Bioactive diterpenes from the fruits of Detarium microcarpum

Lauinoids A-X: Labdane-type diterpenoids with anti-inflammatory activity from Croton laui

Croton laui (Euphorbiaceae) is a traditional medicinal plant used by the Li ethnic group in China to treat headaches, stomachaches, and diphtheria. To understand the pharmacological basis of its medicinal use, an extensive investigation of the ethanolic extract of the bark of C. laui was performed. After repeated chromatography, twenty-four undescribed labdane-type diterpenoids, lauinoids A-X (1-24), and five known analogs (25-29) were isolated. Their structures and absolute configurations were established using a combination of spectroscopic analyses, electronic circular dichroism, nuclear magnetic resonance calculations, and single-crystal X-ray diffraction. Among them, compounds 1-3 exhibited an 11(12 → 13)-abeo-16-nor-labdane skeleton, which originated putatively from 9 through a plausible pathway that involves a semipinacol rearrangement process. Compounds 11 and 12 belong to the rare class of 14,15-dinor-labdane diterpenoids. Compounds 18 and 28 exhibited substantial inhibitory effects by suppressing lipopolysaccharide-induced NO production in RAW 264.7 macrophages, with IC50 values of 3.37 ± 0.23 and 5.82 ± 0.28 μM, respectively. This study has greatly expanded the chemical diversity of labdane diterpenoids from C. laui and will guide future research on this ethnomedicinal plant.

A New Clerodane from the Leaves of Croton krabas and Its Cholinesterase Inhibitory Activities

Chromatographic separation of the leaves of Croton krabas resulted in the isolation of one new clerodane, crotoeurin D (1), along with two known compounds, 6S-crotoeurin C (2) and blumenol A (3). Their structures were determined based on extensive nuclear magnetic resonance spectroscopic data analysis and mass spectrometry. The absolute configuration of the new clerodane was assigned by nuclear overhauser effect spectroscopy correlations and electronic circular dichroism calculations. Compound 1 exhibited significant acetylcholinesterase and butyrylcholinesterase inhibitory activities. Moreover, the binding modes of 1 revealed that its structure formed strong hydrogen bonds and hydrophobic interactions with the active sites of both enzymes.

A review of plant antipathogenic constituents: Source, activity and mechanism

Green prevention and control of plant pathogens is a development direction of sustainable and low-carbon agriculture given the limitation of traditional chemicals. Plant-derived antipathogenic constituents (PAPCs) exhibit the advantages of being environmental benign and a broad spectrum of target pathogens over traditional chemicals. Here, we review the research advances on plant sources, chemical compositions, activities of antipathogenic constituents in the past 20 years. Reported PAPCs are classified into categories of phenols, flavonoids, terpenoids, alkaloids and antimicrobial peptides. Angiosperms, gymnosperms and some lower plants are the main plant source of detected PAPCs. The PAPCs act on pathogens through multiple pathways including destroying cell structures, blocking key composition synthesis and inhibiting cell metabolism. The development trends of PAPCs are finally prospected. This review serves as a comprehensive review on the study of plant antipathogenic constituents and a key reference for forecasting the source, characteristic and activity of PAPC.

Biological Activity and Chemical Composition of Detarium microcarpum Guill. and Perr-A Systematic Review

Historically, natural products have been the principal source of medications for the treatment of human diseases. Traditional medical practitioners employ Detarium microcarpum as a treatment for diabetes, malaria, wounds, inflammation, and even cancer. This study emphasizes the importance of harmonizing D. microcarpum research so that results from various sources may be directly compared to reach a scientific conclusion. We searched Google Scholar, Science Direct, Google.com, Wiley, PubMed, Hindawi, and Springer for research papers on Detarium microcarpum. This analysis excludes untrustworthy online data, thesis papers, and review publications on D. microcarpum. The leaves and stem bark were shown to have high antioxidant, anti-inflammatory, antibacterial, antidiabetic, and anticancer properties. The study also discovered that too much consumption is harmful. Polyphenols and flavonoids were the most commonly reported compounds. However, human safety and efficacy are yet to be fully evaluated, and further well-designed clinical trials are needed to confirm preclinical findings. The leaves and stem bark extracts and isolated compound mechanism of action should be investigated. It is necessary to set a standard dose and ensure its safety.

