Anti-oxidative and cholinesterase inhibitory effects of leaf extracts and their isolated compounds from two closely related Croton species

Dereplication of polar extracts from Croton antisyphiliticus Mart. roots and its anti-inflammatory and antinociceptive potential

Croton antisyphiliticus Mart. is a plant popularly used in folk medicine by traditional communities from Brazilian savannah to treat general inflammation. According to ethnopharmacological data, this specie can be considered a source of biologically active molecules for the development of new drugs. Thereby, this study reports the results of the dereplication approach of C. antisyphiliticus roots extracts and the in vivo evaluation of its potential antinociceptive and anti-inflammatory in albino Swiss mice. Based on HPLC coupled to Q-Exactive Orbitrap Mass Spectrometer and using GNPS, a total of thirteen polyphenolic compounds were noticed, including four compounds that have been reported for the first time in the genus Croton. Ethanolic and aqueous roots extracts demonstrated a dose-dependent inhibition for the number of writes, reduced pain induced by formalin and hyperalgesia induced by carrageenan. These extracts also reduced paw edema, cell migration, and myeloperoxidase activity, with effects similar to indomethacin and dexamethasone drugs.

Phytochemical Properties of Croton gratissimus Burch (Lavender Croton) Herbal Tea and Its Protective Effect against Iron-Induced Oxidative Hepatic Injury

Oxidative stress plays a vital role in the pathogenesis and progression of various liver diseases. Traditional medicinal herbs have been used worldwide for the treatment of chronic liver diseases due to their high phytochemical constituents. The present study investigated the phytochemical properties of Croton gratissimus (lavender croton) leaf herbal tea and its hepatoprotective effect on oxidative injury in Chang liver cells, using an in vitro and in silico approach. C. gratissimus herbal infusion was screened for total phenolic and total flavonoid contents as well as in vitro antioxidant capacity using ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) methods. Oxidative hepatic injury was induced by incubating 0.007 M FeSO4 with Chang liver cells which has been initially incubated with or without different concentrations (15-240 μg/mL) of C. gratissimus infusion or the standard antioxidants (Gallic acid and ascorbic acid). C. gratissimus displayed significantly high scavenging activity and ferric reducing capacity following DPPH and FRAP assays, respectively. It had no cytotoxic effect on Chang liver cells. C. gratissimus also significantly elevated the level of hepatic reduced glutathione (GSH), superoxide dismutase (SOD), and catalase activities as well as suppressed the malondialdehyde (MDA) level in oxidative hepatic injury. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis of the herbal tea revealed the presence of 8-prenylnaringenin, flavonol 3-O-D-galactoside, caffeine, spirasine I, hypericin, pheophorbide-a, and 4-methylumbelliferone glucuronide. In silico oral toxicity prediction of the identified phytochemicals revealed no potential hepatotoxicity. Molecular docking revealed potent molecular interactions of the phytochemicals with SOD and catalase. The results suggest the hepatoprotective and antioxidative potentials of C. gratissimus herbal tea against oxidative hepatic injury.

Kaempferol as a therapeutic agent in Alzheimer's disease: Evidence from preclinical studies

BACKGROUND

Alzheimer's disease (AD) is the most common type of dementia and seriously affects human life and health. Kaempferol (KMP) is a common flavonoid, that is mainly derived from the rhizomes of Kaempferol galanga L. and is widely found in various fruits and vegetables. Previous studies have suggested that KMP has multiple pharmacological activities. However, the anti-AD mechanism of KMP has not been elucidated.

METHODS

This systematic review aims to summarize the existing preclinical experiments on KMP, further confirm the therapeutic effect of KMP in an AD model, and summarize the possible mechanism by which KMP exerts anti-AD effects. Electronic databases, including PubMed, China National Knowledge Infrastructure (CNKI), Baidu Academic, and Wanfang, were searched using the keywords of 'Kaempferol,' 'KMP,' 'pharmacology,' and 'Alzheimer's disease'.

