Bioassay-guided Isolation Of Active Compounds Research Articles

Phenolic Composition, In-vitro Antioxidant and Enzyme Inhibition Activities of Cardaria draba Different Parts

The plant Cardaria draba (L.) Desv. subsp. draba (Brassicaceae), is traditionally used for various ailments in different cultures. We investigated different solvent extracts such as methanol, ethanol, and water extracts obtained from flowers, leaves, stems, and roots of C. draba for their chemical composition, as well as antioxidant and enzyme inhibition activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glucosidase, α-amylase, and tyrosinase). RP-HPLC technique was used to determine the phenolic profile of each extracts. The antioxidant activities of the extracts were determined by using DPPH and ABTS method, total phenol and flavonoid content analysis, and iron chelating assay. Enzyme inhibitory potential was evaluated by 96-microplate method. According to the results, aqueous extract of flower demonstrated the highest total phenolic content (64.32 µgGAE/ mg), while leaf ethanol extract showed the highest total flavonoid content (141.47 µgQE/ mg) among all extracts. The methanol, and water extracts of flowers were the most effective DPPH scavenger while aqueous extract of flower was the most active on ABTS scavenging. It is shown that the extracts possess promising activity against α-glucosidase than α-amylase enzyme. The methanolic extract of flower showed anti-acetylcholinesterase activity, and the ethanolic extract of the stem exhibited the best anti-butyrylcholinesterase activity among the 12 extracts. As for the anti-tyrosinase activity, higher kojic acid equivalent values were found for the aqueous extracts of roots and leaves. In conclusion, the data obtained from this study may serve as the basis for the bioassay-guided isolation of active compounds and the development of novel drugs from Cardaria draba.

Bioassay-guided isolation of active compounds from Adenosma buchneroides essential oil as mosquito repellent against Aedes albopictus

Ethnopharmacological relevanceA folk herb Adenosma buchneroides found in the previous ethnobotanical investigation plays an important role as an insect repellent among the Aini people in southwest of China, but the active compounds responsible for repellent activity of the plant have not yet been investigated. Aim of the studyThe main purpose of the study is to identify the active components of the essential oil which responsible for its repellent activity against Aedes albopictus to support the usage of the plant as mosquito repellent by Aini people. In addition, to supply a class of potential alternatives characterized carvacrol analogues to develop natural repellent products. Material and methodsThe essential oil from aerial part of Ad. buchneroides was extracted by hydrodistillation. A systematic bioassay-guided isolation of repellent compounds from the essential oil was conducted through chromatographic fractionation combined with in-cage mosquito repellent bioassay. The identification of the essential oil components was accomplished by GC-MS and GC-FID techniques. The structural elucidation of compounds was performed on the basis of IR, HR-ESI-MS and NMR. Larvicidal activity and cytotoxicity of all repellent compounds also tested by larval bioassays and MTS assays, respectively. Structure-activity relationship (SAR) of carvacrol analogues was investigated by in-cage mosquito repellent bioassay. ResultsThe essential oil of the plant showed strong mosquito repellent activity with minimum effective dosage (MED) of 0.019 ± 0.007 mg/cm2, compared to reference standard N,N-diethyl-3-methylbenzamide (DEET) (0.031 ± 0.014 mg/cm2). 26 compounds representing 97.8% of the essential oil were identified. Carvacrol, carvacrol methyl ether and a new fragrant compound, adenosmin A (1) were found to be repellent compounds by systematic bioassay-guided isolation, with MEDs in the range of 0.011–0.125 mg/cm2. An investigation on SAR of carvacrol analogues led to the discover of three analogues with further lower MEDs (0.002–0.009 mg/cm2) than that of DEET, and other three compounds with similar MEDs (0.029–0.039 mg/cm2) to that of DEET. Carvacrol (LD50 of 24.8 ppm) was the best larvicide among tested repellent compounds. The essential oil and repellent compounds against seven mammalian cell lines revealed low or no cytotoxicity. ConclusionsScientific evidences reported here validate the plant's traditional use as insect repellent and imply promising application of the essential oil and carvacrol analogues as natural mosquito repellents.

