Potential anti-inflammatory phenolic glycosides from the medicinal plant Moringa oleifera fruits.
Bioassay-guided isolation and purification of the ethyl acetate extract of Moringa oleifera fruits yielded three new phenolic glycosides; 4-[(2'-O-acetyl-alpha-l-rhamnosyloxy) benzyl]isothiocyanate (1), 4-[(3'-O-acetyl-alpha-l-rhamnosyloxy)benzyl]isothiocyanate (2), and S-methyl-N-{4-[(alpha-l-rhamnosyloxy)benzyl]}thiocarbamate (3), together with five known phenolic glycosides (4-8). The structures of the new metabolites were determined on the basis of spectroscopic analyses including 1D- and 2D-NMR and mass spectrometry. The anti-inflammatory activity of isolated compounds was investigated with the lipopolysaccharide (LPS)-induced murine macrophage RAW 264.7 cell line. It was found that 4-[(2'-O-acetyl-alpha-l-rhamnosyloxy)benzyl]isothiocyanate (1) possessed potent NO-inhibitory activity with an IC(50) value of 1.67 microM, followed by 2 (IC(50)=2.66 microM), 4 (IC(50)=2.71 microM), and 5 (IC(50)=14.4 microM), respectively. Western blots demonstrated these compounds reduced LPS-mediated iNOS expression. In the concentration range of the IC(50) values, no significant cytotoxicity was noted. Structure-activity relationships following NO-release indicated: (1) the isothiocyanate group was essential for activity, (2) acetylation of the isothiocyanate derivatives at C-2' or at C-3' of rhamnose led to higher activity, (3) un-acetylated isothiocyanate derivatives displayed eight times less activity than the acetylated derivatives, and (4) acetylation of the thiocarbamate derivatives enhanced activity. These data indicate compounds 1, 2, 4 and 5 are responsible for the reported NO-inhibitory effect of Moringa oleifera fruits, and further studies are warranted.
Cheenpracha
Sarot
S
Department of Pharmaceutical Sciences, College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, HI 96720, USA.
Park
Eun-Jung
EJ
Yoshida
Wesley Y
WY
Barit
Chaz
C
Wall
Marisa
M
Pezzuto
John M
JM
Chang
Leng Chee
LC
D000893:Anti-Inflammatory Agents / Q000302:isolation & purification / Q000494:pharmacology*; D006027:Glycosides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017879:Isothiocyanates / Q000737:chemistry; D029588:Moringa oleifera / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry; D010636:Phenols / Q000302:isolation & purification / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D013329:Structure-Activity Relationship
D000893:Anti-Inflammatory Agents; D006027:Glycosides; D017879:Isothiocyanates; D010636:Phenols; D010936:Plant Extracts; D009569:Nitric Oxide