Effect of chronic treatment with a purified flavonoid fraction on inflammatory granuloma in the rat. Study of prostaglandin E2 and F2 alpha and thromboxane B2 release and histological changes.

S-5682 (Daflon-500 mg), a purified flavonoid fraction, consisting of 90% diosmin (a flavone derivative) and 10% hesperidin (a flavanone derivative), was administered to rats by intubation in the daily dose of 100 mg/d. 15 days after the start of treatment, polyurethane sponges were implanted in the subcutaneous connective tissue in the dorsolumbar region under rapid ether anaesthesia. Similar fragments of sponge were implanted in a group of control animals who received the vehicle (saccharose syrup) only, also by the oral route. The rats were sacrificed in fractions of 7 animals drawn from each of the two groups (control and treated) after 4, 8, 16 and 30 days (only 5 animals from each group on day 30) after implantation of the polyurethane sponges. The granulomas formed were removed, weighed and their prostaglandin (PG)E2, PGF2 alpha and thromboxane (Tx)B2 contents were determined. In addition a full cell count (polymorphs, lymphocytes, macrophages, plasmocytes and giant cells) was performed and the animals were histologically examined. The results show that treatment of the animals with S-5682 had the following effects: 1. A significant fall in the mean weight of the granulomas formed after 4 and 8 days was observed, reflecting inhibition of oedema formation during the early phase of the inflammatory reaction. 2. The synthesis of PGE2 (78.5% inhibition on day 4) and PGF2 alpha (45.2% on day 16) was inhibited. 3. There was very early inhibition of TxB2 synthesis (59.5% inhibition on day 4). 4. A later reduction in cell migration towards the inflammatory focus occurred which was statistically significant on day 16 (49.6% reduction in the total number of migrant cells). 5. Multiple histological aspects of the acute inflammatory reaction (diapedesis of polymorphs, lymphocytes, histiocytes and macrophages) and features of the chronic inflammatory reaction (newly formed microvascularisation of the granuloma tissue, perivascular oedema, presence of collagen fibres) were improved.