Aflatoxin B1 is considered the most toxic aflatoxin highly implicated in hepatocellular carcinoma (HCC) in humans, and a common contaminant in a variety of foods including peanuts, cottonseed meal, corn, and other grains, as well as animal feeds. Dr Adetayo Sadudeen Amid presents his findings on how slams shrubs can cure diseases caused by Aflatoxin B1, especially ulcer.
Gastrointestinal tract (GIT) is the major part of the body responsible for ingestion, mastication, digestion and absorption of nutrients for the maintenance of body homeostasis. Many disorders of gastrointestinal tracts are common problems in humans and animals and can present considerable diagnostic and therapeutic challenges to the clinicians. Diseases of gastrointestinal tracts are numerous ranging from mechanical obstruction to ulceration, with gastric ulcer being the most common of the GIT ulcerations. Gastric ulcer is a clear and distinct discontinuity in the mucosa that penetrates the muscularis mucosa (Stanton and Bright, 1989). Gastric ulcers have been reported in dogs, rodents, horses and humans secondary to administrations of a variety of Non-Steroidal Anti-inflammatory drugs (Lanza et al., 2009) including aspirin, ibuprofen (Godshalk, et al., 1992), naxopren (Malfertheiner, et al., 2009), indomethacin (Spee, 2010) and ketrolac (Mathew, et al., 1996). Steroidal Anti-inflammatory drugs like glucocorticoids, which are prescribed for the treatment of spinal insult and inter-vertebral disk disease (Neiger, et al., 2000) have also been incriminated as one of the causes of gastric ulceration (Grainek, et al., 2008).
Primary neoplastic condition of the stomach like carcinoma, gastro-intestinal lymphoma (Grooters et al., 1994), gastrinoma and disseminated mast cell disease (Giannini et al., 2006) are also responsible for gastric ulceration. Three dogs experienced severe oral and gastric ulceration following administration of Phenol with a total dose of 24-30mg (Gieger, et al., 2000). In another study, bitches that underwent auto transplantation of the ovary to the portal vein drainage as a possible method of preventing obesity have been reported to experience gastric ulcer as a complication of ovariectomy (Davis, et al., 2003). While some veterinary surgeons often overlook mycotoxins as the possible cause of gastric mucosa damage (Boermans and Leung, 2007) many cases of gastro-intestinal injury suspected to be caused by aflatoxins have been reported in Nigeria (Akinrinmade, et al., 2012) but only few of them have been published as one of the possible causes of gastric ulceration. Several reports on mycotoxin survey of commercial pet foods have been documented in United States (Henke et al, 2001) and the United Kingdom (Scudamore et al, 1997) and recently in Nigeria, where i t was confirmed that most commercial dry dog food marketed in Ibadan, Nigeria are frequently contaminated with aflatoxins at levels that potentially produce chronic aflatoxicosis.
Aflatoxins are naturally occurring mycotoxins (Puschner, 2002). Mycotoxins are poisonous, toxic secondary metabolic chemical compounds produced by certain fungi (Richard, 2007). Aflatoxins are synthesised by Aspergillus flavus and Aspergillus parasiticus species of fungi and they represent a major toxic threat in animal feeds (Wannop, 1961). There are over 14 different types of aflatoxins produced in nature (Boutrif, 1998) out of which four are naturally occurring, namely Aflatoxin B1, B2, G1 and G2, with B1 being the most potent (Puschner, 2002) and has been reported and announced as a natural carcinogenic agent by the International Agency for Research on Cancer (IARC, 1993). Animals get exposed to aflatoxins by direct ingestion of aflatoxin-contaminated foods (Agag, 2004). Following ingestion of aflatoxins into the gastro-intestinal tract, it is easily absorbed across the cell membranes where they reach the blood circulation within minutes of ingestion. In vivo and in vitro studies have revealed that Aflatoxin B1 (AFB1) when ingested leads to elevation of free radicals like Nitric Oxide (NO), Superoxide (O⁻₂) and Hydrogen Peroxide (H₂O₂), depending on dose (Towner et al., 2002). These free radicals promote mucosal damage by causing degradation of the epithelial basement membrane components, complete alteration of the cell metabolism and DNA damage (Schraufstatter et al., 1988) resulting in necrosis, ulceration and neoplasia.
A variety of prevention and control strategies have been suggested to minimize the risk of mycotoxin poisoning in food ingredients used in Nigeria but there is a dearth of information on the treatment of gastric mucosa damage caused by aflatoxicosis.
Melatonin (Mel) is a powerful antioxidant (Reiter et al., 2009).Unlike other antioxidants, melatonin does not undergo redox cycling, which is the ability of a molecule to undergo repeated reduction and oxidation. Melatonin, once oxidized, cannot be reduced to its former state because it forms several stable end-products upon reacting with free radicals. Therefore, it has been referred to as a terminal (or suicidal) antioxidant (Tan et al., 2007). In a rat model, melatonin protected the gastric mucosa from its various insults (Brzozowski et al., 2005). Melatonin has been recognised as a powerful free-radical scavenger with wide-spectrum antioxidant as discovered in 1993 (Tan et al., 1993). Anti-inflammatory effect seems to be the most relevant and most documented in the literature (Arushanian and Beĭer, 2002). Melatonin works with other antioxidants to improve the overall effectiveness of each antioxidant. Melatonin has been proven to be twice as active as vitamin E, believed to be the most effective lipophilic antioxidant (Pieri et al., 1994).
