Ursane-type triterpenoids, such as ursolic acid and corosolic acid, are naturally occurring compounds found in various medicinal plants. There is emerging scientific interest in their potential role in supporting or treating diabetic retinopathy, primarily based on preclinical studies. Diabetic retinopathy is characterized by retinal inflammation, oxidative stress, and vascular dysfunction due to chronic hyperglycemia. Ursane-type triterpenoids have demonstrated antioxidant, anti-inflammatory, and anti-angiogenic properties in cellular and animal models relevant to diabetic retinopathy.

For example, ursolic acid has been shown to inhibit retinal vascular leakage and reduce the expression of inflammatory cytokines in diabetic animal models (PMID: 29444073). Corosolic acid has also been reported to suppress hyperglycemia-induced oxidative stress and apoptosis in retinal cells. These effects are thought to be mediated, in part, through modulation of the NF-κB and VEGF signaling pathways, both of which are implicated in diabetic retinopathy progression.

However, despite these promising findings in vitro and in vivo, clinical evidence in humans is lacking. There are no published randomized controlled trials that directly evaluate the efficacy of ursane-type triterpenoids for diabetic retinopathy in patients. Thus, while the scientific basis is plausible and supported by mechanistic and preclinical research, the overall evidence remains preliminary (rated 2/5).