Chemical Composition and Neuroprotective Properties of Indonesian Stingless Bee (Geniotrigona thoracica) Propolis Extract in an In-Vivo Model of Intracerebral Hemorrhage (ICH)

Abstract

Stroke is the world’s second-leading cause of death. Current treatments for cerebral edema following intracerebral hemorrhage (ICH) mainly involve hyperosmolar fluids, but this approach is often inadequate. Propolis, known for its various beneficial properties, especially antioxidant and anti-inflammatory properties, could potentially act as an adjunctive therapy and help alleviate stroke-associated injuries. The chemical composition of Geniotrigona thoracica propolis extract was analyzed by GC-MS after derivatization for its total phenolic and total flavonoid content. The total phenolic content and total flavonoid content of the propolis extract were 1037.31 ± 24.10 μg GAE/mL and 374.02 ± 3.36 μg QE/mL, respectively. By GC-MS analysis, its major constituents were found to be triterpenoids (22.4% of TIC). Minor compounds, such as phenolic lipids (6.7% of TIC, GC-MS) and diterpenic acids (2.3% of TIC, GC-MS), were also found. Ninety-six Sprague Dawley rats were divided into six groups; namely, the control group, the ICH group, and four ICH groups that received the following therapies: mannitol, propolis extract (daily oral propolis administration after the ICH induction), propolis-M (propolis and mannitol), and propolis-B+A (daily oral propolis administration 7 days prior to and 72 h after the ICH induction). Neurocognitive functions of the rats were analyzed using the rotarod challenge and Morris water maze. In addition, the expression of NF-κB, SUR1-TRPM4, MMP-9, and Aquaporin-4 was analyzed using immunohistochemical methods. A TUNEL assay was used to assess the percentage of apoptotic cells. Mannitol significantly improved cognitive–motor functions in the ICH group, evidenced by improved rotarod and Morris water maze completion times, and lowered SUR-1 and Aquaporin-4 levels. It also significantly decreased cerebral edema by day 3. Similarly, propolis treatments (propolis-A and propolis-B+A) showed comparable improvements in these tests and reduced edema. Moreover, combining propolis with mannitol (propolis-M) further enhanced these effects, particularly in reducing edema and the Virchow-Robin space. These findings highlight the potential of propolis from the Indonesian stingless bee, Geniotrigona thoracica, from the Central Tapanuli region as a neuroprotective, adjunctive therapy.