Allixin is a phytoalexin found in garlic (Allium sativum) bulbs. It was first isolated and characterized in 1989.[1] When garlic is stored for long periods of time, it can form visible accumulations of crystalline allixin on its surface, particularly in areas where tissue has become necrotic.[2] After 2 years of storage, the amount of allixin accumulated can approach 1% of the dry weight of the cloves. Since allixin has weak antimicrobial activity,[1] these high concentrations are thought to be produced by the garlic bulb to protect itself from further damage from microorganisms.

Allixin
Names
Preferred IUPAC name
3-Hydroxy-5-methoxy-6-methyl-2-pentyl-4H-pyran-4-one
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/C12H18O4/c1-4-5-6-7-9-10(13)11(14)12(15-3)8(2)16-9/h13H,4-7H2,1-3H3 checkY
    Key: OHRPDNHRQKOLGN-UHFFFAOYSA-N checkY
  • InChI=1S/C12H18O4/c1-4-5-6-7-9-10(13)11(14)12(15-3)8(2)16-9/h13H,4-7H2,1-3H3
  • O=C1C(/OC)=C(\O/C(=C1/O)CCCCC)C
Properties
C12H18O4
Molar mass 226.272 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Since allixin is found in high concentrations in garlic, there has been scientific interest in determining if it is responsible for any of the known health benefits of garlic. As a result of ongoing research, a variety of biological activities have been attributed to allixin. Pharmaceutical drug discovery research based on derivatives of allixin has followed.[3]

Laboratory synthesis edit

Two laboratory syntheses of allixin have been developed. In the first method, reported in 1997, allixin was synthesized in 22 steps starting from D-mannose.[4] A shorter synthesis was developed in 1998 which involved only 5 steps, starting from 5-methylfurfural.[5]

Biological activities edit

In in vitro studies, allixin demonstrates neurotrophic activity, but at high concentrations it has cytotoxic effects.[6] Simple chemical analogs of allixin were found to have more potent neurotrophic activity, but without the cytotoxic effects.[6] Allixin may therefore be a useful starting point for the development of pharmaceutical drugs for the treatment of neurodegenerative disorders or for neuronal regeneration in the brain.[6]

Pharmacological studies have demonstrated that allixin exerts an anti-promoting activity against skin tumors induced by the chemical 12-O-tetradecanoylphorbol-13-acetate (TPA)[7] and an inhibitory effect on aflatoxin B1-induced mutagenesis.[8] Allixin may therefore be responsible, at least in part, for the tumor-preventative effects of garlic extract.[9][10]

Allixin has also been shown to have a radical scavenging effect.[11]

Metal complexes edit

Metal complexes with allixin have been shown to have beneficial pharmacological effects in animal models of diabetes.[3] A complex with vanadium, bis(allixinato)oxovanadium(IV), is a potent anti-diabetic agent. In studies in streptozotocin-induced diabetic mice, this vanadium complex was shown to be an insulin mimetic with hypoglycemic effects.[12] Similarly, a zinc-allixin complex, bis(allixinato)zinc(II), shows the same insulin mimetic effects.[13][14] The mechanism of action by which these complexes regulate insulin signaling pathways is unclear.[3]

