Extractable polysaccharides of Panax quinquefolius L. (North American ginseng) root stimulate TNFalpha production by alveolar macrophages.

We have investigated the immunostimulatory activity of the medicinal plant Panax quinquefolius L. (North American ginseng). Rat alveolar macrophages were treated with different extracts from 4-year old roots, and tumour necrosis factor alpha (TNF) production was used as a measure of immunostimulatory activity. Aqueous extracts of P. quinquefolius root (1-100 microg/ml) were found to significantly stimulate alveolar macrophage TNF release. Both a P. quinquefolius methanol extract containing ginsenosides (but no polysaccharides), and pure ginsenoside-Rb1, the major ginsenoside present in P. quinquefolius, were found to be inactive as TNF-stimulating agents. Significant TNF-stimulating activity was found in the extractable polysaccharide fraction, which was hydrolyzed and found to contain glucose, galactose, arabinose, rhamnose, and mannose. This represents the first evidence that North American ginseng exerts cytokine-stimulating activity on macrophages.

American ginseng (Panax quinquefolius L.) attenuates postprandial glycemia in a time-dependent but not dose-dependent manner in healthy individuals.

BACKGROUND: We previously showed that 3 g American ginseng administered 40 min before an oral glucose challenge significantly reduces postprandial glycemia in subjects without diabetes. Whether this effect can be replicated with doses <3 g and administration times closer to the oral glucose challenge is unclear. OBJECTIVE: Our objective was to study the dosing and timing effects of American ginseng on postprandial glycemia. DESIGN: In a random crossover design, 12 healthy individuals [X +/- SEM age: 42 +/- 7 y; body mass index (BMI; in kg/m2): 24.1 +/- 1.1] received 16 treatments: 0 (placebo), 1, 2, or 3 g American ginseng at 40, 20, 10, or 0 min before a 25-g oral glucose challenge. Capillary blood was collected before administration and at 0, 15, 30, 45, 60, and 90 min after the start of the glucose challenge. RESULTS: Two-way analysis of variance showed that the main effects of treatment and administration time were significant (P < 0.05). Glycemia was lower over the last 45 min of the test after doses of 1, 2, or 3 g ginseng than after placebo (P < 0.05); there were no significant differences between doses. The reductions in the areas under the curve for these 3 doses were 14.4 +/- 6.5%, 10.6 +/- 4.0%, and 9.1 +/- 6%, respectively. Glycemia in the last hour of the test and area under the curve were significantly lower when ginseng was administered 40 min before the challenge than when it was administered 20, 10, or 0 min before the challenge (P < 0.05). CONCLUSIONS: American ginseng reduced postprandial glycemia in subjects without diabetes. These reductions were time dependent but not dose dependent: an effect was seen only when the ginseng was administered 40 min before the challenge. Doses within the range of 1-3 g were equally effective.

Stimulation of interleukin-1 and -6 production in alveolar macrophages by the neotropical liana, Uncaria tomentosa (uña de gato)

Two extracts of different collections of the traditional medicine uña de gato (Uncaria tomentosa) from Peru were characterized by High Pressure Liquid Chromatography as containing approximately 6 mg/g total oxindole content prior to studies with alveolar macrophages. The plant preparations greatly stimulated IL-1 and IL-6 production by rat macrophages in a dose dependent manner in the range of 0.025-0.1 mg/ml. They were also able to enhance IL-1 and -6 in lipopolysaccharide-stimulated macrophages. The results suggest a strong immunostimulant action of this plant.