RESULTS

We evaluated the reliability of the 12 included studies, and the results showed that the anti-AD mechanism of KMP was reliable and that the prospect of KMP in the treatment of cognitive impairment was promising. We comprehensively assessed the neuroprotective effects of KMP in in vivo and in vitro models of AD. These studies shown that KMP ameliorated AD through several mechanisms, including its antioxidant, anti-inflammatory, anti-apoptotic, and anti-acetylcholinesterase effects.

CONCLUSION

KMP may exert anti-AD effects through various mechanisms and is a potential drug with broad prospects for the treatment of AD.

Phylogeny, Phytomedicines, Phytochemistry, Pharmacological Properties, and Toxicity of Croton gratissimus Burch (Euphorbiaceae)

Croton gratissimus is an important plant in Africa setup and across the globe for its ethnomedicinal uses in managing a wide range of diseases. Its phylogeny, pharmacological properties, ethnomedicinal uses, phytochemistry, and cytotoxicity have been highlighted in various articles and journals. This review article aims to give a comprehensively overviewed literature about Croton gratissimus genus. Authentic literature sources such as books, peer reviewed articles, journals, theses, Google Scholar, Science Direct, and any other validated internet source have been used to develop this review. Croton gratissimus is richly found across different climatic zones because of its ability to adapt to various climatic conditions. It is mainly found in rocky hills as a scrub that is about 12–15 m tall. Its leaves are glossy, green on the top, and silvery underneath. Some of the leaves may look brick red rusty. Croton gratissimus has been explored traditionally to manage a number of diseases among the human race since time immemorial. It has been used to treat different ailments ranging from respiratory tract infections, urinary tract infections, malaria, diabetes, hypertension, dermatological conditions, arthritis, gastrointestinal disorders, fever, sexually transmitted diseases, and infertility. Studies have shown that parts of this plant have antioxidative, antimicrobial, anticholinesterases inhibitory, antidiabetic, antihyperlipidemic, anticonvulsant, antiulcer, antihypertensive, antiproliferative, antiplasmodial, and anti-inflammatory activities. Terpenoids and flavonoids have shown to be the major classes of compounds in this plant. Its toxicity has not been well established; some studies have suggested that Croton gratissimus can cause hepatotoxicity and genotoxicity. More studies are needed to elucidate the compounds and their structures giving this plant a wide range of pharmacological activities, efficacy, safety, and toxicity levels, since the plant has greater ethnomedicinal uses. This would give a great indication of discovering new novelties that can give a breakthrough in drug discovery.

Investigation of Euphorbia nivulia-HAM for Enzyme Inhibition Potential in Relation to the Phenolic and Flavonoid Contents and Radical Scavenging Activity

Euphorbia nivulia-Ham (EN) is a neglected medicinal plant traditionally used for a number of pathologies, but it has not been explored scientifically. In the current study, its various fractions were assessed for their phenolic and flavonoid content, radical scavenging, as well as its enzyme inhibitory potential. The hydro-alcoholic crude extract (ENCr) was subjected to a fractionation scheme to obtain different fractions, namely n-hexane (ENHF), chloroform (ENCF), n-butanol (ENBF), and aqueous fraction (ENAF). The obtained results revealed that the highest phenolic and flavonoid content, maximum radical scavenging potential (91 ± 0.55%), urease inhibition (54.36 ± 1.47%), and α-glucosidase inhibition (97.84 ± 1.87%) were exhibited by ENCr, while the ENBF fraction exhibited the highest acetylcholinestrase inhibition (57.32 ± 0.43%). Contrary to these, hydro-alcoholic crude as well as the other fractions showed no significant butyrylcholinestrases (BChE) and carbonic anhydrase inhibition activity. Conclusively, it was found that EN possesses a significant radical scavenging and enzyme inhibitory potential. Thus, the study may be regarded a step forward towards evidence-based phyto-medicine.

A review of biological activities and phytochemistry of six ethnomedicinally important South African Croton species

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Croton (Euphorbiaceae) encompasses 1300 species, which consist of a variety of trees and shrubs distributed across the world. About 26 species are harboured on the African continent. This genus plays an essential role in African folk medicine. Croton species are traditionally used for the treatment of many diverse conditions such as diabetes, malaria, sexually transmitted diseases, cancer, inflammation, fever, digestive problems and fungal infections.