A new ent-clerodane diterpene from Detarium microcarpum Guill. & Perr. and its protective potential for osteoporosis

A new clerodane diterpene, named 6α-hydroxy-3,13E-clerodien-15-oic acid (1), together with a known clerodane diterpene (2), four known labdane diterpenes (3-6), a triterpenoid (7), a known steroid (8), and two benzenoid compounds (9 and 10) were isolated from Detarium microcarpum Guill. & Perr. The structures of all obtained compounds were determined by chemical properties and spectroscopic evidence, accompanied by comparisons with data in the literature. Electronic circular dichroism (ECD) was performed for compounds 1-4 to confirm the absolute configuration. Compounds 1-3 and 8-10 were evaluated for the protective effect on osteoblasts. Compound 1 was observed to increase the proliferation of dexamethasone (DEX)-treated MC3T3-E1 cells significantly at 1 μM, which was comparable with the positive control geniposide at 10 μM. The results were further confirmed by flow cytometry analysis. In addition, compound 1 increased the level of alkaline phosphatase (ALP) and mineralization in osteoblasts inhibited by DEX. Moreover, Compound 9 (vanillic acid) showed a pronounced inhibition (IC₅₀ 6.5 ± 0.6 μM) on reactive oxygen species (ROS) production, and 10 (4-O-methyl gallic acid) showed a good inhibition with IC₅₀ as 103.3 ± 2.2 μM, compared with the standard drug ibuprofen (IC₅₀ 54.2 ± 9.2 μM). Besides, compounds 1-3 and 8-10 were non-cytotoxic against MCF-7, NCI-H460, Hela, and BJ cell lines.

An Evolving Technology That Integrates Classical Methods with Continuous Technological Developments: Thin-Layer Chromatography Bioautography

Thin-layer chromatography (TLC) bioautography is an evolving technology that integrates the separation and analysis technology of TLC with biological activity detection technology, which has shown a steep rise in popularity over the past few decades. It connects TLC with convenient, economic and intuitive features and bioautography with high levels of sensitivity and specificity. In this study, we discuss the research progress of TLC bioautography and then establish a definite timeline to introduce it. This review summarizes known TLC bioautography types and practical applications for determining antibacterial, antifungal, antitumor and antioxidant compounds and for inhibiting glucosidase, pancreatic lipase, tyrosinase and cholinesterase activity constitutes. Nowadays, especially during the COVID-19 pandemic, it is important to identify original, natural products with anti-COVID potential compounds from Chinese traditional medicine and natural medicinal plants. We also give an account of detection techniques, including in situ and ex situ techniques; even in situ ion sources represent a major reform. Considering the current technical innovations, we propose that the technology will make more progress in TLC plates with higher separation and detection technology with a more portable and extensive scope of application. We believe this technology will be diffusely applied in medicine, biology, agriculture, animal husbandry, garden forestry, environmental management and other fields in the future.

Natural Products as Fungicide and Their Role in Crop Protection

Seeking solutions from nature for solving one and all problems is the age-old practice for mankind, and natural products are proved to be the most effective one for keeping up the balance of development as well as the “healthy, wealthy, and well” condition of mother nature. Fungal pathogens are proved to be a common and popular contaminant of agroecosystem that approximately causes 70–80% of total microbial crop loss. To meet the proper global increasing need of food products as a result of population explosion, managing agricultural system in an eco-friendly and profitable manner is the prime target; thus the word “sustainable agriculture” plays it part, and this package is highly effective when coupled with nature-derived fungicidal products that can minimize the event of fungal infections in agrarian ecosystem. Present study enlists the most common and effective natural products that might be of plant or microbial origin, their mode of action, day-by-day development of phytopathogenic resistance against the prevailing fungicides, and also their role in maintenance of sustainability of agricultural practices with special emphasis on their acceptance over the synthetic or chemical one. A large number of bioactive compounds ranging from direct plant (both cryptogams algae and moss and phanerogams)-derived natural extracts, essential oil of aromatic plants, and low-molecular-weight antimicrobial compounds known as phytoalexins to secondary metabolites that are both volatile and nonvolatile organic compounds of microbes (fungal and actinobacterial members) residing inside the host tissue, called endophyte, are widely used as agricultural bioweapons. The rhizospheric partners of plant, mycorrhizae, are also a prime agent of this chemical warfare and protect their green partners from fungal invaders and emphasize the concept of “sustainable agriculture.”

