New cyclic sulfides, garlicnins I2, M, N, and O, from Allium sativum

Abstract

One atypical thiolane-type sulfide, garlicnin I (1), two 3,4-dimethylthiolane-type sulfides, garlicnins M (2) and N (3), and one thiabicyclic-type sulfide, garlicnin O (4), were isolated from the acetone extracts of Chinese garlic bulbs, Allium sativum and their structures were characterized. Hypothetical pathways for the production of the respective sulfides were discussed.

Allithiolanes: Nine Groups of a Newly Discovered Family of Sulfur Compounds Responsible for the Bitter Off-Taste of Processed Onion

“…Three stereoisomers of these compounds, called garlicnins C 1 , C 2 , and C 3 , were recently isolated from garlic homogenates (Figure ). , …”

Ajothiolanes: 3,4-Dimethylthiolane Natural Products from Garlic (Allium sativum)

“…Our procedure for the isolation of ajothiolane is summarized in Figure 6. Thus, from 6 kg of peeled garlic, macerated in acetone and then extracted with CH 16) from alliin (15): conversion of allicin (17) to ajoene (20) via intermediates 18 and 19, to trisulfide S-oxide 21 and allyl alcohol (22), and to vinyl dithiins 24a and 24b via thioacrolein (23). from Table 1, there was excellent agreement between our 1 H and 13 C NMR data for compounds 14a,b and Nohara's compounds 10a,b; similar agreement is found for the NMR data for the m/z 209 compound 25 we term "methylisoajoene" isolated by us and Nohara's compounds 9, as shown in Table 4.…”

“…In a series of papers from 2010 to 2018, Nohara and co-workers reported the isolation and structural characterization of isomeric families of biologically active 3,4-dimethylthiolanesulfenic acids which they named “onionin A 1–3 ” (C 9 H 16 O 2 S 2 , m / z 220; 7 ) from onion and Allium fistulosum , − and garlicnins A (C 12 H 20 O 2 S 4 , m / z 324; 8 ), D (C 7 H 12 OS 3 , m / z 208; 9 ), and B 1–4 (C 9 H 16 O 2 S 2 , m / z 220; 10a - d ), among others, from garlic (Figure ). − The authors suggest that compounds 7 – 10 originate from alliinase-catalyzed reactions involving isoalliin 1 and its isomer alliin ( 15 ; see Figure below) but propose subsequent steps that are at variance with the extensive body of knowledge on the biosynthetic pathways of Allium compounds , and with the structures of 4 , 6b , c , and allium sulfoxide A 1 ( 11 ; Figure ), recently isolated from Allium fistulosum. For example, it is very difficult to imagine how nine carbons could be connected to form 7 , 8 , and 10 from any likely Allium precursor.…”

“…illustrates the likely sequence of steps from alliin (15) via 2-propenesulfenic acid(16), allicin(17), and sulfonium ions 18 and 19 to ajoene (20), diallyl trisulfide S-oxide(21), and allyl alcohol(22) based on DART-MS studies of crushed garlic.…”

Thiolane-type sulfides from garlic, onion, and Welsh onion

“…Structures of garlicnins and onionins isolated from garlic filtrate was concentrated at 40 °C in vacuum to obtain the extract in a small volume that was partitioned between ethyl acetate and water. The ethyl acetate extractive (5.9 g) was separated by column chromatography on silica gel eluting with n-hexane: acetone (from 6: 1 to 2: 1) to yield 21 new sulfides named garlicnins A (48.2 mg) [12], B 1 (242.0 mg), B 2 (47.2 mg), B 3 (29.8 mg), B 4 (19.3 mg), C 1 (26.4 mg), C 2 (23.4 mg), C 3 (14.6 mg) [13,14], G (17.2 mg), I 1 (17.4 mg) [15], I 2 (15.6 mg) [16], J 1 (17.4 mg) [15], J 2 (19.4 mg) [17], L-1 (47.2 mg), L-2 (19.8 mg), L-3 (19.3 mg), L-4 (23.4 mg) [18], M (21.1 mg) [16], P (18.4 mg) [17], and onionins B 1 (27.4 mg), and B 2 (26.2 mg) [19], together with the known sulfide, (E)-ajoene (279.7 mg) [10], and kujounin A 1 derivative (22.1 mg), which related to kujounin A 1 obtained from Allium fistulosum by Matsuda et al [20]. The structures of the obtained sulfides were characterized using high-resolution fast atom bombardment mass spectroscopy (HR-FABMS), 1 H-NMR, 13 C-NMR, 1 H-1 H NMR correlation spectroscopy (COSY), 1 H-detected heteronuclear correlation through multiplet quantum coherence (HMQC), heteronuclear multiple bond correlation (HMBC) and nuclear Overhauser effect spectroscopy (NOESY).…”