**6. Gypenosides**

The gypenosides (**Figure 7**) were isolated from *Gynostemma pentaphyllum* and from the aerial parts of *G. pentaphyllum*.

 Gypenoside L (**43′**) and gynogenin (**44′**), 20(*S*)-dammar-24-en-2a,3b,12b,20 tetrol, were isolated from *G. pentaphyllum* and tested against A-549 lung carcinoma cells. The IC50 values were 34.94 and 12.54 μg/mL, respectively [36]. Some gypenosides were isolated from the aerial parts of *C. pentaphyllum* (**45′–51′**), and their structures were elucidated with spectroscopic and chemical methods. Their cytotoxic activity was determined against different human cancer cell lines, A549, HT-29, MCF-7, and SK-OV-3. All the compounds showed low activity, with IC50 values between 62.8 and 19.6 μM [37].

**Figure 7.**  *Gypenosides structure.* 

#### **7. Other substances of interest**

In addition to the cucurbitacins, other substances isolated from the Cucurbitaceae family have been identified, including proteins isolated from the sarcocarp of *Cucurbita moschata* (pumpkin) and from the root of *T. kirilowii* Maxim *Cytotoxic and Antitumoral Activities of Compounds Isolated from Cucurbitaceae Plants DOI: http://dx.doi.org/10.5772/intechopen.82213* 

**Figure 8.**  *Overall structure of cucurmosin in stereo view.* 

(Cucurbitaceae). Additionally, the protein from the root of *T. kirilowii* Maxim has been demonstrated to possess important cytotoxicity activity.

#### **7.1 Cucurmosin**

 A novel type-1 ribosome-inactivating protein (RIP) designated cucurmosin was isolated from the sarcocarp of *Cucurbita moschata* (pumpkin). Its structure contains two domains: a large N-terminal domain composed of seven α-helices and eight β-strands and a smaller C-terminal domain consisting of three α-helices and two β-strands (**Figure 8**).

Cucurmosin was tested for its cytotoxicity against human leukemia cells (K562), murine melanoma cells (B16), lung adenocarcinoma cancer cells (A549), and peripheral blood lymphocytes using the standard MTT assay. The IC50 values of cucurmosin were 88.1, 63.4, and 359.3 nM in human leukemia cells (K562), murine melanoma cells (B16), and lung adenocarcinoma cancer cells (A549), respectively, while its IC50 in normal cells (peripheral blood lymphocytes) was higher than 1.4 μM [38].

#### **7.2 Trichosanthin**

Trichosanthin was isolated from the roots of *T. kirilowii* Maxim and has been used in traditional Chinese medicine. This compound was tested against HepG-2 and WRL 68 cells, and the IC50 values obtained were 10.38 and 15.45 μmol/L, respectively [39].

Tianhua, an extract of *T. kirilowii*, was analyzed to determine its mechanism of action against lung cancer cells (A549) using the MTS assay. This compound induced apoptosis via an anti-telomerase effect but had no effect on stimulating peripheral lymphocytes to produce interferon (IFN)-γ; tianhua inhibited the metastatic ability of cells and inhibited the growth of cancer cells in vivo [40].

#### **8. Conclusion**

The aim of this review is to present 51 cucurbitacin compounds and two compounds with different structures isolated from Cucurbitaceae plants, their chemical structures, their biological activities, and the mechanisms by which these compounds reduce the proliferation of cancer cells.
