Natural Compounds Targeting Cancer Stem Cells: A Promising Resource for Chemotherapy.

BACKGROUND: Cancer Stem Cells (CSCs) are the subpopulation of cancer cells which are directly involved in drug resistance, metastases to distant organ and cancer recurrence. METHODS: A systematic literature search was conducted through various electronic databases including, Pubmed, Scopus, Google scholar using the keywords "cancer stem cells" and "natural compounds" in the present study. Articles published between 1999 and 2019 were reviewed. All the expositions concerning CSCs associated cancer pathogenesis and therapy resistance, as well as targeting these properties of CSCs by natural compounds were selected for the current study. RESULTS: Natural compounds have always been thought as a rich source of biologically active principles, which target aberrantly activated signaling pathways and other modalities of CSCs, while tethering painful side effects commonly involved in the first-line and second-line chemo-radiotherapies. In this review, we have described the key signaling pathways activated in CSCs to maintain their survival and highlighted how natural compounds interrupt these signaling pathways to minimize therapy resistance, pathogenesis and cancer recurrence properties of CSCs, thereby providing useful strategies to treat cancer or aid in cancer therapy improvement. Like normal stem cells, CSCs rely on different signaling pathways and other properties for their maintenance. Therefore, the success of cancer treatment depends on the development of proper anti-neoplastic drugs capable of intercepting those signaling pathways as well as other properties of CSCs in order to eradicate this evasive subpopulation of cancer cells. CONCLUSION: Compounds of natural origin might act as an outstanding source to design novel therapies against cancer stem cells.

A regulatory approach on low temperature induced enzymatic and anti oxidative status in leaf of Pui vegetable (Basella alba).

Basella alba is a soft green vegetable, survives in adverse environmental circumstances, for example, very cold temperature although the mechanism and the temperature sensitivity in this species are not clarified. Pot experiment for cultivation of B. alba was carried out to examine the effects of low temperature on the synthesis of two enzymes, polyphenol oxidase (PPO) and peroxidase (POD) in leaf of this plant. They were exposed to 8 °C for 24 h, 48 h and 72 h periods and the respective controls were kept in ambient room temperature for the above mentioned time. Low temperature causes the higher activity of PPO and the threshold level was found after 48 h period when compared to the respective controls. The activity was higher at 10 mM catechol, substrate for this enzyme, than 100 mM and 200 mM concentration, however, the three doses yielded the gradual increase in activity. Similar stimulatory effects on peroxidase (POD) activity in leaf were observed whenever the plants were exposed to cold for 24 h, 48 h and 72 h periods and maximal after 48 h period. Our findings demonstrate that the higher activity of these enzymes in leaf might be an index for the regulatory mechanism of the survival of these species in such adverse environment.