Duckweed (Lemna gibba L.) as a test organism for homeopathic potencies.

OBJECTIVES: A bioassay with duckweed (Lemna gibba L.) was used to study the effects of homeopathic potencies on the plant's growth rate. Screening included 12 substances: argentum nitricum, copper sulfate, gibberellic acid, 3-indole acetic acid, kinetin, lactose, lemna minor, methyl jasmonate, metoxuron, phosphorus, potassium nitrate, and sulfur. Each substance was tested in the potency range 14x-30x. Controls were unsuccussed and succussed water. DESIGN: In randomized and blinded experiments, duckweed was grown in either potentized substances or water controls over 7 days. Frond (leaf) growth was measured regularly with a computerized image analysis system and growth rates were calculated for different time intervals (day 0-7, 0-3, 3-7). Additionally, a water control run with unsuccussed water as the only test substance was performed to determine the variability of the bioassay. RESULTS: For the water control run, the between-group coefficient of variance for groups of five replicates was 0.87% for the frond area-related average specific growth rate r(area) compared to 1.60% for the frond number-related average specific growth rate r(num). Thus, the former is the preferred parameter to be used. Of twelve tested substances, potentized argentum nitricum, phosphorus, and kinetin significantly (p<0.05, analysis of variance F-test) affected the main parameter: frond area-related average specific growth rate (day 0-7). Segmented area growth rates (day 0-3 or 3-7) were affected by potentized argentum nitricum, gibberellic acid, lactose, and phosphorus. CONCLUSIONS: The described experimental set-up with L. gibba as test organism appears to be a promising new model system to investigate effects of potentized substances. Yet larger sets of replication experiments with selected test substances and systematic negative controls are necessary to verify the effects found.

Effects of potentised substances on growth rate of the water plant Lemna gibba L.

OBJECTIVES: This study investigated, whether the growth rate of Lemna gibba L. (duckweed) can be influenced by the application of homeopathic potencies of gibberellic acid, kinetin, argentum nitricum, and lemna minor. METHODS: Duckweed was grown in either potencies (14x-30x, decimal steps) or water controls (unsuccussed and succussed) over seven days. Frond (leaf-like structure) growth was measured using a non-destructive image analysis system. Growth rates were calculated for three time intervals (0-7, 0-3, 3-7 days). Five to six independent, randomized and blinded experiments were analysed for each of the four tested substances. Water control experiments were performed repeatedly to test the reliability of the experimental set-up (systematic negative controls). RESULTS: The systematic negative control experiments did not yield any significant effects. Hence, false positive results could be excluded. The test system had a low coefficient of variation (1.5%). Out of the four tested substances gibberellic acid had the most pronounced effect (p=0.0002, F-test) on the main outcome parameter frond growth rate (r(area) day 0-7). Potency levels 15x, 17x, 18x, 23x and 24x reduced growth rate of Lemna gibba (p<0.05 against the pooled water control, LSD test). CONCLUSIONS: Lemna gibba may be considered as a suitable test organism for further studies on the efficacy of homeopathic potencies. Evidence accumulates, that adjacent potency levels may strongly differ in their biological activity. Potential consequences for therapeutical application might be worth investigating.

Effects of potentised substances on growth kinetics of Saccharomyces cerevisiae and Schizosaccharomyces pombe.

BACKGROUND: Homeopathic potencies are used as specific remedies in complementary medicine. Since the mode of action is unknown, the presumed specificity is discussed controversially. OBJECTIVE: This study investigated the effects of potentised substances on two yeast species, Saccharomyces cerevisiae and Schizosaccharomyces pombe, in a stable and reliable test system with systematic negative controls. MATERIALS AND METHODS: Yeast cells were cultivated in either potentised substances or water controls in microplates and their growth kinetics were measured photometrically. Water control runs were performed repeatedly to investigate the stability of the experimental set-up (systematic negative controls). RESULTS: 4 out of 14 screened substances seem to have affected the growth curve parameters slope or yield. Out of these substances, azoxystrobin and phosphorus were chosen for 8 further replication experiments, which partly confirmed the results of the screening. On the average of all experiments, azoxystrobin affected the slope of the growth curve of Saccharomyces cerevisiae (p < 0.05), and phosphorus affected the slope of the growth curve of Schizosaccharomyces pombe (p < 0.05). No effects were seen in the water control runs. In addition, significant interactions between treatment with potentised substances and experiment number were observed in all experiments with potentised substances (p < 0.01), but not in the water control runs. CONCLUSIONS: Both yeast species reacted to certain potentised substances by changing their growth kinetics. However, the interactions found point to additional factors of still unknown nature, that modulate the effects of potentised substances. This stable test system with yeasts may be suitable for further studies regarding the efficacy of homeopathic potencies.