A natural cyanide generating system used by cassava plant against predators could be harnessed to provide treatment for cancer. It has been shown that cassava plant contains potentially toxic levels of a cyanogen called linamarin which could lead to the destruction of cancer cells. The in vitro cytotoxicity assays showed linamarin extracted from cassava plants inhibited the growth and killed various cancer cells such as – ovarian cancer, breast cancer and leukaemia.
Cancer ranks second only to cardiovascular disease as a cause of mortality, with an overall 5 year survival rate of less than 50%. Although advances have been made in the treatment ofsome cancer patents, yet there is no breakthrough in the chemotherapy, particularly in the discovery of penicillin and its revolutionary effect on antibacterial therapy. Most of chemotherapeutic drugs which are characterised by indiscriminate destruction of both normal and tumour cells can be severely toxic to patients and may lead to drug resistance. Therefore, search for better anticancer treatment continues.
Hence, there is a growing interest in finding new chemotherapeutic agents for cancer treatment. Part of this search is focused on plant-based compounds especially those glycosides showing active anti-cancer properties. The research undertaken investigates a potential of harnessing a natural cyanide generating system used by the cassava plant against predators as a viable alternative for cancer treatment.
Epidemiological studies have shown a link between low incidences of cancer in communities where cassava intake is the main staple diet in human beings. The prophylactic action of cassava intake and its deleterious effect on human beings are attributed mainly to the expressed toxicity of the aglycone moiety of the cyanogenic glucoside linamarin, when the latter breaks down. A preliminary investigation of three possible scenarios of in vitro exposure of ovarian cancer (Caov-3) and cervical adenocarcinoma (HeLa) derived cell lines to, a) a crude water extract of fresh cassava leaves, representing a dietary exposure to cyanogenic glucoside b) commercial linamarin and c) where a combination of commerciallinamarin and crude exogenous linamarase was conducted. The water extract was found to be more efficacious, eliciting an Ie", value of 38(±2.32) llg/ml and 57(±4.72l llg/ml respectively for the ovarian and cervical cell lines, while the commerciallinamarin exhibited a poor growth inhibition of 150(±7.56) and 21O(±11.35) llg/ml, respectively. The inclusion of linamarase enzyme to the linamarin mixture on one of the cell lines was also studied. The linamarase used was obtained from the same cassava plant and pre-treatedappropriately prior to its use.
Results showed a significant improvement in the growth inhibition of cervical cell line to 40(±3.93) llg/ml when the linamarase is added to the linamarin mixture. These in vitro cytotoxicity assays on human cancer cells and the ability of tested compounds to inhibit the growth or kill these cells in culture are taken as indication of potential value as an anticancer agent in vivo. Development of effective drug carriers with least side effects especially for cancer treatment is considered to be as important as the discovery of new anti-cancer drugs. It would be ideal if the chemotherapeutic drugs could exert their actions only on cancerous cells and leave normal cells less affected or even untouched, and this is the expected advantage of the targeted delivery for anticancer drugs.
The administration of appropriate doses at proper intervals is a usual practice to ascertain that the drug concentration is always optimized between its effectiveness and tolerability the drug at modest concentration would have much better effects than a pulsed supply of the drug at a high concentration. Thus, it is of importance that the investigation on a carrier for linamarin is conducted in order to ensure that only the correct amount of linamarin is released in the human system that avoids any side effects. A biodegradable PLGA was chosen as the carrier due to their easy dissolution in the system without exerting any side effects to the body. The in vitro drug delivery findings showed a superior improvement in the controlled release and bioavailability of linamarin when encapsulated in PLGA microparticles