Nowadays, researches are focusing on exploring the pharmacological profile of compounds from natural origin, where promising results aroused. The research activity is growing because of the increasing recognition of the importance of intestinal mucositis. The chemotherapeutic agent (5-FU) is a widely used antimetabolite drug which acts by blocking DNA synthesis, its mechanism of action targets not only cancer cells, but all rapidly dividing cells such as cells of the gastrointestinal tract [26
]. The jejunum appeared to be the most affected intestinal segment. It has been reported that 5-FU preferentially damages the upper small intestine due to the higher cell turnover [27
The study showed that, fluorouracil administration was accompanied by a significant weight reduction at day 8. A similar finding was previously reported in 5-FU treated rats and was attributed to altered intestinal absorptive capacity [28
Microscopic signs of intestinal mucositis were observed in 5-FU / water group. Different signs of mucosal damage such as distortion, fusion, shortening and blunting of villi were observed, with loss of surface epithelium and marked exfoliation of the villi. This was associated with a significant decrease in the villus height and crypt depth. These changes are consistent with those reported by Soares et al. [28
] and Stringer et al. [29
]. Marked detachment of surface epithelium was observed and is suggested to be due to stromal edema [28
A significant decrease in goblet cell number was observed in 5-FU/water group, and this may be a consequence of early stem cell death which has been reflected on the renewal of all cell lineages including goblet cells. The heavy cellular infiltration and dilatation of congestion of blood vessels seen in the mucosa and submucosa are similar to those reported in small intestinal irradiation mucositis [30
]. It was stated that chemotherapy increases the release of proinflammatory cytokines which cause tissue damage and inflammatory response resulting in increased subepithelial vascularity [31
The study showed that, fluorouracil administration was accompanied by a significant reduction in Ki-67 and Bcl-2 positive cells at day 8. It seems that inhibition of DNA synthesis, DNA damage and the production of reactive oxygen species by chemotherapy impair the metabolism in progenitor cells and cause inhibition of mitosis and increase of apoptosis [1
]. Wright et al. [32
] also found that 5-FU administration results in increased apoptosis and decreased cellularity in the small intestine.
Signs of initial recovery with significant increase in crypt depth and mitotic count were detected in 5-FU/water group at day 12. This recovery was accompanied by an increase in goblet cell number, indicating a complete cell renewal and migration of goblet cells to the villi. The elongation of the crypts seems to be a sign of crypt regeneration via hyper proliferation after the initial crypts damage. Carneiro-Filho et al. [33
] observed similar findings by day 8 after 5-FU injection in mice. Duncan and Grant [34
] stated that the structure and functionality of the villi and absorptive surfaces of human gut can return to normal around 1 week after onset of chemotherapy.
There is good evidence that chamomile extract exert their protective effect by many different mechanisms. In the 5-FU/chamomile group, the mean rat body weight was significantly higher than that of 5- FU/water group at day 8. This could be attributed to the improved intestinal mucositis and subsequent improvement of intestinal absorptive function. The current microscopic study demonstrated preserved structural integrity with some mucosal damage in jejunum of the 5-FU/chamomile group, but less than that of 5-FU/water group. Significant increases in the mean villus height and crypt depth were observed in 5-FU/chamomile group, compared to the corresponding 5-FU /water group at day 8, indicating less intestinal damage. Chamomile treatment with 5-FU administration led to significantly reversal of the shortening and fusion of villi and atrophy towards near normal. This suggests that the beneficial effect of chamomile treatment is specially exerted early during damage and the initial recovery phase.
The mean goblet cell number was significantly higher in 5-FU/chamomile group, compared to the corresponding 5-FU/water group at day 8. This increase may be explained by increase in antiapoptosis and stem cell proliferation. This change indicates another protective mechanism of chamomile against the 5-FU-induced damage through the preservation of the intestinal mucous barrier integrity.
Anti apoptosis and proliferation can be determined in the intestinal epithelium by immunohistochemical methods. The Ki-67 and Bcl-2 immunostaining was significantly lowest in the 5 FU/water group than the 5-FU/chamomile group at day 8. Thereby indicating that chamomile increased intestinal proliferation and anti apoptosis. It is probable that this protective effect of chamomile may prove useful in clinical practice to prevent or decrease intestinal injury resulting from 5-FU treatment.
The efficacy of chamomile as a mucosa protective agent has only evaluated in a few studies and their results are controversial [35
]. The chamomile plant contains many different substances with antibacterial and antifungal properties, as chamazulene, alpha bisabolol, bisabol oxides, spiroethers, and flavonides. Considering the local microbial colonization of damaged mucosal surfaces which occurs in the ulcerative phase of mucositis, the intervention with chamomile and the effects of above components might be responsible for the reduction of mucositis in our animals. Flavonoids act as antioxidents, enhance the effects of vitamin C, and strengthen connective tissue around capillaries [36
]. Bhaskaran et al. found that chamomile possesses antioxidant and cytoprotective properties [37
] while Drummond et al. [38
] found that chamomile possesses antiinflammatory activity by reducing IL-6 and TNF-α production.
Curra et al. [39
] study the effect of topical chamomile (mouthwash) on immunohistochemical levels of IL-1β and TNF-α in 5-fluorouracil-induced oral mucositis in hamsters. They found the group treated with chamomile had lower scores for both pro-inflammatory cytokines.
At the same time, chamomile exerts harmful effect to jejunum especially at day 12, due to the severe microscopical changes seen at this day in comparison with the saline /water group. The harmful effect of chamomile may come from its constituents, like bisabolol, volatile oils, anthemic and tannic acid, and chamazulene which can cause gastrointestinal symptoms. Cavalieri et al. [40
] found that α-bisabolol is a small oily sesquiterpene alcohol, it is a pro-apoptotic agent and enhance apoptosis. One study using cadaver skin demonstrated that Bisabolol can enhance the penetration of 5-fluorouracil [41
]. Kamatou and Viljoen [42
] found that Bisabolol was nontoxic in acute oral studies in rats, dogs, and monkeys. Short term oral exposure using rats did produce inflammatory changes in several organs and decrease body weight.
Chamomile is included in the “Generally Regarded as Safe” (GRAS) list by the FDA [43
], and according to Medicine Net. com, chamomile seems safe when taken by mouth for short periods of time. The long-term safety of chamomile is unknown.