Extraction of Anthocyanins from Purple Sweet Potato: Evaluation of Anti-inflammatory Effects in a Rheumatoid Arthritis Animal Model, Mechanistic Studies on Inflammatory Cells, and Development of Exosome-Based Delivery for Enhanced Targeting

Jingjian Dong^1,2Yuntao Lv³Cailiang Zhao¹Yuanrui Shi³Ruiming Tang³Liheng He^1*Ruiwen Fan^4*Xiaoyun Jia^3*

• ¹College of Agriculture, Shanxi Agricultural University, Taigu, Shanxi, China
• ²College of Medicine, Jiaxing University, Jiaxing, China
• ³College of Life Science, Shanxi Agricultural University, Jinzhong, Shanxi Province, China
• ⁴College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong, Shanxi Province, China

Objective: Rheumatoid arthritis (RA) is a chronic autoimmune disease marked by inflammation and joint damage. Anthocyanins, such as those from purple sweet potato are known for their anti-inflammatory effects.Methods: This study evaluated purple sweet potato anthocyanins (PSPA) therapeutic potential in RA using Human RA cells (MH7A) and collagen-induced arthritis (CIA) rat models. Rats were divided into control, CIA model, and three PSPA treatment groups (10, 20, 40 mg/kg) for 14 days. Meanwhile, exosomes were extracted from MH7A cells and loaded with PSPA, then co-incubated with inflammatory cells to observe the targeting capability of the drug-loaded exosomes.Results: PSPA significantly reduced joint swelling and structural damage in CIA rats, with the highest dose (40 mg/kg) reducing tissue hyperplasia and inflammatory infiltration. PSPA also altered the gut microbiota, increasing beneficial bacteria like Akkermansia and Lactobacillus. Molecular analysis showed reduced serum levels of inflammatory cytokines TNF-α, IL-1β, and rheumatoid factor (RF). In MH7A cells, PSPA decreased inflammatory cytokines (IL-1α, IL-6, IL-18), inhibited cell proliferation (IC50 = 1.43 μg/mL), and induced apoptosis by modulating Bcl-2, Bax, Caspase-3, and Caspase-9. PSPA also restored the PI3K/AKT signaling pathway, reversing the suppression seen in CIA models, particularly at 40 mg/kg. Flow cytometry and microscopy confirmed dose-dependent apoptosis and cell cycle modulation. Meanwhile the PSPA-loaded exosomes demonstrated a high targeting capability toward inflammatory cells.Conclusion: These findings indicate that PSPA can alleviate RA symptoms by reducing inflammation, modulating gut microbiota, and promoting apoptosis in synovial fibroblasts, with exosome-encapsulated anthocyanins enhancing its targeting efficiency.