The crude extracts of the seed of
Garcinia kola
(GK) and its constituent biflavonoid, Kolaviron (KV), have been
shown to effectively protect the stomach of rats form ulceration induced by HCl/Ethanol mixture as well as indomethacin.
However, the anti-ulcerogenic mechanisms are yet to be fully elucidated. Since apoptosis has been identified as a potent factor
in ulcerogenesis, the study was designed to examine the anti-apoptotic effect of KV in intact and cultured gastric cells (RGM-
1) of rat. Confluent Rat Gastric Mucosal (RGM-1) cells were challenged with medium containing 500uM indomethacin in the
presence or absence of 0.5ug/ml and 5.0ug/ml KV. Cell viability was measured by the MTT [3-(4, 5– dimethylthiazol-2-yl]-
2,5-deiphenyltetrazolium bromide] assay. The effect of the treatments on the cell cycle phases was determined by flow
cytometry using a Beckman-Coulter FACScan. Apoptosis was measured as the proportion of cells in the sub G
0/G
1 phase of
the cell cycle. An assessment of the generation of reactive oxygen species (ROS) after treatments was also carried out.
Treatment of cells with indomethacin decreased cell viability and was accompanied by apoptotic DNA fragmentation.
Pretreatment of cells with KV significantly suppressed cell death caused by long-term indomethacin treatment. In addition,
indomethacin-induced RGM-1 cell apoptosis was evidenced by an increase in the proportion of cells in the sub-G
0/G
1 phase
from 6.93 ± 2.56% in the unexposed cells to 30.44 ± 2.56% in cells exposed to 500uM indomethacin (P < 0.001). Treatments
with 0.5ug/ml and 5.0ug/ml KV reversed the apoptotic effect of indomethacin. In vivo, pre-treatment of rat with KV
significantly reduced indomethacin-induced ulcer formation and total apoptotic score. These results imply that the inhibition of
apoptosis may be an important mechanism via which KV protects the stomach from ulcerogenesis.
