Polyphenols of Melaleuca quinquenervia leaves – pharmacological studies of grandinin

Abstract

Four polyphenolic acid derivatives and three ellagitannins were isolated from the leaves of Melaleuca quinquenervia (Clav.) S. T. Blake for the first time. Their structures were elucidated as gallic acid (1), ellagic acid (2), 3-O-methylellagic acid (3), 3,4,3'-tri-O-methylellagic acid (4), 2,3-O-hexahydroxydiphenoyl-(alpha/beta)-D-(4)C(1)-glucopyranose (5), castalin (6) and grandinin (7) on the basis of chemical, mass spectrometric (-ve ESI-MS) and spectroscopic (UV, (1)H-, (13)C NMR, (1)H,(1)H-, (1)H,(13)C-COSY, (1)H,(1)H-TOCSY and HMBC) analyses. Grandinin (the major compound) showed radical scavenging properties by its reaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical [EC(50) = 4.3 +/- 0.3 micro g mL(-1)]. It was found to be relatively nontoxic in mice [LD(50) = 316 mg Kg(-1) b.wt.]. It exhibited a significant dose-dependent (35-70 mg Kg(-1)) hypoglycemic effect by significantly reducing blood glucose level in basal condition and after heavy glucose load in normal mice. Moreover, it reduced the elevated blood glucose level in STZ-induced diabetic mice. In addition, grandinin reduced the elevated blood urea nitrogen and serum lipid peroxides in STZ-induced diabetic mice.

Azadirachta indica as a Source for Antioxidant and Cytotoxic Polyphenolic Compounds

“…Characteristic downfield shift of C-3' at δ 114.3 (H"+10 ppm) and upfield shift of the carbonyl carbon C-7' at 162.87 (H"-7 ppm) of the flavogallonoyl moiety. The δand J 12 -values of H-1 glucose proved that the absolute configuration at the anomeric position should be of axial OH and equatorial H, which was completely, agree with those of castalagin (Vivas et al, 1995;Okuda et al, 1983 andMoharram et al, 2003). All assigned 1 H and 13 C signals were confirmed by 2D NMR spectral analysis.…”

“…The 1 H NMR spectrum exhibited three singlets, each one proton assigned at ´ 6.59, 6.52 and 6.37 ppm for a C-glycosidic flavogallonoyl attached to C-1, C-2, C-3 and C-5 and HHDP at C-4 and C-6 of open chain glucose. The ´-and J-values of the glucose moiety, especially that of H-1 at δ 5.48 with J 12 of 5.6 Hz, were confirmative for full substituted open glucose with anomeric axial OH-group (Vivas et al, 1995;Okuda et al, 1983;Moharram et al, 2003). Like in the previous C-glycosidic ellagitannin, 13 C NMR spectrum showed 6 upfield typical carbon resonances of a C-glycosidic glucose and 14 resonances of a HHDP moiety together with 21 of flavogallonoyl forming Cglycosidic linkage with C-1 glucose.…”

Rapid arsenic(V)-reduction by fire in schwertmannite-rich soil enhances arsenic mobilisation

“…SI9), at low pH Fe(III) can be chemically reduced during extraction by interactions with phenolic functional groups (Deiana et al, 1995). Melaleuca quinquenervia leaf material contains abundant phenolic compounds (Moharram et al, 2003). Hence, 1 M HCl extracts in these phenolic-rich samples may result in chemical reduction of Fe(III) and thus cause an over-estimate of Fe(II).…”

Experimental antihyperglycemic effect of diterpenoids of llareta Azorella compacta (Umbelliferae) Phil in rats

“…There is a growing list of medicinal agents derived from the tissue of plants that are used to treat hyperglycemia including the aqueous and ethanol infusion of roots (Abuh et al, 1990), stem bark (Ojewole, 2003), leaves (Farzami et al, 2003;Lemus et al, 1999;Moharram et al, 2003;Ugochukwu and Babady, 2003), flowers (Sachdewa and Khemani, 2003), fruits (Ojewole and Adewunmi, 2003) and seeds (Chakrabarti et al, 2003). This effect has been also described specifically for aqueous infusions of the Andean plant Azorella compacta (Umbelliferae) Phil., commonly known as llareta (Wickens, 1995).…”