Identification of rosmarinic acid and sulfated flavonoids as inhibitors of microfouling on the surface of eelgrass Zostera marina

A bioassay-guided approach was used to identify defense compounds that are present on the surface of Zostera marina and which inhibit settlement of microfoulers at natural concentrations. Moderately polar eelgrass surface extracts inhibited the settlement of seven marine bacteria and one yeast that originated from non-living substrata. In contrast, five other bacterial strains that had been directly isolated from eelgrass surfaces were all insensitive, which suggested a selective effect of surface metabolites on the microbial communities present on eelgrass. Bioassay-guided isolation of active compounds from the extracts in combination with UPLC-MS and 1H-NMR spectroscopy resulted in the identification of rosmarinic acid, luteolin-7-sulfate and diosmetin-7-sulfate or its isomer chrysoeriol-7-sulfate. All three compounds are nontoxic repellents, as they did not inhibit bacterial growth, but prevented bacterial settlement in a dose-dependent manner. Between 15.6 and 106.8 μg ml−1 of rosmarinic acid were present on the eelgrass surface, enough for half maximal settlement inhibition of bacteria.

Antioxidant and antitumour activities of extracts from Patrinia villosa and its active constituents

Patrinia villosa Juss is a famous medicinal herb and is used as an anti-inflammatory and anti-bacterial agent. Its tender leaves have also been used as a wild vegetable in China. In this study, the antioxidant and cytotoxic activities of various fractions of ethanol extract from P. villosa were investigated, the ethyl acetate fraction (EE-PV) exhibited the strongest antioxidant activity and cytotoxic effect on four cancer cell lines. EE-PV also significantly inhibited the tumour growth in vivo. EE-PV was subjected to bioassay-guided isolation of active compounds by column chromatography. Phenolic compounds such as 5,7,4′-trihydroxy-3-methoxyflavone and p-hydroxybenzoic acid are mainly responsible for antioxidant activity. Ursolic acid as one of main constituents contributed to the antitumour activity of EE-PV. These results suggest that this plant extract could be considered as a potential source of functional food and pharmaceutical for preventing cancer and reducing the risk of chronic diseases associated with oxidative damage.

English

Tanzania has over 12,000 plant species, some of which are endemic and have potential to yield useful medicines. This study seeks to document such plants used as traditional medicines for treatment of malaria in Kagera region of northwestern Tanzania and Lindi region in south eastern Tanzania. The study also reports on the antiplasmodial activity against chloroquine-resistant Plasmodium falciparum (Dd2) strain of some of the documented plants using the parasite lactate dehydrogenase method. A total of 108 plant species, among which the families Compositae (14; 12.96%), Fabaceae (12; 11.11%), Euphorbiaceae (8; 7.41%), Melastomataceae (6; 5.56%) and Myrtaceae (4; 3.70%) were documented. Sixteen (16; 44.4%) of 36 extracts from 31 plant species that were tested inhibited malaria parasites growth by more than 50%. Bersema abyssinica stem bark extract was the most active with 86.67% inhibition rate followed by Bridelia micrantha stem bark extract with 71.87% inhibition rate. These results confirm the potential for plants used in traditional medicine to yield active antimalarial compounds. Further in vitro and in vivo screening supported by bioassay-guided isolation of active compounds from plants showing good safety margin is suggested. Key words: Ethnobotanical survey, medicinal plants, malaria, treatment, in vitro antiplasmodial, Tanzania.

Bioassay-guided isolation of active compounds and fingerprinting of an edible nut toward the development of a diabetic zebrafish model

Bioassay-guided isolation of active compounds and fingerprinting of an edible nut toward the development of a diabetic zebrafish model

The Thai Medicinal Plant Gynura Pseudochina var. hispida: Chemical Composition and in vitro NF-κB Inhibitory Activity

Gynura pseudochina (L.) var. hispida Thv. (Asteraceae) has been used in traditional medicine in Thailand for the treatment of conditions associated with chronic and acute inflammation. In continuation of our search for bioactive natural products from Thai medicinal plants, G. pseudochina var. hispida showed potential in vitro NF-kappaB (Nuclear Factor kappa B) inhibitory activity and, therefore, was chosen for bio-assay-guided isolation of active compounds. Bioassay-guided fractionation of the methanol extract of the leaves of G. pseudochina var. hispida led to the isolation and identification, by spectroscopic and mass spectrometric methods, of four compounds previously not reported from this poorly studied species: Quercetin 3- rutinoside (1), 3,5-di-caffeoylquinic acid (2), 4,5-di-caffeoylquinic acid (3), and 5-monocaffeoylquinic acid (4). This paper discusses the current knowledge of these active components as NF-kappaB inhibitors, which lends some support to the use of this plant in traditional medicine. Potential risks associated with pyrrolizidine alkaloids will, however, have to be investigated further.