Evaluation of Physicochemical, Microbiological and Toxicological Aspects of Acacia seyal GUM

Abstract

Eighty gum samples including: 29, 35, 16 samples of A. seyal var. seyal (commercial), A. seyal var. seyal (authentic) and A. seyal var. fistula (authentic), were collected from commodities intended for export and various locations within the gum belt during seasons 2007 to 2009. Two samples of A. senegal var. senegal, one commercial and the other authentic, were used as reference samples in this study. Results obtained for all physico- chemical parameters show high consistency between commercial and authentic gum samples used in this study. The mean values of moisture content, ash, pH, specific optical rotation and intrinsic viscosity were found to be 10.04%, 3.03%, 4.77, +51.4◦, 10.28 cm3g-1, respectively for A. seyal var. seyal (Commercial), 10.02 %, 2.18%, 4.34, +61.1◦, 11.90 cm3g-1 for A. seyal var. seyal (authentic), 9.64%, 2.11%, 4.19, +55.9◦ , and 12.67 cm3g-1 for A. seyal var. fistula (authentic), 10.49 % , 3.53 %, 5.04, -33◦ and 22.84 cm3g-1 for A. senegal var. senegal (commercial) and 9.21 %, 2.95 %, 4.76, -30 and 25.15 cm3g-1 for A. senegal var. senegal (authentic). Mean values of acid equivalent weight and total uronic acid, protein, and tannin content were found to be 1.265 x 103, 15.33 %, 0.96 % and 0.03% respectively for A. seyal var. seyal (Commercial), 1.309 x 103, 14.83 %, 0.85 % and 0.01 % for A. seyal var. seyal (authentic), 1.430 x 103, 13.84%, 0.83% and 0.01 % for A. seyal var. fistula (authentic), 1.304 x 103, 14.87 %, 2.73 and 0.02 % for A. senegal var. senegal (Commercial) and 1.298 x 103, 14.94 %, 2.40 % and 0.00 % for A. senegal var. senegal (authentic) .Two samples from bark and epoxy powder from A. seyal of both varieties and A. senegal var. senegal, were analyzed for tannin. In epoxy powder the tannin content were found to be 0.85 %, 0.38% and 0.30 %, in A. seyal var. seyal, A. seyal var. fistula and A. senegal var. senegal respectively, while in bark of A. seyal var. seyal, A. seyal var. fistula and A. senegal var. senegal the tannin content were found to be 1.65%, 1.48% and 1.23%. Sugar composition was estimated using HPLC. galactose, arabinose, rhamnose content were found to be 31.39 %, 34.38 % and 2.25 % respectively for A. seyal var. seyal (commercial), 31.85 %, 36.19 % and 1.52 for A. seyal var. seyal (authentic), 32 %, 43.57 % and 0.63 % for A. seyal var. fistula (authentics), 23.85 %, 16.47 % and 7.79 % for A. senegal var. senegal (commercial) and 23.26 %, 18.46 % and 7.28 % for A. senegal var. senegal (authentic). Mean values for cationic composition including; Na, K, Ca, Mg, Zn, Cu, Cr, Pb, Cd, Mn and Al were found to be 96.65, 3135.97, 7379.97, 1669.94, 30.62, 2.78, 224.05, 43.77, 9.63, 16.33 and158.18 μg/g respectively, for A. seyal var. seyal (commercial), 44.41, 2123.57, 6556.58, 1727.27, 24.38, 182.63, 215.24, 49.00, 9.86, 16.11 and116.35 μg/g for A. seyal var. seyal (authentic), 31.77, 4696.46, 5029.25, 1323.68, 45.46, 17.58, 224.25, 20.27, 13.51, 8.51 and 53.06 μg/g for A. seyal var. fistula (authentic), 54.31, 1873.7, 6733.26, 2017.08, 2.06, 5.6, 135.89, 51.54, 3.40, 1.15 and 95.01 μg/g for A. senegal var. senegal (commercial) and 51.54, 1875.39, 6776.78, 1999.7, 56.16, 8.05, 17.74, 0.37, 0.03, 4.49 and 40.2 μg/g for A. senegal var. senegal (authentic). The Number average molecular weight (Mn) was also determined using osmotic pressure technique and results were found to be 6.7x105, 9.2 x 105 , 1.1 x 107 , 3.1 x105 and 2.4x105 g.mol-1 respectively, for A. seyal var. seyal (commercial), A. seyal var. seyal (authentic), A. seyal var. fistula (authentics), A. senegal var. senegal (commercial) and A. senegal var. senegal (authentics). FTIR spectra studied shows that all gum samples show the presence of hydroxyl, carbonyl, Alkyl, Alkenyl and amino functions The microbiological criteria, including: areobic plate count, moulds and yeast was undertaken. The mean values were found to be 1.5x103, 2x10, 4.8x10, cfu/g respectively, for all gum samples. The most dominant moulds were found to be Aspergillus niger, Aspergillus fumigatouus, Aspergillus terrus and Pencillum sp. All gum samples were found to be free from either coliform /E.coli sp or Salmonella sp. Only 21 of lactose fermented bacteria (dominant), were identified as Citrobacter sp., Enterobacter sp. and Klebsella sp. Five representative composite samples of; A. seyal var. seyal (commercial), A. seyal var. seyal (authentic), A. seyal var. fistula (authentics), A. senegal var. senegal (commercial) and A. senegal var. senegal (authentic) were used to evaluate toxicological status using in vivo and in vitro methods.The lethal dose (LD50) for the five gum samples was 18 g/ kg body weight and is similar no observed adverse effect level (NOAEL) samples with mean values varying from1428 to 1623 and 2973 to 3108 mg/ kg body weight/day at 2.5 and 5 % dietary level respectively for 12 weeks. No deaths were observed during the study, no clinical signs were observed, on behavior, activities, body weights, food consumption and also on haematological findings and blood biochemistry in any groups during the study. Histopathological results provided supportive evidence for biochemical analysis, and showed absence of significant lesions in heart, kidney, liver, intestine and spleen of tested rats. IC50 on two normal human cell lines, were found to be 841, 794, 735, 599 and 629 μg mL-1 on baby hamster kidney fibroblast cell line (BHK) for A. seyal var. seyal (Commercial), A. seyal var. seyal, A. seyal var. fistula, A. senegal var. senegal ( Commercial) and A. senegal var. senegal, and 917, 875, 934, 870 and 845 μg mL-1 on human normal melanocytes cell line (HFB4), while those on the two cancer cell lines were found to be 572, 612, 499, 659 and 900 μg mL-1 on human hepatocellular carcinoma cell line (HEPG2) and 824, 858, 870, 760 and 938 μg mL-1on the human colon carcinoma cell line (HCT116). The predicted LD50 starting dose was estimated from the mean values of IC50 using Halle’s RC prediction model and was found to range between 3.37 to 4.09 and 3.12 to 4.10 g/kg body weight on both normal and cancer cell lines respectively for all gum samples.