Chemistry of non-protein amino acids

人类的饮食几乎完全由植物或食用植物的动物组成，植物化学在几个方面影响人类健康。 植物是维生素、营养素和抗氧化剂的来源，这些物质对身体健康至关重要，但平均一片叶子含有多达30，000种不同的化学物质，而对其中绝大多数化学物质几乎一无所知。 β-甲氨基-L-丙氨酸（BMAA）是一种天然存在的非蛋白质氨基酸，最初发现于苏铁种子中，由与植物共生或自由生活在淡水或海洋环境中的蓝细菌产生。 “BMAA假说”假设BMAA可以从蓝细菌积累到植物，以植物为食的动物以及食用植物和动物的人，并且高暴露于BMAA可能会诱发进行性神经退行性疾病，如ALS或阿尔茨海默病。 BMAA最初是在了解关岛进行性神经变性疾病流行的研究中描述的，BMAA积累已在各种食物网中得到证实，包括关岛查莫罗人的传统饮食，以及南佛罗里达的蓝蟹、虾和鱼，波罗的海的牡蛎和鱼，以及大西洋的鱼翅。 然而，不同的实验室在研究中报告了非常不同的结果，以识别和量化蓝藻，食品和人体组织中的BMAA，导致争议，使数据解释复杂化，必须在BMAA假设得到充分验证之前解决。 我们提出了一个详细的分析研究，将提供有效的方法和工具，监测食物链和环境样品，并将确定蓝藻BMAA生产的机制和条件。 总之，这些研究是评估BMAA假设和潜在理解神经退行性疾病的第一个重要步骤。

The human diet is made up almost entirely of plants or animals that consumed plants and plant chemistry affects human health in several ways. Plants are the source of vitamins, nutrients and antioxidants that are essential to good health but an average leaf contains up to 30,000 distinct chemicals and virtually nothing is known about the vast majority of these. Beta-methylamino-L-alanine (BMAA) is a naturally-occurring non-protein amino acid that was originally discovered in cycad seeds and is produced by cyanobacteria that live in symbiosis with plants or are free living in fresh water or marine environments. The 'BMAA Hypothesis' postulated that BMAA could accumulate from cyanobacteria to plants to the animals that feed on the plants and to people who eat the plants and animals and that high exposures to BMAA may induce progressive neurodegenerative diseases such as ALS or Alzheimer's Disease. BMAA was originally described in studies to understand an epidemic of progressive neurodegenerative disease in Guam and BMAA accumulation has been demonstrated in various food webs including the traditional diet of the Chamorro people of Guam, as well as blue crabs, shrimp and fish of South Florida, oysters and fish of the Baltic Sea, and shark fins from the Atlantic. However, different labs have reported remarkably very different results in studies to identify and quantify BMAA in cyanobacteria, foods and human tissues leading to controversy that complicates data interpretation and must be resolved before the BMAA hypothesis can be fully tested. We are proposing a detailed analytical study that will provide validated methods and tools for monitoring of food chains and environmental samples and will determine the mechanism and conditions of BMAA production by cyanobacteria. Together, these studies are the first important steps toward evaluating the BMAA hypothesis and potentially toward understanding neurodegenerative disease.