**2. Methodology**

To be able to determine the cytotoxic activity of the extracts, the growth of tumoral cells quantitated by the ability of living cells to reduce the yellow dye 3-(4,5-dimethyl-2-thiazolyl)-2,5- diphenyl-2H-tetrazolium bromide (MTT) to a purple formazan product was used. The cells were seeded and incubated in a 37°C incubator supplemented with 5% CO2. The products to be evaluated were added to the culture of the cells at different concentrations once the cells reach 80% confluence. At the end of the 24 h of incubation of the previously treated cells, 40 μL/well of the MTT solution (5 mg/mL in phosphate-buffered saline) were added, the plates were incubated for 3 h under 5% CO2 and 95% air at 37°C. At the end of the 3 h of incubation, 400 μL/well of the solubilizing solution is added and gently shaken. The microplate is kept at room temperature in darkness for 24 h. The absorbance was then determined by a microplate reader at 490 nm. The percentage of growth inhibition was calculated using the following formula:

$$\text{\textquotedblleft cell viability} = \left[ \frac{\mathbf{A}\_{\text{t}} - \mathbf{A}\_{\text{b}}}{\mathbf{A}\_{\text{c}} - \mathbf{A}\_{\text{b}}} \right] \times \mathbf{100} \tag{1}$$

where, At = absorbance value of test compound, Ab = absorbance value of blank, and Ac = absorbance value of control. The effects of extracts were expressed by LC50 values (the drug concentration necessary to reduce cell viability to 50% with respect to untreated cells) [16].

## **3. Results**

The results obtained in this study showed that the medium polarity extract of aerial parts of the plant of the *Buddleja* genus showed cytotoxic activity against a prostate cancer cell line, while the polar extract of aerial parts has no cytotoxic activity against a prostate cancer cell line. More studies are needed on the extract that showed activity, it is necessary to do a chromatographic separation followed by isolation of the compounds that give the desired cytotoxic activity.

### **4. Conclusions**

Overall, this study evaluates that the medium polarity extract of aerial parts of the plant showed cytotoxic activity against a prostate cancer cell line, the next step is to determine which compounds are responsible for this biological activity and thus obtain potential drugs for the treatment of cancer. This study provides only basic data, further studies are necessary for isolation and identification of biologically active substances from these extracts, as well as to determine what type of death they cause through flow cytometry.

*DOI: http://dx.doi.org/10.5772/intechopen.99973 Evaluation of the Cytotoxic Activity of a Species of the Buddleja Genus in a Prostate Cancer Cell…*
