Hypoglycemic activity of extracts and compounds from the leaves of Hintonia standleyana and H. latiflora: potential alternatives to the use of the stem bark of these species.

The CH(2)Cl(2)-MeOH (1:1) extract of the leaves of Hintonia standleyana and H. latiflora caused significant decrease in blood glucose levels in both normal and streptozotozin (STZ)-induced diabetic rats when compared with vehicle-treated groups (p < 0.05). These extracts were not toxic to mice according to the Lorke criteria. From the hypoglycemic extract of H. standleyana, two new 4-phenylcoumarins, namely, 6''-O-acetyl-5-O-beta-d-galactopyranosyl-7,4'-dihydroxy-4-phenylcoumarin (1) and 6''-O-acetyl-5-O-beta-d-galactopyranosyl-7,3',4'-trihydroxy-4-phenylcoumarin (2), were obtained. The analogous extract of H. latiflora yielded the new 5-O-[beta-d-xylopyranosyl-(1-->6)-beta-d-glucopyranosyl]-7,4'-dimethoxy-4-phenylcoumarin (3) along with several known compounds, including ursolic acid and desoxycordifolinic acid. Phenylcoumarins 1 and 2 showed hypoglycemic activity. HPLC profiles of the leaf extracts of both plants revealed the presence of known hypoglycemic phenylcoumarins as well as chlorogenic acid. The overall results have indicated that the leaves of H. standleyana and H. latiflora possess similar antidiabetic potential to their stem bark. Therefore, the leaves from these species could represent an alternative to the use of their stem bark, which, in turn, would contribute to the conservation of these Mexican medicinal plants.

Antinociceptive, hypoglycemic and spasmolytic effects of Brickellia veronicifolia.

INTRODUCTION: Brickellia veronicifolia (Kunth) Gray (Asteraceae) (BV) is broadly commercialized for treating gastrointestinal diseases (stomach aches, biliary colics and dyspepsia), arthritis, diabetes and painful inflammatory complaints. AIMS OF THE STUDY: In order to complete the preclinical pharmacological profile of BV, first the antinociceptive effect of an organic extract (BVE) and isolated metabolites on the hot plate and writhing tests was assessed. EXPERIMENTAL: Then, their potential hypoglycemic effects were analyzed in normoglycemic and diabetic rats; in addition, an oral glucose tolerance test (OGTT) was performed. Finally, the spasmolytic activity of BVE was assessed in vivo using the gastrointestinal motility test (GMT) in mice. RESULTS: The results revealed that BVE (100-600 mg/kg), 6-methoxysalicylic acid (1), 2-methoxybenzoic acid (2), benzyl-2,6-dimethoxybenzoate (3), and taraxasteryl acetate (4) showed significant analgesic effects. Compounds 2 and 3 were the most active (1-100mg/kg) in the hot plate and writhing tests, respectively. In the antidiabetic assays, BVE (100mg/kg) showed an important hypoglycemic action. Furthermore, at the same dose, it provoked a significant postprandial decrease of blood glucose level after 30 min of a glucose challenge. Finally, the GMT in mice revealed the spasmolytic activity in vivo of BVE (31.6 mg/kg). CONCLUSION: The overall information tends to support the vernacular uses of the plant.