EFFECTS OF DIFFERENT PROCESSING METHODS ON THE THERAPEUTIC AND IMMUNOSTIMULATORY POTENTIALS OF BENISEEDS (SESAMUM INDICUM LINN) IN DIARRHOEA-INDUCED RATS.

Abstract

Diarrhoea is still a serious problem in most developing countries of the world. Although it is self-limiting but in some cases, antibiotic treatment may be required. However, because most bacteria have developed resistance to available antibiotics, efforts are now geared towards searching for alternative therapies. In this study, extensive research was carried out to investigate whether Beniseeds (Sesamum indicum Linn), a local remedy in treating gastrointestinal disorders by the Ebiras of the northern part of Nigeria in folklore medicine can be used as an alternative in treating bacterial diarrhoea. Prior to this, the normal flora of the seeds was first isolated and identified using standard microbiological techniques. The seeds were then divided into 8 groups and subjected to different treatments as follows: group 1 was fermented at 30±2ºC for 7 days (A), group 2 was fermented at 30±2ºC for 3 days but kept at 4ºC for 7 days (B), group 3 was boiled at 100ºC for 10 minutes (C), group 4 was roasted in an oven at 100ºC for 10 minutes (D), while the last four groups were subjected to extraction using different solvents such as methanol (E), n-hexane (F), hot water (G) and cold water (H) respectively. The different products, A-H were then tested for their growth inhibitory activity on the following diarrhoeagenic microorganisms: Bacillus cereus, Enterococcus faecium, Escherichia coli, Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus using agar diffusion assay. Conventional antibiotics were used as control. The best two of the different products in inhibiting the growth of the test organisms on agar plates were then used in treating diarrhoea induced in Wister albino rats using standard methods. Moreover, the biosafety, mechanism of action and the effects of these products on the gastrointestinal flora and the haematological parameters of apparently healthy albino rats were also examined using standard methods. Furthermore, the effect of the different treatments on the proximate composition of the seeds was also investigated. The following microorganisms were isolated and identified from raw beniseeds: Proteus vulgaris, Acinetobacter aceti, Serratia marcescens, Bacillus subtilis and Listeria monocytogenes as bacteria, while Rhizopus stolonifer, Aspergillus niger and Mucor mucedo are fungi. The fermenting liquor of beniseeds at 30±2ºC for 3 days which was kept at 4±2ºC (B) was observed to have the highest growth inhibitory effect on all the test bacteria. Moreover, the growth inhibition mediated by B was superior to that of all the conventional antibiotics used. This was followed by the inhibition mediated by the methanol extract (E) of the seeds. The seeds subjected to cold water extraction (H) however had the least growth inhibitory effect on the test organisms. During fermentation, the pH of B reduced from 5.50 to 3.80 as fermentation progressed while the titratable acidity increased from 10.00 to 56.10. Out of the three microorganisms isolated from B, that is, Lactobacillus acidophilus, Pediococcus cerevisiae and Leuconostoc mesenteroides, only L. acidophilus and P. cerevisiae had growth inhibitory effects on the test bacteria. The mechanism of action was due to the leakage of potassium and sodium ions from these organisms. The daily microbial load of B increased from 3.0 x103 to 9.2 x 107 cfu/ml by day 7 during fermentation. The proximate analyses of B showed that the fermenting beniseeds had the highest protein content (30%) by day 3. The mineral analysis showed the presence of sodium, potassium, Calcium, magnesium, Zinc, Copper, Maganese, iron and phosphorous. The phytochemical analysis of the fermented seeds showed the presence of tannin, phenol, saponin, alkaloid, phytate, oxalate, trypsin inhibitor and glycoside. The results of the animal bioassay showed that the administration of B to rats infected with the three test organisms used for the therapeutic assay that is, Salmonella typhi, Shigella dysenteriae and Bacillus cereus did not only lead to the recovery of the infected rats but also led to increased packed cell volume, haemoglobin concentration and lymphocyte counts significantly (P < 0.05), while the white blood cell count, monocytes, neutrophils, eosinophils and basophils were maintained. Similar results were also obtained with E but B caused a greater increase of the blood parameters than E. The histopathological analyses of the vital organs of rats fed with B and E respectively showed no form of distortion on the tissues of the heart, liver, kidneys, intestine and the spleen examined. The biochemical analyses showed that both B and E caused significant increase (P ≤ 0.05) in the level of bicarbonate, urea, uric acid and calcium. The liver functioning tests for the experimental rats showed that both B and E caused an increase in the serum total proteins, alkaline phosphatase and cholesterol level when compared with the control. There was, however a greater increase in the cholesterol level of the rats fed with E than those fed with B. Both B and E caused a significant reduction (P < 0.05) in the microbial loads and types in the gastrointestinal tract (GIT) of the rats. This investigation revealed that beniseeds has antibacterial potential against bacteria that cause diarrhoea and that when administered to rats infected with S. typhi, S. dysenteriae and B. cereus; it caused the rats to recover quickly than the untreated ones. Moreover, beniseeds was also observed to have immunostimulatory potential. This study therefore has been able to provide scientific credence to the use of beniseeds in folklore medicine to treat gastrointestinal disorders, specifically bacterial diarrhoea. For maximal result however, it is recommended that the liquor of fermenting beniseeds at 30±2ºC kept at 4ºC within 7 days should be exploited