The synergistic neurotoxins of palmyrah (Borassus flabellifer L.) flour

Palmyrah (Borassus flabellifer L.) is consumed in various forms in different parts of Sri Lanka. Although a neurotoxic syndrome had been described in rats it is being consumed by humans. However, the chemical nature of the neurotoxin is unknown. Thus the objective of the present study was to determine the neurotoxic principle using palmyrah seed shoot and bioactivity directed separations. Two primary amines were isolated. These were not toxic individually but toxic when given together showing synergism. Studies of the amines by 1H NMR and 13C-NMR showed a steroidal aglycone (spirostane) linked to a carbohydrate moiety containing three a-rhamnosyl residues and a b-pyranosyl residue. Comparison with known spectral data showed that the b-pyranosyl is likely to be a β-glucosaminosyl which is probably in position 6 of glucose in one compound and most likely to be in the position 3 of glucose in the other. Synergism appears to be at two levels (i.e. at the absorption level) where the high content of neutral saponins present appears to be needed to facilitate absorption of the cationic toxin and at the point of action. The synergistic mechanism of the toxic amines remains to be explained

Effect of processing of sword beans (Canavalia gladiata) on physicochemical properties of starch

The effect of various processing methods on physico-chemical properties of sword bean starch was studied. Seed grits and flour were cooked with and without soaking, wet-autoclaved, and roasted. The changes in starch associated with these processing methods were studied by observing changes in granular structure, water solubility index, water absorption index, molecular size distribution and the degree of gelatinization estimated by differential scanning calorimetry. Intact, ungelatinized starch granules of raw and dry-heat treated samples were observed under the light microscope. The starch granules were elliptical in shape and had an average length and breadth of 37-40 mu m and 27 mu m, respectively. Wet-processed samples had the lowest water solubility, higher water absorption and lower gelatinization enthalpies than the raw bean flour, whereas the dry heat-treated samples showed higher water solubility and higher gelatinization enthalpies. The starch molecular size distribution pattern showed a higher amount of high molecular size carbohydrates in dry heat-treated samples and a large fraction of intermediate molecular size carbohydrates in the wet-processed samples. The low molecular size carbohydrate content was low in wet-processed samples where processing was done with excess water