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

IN VITRO ANTIBACTERIAL ACTIVITY OF SELECTED UNDERUTILIZED PLANTS AND CYTOTOXIC PROPERTY OF TERMINALIA CATAPPA

Objective: This study aimed at determining the antibacterial activity of the underutilized plants of Sri Lanka, Kottamba†(Terminalia catappa), Purpurata†(Alpinia purpurata) and Harankaha†(Curcuma zedoaria), against food-borne pathogens. Chemical composition and in vitro cytotxicity of the most active antibacterial plant extract(s) were examined.Methods: Crude rhizome extracts were obtained for all plants whereas in respect of T. catappa, the red pericarp of the fruit was used. The antibacterial activity was determined using the agar disc diffusion and broth dilution assays. Total phenol content, Gas Chromatograph-Mass Spectrometry analysis and cytotoxicity assay were conducted only with the plant which showed the most effective antibacterial activity.Results: T. catappa extract showed significantly (p<0.05) high DIZ (19.6±0.47 mm) against S. aureus 113. A. purpurata showed DIZ (16.3±0.94, 15.0±1.00, 14.3±0.57 mm) against L. monocytogenes V7 (1/2a), S. aureus 25925 and S. aureus MSSASS 25D. The MIC of T. catappa ethanol extract was 10 mg/ml, while MBC was 80 mg/ml for S. aureus 113. The phenolic content of T. catappa ethanol extract was 81.54±1.28 mg GAE/g dry sample and the major compound (31.86 %) was 2, 5-Furandione, 3 methyl. The No-Observed Adverse Effect Concentration (NOAEC) of this extract for COS7 cells was 100 µg/ml whereas for 3T3 it was 300 µg/ml. This indicates that the extract is cytotoxic only at a very high concentration, suggesting that at lower concentrations the extract could be used as a food preservative.Conclusion: The results indicate that T. catappa has potential antibacterial activity as a safe bio-preservative