Allium species of the subgenus Melanocrommyum are a rich source for cysteine sulphoxides

The plant genus Allium (onions) is highly diverse. About 800 species are currently known belonging to several subgenera [1]. The main centre of distribution is the northern hemisphere, especially the area of Southwest und Central Asia. Inside this area, the subgenus Melanocrommyum is most prominent. Methiin 1 seems to be a nearly ubiquitous cysteine sulphoxide for the genus Allium (Figure 1). Propiin 2 is a minor compound, which was found in A. ubipretense R.M. Fritsch. The L-(+)-S-(3-pyridyl)cysteine sulphoxide 3 is the major cysteine sulphoxide of A. stipitatum Regel (0.22%, related to the fresh weight of bulbs) as well as the closely related A. altissimum Regel (0.50%) [2]. It seems to be possible that the corresponding N-oxide 3a is also present in these plants. Most species of the subgenus do also contain the L-(+)-S-(3-pyrrolyl)cysteine sulphoxide 4 [3]. High amounts of 4 were found in A. jesdianum Boiss. & Buhse subsp. remediorum R.M. Fritsch (0.52%), A. macleanii Baker (0.29%), A. tschimganicum (0.23%) and A. rosenorum (0.20%). Highest amounts of marasmin 5 were detected in A. suworowii (2.25%). Compound 5 is also present in A. altissimum and A. stipitatum. Especially the latter species is widely used as vegetable, spice and traditional medicine.

Figure 1: Typical cysteine sulphoxides of the subgenus Melanocrommyum

Keywords: Allium, Melanocrommyum, A. stipitatum, A. altissimum, A. jesdianum, A. rosenorum, A. suworowii, cysteine sulphoxides, marasmin

References: 1 Fritsch R M. et al. [2010) Phyton (Horn, Austria) 49(2):145–220

2 Kusterer J et al. (2010)J Agric Food Chem 58(1): 520–526

3 Jedelská J et al. (2008)J Agric Food Chem 56(4): 1465–1470