Chromolaena odorata is a tropical species of flowering shrub in the sunflower family, Asteraceae. Native to North America, from Texas to Florida, to Mexico and the Caribbean and has been introduced to tropical Asia, West Africa and parts of Australia. Its common names are siam weed, Christmas bush, Devil weed, Camfhur grass and common Floss fower (Lalith, 2009). The medicinal values of plants lie in their component phytochemicals such as alkaloids, tannins, flavonoids and other phenolic compounds, which produce a definite physiological action on the human body (Hill, 1952). Phytochemical screening of Chromolaena odorata showed that its aqueous extract is rich in saponin, tannins, phlobatannins, steroids, terpenoids, flavonoids (Afolabi et al., 2007) (Suksamrarn et al., 2004), xanthones (Duan et al., 2010), triterpenoids (Siddiqui et al., 2004) and coumarins (Jiwajinda et al., 2000) which possess anti-inflammatory activities. The ethanolic and methanolic extracts of the leaves of Chromolaena odorata have been reported to possess free radical scavenging and antioxidant properties necessary to scavenge nitric oxide, hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) (Bhargava et al., 2013). Its methalonic extract has also been reported to prevent reperfusion injury by preventing oxidative damage to the cells (Akinrinmade et al., 2014). It would be necessary to find means of using Chromolaena odorata for the prevention of Aflatoxin B1 (AFB1) induced gastric mucosa damage.
Based on the anti-inflammatory, antioxidant and free radical scavenging properties of Chromolaena odorata that are known, we therefore hypothesized that its flavonoid-rich extract (FREC) could serve as a locally sourced toxin binder for the prevention of food related gastric ulceration induced by Aflatoxin B1 (AFB1) in a rat model by evaluating the in-vivo protective effects of FREC and Melatonin (a standard antioxidant and anti-inflammatory agent) against AFB1 induced gastric mucosa damage.
35 Wistar-Albino rats of mean body weight 211.86 ± 27.23g were randomly divided into 5 groups as to include 7 rats in each group. Group A (Control) received distilled water for 7days. Group B received a single intraperitoneal dose of 2.5mg AFB1 per kg body weight (2.5mg/kg.bwt) on the 5th day of study. Group C received intraperitoneal injection of 10mg Melatonin/kg.bwt daily for 7days & a single intraperitoneal dose of 2.5mg AFB1/kg.bwt on the 5th day of study. Group D and E received 50mg/kg/day and 100mg/kg/day of FREC for 7days orally & a single intraperitoneal dose of 2.5mg AFB1/kg.bwt on the 5th day respectively. Biochemical assay, histopathology and Enzyme Linked Immunosorbent Assay for cytokines (Interleukin-1 Beta (IL-1 β) & Tumor Necrosis Factor alpha, TNF-α) were evaluated. We observed a distinct breach in continuity of group B gastric mucosa with a significant (p˂0.05, p˂0.01) elevation in serum IL-1 β and TNF-α as evidences of gastric mucosa damage with resultant inflammatory response respectively. Conversely, a significant reduction in serum IL-1 β and TNF-α in group C, D and E was observed but with a more significant reduction in group E which shows a dose dependent anti-inflammatory activity of FREC. Reduced Glutathione peroxidase (GPx) and Superoxide dismutase (SOD) activities observed in group B were significant (p˂0.05, p˂0.01). There was a significant increase in the activities of GPx and SOD in group C, D and E. It was also observed that the significant increases in the productions of Malondialdehyde (MDA), Nitric Oxide (NO) and Hydrogen Peroxide (H₂O₂) in group B were brought down significantly in group C, D & E with group E showing much more significant reductions. These significant reductions observed are evidences of free radical scavenging and antioxidant properties of FREC and Melatonin. FREC and Melatonin produced significant protective effects on gastric mucosa from being damaged by AFB1 but with FREC being more favorable.
In conclusion, this flavonoid rich extract of Chromolaena odorata has a potential of being used on commercial dog foods as a toxin binder because it compared favourably, even superior to Melatonin which is the standard antioxidant.
A step further was made to purify methanolic extract of Chromolaena odorata to yield flavonoid which has been shown to have anti-inflammatory, antioxidant and free radical scavenging properties but further fractionalization of the extract may be necessary for purification purposes to determine the active ingredient responsible for the results documented from this study.
Dr Adetayo Sadudeen Amid, a Lecturer I and Veterinary Surgeon at the Department of Veterinary Surgery and Radiology as well as the Veterinary Teaching Hospital, University of Ilorin, acknowledges Dr. Joseph Atehnkeng of the Aflasafe Laboratory at the International Institute of Tropical Agriculture, Ibadan, Nigeria for the provision of aflatoxin B1 used in this study. More so, this study is in compliance with ethical standards and there is no conflict of interest. He can be reached via his email: [email protected]