Trichosanthis Semen Exerts Neuroprotective Effects in Alzheimer's Disease Models by Inhibiting Amyloid-β Accumulation and Regulating the Akt and ERK Signaling Pathways

Background

Alzheimer's disease (AD), the most common form of dementia, is characterized by memory loss and the abnormal accumulation of senile plaques composed of amyloid-β (Aβ) protein. Trichosanthis Semen (TS) is a traditional herbal medicine used to treat phlegm-related conditions. While TS is recognized for various bioactivities, including anti-neuroinflammatory effects, its ability to attenuate AD remains unknown.

Objective

To evaluate the effects of TS extract (TSE) on neuronal damage, Aβ accumulation, and neuroinflammation in AD models.

Methods

Thioflavin T and western blot assays were used to assess effects on Aβ aggregation in vitro. TS was treated to PC12 cells with Aβ to assess the neuroprotective effects. Memory functions and histological brain features were investigated in TSE-treated 5×FAD transgenic mice and mice with intracerebroventricularly injected Aβ.

Results

TSE disrupted Aβ aggregation and increased the viability of cells and phosphorylation of both protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) in vitro. TSE treatment also suppressed the accumulation of Aβ plaques in the brain of 5×FAD mice, protected neuronal cells in both the subiculum and medial septum, and upregulated Akt/ERK phosphorylation in the hippocampus. Moreover, TSE ameliorated the memory decline and glial overactivation observed in 5×FAD mice. As assessing whether TS affect Aβ-induced neurotoxicity in the Aβ-injected mice, the effects of TS on memory improvement and neuroinflammatory inhibition were confirmed.

Conclusions

TSE disrupted Aβ aggregation, protected neurons against Aβ-induced toxicity, and suppressed neuroinflammation, suggesting that it can suppress the development of AD.

Anti-tumor effects of the ethanolic extract of Trichosanthes kirilowii seeds in colorectal cancer

Background

Trichosanthis semen, the seeds of Trichosanthes kirilowii Maxim. or Trichosanthes rosthornii Harms, has long been used in Korean medicine to loosen bowels and relieve chronic constipation. Although the fruits and radixes of this medicinal herb and their constituents have been reported to exhibit therapeutic effects in various cancers, the anti-cancer effects of its seeds have been relatively less studied. In this study, we investigated the effects of an ethanolic extract of T. kirilowii seeds (TKSE) against colorectal cancer and its mechanism.

Methods

The anti-tumor effects of the TKSE were evaluated in HT-29 and CT-26 colorectal cancer cells and in a CT-26 tumor-bearing mouse model.

Results

TKSE suppressed the growth of HT-29 and CT-26 cells (both colorectal cancer cell lines) and the cytotoxic effect of TKSE was greater than that of 5-fluorouracil (5-Fu) in HT-29 cells. TKSE significantly induced mitochondrial membrane potential loss in HT-29 and CT-26 cells and dose-dependently inhibited Bcl-2 expression and induced the cleavages of caspase-3 and PARP. In particular, TKSE at 300 µg/mL induced nuclear condensation and fragmentation in HT-29 cells. Furthermore, TKSE dose-dependently inhibited activations of the Akt/mTOR and ERK pathways, and markedly induced the phosphorylation of AMPK. An AMPKα inhibitor (compound C) effectively blocked the TKSE-induced mitochondrial dysfunction. In addition, TKSE attenuated the hypoxia-inducible factor-1α/vascular endothelial growth factor signaling pathway in HT-29 cells under hypoxic-mimic conditions and inhibited migration and invasion. Oral administration of TKSE (100 or 300 mg/kg) inhibited tumor growth in a mouse CT-26 allograft model but was not as effective as 5-Fu (the positive control), which was administered intraperitoneally. In the same model, 5-Fu caused significant body weight loss, but no such loss was observed in TKSE-treated mice.

Conclusion

Taken together, these results suggest TKSE has potent anti-tumor effects which might be partly due to the activation of AMPK, and the induction mitochondrial-mediated apoptosis in colorectal cancer cells. These findings provide scientific evidence supporting the potential use of TKSE as a complementary and alternative medicine for the treatment of colorectal cancer.