In the journal Nutrition and Cancer, an article on the “Action Mechanism and Signal Pathways of Psidium guajava L. Aqueous Extract in Killing Prostate Cancer LNCaP Cells” was published in 2010. The study comes out of Taiwan, a country which makes frequent use of guava leaves for a variety of ailements.
In the article, an ”aqueous extract of Psidium guajava L budding leaves (PE) has been shown to possess anti-prostate cancer activity in a cell line model” (260). The researchers reported that they were drawn to study guava leaves’ effect on prostate cancer cells after conducting a study which showed that guava leaves were “potent anti-glycative agents” (261); this action was ascribed to the unusual free radical scavenging and anti-oxidative capabilities of guava leaf polyphenols. The effects of glycation can result in the formation of irreversible advanced glycation end products (AGE’s), which are associated with many progressive diseases and can also trigger cancer formation. Since guava leaves showed strong anti-glycative properties, the scientists chose to study the leaves’ action against an abundant form of prostate cancer, LNCap: Lymph node-metastasis prostate cancer.
They performed tests both in vitro (petri dish) and in vivo (in mice). In vitro, they found that guava leaves were cytotoxic on the cancer cells, and that the leaves ”arrested cell cycle of LNCaP cells…[guava leaves] inhibited LNCaP cell growth and proliferation by preventing the cells from entering the S phase, and…TUNEL assay also confirmed the apoptic mechanism induced by [guava leaves]” (265).
In vivo, “although no significant difference in body weight was observed among the tumor-implanted [mice], the size of the tumors in the untreated mice was much larger when compared to tumor sizes in the guava leaf-treated mice at week 6 of the study.
“Conclusively,” the authors state, “[guava leaf] is a potent anticancer agent, acting through both cytotoxic and apoptotic action mechanisms; therfore, it [can feasably be used] as a potential adjuvant anti-prostate cancer therapy, in particular, for anti-androgen-responsive PCa” (268).
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