Astringency as antisensitivity marker of some Nigerian chewing sticks

Astringents contract the tissues and canals of the body. Chewing sticks are used for oral hygiene both as an antibacterial and desensitizing agent. Astringency of cold water extracts of Afzelia africana Sm. ex Pers. (Caesalpiniaceae), Dialium guineense Willd. (Fabaceae), Masularia acuminata (G.Don) Bullock ex. Hoyle, Rauwolfia vomitoria Afz. (Apocynaceae), Terminalia glauscens Planch. (Combretaceae), Vernonia amygdalina Del. (Asteraceae) and Zanthoxylum zanthoxyloides (Lam.) Waterman (Rubiaceae) was measured by precipitating extracts with hemoglobin, centrifugation and loss of absorbance measured spectrophotometrically at 578nm relative to tannic acid. Tannic Acid Equivalents (TAE) were determined from standard curve obtained. Total Tannin (TT) was determined using the protein tannin precipitation method. Relative Astringency (RA) was astringency of tannin present relative to tannic acid.

Activity was in the order of Afzelia > Terminalia > Zanthoxylum >Masularia > Vernonia > Rauwolfia > Dialium. TT ranged from 106.92±0.03mg/100g dry plant in Dialium to 632.86±0.42mg/100g dry plant in Afzelia. TAE was 27.37±0.07mg/100g dry plant in Dialium to 148.11±0.07mg/100g dry plant in Afzelia. RA correlated positively with TAE (R²=0.8763); TT (R² =0.9493). It is proposed that the desensitization may be due to the astringent activity; as these extracts will form a protective layer on the exposed dentine; contract / block the tube like channels that pass through teeth and connect to nerves thereby reduce the ability of the nerves to transmit pain.