The increase in size and changes in shape of a developing organism depends on the increase in the number of cells that make up the individual. Increase in cell number occurs by a precise cellular reproductive mechanism called mitosis. Mitosis is the division of cells for growth and repair. Mitosis occurs at the fastest rate during periods of growth, such as when the organism is a single-celled zygote, an embryo and young. The rate of mitosis is affected by the location of the tissue the cell is in. Some areas of the body need to constantly create more cells, such as the dermis of the skin, as many cells of the epidermis layer are lost daily and must be replaced. Other examples of tissues with high mitotic rates include bone marrow, hair, and the tips of roots, stems and side branches in plants. The rate of mitosis is also high when the organism is in repair. This may be because of tissue damage, for example a cut or graze causes more skin cells to be needed than usual. The availability of nutrients essential to mitosis, such as phosphorous that is needed for DNA replication, also affects the rate of mitosis. Mutagens and carcinogens will also affect the process of mitosis. When growth is not properly regulated, anomalies and tumours may result. Tumours may vary widely in their growth rates. They may grow very rapidly or so slowly that the rate approaches that of normal cell division in adult tissues. Tumours are characterized not only by an increase in the rate of cell division but also by abnormal patterns of growth. The new cells formed in the tumour are not organized and incorporated into the structure of the organ and may form large nodules. These abnormal growths may present no medical problems (e.g., moles) or may cause disastrous effects, as is the case of the pressure on the brain caused by a tumorous mass of the meningeal covering of the brain.

Cancerous cells ignore or override some of the control measures of this type of cell division. Cancer and mitosis are closely related. Mitosis is the process by which cells reproduce, and without it cancerous cells wouldn't be able to form tumors and spread through the body. Cancer starts with normal cell changing into a cancerous cell, this may be due to the mutation in the cell’s DNA that affect its growth. Once a cell in the body has changed in this way it tends to multiply at a much more rapid rate than normal and the cancerous cells proliferate and pile up. In this project, efforts are made to find out the effect of aqueous extracts of Vinca rosea (Catharanthus roseus), Betel leaf (Piper betle), Papaya seed (Carica papaya), Mussanda (Mussaenda queensirkit), Rootex, turmeric powder (Curcuma longa), tobacco (Nicotina tabacum), and ajinomotto on the rate of cell division in terms of the mitotic index.

Catharanthus roseus, commonly known as the Madagascar periwinkle or rosy periwinkle. Tobacco is the product prepared from the leaves of the tobacco plant by curing.Papaya is the fruit of the plant Carica papaya whose seeds are used for the present study. Turmeric is most usually used as a condiment and is made by drying and grinding into powder the underground stem of the herbaceous plant of the ginger family. The betel (Piper betle) is the leaf of a vine belonging to the Piperaceae family, mostly consumed in Asia, and elsewhere in the world as betel quid or in pan, with or without tobacco. Mussaenda queensirkit, an ornamental plant grown in tropical countries is shown to exhibit cytotoxic property. Ajino motto, is the best-known taste enhancer, chemically Monosodium glutamate. Rootex is used as root booster. Its ingredients are Indole -3 Butyric acid and Humic acid. 

Concentrated aqueous extracts of leaves of vinca rosea, mussaenda and betle and papaya seed, tobacco, turmeric powder, ajinomotto and rootex were made in distilled water. Onion which was just sprouted by keeping in cotton soaked in distilled water, were placed in these test solutions for one day and served as the test. A group of sprouted onions which was retained in cotton soaked in distilled water worked as the control. Roots were typically ready after 36 hours. The root tips were cut from actively growing onion and kept in Carnoy solution for 30 minutes, washed with 70% alcohol, subjected to acid hydrolysis and smear was prepared according to the routine procedure. Microscopic examination was performed under high magnification using 40X objective to determine mitotic index. The mitotic index was calculated as:

Mitotic Index (%) = (Number of dividing cells ÷ Total counted cells) X100.

The difference of mitotic index of various parameters with the control was analysed statistically using Student’s t test.

Table 1 showing the mitotic index of the cells of onion root tip grown in control and various test solutions and t and p values by pooled variance t test for the difference between mitotic indices of onion root tip cells grown in control and various test solutions at 5% significance level.

Table 1: Mitotic Index of the Cells of Onion Root Tip

Figure 1 showing the mitotic index in the onion root tip cells exposed to control and various test solutions.

Figure 1: The Mitotic Index in the Onion Root Tip Cells Exposed to Control and Various Test Solutions

A major objective of this study was to evaluate the effect of aqueous extracts selected natural and synthetic products on the proliferation of cells. The result reflected that the extracts of Vinca rosea, Papaya seed and concentrated solution of Turmeric powder have an anti-proliferative action on cells. On the contrary, extracts of tobacco, Ajinomoto, Rootex, and betel leaf caused an elevation in mitotic index. Though Vidyalakshmi et al. [1] reported a significant antimitotic activity of Mussaenda leaf extract, our study could observe a very little difference in mitotic index when compared to the control value [1].