AIM OF THE REVIEW

To provide a comprehensive overview of the ethnobotany, traditional uses, phytochemistry and biological activities of six selected southern Africa Croton species; C.gratissimus Burch., C. megalobotrys Müll.-Arg., C. menyhartii Gȕrke, C. pseudopulchellus Pax, C. steenkampianus Gerstner and C. sylvaticus Schltdl.).

MATERIALS AND METHODS

Various electronic databases, namely Google, Google Scholar, Scopus, ScienceDirect, Biomed Central and Pubmed, were used to search for information related to the traditional uses, chemistry and pharmacology of Croton species. Books were also consulted to collect all pertinent information.

RESULTS AND DISCUSSION

The ethnopharmacology, phytochemistry and biological activities of southern African Croton species are reviewed. The literature revealed that Croton species are trusted traditional medicines for the treatment of microbial infections and malaria. The non-volatile components of Croton species include flavonoids, terpenoids and alkaloids, while the volatile constituents comprise mainly of monoterpenes (α-phellandrene, α-pinene and 1,8-cineole) and sesquiterpenes (caryophyllene oxide). Most of the reported biological activities (anti-oxidant, antimicrobial, anticancer and antimalarial) were based on in vitro assays and were accredited to various extracts. However, both in vitro and in vivo studies, linking the reported activities to specific compounds, are still lacking.

CONCLUSIONS

Croton species are used in traditional medicine to treat a range of ailments, and various in vitro biological activities have been investigated, with some extracts exhibiting good activity that could be considered for further investigation. The in vitro activities obtained seem to justify the use of Croton species in traditional medicine. Data on in vivo studies are scarce and studies usually focused on a single collection. The need to establish a quality control protocols for the standardisation of these herbal drugs is also important.

Multitargeted Effects of Vitexin and Isovitexin on Diabetes Mellitus and Its Complications

BACKGROUND

Till date, there is no known antidote to cure diabetes mellitus despite the discovery and development of diverse pharmacotherapeutic agents many years ago. Technological advancement in natural product chemistry has led to the isolation of analogs of vitexin and isovitexin found in diverse bioresources. These compounds have been extensively studied to explore their pharmacological relevance in diabetes mellitus. Aim of the Study. The present review was to compile results from in vitro and in vivo studies performed with vitexin and isovitexin derivatives relating to diabetes mellitus and its complications. A systematic online literature query was executed to collect all relevant articles published up to March 2020.

RESULTS

In this piece, we have collected data and presented it in a one-stop document to support the multitargeted mechanistic actions of vitexin and isovitexin in controlling diabetes mellitus and its complications.

CONCLUSION

Data collected hint that vitexin and isovitexin work by targeting diverse pathophysiological and metabolic pathways and molecular drug points involved in the clinical manifestations of diabetes mellitus. This is expected to provide a deeper understanding of its actions and also serve as a catapult for clinical trials and application research.

Modulation of Cardiopulmonary Toxicity and Oxidative Stress by Phenolic-Rich Fraction of Croton zambiscus Leaves in Rat Exposed to Chronic Mixture of Environmental Toxicants

Chronic mixed toxicant exposure has been implicated in the aetiology of lung and heart failure through prolonged free radical generations. This study was carried out to assess the protective effect of naturally occurring phenolic components from Croton zambesicus (400 mg/kg C-ZAMB) leaves against cardiopulmonary toxicity induced by chronic mixed toxicant (0.5 mL EOMABRSL) in rats. Chronic cardiopulmonary injury via oral administration of 0.5 ml EOMABRSL for 98 days (non-withdrawal) and 70 days (withdrawal) caused unhealthy alteration in the levels of oxidative stress biomarkers [malondialdehyde (MDA), reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase]. Similarly, both withdrawal and non-withdrawal approaches of EOMABRSL-exposed animals exhibited increase in the activity of eco-51-nucleotidase (51ENT) with corresponding diminution in the activity of lactate dehydrogenase (LDH), i.e. the metabolic fuel for cardiopulmonary wellness. Ultimately, histology examination confirmed hyperplastic, bronchopneumonia and cloudy swelling of cardiovascular cells followed by the accumulation of cellular exudates and haemorrhage in the alveoli and bronchioles. The active antioxidants of 400 mg/kg C-ZAMB leaves were responsible for the biological protection of cardiopulmonary toxicity by modulating the activities of 51ENT and LDH. The oxidative stress was also reversed by 400 mg/kg phenolic C-ZAMB leaves in the heart and lungs. Hence, 400 mg/kg phenolic C-ZAMB leaves may be a natural therapy for the treatment of cardiovascular disorder associated with pulmonary dysfunction in rats.

