Relationship between total phenolic content, antioxidant potential, and antiglycation abilities of common culinary herbs and spices.

Advanced glycation endproducts and oxidative stress contribute to the pathogenesis of diabetic complications. The total phenolic content (TPC), antioxidant, and antiglycation properties of crude ethanolic extracts of 10 common culinary herbs and spices from Mauritius were investigated in vitro. Fluorescence at 370 nm/440 nm was used as an index of albumin glycation. Allium sativum had the highest TPC (3.1 mg GAE/mL), whereas Allium cepa L. showed the highest radical scavenging capacity (72%) and Zingiber officinale had the most potent ferric-reducing antioxidant power (FRAP; 2.99 mg AAE/mL). In contrast, Thymus vulgaris and Petroselinum crispum had the most potent antiglycation activity with IC(50) values of 21.8 and 200 mg/mL, respectively. There was no significant correlation between TPC (r=0.001), FRAP (r=0.161), and the antiglycation activity (r=0.034) for the extracts studied. Therefore, the results showed that antiglycation properties of plant-derived extracts cannot always be attributed to their phenolic content or antioxidant potential.

Antioxidant, antiglycation and cytotoxicity evaluation of selected medicinal plants of the Mascarene Islands.

BACKGROUND: Many indigenous plants of Mascarene Islands have been used in folkloric medicine to manage diabetes but few species have received scientific attention. Selected traditional medicinal plants (Antidesma madagascariense Lam. -Euphorbiaceae (AM), Erythroxylum macrocarpum O.E.Schulz -Erythroxylaceae (EM), Pittosporum senacia Putterl -Pittosporaceae (PS), Faujasiopsis flexuosa Lam. C.Jeffrey -Asteraceae (FF), Momordica charantia Linn -Cucurbitaceae (MC) and Ocimum tenuiflorum L -Lamiaceae (OT) were evaluated for their antioxidant, antiglycation and cytotoxic potential in vitro. METHODS: Graded concentrations (1.25-100 µg/mL) of the crude methanolic and water extracts and fractions (dichloromethane, ethyl-acetate, n-butanol and water) were evaluated for abilities to scavenge 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH), nitric oxide (NO), superoxide (SO) radicals and to inhibit lipoxygenase and formation of advanced glycation endproduct (AGE) in vitro. The MTT (3-(4, 5-dimethylthazol-2-yl)-2,5-diphenyl tetrazonium bromide) cytotoxicity test was performed on 3T3 cell line. RESULTS: Only IC50 for DPPH, SO, NO and lipoxygenase for AM, FF and OT crude extracts and fractions were comparable to ascorbic acid and quercetin activity. Crude aqueous extracts of AM and FF showed IC50 of 4.08 and 3.89 µg/mL respectively for lipoxygenase which was significantly lower (p < 0.05) than quercetin (10.86 ± 0.68 µg/mL). The three crude aqueous extracts of these plants and their n-butanol fractions also showed antiglycation activities (p < 0.05) comparable to aminoguanidine. Increasing concentrations (250-2000 µg/mL) of the six crude extracts (Methanol and water) and their fractions did not inhibit mitochondrial respiration as measured by MTT cytotoxicity assay. CONCLUSION: AM, FF and OT crude extracts and fractions have potent antioxidant and antiglycation properties with no apparent cytotoxicity and might have prophylactic and therapeutic potentials in the management of diabetes and related complications. Our study tends to validate the traditional use of these medicinal herbs and food plants as complementary and alternative medicines.

In vitro modulation of oxidative burst via release of reactive oxygen species from immune cells by extracts of selected tropical medicinal herbs and food plants.

OBJECTIVE: To evaluate in vitro immunomodulating properties and potential cytotoxicity of six tropical medicinal herbs and food plants namely Antidesma madagascariense (Euphorbiaceae) (AM), Erythroxylum macrocarpum (Erythroxylaceae) (EM), Faujasiopsis flexuosa (Asteraceae) (FF), Pittosporum senacia (Pittosporaceae) (PS), Momordica charantia (Cucurbitaceae) (MC) and Ocimum tenuiflorum (Lamiaceae) (OT). METHODS: Initially, the crude water and methanol extracts were probed for their capacity to trigger immune cells' NADPH oxidase and MPO-dependent activities as measured by lucigenin- and luminol-amplified chemiluminescence, respectively; as compared to receptor-dependent (serum opsonised zymosan- OPZ) or receptor-independent phorbol myristerate acetate (PMA). RESULTS: Preliminary screening on whole human blood oxidative burst activity showed significant and concentration-dependent immunomodulating properties of three plants AM, FF and OT. Further investigations of the fractions on isolated human polymorphonuclear cells (PMNs) and mice monocytes using two different pathways for activation of phagocytic oxidative burst showed that ethyl acetate fraction was the most potent extract. None of the active samples had cell-death effects on human PMNs, under the assay conditions as determined by the trypan-blue exclusion assay. Since PMA and OPZ NADPH oxidase complex is activated via different transduction pathways, these results suggest that AM, FF and OT does not affect a specific transductional pathway, but rather directly inhibit a final common biochemical target such as the NADPH oxidase enzyme and/or scavenges ROS. CONCLUSIONS: Our findings suggest that some of these plants extracts/fractions were able to modulate significantly immune response of phagocytes and monocytes at different steps, emphasizing their potential as a source of new natural alternative immunomodulatory agents.