The oldest groups of the plant alkaloids that are used to treat cancer are the vinca alkaloids found out in 1958 by Canadian scientists, Robert Noble and colleagues [2]. The main mechanisms of vinca alkaloid cytotoxicity is due to their interactions with tubulin and disruption of microtubule function, particularly of microtubules comprising the mitotic spindle apparatus, directly causing metaphase arrest. Vinca alkaloids and other antimicrotubule agents also have an effect on both non-malignant and malignant cells in the non-mitotic cell cycle, because microtubules are involved in many non-mitotic functions. The vinca alkaloids and other microtubule disrupting agents have power to inhibit malignant angiogenesis in vitro. Vinca alkaloids inhibit cell proliferation by binding to microtubules, which can cause a mitotic block and apoptosis. VCR and related compounds produce destabilization of microtubules by binding to tubulin and blocking the polymerization [3]. Our study showed a low mean mitotic index and the difference from control is statistically significant at 0.05 level. t-value is 2.6330 and p’value is 0.0250.

Tobacco contains the alkaloid nicotine, a stimulant. Dried tobacco leaves are mainly used in cigarettes, cigars, pipe tobacco and flavored shisha tobacco. In 2008, WHO named tobacco as the world’s single greatest cause of preventable death. Mean mitotic index is higher than the control value and the variation is statistically significant at 0.05 level of significance t-value is -5.0319 and P’value is 0.0005. 

Papayas can be used as a food, a cooking aid and in traditional medicine. Laboratory studies have shown that papaya seeds have contraceptive effects in adult male langur monkeys, and possibly in adult male human. ^[4] Phytochemicals in papaya may suppress the effects of progesterone. Papaya juice has an in vitro antiproliferative effect on liver cancer cells, possibly due to lycopene [5].The latex concentration of unripe papayas is speculated to cause uterine contractions, which may lead to a miscarriage [6]. Papaya seed extracts in large doses have a contraceptive effect on rats and monkeys, but in small doses have no effect on the unborn animals. Papaya seeds also contain a special compound, which helps to stop formation of tumor [5]. Mitotic index value obtained in our study, which is significantly less than the control provides information about its antimitotic activity. The difference between mean mitotic index of onion root tip cells exposed to papaya seed extract and that of control was statistically significant at 0.05 level. t-value is 1.9344 and p’value is 0.0818. 

From the results the antimitotic activity of Turmeric is very evident. Similarly, Dr William LaValley, focused most of his clinical work on the treatment of cancer using curcumin – a derivative of turmeric and the pigment that gives the curry spice turmeric its yellow – orange colour. Curcumin has the ability to modulate genetic activity and expression- both by destroying cancer cells and by promoting healthy cell function. It also promotes anti –angiogenesis, meaning it helps prevent the development of additional blood supply necessary for cancer cell growth. Turmeric is being evaluated for its potential efficacy against several human diseases in clinical trials, including kidney and cardiovascular diseases, arthritis, several types of cancer and irritable bowel diseases [7]. Variation of mean mitotic index is statistically significant at 0.05 level of significance. t-value is 2.5656 and p’value is 0.0281. 

The World Health Organization expert group for research on cancer reported in 2004 that the percentage of oral cancer among all cancers diagnosed in hospitals in Asia has always been much higher than that usually found in western countries, where the habit of chewing betel quid, with or without tobacco, is virtually unknown. In many descriptive studies, investigators have obtained histories of chewing betel quid with tobacco from series of patients with oral cancer; and in all these studies the percentage of patients who practice betel leaf chewing was found to be extremely large. In an earlier 1985 study, scientists linked malignant tumors to the site of skin or subcutaneous administration of aqueous extracts of betel quid in mice. In hamsters, fore stomach carcinomas occurred after painting of the cheek-pouch mucosa with aqueous extracts or implantation of a wax pellet containing powdered betel quid with tobacco into the cheek pouch; carcinomas occurred in the cheek pouch following implantation of the wax pellets. In human populations, they reported observations of elevated frequencies of micronucleated cells in buccal mucosa of people who chew betel quid in Philippines and India [8]. An investigation studied chromosome damaging effect of betel leaf in human leukocyte cultures. These researchers report an increase in the frequency of chromatid aberrations when the leaf extract was added to cultures. Another scientific study from Japan indicates that the lab rats that ate a mixture of betel leaf and areca nuts all had severe thickening of the upper digestive tract whereas after undergoing a diet of betel leaves alone, only one laboratory rat ended up having a forestomach papilloma [9]. Chewing and smoking as combined by most betel chewers interacted synergistically and was responsible for half of all cancer deaths in this group [10]. In our study also, an elevated cytoprolifertive effect was detected. There is statistically significant variation in mean mitotic index from that of control at 0.05 level of significance. t-value is -2.4917 and p’ value is 0.0319. 

