Angelica sinensis (Oliv.) Diels: Influence of Value Chain on Quality Criteria and Marker Compounds Ferulic Acid and Z-Ligustilide.

Background:Dang gui (Apiaceae; Angelica sinensis radix) is among the most often used Chinese medicinal plants. However, hardly anything is known about its value chain and its influence on the main marker compounds of the drug. The aim of this study is to investigate the value chain of dang gui in Gansu and Yunnan, and the analysis of the marker compounds ferulic acid and Z-ligustilide concentration in relation to quality criteria such as the production area and size of the roots. Methods: During six months of field research in China, semi-structured interviews with various stakeholders of the value chain were undertaken and plant material was collected. High-performance thin layer chromatography (HPTLC) was used for semi-quantitative analysis of ferulic acid and Z-ligustilide. Results: Small-scale household cultivation prevails and in Gansu-in contrast to Yunnan-the cultivation of dang gui is often the main income source of farmers. Farmers and dealers use size and odor of the root as main quality criteria. For Chinese medicine doctors, Gansu as the production area is the main criterion. Higher amounts of ferulic acid in plant material from Yunnan compared to Gansu were found. Additionally, a negative relation of root length with both ferulic acid and Z-ligustilide as well as head diameter with ferulic acid were found. Conclusions: HPTLC is a valid method for semi-quantitative analysis of the marker compounds of dang gui. However, the two main marker compounds cannot explain why size and smell of the root or production area are seen as quality criteria. This hints at the inherent difficulty to correlate quality notions of medicinal plants with specific chemical compounds. With respect to this, more attention should be paid to quality in terms of cultivation and processing techniques.

HPTLC Fingerprinting and Cholinesterase Inhibitory and Metal-Chelating Capacity of Various Citrus Cultivars andOlea europaea.

Inhibitory activity of thirty-one ethanol extracts obtained from albedo, flavedo, seed and leaf parts of 17 cultivars of Citrus species from Turkey, the bark and leaves of Olea europaea L. from two locations (Turkey and Cyprus) as well as caffeic acid and hesperidin was tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), related to the pathogenesis of Alzheimer's disease, using ELISA microtiter assays at 500 µg/mL. Metal-chelating capacity of the extracts was also determined. BChE inhibitory effect of the Citrus sp. extracts was from (7.7±0.7) to (70.3±1.1) %, whereas they did not show any inhibition against AChE. Cholinesterase inhibitory activity of the leaf and bark ethanol extracts of O. europaea was very weak ((10.2±3.1) to (15.0±2.3) %). The extracts had either no or low metal-chelating capacity at 500 µg/mL. HPTLC fingerprinting of the extracts, which indicated a similar phytochemical pattern, was also done using the standards of caffeic acid and hesperidin with weak cholinesterase inhibition. Among the screened extracts, the albedo extract of C. limon 'Interdonato', the flavedo extracts of 'Kara Limon' and 'Cyprus' cultivars and the seed extract of C. maxima appear to be promising as natural BChE inhibitors.

Antidiabetic potential of two medicinal plants used in Gabonese folk medicine.

BACKGROUND: Diabetes mellitus is a metabolic disorder which is rising globally in rich and developing countries. In the African region this rate is the highest, with 20 million diagnosed diabetics. Despite a noticeable progress in the treatment of diabetes mellitus by synthetic drugs, the search for new natural anti-diabetic agents is going on. Nauclea diderrichii (De Wild.) Merr. (ND) and Sarcocephalus pobeguinii Hua ex Pellegr. (SP) are used as traditional medicines in Gabon for the treatment of different diseases, especially in the case of diabetes. The aim of this study was to evaluate the antidiabetic potential of these two medicinal plants traditionally used in Gabon. METHODS: Pharmacological (inhibitory action on α and ß-glucosidases) and toxicological (effect on human T cell proliferation) studies were conducted on aqueous extracts of ND (leaves and bark) and SP (bark) collected in Gabon. All raw extracts were analyzed by HPTLC and their content in phenolic compounds was determined by using standard method. The most active extracts were submitted to preparative HPLC in order to evidence the most efficient subfractions by biological evaluation. RESULTS: The results showed that two extracts from ND were potent α-glucosidase inhibitors, the leaf extract being more active that the bark extract: the first one was more than 60 fold more active than Acarbose, which is an oral medication used to treat type 2 diabetes; the extract from SP bark was less efficient. The HPLC subfractions of the extracts of ND leaves and SP bark were tested in the same experimental conditions. In each case, the most active subfractions still show very potent inhibitory effect on α-glucosidase (80-90% inhibition at 0.1 mg/mL). The most efficient extract, from ND leaves, was also characterized by the highest percentage of phenolic compounds, which suggests a relationship between its inhibitory potential on α-glucosidase and its content in phenolic compounds. Conversely, only a moderate inhibitory activity of the three extracts was observed on ß-glucosidase. CONCLUSION: These results clearly indicated that active compounds present in N. diderrichii and S. pobeguinii leaves or/and bark were selective and highly potent inhibitors of α-glucosidase and validate their popular use for the treatment of diabetes.

Prevention of False-Positive Results: Development of an HPTLC Autographic Assay for the Detection of Natural Tyrosinase Inhibitors.

