Stable, water extractable isothiocyanates from Moringa oleifera leaves attenuate inflammation in vitro

Abstract

Moringa (Moringa oleifera Lam.) is an edible plant used as food and medicine throughout the tropics. A moringa concentrate (MC) made by extracting fresh leaves with water utilized naturally occurring myrosinase to convert four moringa glucosinolates (1–4) into moringa isothiocyanates (5–8). Optimum conditions maximizing MC yield, compound 5 (4-[(α-L-rhamnosyloxy)benzyl]isothiocyanate), and compound 8 (4-[(4’-O-acetyl-α-L-rhamnosyloxy)benzyl]isothiocyanate) content were established (1:5 fresh leaf weight to water ratio at room temperature). The optimized MC contained 1.66% isothiocyanates and 3.82% total polyphenols. Compound 8 exhibited 80% stability at 37 °C for 30 days. MC, 5, and 8 significantly decreased gene expression and production of inflammatory markers in RAW macrophages. Specifically, 5 and 8 attenuated expression of iNOS and IL-1β and production of nitric oxide and TNFβ at 1 and 5 µM. Our results suggest a potential for stable and concentrated moringa isothiocyanates (5–8), delivered in MC as a food-grade product, to alleviate low-grade inflammation associated with chronic diseases.

Direct and Indirect Antioxidant Activity of Polyphenol- and Isothiocyanate-Enriched Fractions fromMoringa oleifera

“…Compounds 1 and 4 were previously purified in our laboratory from a methanolic extract of fresh moringa leaves by HPLC as described by Waterman et al 8 The chemical purity of isolated ITCs was confirmed by LC-MS and 1 H NMR analyses. 8 …”

“…The MS data obtained for the ITCs ( 1 – 4 ) gave the expected m / z values and fragment ions that were characteristic for these compounds. 8 In the current study, the quantification of ITCs in the fractions were done by using standard curves generated for pure 1 and 4 , which were purified (>98%) previously as described by Waterman et al 8 Briefly, 1 µL LC-MS injections of compound 1 at 20, 100, and 200 ng/µL generated a standard curve ( y = 123 x − 0.098, R 2 = 1), and injections of compound 4 at 10, 50, and 100 ng/µL generated a standard curve ( y = 104.32 x − 0.098, R 2 > 0.99). The concentrations of compounds 2 and 3 in the fractions and crude extract were estimated by using the standard curve of compound 4 .…”

“…(Moringaceae family, Brassicales order), commonly known as moringa, have emerged as highly stable analogues due to an additional sugar moiety in the aglycone portion of the molecule (Figure 1B). 8 The presence of a rhamnose sugar moiety is unique to moringa ITCs in nature and likely explains their observed stability and solid appearance at room temperature. It has been shown that compound 1 (4-[(α- l -rhamnosyloxy)benzyl]isothiocyanate) and compound 4 (4-[(4′- O -acetyl-α- l -rhamnosyloxy)benzyl]isothiocyanate) (Figure 1B) from M. oleifera Lam.…”

“…demonstrated 70 and 100% stability, respectively, over 30 days at room temperature. 8 In addition to distinguished stability, studies of moringa ITCs ( 1 – 4 ) revealed possible pharmacological advantages as anti-inflammatory agents over well-studied crucifer ITCs including SF. For example, compound 1 was found to be a stronger inhibitor of nuclear factor kappa B (NF-κB) expression and myeloma growth in nude mice than SF.…”

“…11 Recently, we showed that both compound 1 and 4 attenuated expression of iNOS and IL-1β and formation of NO and tumor necrosis factor alpha (TNFα) in RAW macrophages at 1 and 5 µM concentrations. 8 …”