Diabetes is a group of metabolic diseases characterised by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The chronic hyperglycemia of diabetes is associated with long-term damage and dysfunction of many organs. Diabetes caused 1.5 million deaths in 2012, with hyperglycemia causing an additional 2.2 million deaths, as it is associated with increased risk of cardiovascular and other diseases. Various types of plants have been used for several centuries worldwide not only as dietary supplements but also as traditional treatment regimens for many diseases. So far, a large number of traditionally claimed plant medicine has been tested for diabetes and some of them showed a promising therapeutic potential. The main focus of this review is to describe what we know to date of herbal extracts, along with their glucose-lowering mechanisms, which are either through insulin-mimicking activity, enhanced β-cells regeneration, or glucose uptake.

Hyperlipidemia is an abnormality of lipid metabolism, characterized by an elevation of total cholesterol, triglyceride, and low density lipoprotein-cholesterol, and/or a decreasing of high density lipoprotein cholesterol in circulating levels. Hyperlipidemia has been ranked as one of the greatest risk factors contributing to prevalence and severity of coronary heart diseases. Hyperlipidemia-associated lipid disorders are considered the cause of atherosclerotic cardiovascular disease. There has been a growing interest in natural products and their role in the maintenance and improvement of health and wellness. The cholesterol-lowering effect of dietary plants has been well studied and various natural products were shown to be helpful in lowering plasma cholesterol levels and encouraging safety profile. The main focus of this review is to describe what we know to date of natural products, along with their lipid-lowering mechanisms, which are either through inhibition of cholesterol absorption, inhibition of cholesterol synthesis or antioxidant mechanisms.

The potential of heat shock protein 90 (Hsp90) as a therapeutic target for numerous diseases has made the identification and optimization of novel Hsp90 inhibitors an emerging therapeutic strategy. A surface plasmon resonance (SPR) approach was adopted to screen some iridoids for their Hsp90 α binding capability. Twenty-four iridoid derivatives, including 13 new natural compounds, were isolated from the leaves of Tabebuia argentea and petioles of Catalpa bignonioides. Their structures were elucidated by NMR, electrospray ionization mass spectrometry, and chemical methods. By means of a panel of chemical and biological approaches, four iridoids were demonstrated to bind Hsp90 α. In particular, the dimeric iridoid argenteoside A was shown to efficiently inhibit the chaperone in biochemical and cellular assays. Our results disclose C9-type iridoids as a novel class of Hsp90 inhibitors.

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