An Upcoming Approach to Alzheimer's Disease: Ethnopharmacological Potential of Plant Bioactive Molecules

BACKGROUND

Neurodegenerative disorders have achieved epidemic levels in the last decades; not only the elderly but also adult individuals have been increasingly affected. Among them, Alzheimer's disease is one of the most prevalent and crippling diseases, associated with high rates of multi-morbidities and dependency. Despite the existence of a wide variety of drugs used as the symptomatic treatment, they have some side effects and toxicity, apart from their limited effectiveness. Botanical preparations have a secular use, being widely recommended for a multitude of purposes, such as for the improvement of brain health.

OBJECTIVE

The aim of the present report is to systematize the knowledge on plant-food derived bioactive molecules with promising in vitro enzymatic inhibitory activities.

RESULTS

Alkaloids, phenolic compounds and terpenes are the most studied phytochemicals, both derived from natural and commercial sources. In spite of their efficient activity as enzymatic inhibitors, the number of in vivo studies and even clinical trials have confirmed that their real bioactive potential remains scarce.

CONCLUSION

Thus, it is of the utmost importance to deepen knowledge in this area, once those relevant and informative tools can significantly contribute to the promising advances in the field of Alzheimer's disease treatment.

Antiplasmodial Diterpenoids from Psiadia arguta

An ethyl acetate extract of Psiadia arguta leaves showed in vitro antiplasmodial activity against Plasmodium falciparum with IC₅₀ values of 12.3 ± 2.4 μg/mL (3D7 strain) and 13.5 ± 3.4 μg/mL (W2 strain). Phytochemical investigation led to the isolation and characterization of 16 compounds including four new diterpenoids: labdan-8α-ol-15-yl-(formate) (1), labdan-8α-ol-15-yl-(2-methylbutanoate) (2), labdan-8α-ol-15-yl-(3-methylpentanoate) (3), and labdan-8α-ol-15-yl-(labdanolate) (4). The latter compounds were characterized by spectroscopic methods (1D and 2D NMR, HRMS, and IR). The in vitro antiplasmodial activities of all compounds were evaluated. The known compounds labdan-13( E)-en-8α-ol-15-yl acetate (5), labdan-8α-ol-15-yl acetate (6), 13- epi-sclareol (7), labdan-13( E)-ene-8α,15-diol (8), and (8 R,13 S)-labdane-8α,15-diol (9) exhibited antiplasmodial effects, with IC₅₀ values of 29.1, 33.2, 35.0, 36.6, and 22.2 μM, respectively.

3,4- seco-Norclerodane Diterpenoids from the Roots of Polyalthia laui

Ten new clerodane diterpenoids, polylauioids A-J (1-10), and five known analogues (11-15) were isolated from the roots of Polyalthia laui. Among the new compounds, 3 and 8 are artifacts. The structures were elucidated using spectroscopic methods and by comparison with published NMR spectroscopic data. The absolute configurations of 4, 5, and 7 were defined based on single-crystal X-ray diffraction and electronic circular dichroism data. Compounds 1 and 2 represent the first examples of rearranged 3,4- seco-norclerodane diterpenoids, and a putative biosynthesis pathway for these compounds is proposed. Compounds 1, 4, 6, 7, 9, and 10 showed anti-HIV activities with EC₅₀ values ranging from 12.2 to 35.2 μM.

Nutritional and medicinal properties of underexploited legume trees from West Africa

This review concerns three legume trees (family Fabaceae, subfamily Caesalpinioideae) from West Africa, namely Detarium microcarpum, Parkia biglobosa and Dialium guineense, and illustrates their nutritional value and therapeutic properties. These species are an important source of nutrition for West African populations, but their agricultural exploitation is still incomplete. The survey was conducted on Scopus, Web of Science, and Medline, using scientific and common English names of the species as keywords and then selecting papers related to nutritional and medicinal properties. Main food products are fruit pulp and seeds, though leaves can also be used. Most relevant dietary features are high protein, vitamin, and micronutrient contents. Various therapeutic and nutritional benefits of these plants have been documented by ethnobotanical and experimental studies, stimulating an interest for their possible use as functional food or drug sources. Most studied medicinal properties include antidiabetic and antimicrobial activities of D. microcarpum, cardiovascular protective and antidiabetic activities of P. biglobosa, and bilharzia-preventing molluscicidal activity of D. guineense. Phytochemical characterizations have revealed potential sources of active drugs, such as D. guineense saponins and D. microcarpum diterpenes. Scientific results support popular uses of these legume trees, indicating a prominent nutritional and health value.

