Tannins, peptic ulcers and related mechanisms.

This review of the current literature aims to study correlations between the chemical structure and gastric anti-ulcer activity of tannins. Tannins are used in medicine primarily because of their astringent properties. These properties are due to the fact that tannins react with the tissue proteins with which they come into contact. In gastric ulcers, this tannin-protein complex layer protects the stomach by promoting greater resistance to chemical and mechanical injury or irritation. Moreover, in several experimental models of gastric ulcer, tannins have been shown to present antioxidant activity, promote tissue repair, exhibit anti Helicobacter pylori effects, and they are involved in gastrointestinal tract anti-inflammatory processes. The presence of tannins explains the anti-ulcer effects of many natural products.

Matrix effect and optimization of LC-MSn determination of trachylobane-360 in mice blood.

Xylopia langsdorffiana A. St.-Hil. & Tul. (Annonaceae) is popularly known as "pimenteira-da-terra". Various constituents have been isolated from this species, including diterpenes, such as 8(17), 12E, 14-labdatrien-18-oic acid, ent-atisan-7α, 16α-diol (xylodiol), ent-7α-hydroxytrachyloban-18-oic acid (trachylobane-318) and ent-7α-acetoxytrachyloban-18-oic acid, a crystalline solid with a molecular weight of 360 and molecular formula of C22H32O4 (trachylobane-360). When administered intraperitoneally to mice, trachylobane-360 (T-360) significantly inhibits growth of the solid tumor sarcoma 180 transplanted in mice, without causing alterations in biochemical, hematological and histopathological parameters that are frequently associated with the clinical use of antineoplastic. Furthermore, this diterpene blocks voltage-dependent calcium channels (Cav), showing spasmolytic activity. The present study shows that variables such as extraction solvent (methanol, acetonitrile and chloroform), centrifugation force (1000, 7000 and 14,000×g), and centrifugation time (5, 15 and 25min), are important in the liquid-liquid extraction of T-360 from male Swiss mice blood in HPLC-MSn studies. The study confirms matrix influence on recovery and detection of T-360. The recovery for T-360 was 37.02% using chloroform as better extractor solvent, while centrifuged at 14,000×g for 15min demonstrated the importance of the parameters chosen for the extraction/recovery process of analyte. The effect of mice blood matrix for T-360 was -51.23%. This method was optimized by repeating the extraction procedure and acidification of samples. These conditions were essential in increasing recovery (49.47%) by decreasing the matrix effect (-37.60%). The efficiency of the process, after optimization with two extractions and acidification, increased by 14.19% when compared to the initial method, from 18.05% to 32.24%. According to Marchi et al. (2010), the matrix effect does not necessarily need to be reduced or eliminated, but it does need to be identified and quantified. Therefore, these findings are essential for the subsequent evaluation of the pharmacokinetic parameters of this promising natural product.

Gastroprotective activity of the ethanolic extract and hexane phase of Combretum duarteanum Cambess. (Combretaceae).

Combretum duarteanum Cambess. is found in South America, particularly in Bolivia, Paraguay, and Brazil. In Paraiba state (Brazil), the species usually occurs in the Caatinga biome. It is popularly known as mofumbo, cipiúba, or cipaúba. This work aims to evaluate the gastroprotective activity and the cytoprotective mechanisms of the ethanolic extract (Cd-EtOHE) and hexane phase (Cd-HexP) obtained from the leaves of C. duarteanum. Doses at 62.5, 125, 250, and 500 mg/kg of Cd-EtOHE and Cd-HexP were tested in models of gastric ulcers induced by HCl/ethanol, absolute ethanol, stress, non-steroidal anti-inflammatory drugs, and pylorus ligation in male rats or mice. Cd-EtOHE and Cd-HexP significantly reduced gastric injuries induced in all models. Cd-EtOHE and Cd-HexP did not alter gastric juice parameters such as pH, [H(+)], or volume after pylorus ligation. Cytoprotective mechanisms of Cd-EtOHE and Cd-HexP in relation to mucus, nitric oxide (NO), and sulfhydryl (SH) groups were evaluated. Neither product increased the mucus, and they both showed dependence on NO and SH groups to prevent gastric ulcer. Both Cd-EtOHE and Cd-HexP demonstrated gastroprotective activity.