Plant-Based Phytochemicals as Possible Alternative to Antibiotics in Combating Bacterial Drug Resistance

The unprecedented use of antibiotics that led to development of resistance affect human health worldwide. Prescription of antibiotics imprudently and irrationally in different diseases progressed with the acquisition and as such development of antibiotic resistant microbes that led to the resurgence of pathogenic strains harboring enhanced armors against existing therapeutics. Compromised the treatment regime of a broad range of antibiotics, rise in resistance has threatened human health and increased the treatment cost of diseases. Diverse on metabolic, genetic and physiological fronts, rapid progression of resistant microbes and the lack of a strategic management plan have led researchers to consider plant-derived substances (PDS) as alternative or in complementing antibiotics against the diseases. Considering the quantitative characteristics of plant constituents that attribute health beneficial effects, analytical procedures for their isolation, characterization and phytochemical testing for elucidating ethnopharmacological effects has being worked out for employment in the treatment of different diseases. With an immense potential to combat bacterial infections, PDSs such as polyphenols, alkaloids and tannins, present a great potential for use, either as antimicrobials or as antibiotic resistance modifiers. The present study focuses on the mechanisms by which PDSs help overcome the surge in resistance, approaches for screening different phytochemicals, methods employed in the identification of bioactive components and their testing and strategies that could be adopted for counteracting the lethal consequences of multidrug resistance.

Rat liver and kidney post-mitochondrial dysfunction by addition of chronic mixed metal intoxication and hepatorenal wellness mediated by phenolic components from Croton zambiscus leaves

Chronic exposure of mixed-metal intoxication has been associated with prolonged oxidative stress and severe hepatorenal damage. This present study demonstrates the hepatoprotective and renoprotective activity of Croton zambesicus (C-ZAMB) leaves, naturally occurring phenolic compounds against chronic mixed-metal (EOMABRSL) induced toxicity. 0.5 ml of EOMABRSL via oral route induced chronic hepatoxicity and nephrotoxicity on exposure for 98 days (non-withdrawal) and 70 days (withdrawal) by abnormal alteration in the levels of endogenous antioxidants. Moreover, EOMABRSL induced hepatorenal damage by increasing the markers of liver toxicity (ALT, AST, ALP, GGT and bilirubin) and kidney failure (creatinine, urea, uric acid, and renal electrolytes-Na⁺ and K⁺). Both non-withdrawal and withdrawal approaches of EOMABRSL-exposed animals exhibited hepatorenal dysfunctions by increasing the activity of eco-5¹-nucleotidase (5¹ENT) followed by the decreased in the activity of lactate dehydrogenase (LDH)-index of cellular ATP. These results were further supported by the histopathological examination of nephritic cells, hepatocytes and splenocytes, manifested by hepatocellular necrosis, swelling or degeneration of tubular kidney epithelial cells as well as coalescing splenic periarteriolar lymphoid sheaths (PALSs) and lymphoid haemosiderin. The chronic EOMABRSL intoxication was ameliorated by administration of phenolic antioxidants from C-ZAMB leaves. Therefore, our study supports the view that phenolic C-ZAMB leaves may mediate hepatorenal wellness on chronic exposure to mixed-metal intoxication.

Does Croton Argyrophyllus Extract Has an Effect on Muscle Damage and Lipid Peroxidation in Rats Submitted to High Intensity Strength Exercise?