Detarium microcarpum: A novel source of nutrition and medicine: A review

Detarium microcarpum is a plant indigenous to Africa, which occurs naturally in many African countries, particularly in savannah regions. Its leaves and fruits are used mainly as food and as folk medicine. It has anti-diabetic, antioxidant, and hepatitis C inhibitor properties and has been traditionally utilised in cancer treatment. This review examines published work on the nutritional, pharmacological, and traditional uses of Detarium microcarpum. This plant may become valuable if the fruit, stems, roots, and leaves are extracted for nutraceutical purposes.

Human Lymphocyte-Protective Effects of an Ethanol Extract from Detarium microcarpum Guill. and Perr. (Caesalpiniaceae) Fruit Pulp

The current study aimed to evaluate, in vitro, the antioxidant capacity and the human lymphocyte-protective effect of the ethanolic extract from Detarium microcarpum fruit pulp against oxidative stress damage. Human lymphocytes were incubated with different concentrations of extract, followed by the addition of hydrogen peroxide or tert-butyl hydroperoxide. Cell viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, the antioxidant property of the extract was evaluated in vitro using hydrogen peroxide and nitric oxide radical-scavenging assays. Compared to the vehicle, the fruit pulp ethanol extract did not exhibit a cytotoxic effect on human lymphocytes. Furthermore, the cytotoxicity of hydrogen peroxide and tert-butyl hydroperoxide to human lymphocytes was significantly reduced by fruit extract pretreatment. The extract and ascorbic acid exhibited similar cytoprotective activity (p > 0.05). The fruit pulp extract showed more antioxidant activity than gallic acid in the hydrogen peroxide-scavenging model, while in the nitric oxide-quenching model, the fruit extract and gallic acid showed similar activity. The fruit pulp of D. microcarpum contains potent antioxidant and cell-protective compounds. The use of the fruit pulp of D. microcarpum as a food supplement could rescue cellular oxidative damage responsible for numerous pathologies.

Clerodane diterpenes: sources, structures, and biological activities

Covering: 1990 to 2015The clerodane diterpenoids are a widespread class of secondary metabolites and have been found in several hundreds of plant species from various families and in organisms from other taxonomic groups. These substances have attracted interest in recent years due to their notable biological activities, particularly insect antifeedant properties. In addition, the major active clerodanes of Salvia divinorum can be used as novel opioid receptor probes, allowing greater insight into opioid receptor-mediated phenomena, as well as opening additional areas for chemical investigation. This article provides extensive coverage of naturally occurring clerodane diterpenes discovered from 1990 until 2015, and follows up on the 1992 review by Merritt and Ley in this same journal. The distribution, chemotaxonomic significance, chemical structures, and biological activities of clerodane diterpenes are summarized. In the cases where sufficient information is available, structure activity relationship (SAR) correlations and mode of action of active clerodanes have been presented.

Labdane and Clerodane Diterpenoids from Colophospermum mopane

Five labdane (1-5), an isolabdane (6), and five clerodane diterpenoids (7-11), were isolated from seeds, husks, and leaves of Colophospermum mopane. Compounds 1-3 and 6-9 are new, and their structures were elucidated by means of physical data analysis (1D and 2D NMR, HRESIMS). The absolute configurations of 1, 7, and 10 were determined by single-crystal X-ray diffraction with Cu Kα radiation. For compounds 2 and 6, the absolute configurations were established by the modified Mosher's method and corroborated by comparison of experimental and calculated electronic circular dichroism spectra of their 3-p-bromobenzoate derivatives. The crude extracts and compounds were evaluated for antimicrobial activity. The leaf extract was the most active against Staphylococcus aureus (125 μg/mL). Compound 11 showed the best inhibitory activity, with minimum inhibitory values of 15.6 μg/mL against Escherichia coli and Staphylococcus aureus and 31.3 μg/mL against Enterococcus faecalis.