A simple and rapid high-performance thin-layer chromatography-based autographic assay was established to screen plant extracts for the presence of tyrosinase-inhibiting substances. Three mobile phases were selected for the chromatographic separation of different types of extracts. After development, the plate was sprayed with the substrate solution Levodopa followed by a solution of the enzyme tyrosinase. Several known tyrosinase inhibitors were tested simultaneously as positive controls. They were detected as white spots with white light in remission from the plate as well as with white light transmitted through the plate. Some of the investigated extracts included spots showing a different behaviour; some lipophilic substances appeared as white spots in white light remission but were black in white light transmission. This behaviour, which could lead to false-positive results, was due to poor wettability of the corresponding spots. False-positive results were eliminated by adding Triton X-100 to the Levodopa solution and drying the plate after 10 minutes incubation with a molecular sieve. Tyrosinase inhibitors can be clearly identified as white spots against a dark background in white light remission as well as in white light transmitted through the plate. The established high-performance thin-layer chromatography autographic assay was validated and can be used as a standard method for the detection of tyrosinase inhibitors in plant extracts without causing false-positive results.

Screening and determination of sibutramine in adulterated herbal slimming supplements by HPTLC-UV densitometry.

The adulteration of herbal supplements is of growing importance, especially when they contain undeclared compounds like sibutramine that are unsafe drugs. Sibutramine was withdrawn from US and European markets in 2010. In this study, an HPTLC-UV densitometric method was developed for the quantification of sibutramine in herbal diet foods. Sample extracts were directly applied onto HPTLC silica gel plates and separated with a mobile phase made of a toluene-methanol mixture. Sibutramine was quantified at 225 nm and its unequivocal identification was confirmed by MS using a TLC-MS interface. During two surveys, 52 weight loss supplements obtained via the Internet were screened. Half of those were adulterated with sibutramine at amounts reaching up to 35 mg per capsule. The results of this validated HPTLC method were compared with those obtained by HPLC-UV and HPLC-MS/MS. The results were not significantly different with the three methods.

Rapid high-performance thin-layer chromatographic method for detection of 5% adulteration of black cohosh with Cimicifuga foetida, C. heracleifolia, C. dahurica, or C. americana.

Black cohosh (Cimicifuga racemosa) is used to treat discomfort during menopause and as a substitute for synthetic drugs in hormone replacement therapy. The mostly wildcrafted plant is ranked among the top-selling herbs in the United States. There is a risk for adulteration with the similar-looking C. americana, which grows in the same habitats of the eastern United States. Other adulterants found in today's global marketplace are the 3 Asian Cimicifuga species C. foetida, C. heracleifolia, and C. dahurica. A very practical, rapid, and reliable high-performance thin-layer chromatographic (HPTLC) method was developed for identification of C. racemosa and detection of its most common adulterants by fingerprint profiles. With specific derivatization reagents, mixtures of C. racemosa with a minimum of 5% of one of the adulterants can be detected. The proposed method was validated with respect to specificity, stability, precision, and robustness. It can be used for quality control of black cohosh raw material in a current Good Manufacturing Practices environment.

Spasmolytic and antidiarrhoeal properties of the Yucatec Mayan medicinal plant Casimiroa tetrameria.

The Maya of the Yucatán peninsula commonly use the leaves of Casimiroa tetrameria for treating gastrointestinal disorders, notably diarrhoea and dysentery, as well as gastrointestinal cramps. The phytochemical investigation resulted in the isolation of 13 compounds: eight polymethoxylated flavonoids (two as minor components with a main constituent), four flavonoid glycosides and one furanocoumarin. In this study we used two well-established models in order to assess the gastrointestinal effects of C. tetrameria extracts and isolated compounds: the USSING-chamber, a pharmacological model for diarrhoea, and the isolated guinea pig ileum, a model for modulatory effects on ileum contraction. Extracts and the class of polymethoxylated flavonoids showed strong inhibitory effects in both models, which provides ex-vivo evidence for the use of this botanical drug in the treatment of several gastrointestinal problems, most notably diarrhoea. The crude extract, polymethoxylated flavonoid-rich fractions and the polymethoxylated flavonoids tested showed prominent antisecretory activity. Polymethoxylated flavonoid-rich fractions also inhibited the histamine-induced contractions in the guinea pig model. The effects are not due to a single compound, but to a large number of structurally related compounds that all contribute to the effect.

A furanocoumarin and polymethoxylated flavonoids from the Yucatec Mayan plant Casimiroa tetrameria.

As part of an ongoing study of the medicinal plants of the Yucatec Maya, Casimiroa tetrameria was investigated for its phytochemistry. From an ethyl acetate partition of an ethanol extract of the leaves, eight flavonoids and a furanocoumarin were isolated and characterised as 5,6,2',3',5',6'-hexamethoxyflavone, 5,6,2',3',6'-pentamethoxyflavone and 5-methoxy-8-(3''-hydroxymethyl-but-2''-enyloxy)-psoralen using a combination of 1H, 13C NMR and NOESY spectroscopy.

Yucatec Mayan medicinal plants: evaluation based on indigenous uses.

As part of an ethnopharmacological field study 48 medicinal plants were evaluated using several biological assays with the goal to obtain information on the pharmacological effects of these plants, which may be of direct relevance to the indigenous uses. Three species used to treat gastrointestinal disorders showed remarkable activity against Helicobacter pylori. One of them showed activity against Giardia duodenalis. Cytotoxic effects against KB cells were found for six species. In the group of plants used for dermatological conditions several species were active against gram-positive bacteria and Candida albicans. Two plant species of this group were found to be active in an Nuclear Factor-kappaB (NF-kappaB) assay measuring inhibition of this pro-inflammatory transcription factor. A species of the Solanaceae, applied in cases of pain and fever, showed a weak activity against Plasmodium falciparum. One species traditionally used for diabetes exhibited antihyperglycemic activity. None of the six species from the group of 'women's medicine' showed relevant affinity to the D(2) dopamine receptor. Based on this evaluation, plants with strong activities should be further investigated phytochemically and pharmacologically to identify active fractions and compounds.