RESUMEN
Aloe vera products, both in food and cosmetics, are becoming increasingly popular due to their claimed beneficial effects, which are mainly attributed to the active compound acemannan. Usually, these end products are based on powdered starting materials. High temperatures during the drying process to obtain the starting materials have several advantages, like shortening the drying time, eliminating toxic aloin and reducing bacterial contamination. Nevertheless, there are two major drawbacks: first, at temperatures of 80 °C or higher, structural changes in acemannan, especially its deacetylation (>46%), are triggered, which does not happen at lower temperatures (14% at 60 °C); secondly, a toxic principle is formed at higher temperatures, resulting in a higher cytotoxicity. Thus, two temperature-dependent but opposing effects cause with a median cytotoxic concentration of CC50 = 0.4× a peak of cytotoxicity at 80 °C; at 60 °C this cytotoxic substance is not formed and at 100 °C aloin is more readily eliminated, resulting in a CC50 = 1.1× and CC50 = 1.4×, respectively. The cytotoxic substance generated by dry heat at 80 °C is not a modified polysaccharide because its polysaccharide-enriched alcohol-insoluble fraction is with CC50 = 0.9× less cytotoxic. Moreover, this substance is polar enough to be washed away with ethanol. Additionally, when Aloe gel is heated at 80 °C under humid conditions (pasteurization), the cytotoxicity does not increase (CC50 = 1.6×). Finally, to produce powdered starting materials from Aloe gel, it is recommended to use temperatures of around 60 °C in order to preserve the acemannan structure (and thus biological activity) and the low cytotoxicity.
RESUMEN
Food industries typically use Aloe vera as concentrated (100× to 200×) and dried powders in their final products. These powders are obtained by extrusion of Aloe inner leaf gel (ILG) or Aloe whole leaf (WLP); the juice is filtered through diatomaceous earth and activated carbon before spray drying at temperatures below 70 °C. In another process, Aloe inner leaf gel was dried at ~80 °C and mashed to a powder rich in high molecular weight fibres and soluble polysaccharides (ILF). In contrast to ILG and WLP, the ILF sample was cytotoxic for the human intestinal cell line Caco-2 (CC50 = 1 g/l), even at concentrations below the recommended dose for human consumption. At lower concentrations (250 mg/l) with LPS challenged macrophage-like THP-1 cells decreased by 40% the release of the anti-inflammatory cytokine IL-10, whereas the release of the proinflammatory cytokine IL-1ß increased by 35% (compared to untreated but challenged macrophage-like THP-1 cells). Unexpectedly, under the same conditions, the less cytotoxic ILG and WLP, both samples with a lower fibre content, significantly increased (up to 2.4 times) the release of IL-10, while the concentration of IL-1ß remained unaltered and of TNFα decreased by 35%. Even more interesting is that a treatment of the ILF sample with activated carbon reduced its cytotoxicity and increased the IL-10 release (3.1 times). Based on these results, we suggest applying an activated carbon treatment on Aloe-starting products, which have high fibre content and have received high temperature treatment, in order to reduce their cytotoxicity and improve their immunomodulatory properties.
RESUMEN
Seven out of eight methanolic extracts from five plants native to Mexico were inactive against ten bacterial strains of clinical interest. The fruit extract of Chenopodium ambrosioides inhibited the bacteria Enterococcus faecalis (MIC = 4375 µg/ml), Escherichia coli (MIC = 1094 µg/ml), and Salmonella typhimurium (MIC = 137 µg/ml). The fruit extract of C. ambrosioides was with CC50 = 45 µg/ml most cytotoxic against the cell-line Caco-2, followed by the leaf extract from Pithecellobium dulce (CC50 = 126 µg/ml); interestingly, leaves of C. ambrosioides (CC50 = 563 µg/ml) and bark of P. dulce (CC50 = 347 µg/ml) extracts were much less cytotoxic. We describe for the first time the cytotoxic effect from extracts of the aerial parts and the flowers of Cirsium mexicanum (CC50 = 323 µg/ml and CC50 = 250 µg/ml, resp.). Phytochemical analysis demonstrated for both extracts high tannin and saponin and low flavonoid content, while terpenoids were found in the flowers. For the first time we report a cytotoxicological study on an extract of Eryngium carlinae (CC50 = 356 µg/ml) and likewise the bark extract from Amphipterygium adstringens (CC50 = 342 µg/ml). In conclusion the fruit extract of C. ambrosioides is a potential candidate for further biological studies.