References edit

  1. ^ a b Kodera, Yukihiro; Matsuura, Hiromichi; Yoshida, Susumu; Sumida, Toshihiko; Itakura, Yoichi; Fuwa, Toru; Nishino, Hoyoku (1989). "Allixin, a stress compound from garlic". Chemical & Pharmaceutical Bulletin. 37 (6): 1656–1658. doi:10.1248/cpb.37.1656.
  2. ^ Kodera, Y; Ayabe, M; Ogasawara, K; Yoshida, S; Hayashi, N; Ono, K (2002). "Allixin Accumulation with Long-term Storage of Garlic". Chemical & Pharmaceutical Bulletin. 50 (3): 405–7. doi:10.1248/cpb.50.405. PMID 11911208.
  3. ^ a b c Hiromura, Makoto; Sakurai, Hiromu (2008). "Action mechanism of metallo-allixin complexes as antidiabetic agents". Pure and Applied Chemistry. 80 (12): 2727–2733. doi:10.1351/pac200880122727.
  4. ^ Arimoto, H (1997). "Total synthesis of allixin; an anti-tumor promoter from garlic". Tetrahedron Letters. 38 (44): 7761–7762. doi:10.1016/S0040-4039(97)10072-7.
  5. ^ Matsumura, Y (1998). "Facile Synthesis of Allixin and Its Related Compounds". Tetrahedron Letters. 39 (16): 2339–2340. doi:10.1016/S0040-4039(98)00148-8.
  6. ^ a b c Moriguchi, T; Matsuura, H; Itakura, Y; Katsuki, H; Saito, H; Nishiyama, N (1997). "Allixin, a phytoalexin produced by garlic, and its analogues as novel exogenous substances with neurotrophic activity". Life Sciences. 61 (14): 1413–20. doi:10.1016/S0024-3205(97)00687-5. PMID 9335231.
  7. ^ Nishino, H.; Nishino, A.; Takayasu, J.; Iwashima, A.; Itakura, Y.; Kodera, Y.; Matsuura, H.; Fuwa, T. (1990). "Antitumor-promoting activity of allixin, a stress compound produced by garlic". Cancer Journal. 3 (1): 20–21.
  8. ^ Yamasaki, T.; Teel, R.W.; Lau, B.H.S. (1991). "Effect of allixin, a phytoalexin produced by garlic, on mutagenesis, DNA-binding and metabolism of aflatoxin B1". Cancer Letters. 59 (2): 89–94. doi:10.1016/0304-3835(91)90171-D. PMID 1909211.
  9. ^ Dorant E, van den Brandt PA, Goldbohm RA, Hermus RJ, Sturmans F (1993). "Garlic and its significance for the prevention of cancer in humans: a critical view". British Journal of Cancer. 67 (3): 424–429. doi:10.1038/bjc.1993.82. PMC 1968250. PMID 8439494.
  10. ^ Agarwal, Kailash C. (1996). "Therapeutic actions of garlic constituents". Medicinal Research Reviews. 16 (1): 111–124. doi:10.1002/(SICI)1098-1128(199601)16:1<111::AID-MED4>3.0.CO;2-5. PMID 8788216. S2CID 20891167.
  11. ^ Imai, J.; Ide, N.; Nagae, S.; Moriguchi, T.; Matsuura, H.; Itakura, Y. (1994). "Antioxidant and radical scavenging effects of aged garlic extract and its constituents". Planta Medica. 60 (5): 417–420. doi:10.1055/s-2006-959522. PMID 7997468. S2CID 44533555.
  12. ^ Adachi, Yusuke; Yoshida, Jiro; Kodera, Yukihiro; Katoh, Akira; Takada, Jitsuya; Sakurai, Hiromu (2006). "Bis(allixinato)oxovanadium(IV) Complex Is a Potent Antidiabetic Agent: Studies on Structure−Activity Relationship for a Series of Hydroxypyrone−Vanadium Complexes". Journal of Medicinal Chemistry. 49 (11): 3251–6. doi:10.1021/jm060229a. PMID 16722643.
  13. ^ Adachi, Yusuke; Yoshida, Jiro; Kodera, Yukihiro; Kato, Akira; Yoshikawa, Yutaka; Kojima, Yoshitane; Sakurai, Hiromu (2004). "A new insulin-mimetic bis(allixinato)zinc(II) complex: structure?activity relationship of zinc(II) complexes". Journal of Biological Inorganic Chemistry. 9 (7): 885–893. doi:10.1007/s00775-004-0590-8. PMID 15378407. S2CID 11210678.
  14. ^ Adachi, Yusuke; Yoshida, Jiro; Kodera, Yukihiro; Sakurai, Hiromu (2005). "A Highly Potent Insulin–mimetic Zinc(II) Complex with a Zn(S2O2) Coordination Mode: Bis(1,6-dimethyl-3-hydroxy-5-methoxy-2-pentyl-1,4-dihydropyridine-4-thionato)zinc(II)". Chemistry Letters. 34 (5): 656–657. doi:10.1246/cl.2005.656.