Content of the neurotoxins cycasin (methylazoxymethanol β‐D‐glucoside) and BNLAA (β‐ N ‐methylamino‐L‐alanine) in cycad flour prepared by Guam Chamorros

Abstract

Exposure to cycad seed kernel is an etiologic factor for the western Pacific amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC). Traditionally processed cycad flours (n = 17) obtained from Chamorro residents of Guam and the adjacent island of Rota at risk for neurodegenerative disease were extracted and analyzed by high-performance liquid chromatography for content of beta-N-methylamino-L-alanine (BMAA) and methyl-azoxymethanol beta-D-glucoside (cycasin). Cycasin (detection limit: picomole) was present in concentrations of 0.004 to 75.93 micrograms/g (mean, 12.45 +/- 5.0 micrograms/g), and levels of BMAA (detection limit: subpicomole) ranged from 0.00 to 18.39 micrograms/g (mean, 5.44 +/- 1.56 micrograms/g). On average, cycasin content was approximately 10 times higher than that of BMAA. The largest concentrations of cycasin were found in samples from villages with a high reported prevalence of ALS/PDC. Ingestion of cycad-derived food would result in estimated human exposure to milligram amounts of cycasin per day. The cytotoxic properties of cycasin merit consideration in relation to the etiology of western Pacific ALS/PDC.

A mechanism for slow release of biomagnified cyanobacterial neurotoxins and neurodegenerative disease in Guam

“…Samples of five processed cycad flours prepared on Guam from the sliced gametophytes of the seeds of C. micronesica in the traditional manner by Chamorros and collected in 1987-1988 by neurologist J. C. Steele (Guam Memorial Hospital, Tamuning, Guam) were analyzed. Comparable flour samples have been analyzed by other workers (11,(14)(15)(16)(17)(18).…”

Ageing and the brain

“…Other beneficial influences on brain function in old age are physical exercise [90], extended years of education [91,92], cognitive stimulation [93] and a high intake of polyunsaturated fatty acids [94] and B vitamins, particularly vitamins B6, B12 and folate [95] and statins [96]. The influence of toxins in causing brain damage in normal brain ageing is not clear but vigilance is called for, as some environmental toxins have been implicated as risk factors in age-related disease, for example, the pesticide rotenone and the herbicide paraquat in PD [97] and a product of cycad seeds, β-methylamino-L-alanine (BMAA), in Guam disease [98].…”

Analysis, occurrence, and toxicity of ß-methylaminoalanine (BMAA)

“…Kisby, Spencer and collaborators presented an HPLC method for BMAA using FMOC (9-fluorenylmethyl chloroformate) as derivatisation reagent and detection of the formed fluorescent adduct (Kisby et al, 1988, andKisby et al, 1992). Samples analyzed were derived from cycads or were tissues from monkeys and rats supplied cycad material in the fed.…”

“…Traditional Chamorro foods include tortillas, dumplings, and cakes that up to the 1950's was prepared from flour of Cycas circinalis seeds (Kisby et al, 1992;Banack and Cox, 2006). 4 When preparing the flour, the relatively large cycad seed sclerotesta is cracked, the sarcotesta (kashkada) removed, and the gametophyte (piptega) cut into slices.…”