A study on the Tannin Contents of three Subspecies of Acacia nilotica in the Sudan.

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Date
2015-06-22
Authors
Ibrahim Mohammed, Suliman
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UOFK
Abstract
The present study involved studying the variation in tannin contents of Acacia nilotica subspecies tomentosa, nilotica and adansonii which are grown naturally in the Sudan, according to: 1- Subspecies 2- Part of the tree. 3-Pods developmental stages 4- Site of growth. The samples were collected from six different sites, namely: EI Faw, EGazaire, Shambat, EI Obied, Nayala and EI Fasher. The samples consisted of green or immature fruits, mature fruits and bark for each sub species and site of growth separately Hot water extraction method was used to prepare the extraction of the crude drug. The Hide powder method was used for the determination of the percentages of total tannin content. Thin layer Chromatography test was carried out to compare between the studied subspecies samples from a quantitative point of view using a polyamide paper, the solvent system consisted of methanol and water (40 ml: 60 ml respectively). Significant variations are found among the studied subspecies in their tannin content. The total tannin content of sub species nilotica was 45%, while, the total tannin contents of subspecies tomentosa was 37 %, whereas the total tannin contents of subspecies adansonii is 31%; however, the bark has a lower amount of tannin in all the subspecies (25%) compared to the pods. On the other hand, the present study presented that the mature and immature fruits are varying in their total tannin contents, the percentage of total tannin contents of the immature pods was 49 % whereas at the mature pods was 33%. The total tannin contents of the immature fruits of subspecies adansonii was 58 %, sub species nilotica 54% and the total tannin contents of subspecies tomentosa immature fruits was 42 %. It is worth mentioning that the site of growth has no significant effect on the percentages of total tannin contents. Apart from the variation in tannin content between the studied subspecies, there are also variations between them from the qualitative point of view. These variations obtained in the Ratio of Fractionation's values (Rf) of the tannin compounds are attributed to the subspecies, part of the tree, pods developmental stage, while the site factor had no clear effect indication that this tannin is of mixed type (gallocatechol). This work confirms the garad tannins as the best of the tannins of all species investigated and as most suitable for modifications. It is recommended to be used confidently as a pretanning and retanning agent for upper leather with the recipes outlined in the present work.
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A study on the Tannin Contents of three Subspecies of Acacia nilotica in the Sudan
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