Engineered Sporopollenin Exine Capsules for Colon-Targeted Delivery and Antioxidant Therapy of Pogostemon Oil in Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease associated with oxidative stress. Pogostemon oil (PO) exhibits potent antioxidant and anti-inflammatory activities but is limited by high volatility and poor gastrointestinal stability. In this study, sporopollenin exine capsules (SECs) were engineered as natural micro-carriers for PO, achieving efficient encapsulation (η > 69%) and a high adsorption capacity (27.64 g/g). A pH-sensitive calcium alginate shell was subsequently applied to construct colon-targeted microspheres (Ca-Alg@PO-SECs). The resulting system improved the thermal and photostability of PO. In vitro dissolution assays confirmed the system's pH-responsiveness, maintaining integrity under simulated gastric conditions while enabling localized release at intestinal pH. In a DSS-induced acute UC mouse model, Ca-Alg@PO-SECs effectively alleviated clinical symptoms, as evidenced by improved body weight, colon length, and disease activity index. At the inflammatory level, the formulation modulated key cytokines (IL-1β, IL-6, and IL-10). Overall, Ca-Alg@PO-SECs provides a biocompatible, colon-targeted delivery strategy that preserves the bioactivity of essential oils and offers a promising preclinical approach for localized UC therapy.