Plant extracts from Cameroonian medicinal plants strongly inhibit hepatitis C virus infection in vitro

According to some recent studies, Cameroon is one of the sub-Saharan African countries most affected by hepatitis C, with low access to the standard therapy based on the combination of pegylated interferon and ribavirin. A first ethnobotanical survey, conducted in the Western region of Cameroon, reported the use of several medicinal plants in traditional medicine for the healing of liver-related disorders. Crude organic extracts of five plants surveyed were prepared and their effect against hepatitis C virus (HCV) infection investigated. The HCV JFH1 strain cell culture system HCVcc was used. The antiviral activity was quantified by immunofluorescent labeling of HCV E1 envelope protein at 30 h post-infection in the presence of the plant extracts. Active compounds were then tested in time course infection experiments. Dose-response and cellular toxicity assays were also determined. Three extracts, methanol extracts from roots of Trichilia dregeana, stems of Detarium microcarpum and leaves of Phragmanthera capitata, showed anti-HCV activity, with half-maximal inhibitory concentration of 16.16, 1.42, and 13.17 μg/mL, respectively. Huh-7 cells were incubated with the extracts for 72 h and it appears that T. dregeana extract is not toxic up to 200 μg/mL, D. microcarpum up to 100 μg/mL and P. capitata up to 800 μg/mL. All the three extracts showed a strong inhibition of HCV entry and no effect on replication or secretion. Taken together, these results showed that extracts from Cameroonian medicinal plants are promising sources of anti-HCV agents.

The use of plants in the traditional management of diabetes in Nigeria: pharmacological and toxicological considerations

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system.

MATERIALS AND METHODS

Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. 'Diabetes' and 'Nigeria' were used as keywords for the primary searches; and then 'Plant name - accepted or synonyms', 'Constituents', 'Drug interaction' and/or 'Toxicity' for the secondary searches.

RESULTS

The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs.

CONCLUSION

This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb-drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided.

Natural products as a source of Alzheimer's drug leads

This review focuses on recent developments in the use of natural products as therapeutics for Alzheimer's disease. The compounds span a diverse array of structural classes and are organized according to their mechanism of action, with the focus primarily on the major hypotheses. Overall, the review discusses more than 180 compounds and summarizes 400 references.

Natural products--antifungal agents derived from plants

A new spectrum of human fungal infections is increasing due to increased cancer, AIDS, and immunocompromised patients. The increased use of antifungal agents also resulted in the development of resistance to the present drugs. It makes necessary to discover new classes of antifungal compounds to cure fungal infections. Plants are rich source of bioactive secondary metabolites of wide variety such as tannins, terpenoids, saponins, alkaloids, flavonoids, and other compounds, reported to have in vitro antifungal properties. Since the plant kingdom provides a useful source of lead compounds of novel structure, a wide-scale investigation of species from the tropics has been considered. Therefore, the research on natural products and compounds derived from natural products has accelerated in recent years due to their importance in drug discovery. A series of molecules with antifungal activity against different strains of fungus have been found in plants, which are of great importance to humans. These molecules may be used directly or considered as a precursor for developing better molecules. This review attempts to summarize the current status of important antifungal compounds from plants.

13C-NMR data of diterpenes isolated from Aristolochia Species

The genus Aristolochia, an important source of physiologically active compounds that belong to different chemical classes, is the subject of research in numerous pharmacological and chemical studies. This genus contains a large number of terpenoid compounds, particularly diterpenes. This work presents a compilation of the ¹³C-NMR data of 57 diterpenoids described between 1981 and 2007 which were isolated from Aristolochia species. The compounds are arranged skeletonwise in each section, according to their structures, i.e., clerodane, labdane, and kaurane derivatives. A brief discussion on the ¹³C chemical shifts of these diterpenes is also included.

Evaluation of insecticidal activity of diterpenes and lignans from Aristolochia malmeana against Anticarsia gemmatalis

The insecticidal activity of hexane extracts from the roots and leaves of Aristolochia malmeana was evaluated against Anticarsia gemmatalis larvae by topical application. Extract from the roots was the most active and caused 50% mortality in larvae at 308.4 microg/microL. From this extract, a clerodane diterpene, (-)-kolavenic acid, and three lignans, (-)-kusunokinin, (-)-hinokinin, and (8 S,8' R,9 S)-cubebin, were isolated by chromatography and partition procedures and then evaluated for their insecticidal activities either individually or in pairs. (-)-Kusunokinin showed higher activity against A. gemmatalis (LD10=9.3, LD50=230.1 microg/microL) than the crude extract, and its activity was dose-dependent, whereas the other constituents did not exhibit any significant activity. Together with (-)-kusunokinin and (-)-hinokinin, (-)-copalic acid, (-)-2-oxokolavenic acid, (-)- ent-6-beta-hydroxy-copalic acid, (8 R,8' R,9 R)- and (8 R,8' R,9 S)-cubebins, (-)-fargesin, and (-)-phillygenin were isolated from the hexane extract of the leaves. The compounds were identified on the basis of spectroscopic analysis.

