Recent discovery of plant-derived anti-diabetic natural products.

Covering: 2005 to 2010. This review covers recent discoveries of anti-diabetic compounds. Diabetes mellitus (DM) is a complex disease affecting patients' daily life and elevating patients' risk of developing other diseases. There are several forms of diabetes, including type-1 diabetes (insulin-dependent), type-2 diabetes (noninsulin-dependent), and gestational diabetes. Type-2 diabetes is the most common form and the patient population with type-2 DM rises every year. Current treatments meet some but not all patients' needs. Therefore, new anti-diabetic drugs are in great demand. Traditional herbal medicine provides a rich source for new drug discovery. In this review, recent discoveries of anti-diabetic compounds have been summarized according to their chemical structures and mechanisms of action. Anti-diabetic plant extracts, many of which have been used and marketed as dietary supplements, were also included and discussed, and are classified according to the positive control used in the anti-diabetic animal studies. New anti-diabetic natural products found in the recent patent literature are also summarized.

Structure of cymbidine A, a monomeric peptidoglycan-related compound with hypotensive and diuretic activities, isolated from a higher plant, Cymbidium goeringii (Orchidaceae).

The structure of a new monomeric peptidoglycan-related compound with hypotensive and diuretic activities, cymbidine A (1) isolated from the orchid Cymbidium goeringii, was elucidated mainly by spectroscopic analysis. The structure of 1 was shown to involve four amino acids (D-alanin, meso-diaminopimelic acid, D-gultamic acid, and L-valine) and two amino sugars (N-acetylglucosamine and 1,6-anhydro-N-acetylmuramic acid). The sequence of the amino acids and amino sugars was determined by the analysis of 2D NMR data. The absolute stereochemistries of the three amino acids (D-Ala, D-Glu and L-Val) were determined by the modified Marfey's method, and the (6S,10R) configurations of meso-diaminopimelic acid in 1 were indicated on the basis of the CD analysis. The absolute stereochemistry of 1,6-anhydro-N-acetylmuramic acid was also determined by CD data.