R. Tundis

Natural Products as α-Amylase and α-Glucosidase Inhibitors and their Hypoglycaemic Potential in the Treatment of Diabetes: An Update

The inhibition of alpha-glucosidase and alpha-amylase, enzymes involved in the digestion of carbohydrates, can significantly reduce the post-prandial increase of blood glucose and therefore can be an important strategy in the management of blood glucose level in type 2 diabetic and borderline patients. Currently, there is renewed interest in plant-based medicines and functional foods modulating physiological effects in the prevention and cure of diabetes and obesity. The plant kingdom is a wide field to search for natural effective oral hypoglycaemic agents that have slight or no side effects. More than ca. 1200 plant species have been recorded to be used empirically worldwide for their alleged hypoglycaemic activity. Therefore, natural alpha-glucosidase and alpha-amylase inhibitors from plant sources offer an attractive strategy for the control of hyperglycaemia. This article reviews recent data on plant extracts and isolated natural compounds that are being tested for their hypglycaemic activity, highlights ongoing research and considers the future persepctives.

Biological and Pharmacological Activities of Iridoids: Recent Developments

Iridoids represent a large group of cyclopenta[c]pyran monoterpenoids that occur wide-spread in nature, mainly in dicotyledonous plant families like Apocynaceae, Scrophulariaceae, Diervillaceae, Lamiaceae, Loganiaceae and Rubiaceae. Recently, more extensive studies revealed that iridoids exhibit a wide range of bioactivity, such as neuroprotective, antinflammatory and immunomodulator, hepatoprotective and cardioprotective effects. Anticancer, antioxidant, antimicrobic, hypoglycaemic, hypolipidemic, choleretic, antispasmodic and purgative properties were also reported. The aim of the present review is to discuss the recent developments on biological and pharmacological activities of iridoids, supporting the new therapeutic possibilities for the use of these compounds.

Pyrrolizidine alkaloid profiles of the Senecio cineraria group (Asteraceae).

Alkaloid profiles of five Senecio species (Asteraceae), including S. ambiguus subsp. ambiguus, S. ambiguus subsp. nebrodensis, S. gibbosus subsp. bicolor, S. gibbosus subsp. gibbosus, and S. gibbosus subsp. cineraria, were studied. Eleven pyrrolizidine alkaloids were identified and their content was evaluated by GLC-MS and GLC analysis. Otosenine and florosenine were found to be the major alkaloids in all studied species. It is interesting that only S. ambiguus subsp. nebrodensis was characterized by a high content of the alkaloids jacobine, jacoline, jaconine, and jacozine

In vitro Cytotoxic Activity of Salsola oppositifolia Desf. (Amaranthaceae) in a Panel of Tumour Cell Lines

The aim of the present study was to evaluate for the first time the in vitro cytotoxic activity of fractions and isolated flavonols from Salsola oppositifolia Desf. (Amaranthaceae). The nhexane fraction demonstrated an effective cytotoxic activity on the large lung carcinoma and amelanotic melanoma cell lines with IC50 values of 19.1 μg/ml and 24.4 μg/ml, respectively. Also the dichloromethane fraction exhibited cytotoxic activity against COR-L23 (IC50 30.4 μg/ml) and C32 (IC50 33.2 μg/ml) cells, while the EtOAc fraction demonstrated a selective cytotoxic activity against MCF-7 cells (IC50 67.9 μg/ml). The major active constituents of this fraction were isorhamnetin-3-O-glucoside (1) and isorhamnetin-3-O-rutinoside (2), which showed an interesting activity against the cell line MCF-7 with IC50 values of 18.2 and 25.2 μg/ml, respectively. Compound 2 exhibited a strong activity against the hormonedependent prostate carcinoma LNCaP cell line with an IC50 of 20.5 μg/ml. Constituents of S. oppositifolia were identified by GC-MS and NMR analyses.