Many species of the genus Croton have been used for anti-inflammatory, antiproliferative, antidiabetic, and antitumor purposes. The objective was to evaluate the effect of a hydroethanolic extract (HEE) from the inner bark of Croton argyrophyllus (Euphorbiaceae) on muscle damage and oxidative stress in rats after high intensity exercise. The animals were divided into four groups: (i) the sedentary group (SV; n = 7), (ii) the exercise vehicle group (EV, n = 7), (iii) the sedentary group HEE (SHG; n = 7) composed of sedentary animals and treated with the hydroethanolic extract of C. argyrophyllus (200 mg/kg, v.o.), and (iv) the HEE exercise group (HEE; n = 7) composed of animals submitted to resistance exercise (RE) and treated with the hydroethanolic extract of C. argyrophyllus (200 mg/kg, v.o.). In the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) test, the HEE showed lower values of inhibition potential (IP%) at 39.79% compared to gallic acid, 87.61%, and lipoperoxidation inhibition at 27.4% (100 µg/mL) or 28.6% (200 µg/mL) (p < 0.001). There was inhibition in free radicals in vivo. The HEE of C. argyrophyllus partially reduced the biomarkers of oxidative stress in muscle tissue and muscular damage (creatine kinase (CK) and Lactate Dehydrogenase (LDH)) (p < 0.05) in rats, and in this sense it can be an aid to the recovery process after exhaustive efforts.

Croton gratissimus leaf extracts inhibit cancer cell growth by inducing caspase 3/7 activation with additional anti-inflammatory and antioxidant activities

BACKGROUND

Croton species (Euphorbiaceae) are distributed in different parts of the world, and are used in traditional medicine to treat various ailments including cancer, inflammation, parasitic infections and oxidative stress related diseases. The present study aimed to evaluate the antioxidant, anti-inflammatory and cytotoxic properties of different extracts from three Croton species.

METHODS

Acetone, ethanol and water leaf extracts from C. gratissimus, C. pseudopulchellus, and C. sylvaticus were tested for their free radical scavenging activity. Anti-inflammatory activity was determined via the nitric oxide (NO) inhibitory assay on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, and the 15-lipoxygenase inhibitory assay using the ferrous oxidation-xylenol orange assay. The cytotoxicity of the extracts was determined on four cancerous cell lines (A549, Caco-2, HeLa, MCF-7), and a non-cancerous African green monkey (Vero) kidney cells using the tetrazolium-based colorimetric (MTT) assay. The potential mechanism of action of the active extracts was explored by quantifying the caspase-3/- 7 activity with the Caspase-Glo® 3/7 assay kit (Promega).

RESULTS

The acetone and ethanol leaf extracts of C. pseudopulchellus and C. sylvaticus were highly cytotoxic to the non-cancerous cells with LC₅₀ varying between 7.86 and 48.19 μg/mL. In contrast, the acetone and ethanol extracts of C. gratissimus were less cytotoxic to non-cancerous cells and more selective with LC₅₀ varying between 152.30 and 462.88 μg/mL, and selectivity index (SI) ranging between 1.56 and 11.64. Regarding the anti-inflammatory activity, the acetone leaf extract of C. pseudopulchellus had the highest NO inhibitory potency with an IC₅₀ of 34.64 μg/mL, while the ethanol leaf extract of the same plant was very active against 15-lipoxygenase with an IC₅₀ of 0.57 μg/mL. A linear correlation (r<0.5) was found between phytochemical contents, antioxidant, anti-inflammatory and cytotoxic activities of active extracts. These extracts induced differentially the activation of caspases - 3 and - 7 enzymes in all the four cancerous cells with the highest induction (1.83-fold change) obtained on HeLa cells with the acetone leaf extract of C. gratissimus.

CONCLUSION

Based on their selective toxicity, good antioxidant and anti-inflammatory activities, the acetone and ethanol leaf extracts of C. gratissimus represent promising alternative sources of compounds against cancer and other oxidative stress related diseases.

