Consumption of fa cai Nostoc soup: A Potential for BMAA exposure from Nostoc cyanobacteria in China?

Grown in arid regions of western China the cyanobacterium Nostoc flagelliforme - called fa cai in Mandarin and fat choy in Cantonese - is wild-harvested and used to make soup consumed during New Year's celebrations. High prices, up to $125 USD/kg, led to overharvesting in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang. Degradation of arid ecosystems, desertification, and conflicts between Nostoc harvesters and Mongol herdsman concerned the Chinese environmental authorities, leading to a government ban of Nostoc commerce. This ban stimulated increased marketing of a substitute made from starch. We analysed samples purchased throughout China as well as in Chinese markets in the United States and the United Kingdom. Some were counterfeits consisting of dyed starch noodles. A few samples from California contained Nostoc flagelliforme but were adulterated with starch noodles. Other samples, including those from the United Kingdom, consisted of pure Nostoc flagelliforme. A recent survey of markets in Cheng Du showed no real Nostoc flagelliforme to be marketed. Real and artificial fa cai differ in the presence of beta-N-methylamino-L-alanine (BMAA). Given its status as a high-priced luxury food, the government ban on collection and marketing, and the replacement of real fa cai with starch substitutes consumed only on special occasions, it is anticipated that dietary exposure to BMAA from fa cai will be reduced in the future in China.

应用量化参数和CoM FA法研究苯甲酸类化合物的结构和其pK_a值的相关性

提取量子化学参数来表征苯甲酸类化合物的结构 ,应用多元回归方法和人工神经网法在该类化合物的结构和 p Ka 值间构造了二维空间的数学模型 ,并进一步运用 Co MFA法在三维空间进行研究。人工神经网络法和 Co MFA法获得了比较好的结果 ,同时 ,讨论了空间作用和静电作用对 p Ka值的影响。