Mussaenda queensirkit, an ornamental plant grown in tropical countries is shown to exhibit cytotoxic property. The 70% methanolic extract of fresh flowers of Mussaenda queensirkit (MQF) was studied for its cytotoxic and antimitotic activity with Brine Shrimp Lethality assay and Allium cepa root tip mitosis experiment, respectively. The LC50 value for MQF was found to be 83.33 μg mL-1 in Brine Shrimp Lethality Assay. The extract showed maximum anti-mitotic activity at the highest concentration studied (2000 μg mL-1) with a mitotic index of 9.0. The observed cytotoxic and anti-mitotic activity of the extract shows the potential of the plant in the exploration of anti-cancer molecules.^[1] From the result obtained from the study the mean mitotic index varies significantly from the control, at 0 .05 level t ‘value is -2.5422 and p’ value is 0.0293 hence the null hypothesis was rejected.

Mean mitotic index of root tip exposed to ajinomotto also shows value above the control value. Russell L. Blaylock [11] argues that nerve cells in the brain and elsewhere are killed by excessive stimulation of neurotransmitters, including glutamate [11]. The argument for brain damage originates in a 1969 article about mono sodium glutamate (MSG) injections in young mice. The newborn mice were injected with heavy doses of MSG under the skin, which can't be fairly compared to amount and manner in which humans typically consume. MSG is an excitotoxin that can cause brain cell death, but that role is actually essential for normal brain function.” In fact, recent studies have found that 95 percent of dietary glutamate is metabolized in the digestive tract and turned into fuel or other amino acid. What little glutamate does make it into the bloodstream is prevented from entering our brains in any significant quantity by the blood brain barrier. Given this information, the idea that the MSG we eat somehow travels to the brain and causes damage is a stretch. The mean mitotic index varies significantly at 0.05 level. t’value is -2.3793 and p’value is 0.0387. 

Rootex is a plant growth hormone mixture. The root tip exposed to rootex has the highest value of mean mitotic index. This indicate that the rate of mitosis is very fast by the action of Indole- 3 butyric acid and humic acid. The mean mitotic index is 23.65. The variation from control is significant at 5% level. t’ value is -2.7477 and p’ value is 0.0206. 

Rate of mitosis was studied using onion as they germinate easily without soil so the chemicals provided to the plant can be easily controlled and also that they grow quickly and are only a few cells thick. Onion root tip cells exposed to extracts of Vinca rosea, papaya seed and turmeric powder have the ability to inhibit mitotic activity and so are potential remedies for uncontrolled cell division. In short, they are anticancerous. Onion root tip cells exposed to extracts of Ajinomotto, Rootex, Tobacco and Betel leaf show higher mitotic index values than that of the control indicating their ability to promote mitosis. This indicates that their excess use can lead to cancer.

1. Vidyalakshmi, K.S. et al. “Anti-mitotic and cytotoxic effect of mussaenda queensirkit.” Journal of Pharmacology & Toxicology, vol. 2, no. 7, 2007, pp. 660.

2. Noble, R.L. et al. “Role of chance observations in chemotherapy: Vinca rosea.” Annals of the New York Academy of Sciences, vol. 76, 1958, pp. 882–894.

3. Moudi, M. et al. “Vinca alkaloids.” International Journal of Preventive Medicine, vol. 4, no. 11, 2013, pp. 1231–1235.

4. Lohiya, N.K. et al. “Chloroform extract of carica papaya seeds induces long-term reversible azoospermia in langur monkey.” Asian Journal of Andrology, vol. 4, no. 1, 2002, pp. 17–26.

5. Naseem, M. and M.K. Nasir. “How a papaya can save you from cancer, heart attack and diabetes.” March 2013.

6. Oderinde, O. et al. “Abortifacient properties of carica papaya (linn) seeds in female sprague-dawley rats.” Nigerian Postgraduate Medical Journal, vol. 9, no. 2, 2002, pp. 95–98.

7. Mishra, S., and K.Palanivelu. “The Effect of Curcumin (Turmeric) on Alzheimer’s Disease: An Overview.” Annals of Indian Academy of Neurology, vol. 11, no. 1, 2008, pp. 13–19. https://doi.org/10.4103/0972-2327.40220.

8. Sadasivan, G. et al. “Chromosome-damaging effect of betel leaf.” Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, vol. 57, no. 2, 1978, pp. 183–185. https://doi.org/10.1016/0027-5107(78)90266-X.

9. Mori, H. et al. “Carcinogenicity examination of betel nuts and piper betel leaves.” Experientia, vol. 35, no. 3, 1979, pp. 384–385. https://doi.org/10.1007/BF01964368.

10. Morton, J.F. “Widespread tannin intake via stimulants and masticatories, especially guarana, kola nut, betel vine, and accessories.” 1992, pp. 739–765.

11. Blaylock, R.L. and T. Weiner. Excitotoxins: The Taste That Kills. 2011, infiniteunknown.net.