Screening of natural products for therapeutic activity against solid tumors.
Most of the currently used cancer therapeutics are natural products. These agents were generally discovered based on their toxicity to tumour cells using various bioassays. Although the exact mechanisms of action of the most commonly used cancer therapeutics such as anthracyclins, podophyllotoxins and camptothecin are incompletely understood, it is becoming increasingly clear that these agents often show complex modes of action at the cellular level, interacting with numerous targets. Such complex modes of action may be the very reason for clinical efficacy. For discovering new cytotoxic anticancer drugs sophisticated screening methods were used. The principles of such screening projects conducted, using collections of purified natural products or extracts from plants have been described. By performing simple but robust prescreening tests such as the brine shrimp assay, bioactive extracts can be identified. Extracts (65) prepared from a collection of Egyptian plants were identified that showed cytotoxity on HepG2 cells. Interestingly, 22 (33%) of these raw extracts, induced > 2-fold induction of caspase-cleavage activity in a colon carcinoma cell line, consistent with induction of apoptosis. Only a fraction of the diversity of the biosphere has been tested for biological activity and novel cancer therapeutics remains to be discovered.
Department of Pharmacognosy, Pharmaceutical Sciences Division, National Research Centre, Dokki, Giza 12622, Egypt.
Bassem S
BS
El-Menshawi
Walid
W
Fayad
Khaled
K
Mahmoud
Salwa M
SM
El-Hallouty
May
M
El-Manawaty
Maria Hägg
MH
Olofsson
Stig
S
Linder
D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001688:Biological Products / Q000302:isolation & purification / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation / Q000187:drug effects; D045325:HCT116 Cells; D056945:Hep G2 Cells; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D013045:Species Specificity
D000970:Antineoplastic Agents; D001688:Biological Products; D010936:Plant Extracts; D020169:Caspases