Encapsulation of wild oregano, Plectranthus amboinicus (Lour.) Spreng, phenolic extract in baker's yeast for the postharvest control of anthracnose in papaya.

BACKGROUND: Anthracnose caused by Colletotrichum gloeosporioides is considered as a major postharvest disease affecting many fruits. This plant disease is traditionally managed with synthetic fungicides, which are generally toxic and are linked to pathogen resistance. Recently, microencapsulated bioactives have been developed as potential alternative strategies to these methods, while utilizing natural fungicides and other phytochemicals. Wild oregano, Plectranthus amboinicus (Lour.) Spreng, contains potent antimicrobial phenolics, but these compounds are volatile and relatively unstable, which limits their efficacy during application. Herein, a baker's yeast microencapsulation system was applied to improve the stability of wild oregano phenolic extract (WOPE) and enhance its antifungal activity against anthracnose. RESULTS: Encapsulation of WOPE in plasmolyzed yeast cells afforded a high encapsulation efficiency (93%) and yielded WOPE-loaded yeast microcapsules (WLYMs) with an average diameter of 2.65 µm. Storage stability studies showed WLYMs are stable for at least 4 months. A 24 -h in vitro release experiment showed that WLYMs had an initial burst release upon redispersion in water, followed by a controlled release to about 80% of the loaded WOPE. Upon application as a spray-type postharvest treatment for papaya, WLYMs exhibited a significantly improved mycelial inhibitory action against C. gloeosporioides and greatly reduced the anthracnose symptoms in papaya fruits. CONCLUSION: This study presented a yeast microencapsulation system that can effectively stabilize WOPE and enhance its antifungal activity, making this microparticle formulation a promising environmentally safe postharvest treatment option to combat anthracnose symptoms in papaya fruits. © 2022 Society of Chemical Industry.

Enhanced bioactivity and efficient delivery of quercetin through nanoliposomal encapsulation using rice bran phospholipids.

BACKGROUND: Quercetin is a phenolic compound occurring in many food plants and agricultural crops. It is reported to possess various health-promoting properties. However, the poor bioavailability of quercetin, due to its low aqueous solubility and its degradation during digestion, limits its nutraceutical applications. This study aimed to encapsulate quercetin in nanoliposomes using rice-bran phospholipids for its efficient delivery and controlled release, the protection of its structural stability, and enhancement of its bioactivity. RESULTS: Nanoliposomal encapsulation of quercetin by thin film-sonication method yielded spherical nanoparticles (157.33 ± 23.78 nm) with high encapsulation efficiency (84.92 ± 0.78%). Storage stability studies showed that nanoliposomal quercetin was stable at 4 °C and 27 °C for 6 and 5 months, respectively, as indicated by unchanged antioxidant activity and quercetin retention. Nanoliposomal quercetin showed a slow, limited release pattern in simulated gastric fluid (SGF), and an initial burst release followed by a slow constant releasing pattern in simulated intestinal fluid (SIF). A 1004-fold increase in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity was observed in quercetin nanoliposomes (SC50 = 4.04 ± 0.01 ppm) compared to non-encapsulated quercetin (SC50 = 4053.03 ± 5.61 ppm). Similarly, the anti-angiogenic activity of quercetin, as evaluated by duck embryo chorioallantoic membrane (CAM) assay, was enhanced twofold to fivefold by nanoliposomal encapsulation. CONCLUSION: This study showed that nanoliposomal encapsulation in rice-bran phospholipids enhanced the radical-scavenging and anti-angiogenic activities of quercetin. Furthermore, this study demonstrated that nanoliposomes can serve as efficient oral delivery system for quercetin. © 2018 Society of Chemical Industry.