## 3 Results
### Zinc Nanoparticles  
Four in vitro assays were studied on colon tumor cells. In two of them, the action of the extract alone was examined in comparison with NPs loaded with the extract [36; 38], while in the other two, unloaded NPs were compared with NPs encapsulating the extract [37; 39]. Overall, the results shown in Table 1 indicate that encapsulation of these extracts in nanoformulations is able to improve the therapeutic efficacy of the extracts alone. Among these studies, [PERSON] et al. (2022) obtained three extracts from _Croton tiglium_ seeds: one ethanolic extract, one aqueous extract and one petroleum ether extract. Once obtained, a comparative study was carried out between these three extracts in isolation to compare them after being bound to zinc NPs. Based on the IC\({}_{50}\) values obtained for the isolated extracts, the best results were obtained for the aqueous one, with a concentration of 176.90 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, followed by ethanol (309.70 \(\mathrm{\SIUnitSymbolMicro g}\)/mL) and petroleum ether (692.10 \(\mathrm{\SIUnitSymbolMicro g}\)/mL). Next, analyzing the values for the binding of the extracts and nanoparticles, the data yielded results in a similar order, but with a higher efficiency, being 100.20 \(\mathrm{\SIUnitSymbolMicro g}\)/mL for ZnO-aqueous extract, 252.50 \(\mathrm{\SIUnitSymbolMicro g}\)/mL for ZnO-ethanol extract and, finally, 353.30 \(\mathrm{\SIUnitSymbolMicro g}\)/mL for ZnO-petroleum ether extract. Thus, we can observe the superiority in terms of antitumor activity that the nano-extracts offer, compared to the isolated extracts, with the aqueous extract being the best. This increased cytotoxic effect is due to the rupture of the nanoformulations, generating Zn\({}^{+2}\) ions which are released, thereby inducing ROS production and cell apoptosis [36]. [PERSON] et al. (2020) generated an aqueous extract of _Devera tortuosa_ leaves and compared the isolated extract with the extract encapsulated in zinc NPs and a chemotherapy traditionally used in CRC, Doxorubicin. The highest antitumor activity was obtained with the extract-bound NPs, with an IC\({}_{50}\) value of 50.81 \(\mathrm{\SIUnitSymbolMicro g}\)/mL. Meanwhile, the isolated aqueous extract yielded a value of 136.12 \(\mathrm{\SIUnitSymbolMicro g}\)/mL, with the IC\({}_{50}\) of Doxorubicin being higher than both (145.26 \(\mathrm{\SIUnitSymbolMicro g}\)/mL) [38].  
[PERSON] et al. (2021) created an aqueous extract of _Spondius pimata_ leaves and this was encapsulated in Zinc nanoparticles. After their test on the CRC cell line HCT-116, the results showed that after 72 h, the IC\({}_{50}\) obtained was 53 \(\mathrm{\SIUnitSymbolMicro g}\)/mL for the nanoformulations, while the extract alone did not exert any toxic effect. This encapsulation of the extract by NPs led to a decrease in the clonogenic and migration capacity of the CRC cell line. In addition, the treatment induced intracellular calcium release, thereby inducing damage through oxidative stress, genotoxicity and induction of apoptosis, as demonstrated by the RT-qPCR results through an overexpression of genes such as _PARP_ and caspases 3, 8 and 9 [37]. Finally, [PERSON] et al. (2019) obtained an aqueous extract from sourosp fruit. Subsequently, they performed nanoc encapsulation of this extract in Zinc nanoparticles and compared its activity against uncharged nanoparticles. Despite the interesting results of the previously mentioned formulations, in this case, these nanoparticles did not show a great cytotoxic effect, having a very similar IC\({}_{50}\) without the extract and with its encapsulation (60 \(\mathrm{\SIUnitSymbolMicro g}\)/mL) [39].