potent antioxidant, antimicrobial, anti-inflammatory, antidiabetic, anticancer, and hair growth–promoting effects. This review highlights the phytochemical variability, pharmacological properties, and the impact of genetic and environmental factors on their composition. Advanced analytical tools like HPLC, LC-MS, and NMR are used for precise identification and standardization of these bioactives. Modern extraction methods, including ultrasound-assisted and supercritical fluid extraction, enhance the effectiveness of obtaining these compounds. Guava leaves hold promise as a sustainable source of natural therapeutic agents for pharmaceutical, nutraceutical, and cosmeceutical applications.