Effect of Pholiota nameko Polysaccharides Inhibiting Methylglyoxal-Induced Glycation Damage In Vitro

Natural polysaccharides: The potential biomacromolecules for treating diabetes and its complications via AGEs-RAGE-oxidative stress axis

Diabetes mellitus, a chronic metabolic disorder, poses a significantly public health challenge. Extensive research highlights that contemporary dietary patterns, characterized by excessive intake of sugar, fat, and protein, are major contributors to the onset and progression of diabetes. The central element to this process is the aberrant activation of the advanced glycation end products (AGEs) - receptor for AGEs (RAGE) - oxidative stress axis, which plays a pivotal role in disrupting normal carbohydrate metabolism. This pathway presents a critical target for developing interventions aimed at mitigating diabetes and its complications. In recent years, natural polysaccharides have emerged as promising agents in the prevention and treatment of diabetes, due to their ability to inhibit AGE formation, regulate RAGE expression, and modulate the AGEs-RAGE-oxidative stress axis. In this paper, we explore the pathogenic mechanism of this axis and review the therapeutic potential of natural polysaccharides in managing diabetes and its complications. Our goal is to provide new insights for the effective management of diabetes and its associated health challenges.

Advanced glycation end products impair the repair of injured tendon: a study in rats

BACKGROUND

The AGEs levels in tissues of diabetics and elderly tend to be higher than in normal individuals. This study aims to determine the effects of AGEs on Achilles tendon repair.

MATERIALS AND METHODS

Thirty-six male eight-week-old Sprague Dawley rats were selected in this study. The rats were randomly divided into two experimental groups and a control group after the transection of the Achilles tendon. During the tendon repair, the experimental groups were injected around the Achilles tendon with 350mmol/L (low dose group) and 1000mmol/L (high dose group) D-ribose 0.2 ml respectively to increase the AGEs level, while in the control group were given the same amount of PBS. The injections were given twice a week for six weeks. Collagen-I, TNF-α, and IL-6 expression in the healed Achilles tendon was assessed. Additionally, macroscopic, pathological, and biomechanical evaluations of Achilles tendon repair were conducted.

RESULTS

The repaired Achilles tendons in the high dose group showed severe swelling and distinctive adhesions. The histological score went up with the increase of the AGEs in the Achilles tendon (p<0.001). TNF- α and IL-6 in the Achilles tendon increased (p<0.001, p<0.001), and the production of collagen-I decreased with the accumulation of AGEs in the repaired Achilles tendon (p<0.001). The tensile strength of Achilles tendon in the high dose group was impaired significantly.

CONCLUSION

In current study, the compromised tendon repair model induced by AGEs was successfully established in rat. The study demonstrated that AGEs significantly impair Achilles tendon repair.

Pioglitazone Antagonized the Effects of Advanced Glycation End Products on Achilles Tendon Healing and Improved the Recovery of Tendon Biomechanical Properties

Purpose

Advanced glycation end products (AGEs) often accumulate in the Achilles tendon during the course of diabetes. This study aims to determine the impact of AGEs on tendon repair and explore the role of pioglitazone in mitigating this impact.

Methods

Forty-eight male 8 week-old Sprague Dawley rats were selected in this study. After transection of Achilles tendon, the rats were randomly divided into four groups. The Achilles tendons of rats were injected with 1000 mmol/L D-ribose to elevate the content of AGEs within the tendons in two groups, the remaining two groups received injections of phosphate buffered saline (PBS) solution. Subsequently, the first two groups were respectively received oral administration of pioglitazone (20 mg/kg/day) and PBS. The remaining two groups were given the same treatment. The expression of the collagen-I, TNF-α, IL-6 of the repaired tendon were detected. The macroscopic, pathologic and biomechanical aspects of tendon healing were also evaluated.

Results

AGEs accumulation in tendon during the healing process increases the expression of inflammatory factors such as TNF-α and IL-6, leading to insufficient synthesis of collagen-I and delayed recovery of the tendon's tensile strength. Pioglitazone significantly attenuated the damage caused by AGEs to the tendon healing process, effectively improving the recovery of tendon tensile strength. Pioglitazone could not inhibit the generation of AGEs in the tissue and also had no impact on the normal healing process of the tendon.

Conclusions

Pioglitazone could prevent the deleterious impact of AGEs on the Achilles tendon healing and improve the biomechanical properties of the tendon.

Polysaccharides from natural resource: ameliorate type 2 diabetes mellitus via regulation of oxidative stress network

Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia that can occur in children, adults, elderly people, and pregnant women. Oxidative stress is a significant adverse factor in the pathogenesis of DM, especially type 2 diabetes mellitus (T2DM), and metabolic syndrome. Natural polysaccharides are macromolecular compounds widely distributed in nature. Some polysaccharides derived from edible plants and microorganisms were reported as early as 10 years ago. However, the structural characterization of polysaccharides and their therapeutic mechanisms in diabetes are relatively shallow, limiting the application of polysaccharides. With further research, more natural polysaccharides have been reported to have antioxidant activity and therapeutic effects in diabetes, including plant polysaccharides, microbial polysaccharides, and polysaccharides from marine organisms and animals. Therefore, this paper summarizes the natural polysaccharides that have therapeutic potential for diabetes in the past 5 years, elucidating their pharmacological mechanisms and identified primary structures. It is expected to provide some reference for the application of polysaccharides, and provide a valuable resource for the development of new diabetic drugs.

Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors

Our skin is an organ with the largest contact area between the human body and the external environment. Skin aging is affected directly by both endogenous factors and exogenous factors (e.g., UV exposure). Skin saccharification, a non-enzymatic reaction between proteins, e.g., dermal collagen and naturally occurring reducing sugars, is one of the basic root causes of endogenous skin aging. During the reaction, a series of complicated glycation products produced at different reaction stages and pathways are usually collectively referred to as advanced glycation end products (AGEs). AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with aging. AGEs are also associated with a variety of age-related diseases, such as diabetes, cardiovascular disease, renal failure (uremia), and Alzheimer's disease. AGEs accumulate in the skin with age and are amplified through exogenous factors, e.g., ultraviolet radiation, resulting in wrinkles, loss of elasticity, dull yellowing, and other skin problems. This article focuses on the damage mechanism of glucose and its glycation products on the skin by summarizing the biochemical characteristics, compositions, as well as processes of the production and elimination of AGEs. One of the important parts of this article would be to summarize the current AGEs inhibitors to gain insight into the anti-glycation mechanism of the skin and the development of promising natural products with anti-glycation effects.