D-myo-Inositol-1,3,4,5-tetraphosphate (Ins(1,3,4,5)-P4) is formed by the phosphorylation of Ins(1,4,5)P3 by inositol 1,4,5-triphosphate 3-kinase. Ins(1,3,4,5)-P4 increases intracellular calcium levels by two distinct mechanisms: opening calcium channels on both the endoplasmic reticulum to release calcium from internal stores and on the plasma membrane to allow the influx of calcium from outside the cell.
The inositol phosphates (IPs) are a family of molecules produced by altering the phosphorylation status of each of the six carbons on the cyclic inositol structure. They act as second messengers, regulating a wide array of cellular functions. D-myo-inositol-1,3,4,6-tetraphosphate(Ins(1,3,4,6)-P4) largely acts an intermediate, serving as substrate for inositol-1,3,4,6-tetraphosphate 5-kinase to produce inositol-1,3,4,5,6-pentaphosphate, or inositol-1,3,4,6-tetraphosphate 2-kinase to give inositol-1,2,3,4,6-pentaphosphate. These inositol pentaphosphates can be further phosphorylated to produce inositol-1,2,3,4,5,6-hexakisphosphate, or phytic acid, which serves diverse roles in eukaryotic tissues. Ins(1,3,4,6)-P4 is a poor activator of the inositol 1,4,5-trisphospate receptor in vitro. Other functions of this IP remain to be elucidated.
Alphitonin is a flavonoid that has been found in L. leptolepis wood.1 It is also a metabolic intermediate that is formed during the catabolism of quercetin by the human gut bacteria E. ramulus.2,3 |1. Chen, K., Ohmura, W., Doi, S., et al. Termite feeding deterrent from Japanese larch wood. Bioresour. Technol. 95(2), 129-134 (2004).|2. Braune, A., Gütschow, M., Engst, W., et al. Degradation of quercetin and luteolin by Eubacterium ramulus. Appl. Environ. Microbiol. 67(12), 5558-55567 (2001).|3. Jaganath, I.B., Mullen, W., Lean, M.E.J., et al. In vitro catabolism of rutin by human fecal bacteria and the antioxidant capacity of its catabolites. Free Radic. Biol. Med. 47(8), 1180-1189 (2009).
Destruxin B2 is a cyclic hexadepsipeptide mycotoxin that has been found in M. anisopliae and has antiviral, insecticidal, and phytotoxic activities.1,2,3 It inhibits secretion of hepatitis B virus surface antigen (HBsAg) by Hep3B cells expressing hepatitis B virus (HBV) DNA (IC50 = 1.3 μM).1 Destruxin B2 is toxic to Sf9 insect cells in an electric cell-substrate impedance sensing (ECIS) test with a 50% inhibitory concentration (ECIS50) value of 92 μM.4 It is also phytotoxic to B. napus leaves.3 |1. Yeh, S.F., Pan, W., Ong, G.-T., et al. Study of structure-activity correlation in destruxins, a class of cyclodepsipeptides possessing suppressive effect on the generation of hepatitis B virus surface antigen in human hepatoma cells. Biochem. Biophys. Res. Commun. 229(1), 65-72 (1996).|2. Male, K.B., Tzeng, Y.-M., Montes, J., et al. Probing inhibitory effects of destruxins from Metarhizium anisopliae using insect cell based impedance spectroscopy: Inhibition vs chemical structure. Analyst 134(7), 1447-1452 (2009).|3. Buchwaldt, L., and Green, H. Phytotoxicity of destruxin B and its possible role in the pathogenesis of Alternaria brassicae. Plant Pathol. 41(1), 55-63 (1992).