Polyphenol content and antioxidant activity of fourteen wild edible fruits from Burkina Faso

A total of fourteen (14) species of wild edible fruits from Burkina Faso were analyzed for their phenolic and flavonoid contents, and their antioxidant activities using the DPPH, FRAP and ABTS methods. The data obtained show that the total phenolic and total flavonoid levels were significantly higher in the acetone than in the methanol extracts.Detarium microcarpum fruit had the highest phenolic and the highest flavonoid content,followed by that of Adansonia digitata, Ziziphus mauritiana, Ximenia americana and Lannea microcarpa. Significant amounts of total phenolics were also detected in the other fruit species in the following order of decreasing levels: Tamarindus indica > Sclerocaryabirrea > Dialium guineense > Gardenia erubescens > Diospyros mespiliformis > Parkiabiglobosa > Ficus sycomorus > Vitellaria paradoxa. Detarium microcarpum fruit also showed the highest antioxidant activity using the three antioxidant assays. Fruits with high antioxidant activities were also found to possess high phenolic and flavonoid contents. There was a strong correlation between total phenolic and flavonoid levels and antioxidant activities.

Inhibitory effects of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid on superoxide anion and elastase release in human neutrophils through multiple mechanisms

Reactive oxygen species and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. In this study, a cellular model in isolated human neutrophils was established to elucidate the anti-inflammatory functions of 16-hydroxycleroda-3,13(14)E-dien-15-oic acid (PL3S), a clerodane diterpenoid from Formosan Polyalthia longifolia var. pendula. PL3S significantly inhibited the generation of superoxide anion and the release of elastase in formyl-l-methionyl-l-leucyl-l-phenylalanine (FMLP)-activated human neutrophils in a concentration-dependent fashion with IC50 values of 3.06+/-0.20 and 3.30+/-0.48 microM, respectively. PL3S did not affect cAMP-dependent pathway, and the inhibitory effect of PL3S was not reversed by protein kinase A inhibitor. PL3S did not display antioxidant or superoxide anion-scavenging ability, and it failed to alter the subcellular NADPH oxidase activity. PL3S concentration-dependently inhibited calcium mobilization caused by FMLP but not thapsigargin. Furthermore, PL3S attenuated the FMLP-induced protein kinase B (AKT) and p38 mitogen-activated protein kinase phosphorylation. However, PL3S had no effect on FMLP-induced phosphorylation of extracellular regulated kinase and c-Jun N-terminal kinase. In summary, these results indicate that the suppressive effects of PL3S on human neutrophil respiratory burst and degranulation are at least partly mediated by inhibition of calcium, AKT, and p38 signaling pathways.

In vitro screening assays to identify natural or synthetic acetylcholinesterase inhibitors: thin layer chromatography versus microplate methods

Acetylcholinesterase inhibitors (AChEI) are currently still the best available pharmacotherapy for Alzheimer patients. Successful screening for new AChEI relies on effective and fast assays. Two colorimetric screening assays frequently used to search for new AChEI, namely a thin layer chromatography (TLC) assay with Fast Blue B salt as reagent and a 96-well plate assay based on Ellman's method, were compared. For the majority (83%) of the 138 test compounds of natural and synthetic origin, the results obtained with the two assays converged and both screening assays were considered suitable for the generation of new hits. Fifteen percent of investigated compounds were classified as active with the microplate assay but were shown to be inactive by TLC and about 2% were measured active by TLC but showed to be inactive with the microplate assay. These divergences were not due to the main differences between the experimental protocols of the two screening assays, namely the different colorimetric methods and pre-incubation of test compounds with acetylcholinesterase (AChE). They might be explained by the interaction of either AChE or test compounds with the silica of the TLC plates, resulting in an altered affinity of the enzyme for the compounds.

Callophycoic acids and callophycols from the Fijian red alga Callophycus serratus

Callophycoic acids A-H (1-8) and callophycols A and B (9 and 10) were isolated from extracts of the Fijian red alga Callophycus serratus, and identified by NMR, X-ray, and mass spectral analyses. These natural products represent four novel carbon skeletons, providing the first examples of diterpene-benzoic acids and diterpene-phenols in macroalgae. Compounds 1-10 exhibited antibacterial, antimalarial, and anticancer activity, although they are less bioactive than diterpene-benzoate macrolides previously isolated from this red alga.