A Review on the Dietary Flavonoid Tiliroside

Among flavonoid derivatives, tiliroside is a flavonoid contained in several edible plants or specific plant parts (fruits, leaves, or roots). These parts are often widely used as both food and medicines, in the treatment of various ailments and, in some cases, as food supplements. Considering the easy access to many publications concerning tiliroside and the lack of a review that summarizes the current progress in studies on its safety, efficacy, and presence in the plant kingdom, we present here a review paper on tiliroside and its principal derivatives. The paper also highlights the basic knowledge regarding this molecule, its derivatives, and the analytical approaches used for extraction and quantification, as well as reports on the biological activities against different key enzymes linked to various human diseases. The reported information is also devoted to highlighting the concept "learn from nature to discover new products," particularly in the development of new drugs, food supplements, and nutraceuticals, starting from a natural lead compound such as tiliroside and improving its biological activities (and selectivities) against a specific target for therapeutic purposes.

Determination of antioxidant potential of Acacia nilotica leaf extract in oxidative stress response system of Saccharomyces cerevisiae

BACKGROUND

From ancient times, plants and plant-derived products have been used as folkloric medicines for a variety of health disorders owing to their tremendous therapeutic potential. The present study aimed to determine the antioxidant efficacy of crude Acacia nilotica extract in the oxidative stress response system of Saccharomyces cerevisiae as a model organism.

RESULTS

Acacia nilotica showed significant antioxidant activity, with IC₅₀ values of 75.157 and 159.57 µg mL^-1 for 2,2-diphenyl-1-picrylhydrazyl radical and hydroxyl radical scavenging activities respectively at a concentration of 500 µg mL^-1 . The total antioxidant activity of A. nilotica showed an ascorbic acid equivalent of 152.79 ± 7.43 µg mL^-1 . The presence of phytoconstituents such as phytol and α-tocopherol from gas chromatography/mass spectrometry analysis confirmed the potential of A. nilotica as an antioxidant. The results were validated using the stress response mechanism in S. cerevisiae wild type and its isogenic deletion strains sod1Δ and tsa1Δ. Acacia nilotica substantially neutralized reactive oxygen species generated by hydrogen peroxide in mutant strains, as evident from spot assay and fluorescence assay using fluorescence microscopy and intensity studies.

CONCLUSION

The results suggested the efficacy of A. nilotica as a potent antioxidant in the S. cerevisiae system for the first time and its use in neutraceuticals/therapeutics. © 2017 Society of Chemical Industry.

Phytochemical analysis and anti-inflammatory evaluation of compounds from an aqueous extract of Croton cajucara Benth

Croton cajucara Benth. is a medicinal plant popularly used in the Brazilian Amazonia, where it is known as sacaca, being consumed as tea, decoction or infusion of the leaves and stem bark. From a decoction of the leaves, a comprehensive phytochemical analysis was developed by liquid chromatography-mass spectrometry. Many compounds were identified for the first time in C. cajucara, such as O-glycosides of kaempferol and quercetin, flavonoid-C-glycosides, tannins and cinnamic acid derivatives. These compounds were fractionated by polarity and assayed for their anti-inflammatory activity, using a model of mice edema, induced by an intraplantar injection of carrageenan. All fractions exhibited anti-inflammatory properties.

Bioactive comparison of main components from unripe fruits of Rubus chingii Hu and identification of the effective component

Dried and unripe fruit of Rubus chingii Hu, known as "Fu-pen-zi" in Chinese, has been used as a food and tonic in China for a long time. In order to analyze its effective ingredients, polysaccharides, flavonoids, saponins and alkaloids were extracted from the unripe fruits and their contents were determined. The in vitro antioxidant, anticomplementary and anticancer activities against human lung adenocarcinoma A549 cells of the four major constituents were investigated. Results showed that total flavonoids exhibited an obvious antioxidant activity, which was very close to ascorbic acid. The anticomplementary and anticancer activities of flavonoids were also the best among the four chemical compositions. Therefore, extraction process optimization of flavonoids was conducted using response surface methodology. The optimal conditions were as follows: extraction temperature 72.8 °C, ethanol concentration 30.67%, extraction time 2.66 h, and a liquid/solid ratio of 19.54 : 1. In addition, total flavonoids were subsequently separated by column chromatography and the major flavonoid was identified as tiliroside. Further experimental data revealed that tiliroside treatment could suppress the proliferation and induced the apoptosis of A549 cells.

Discovery and resupply of pharmacologically active plant-derived natural products: A review

Medicinal plants have historically proven their value as a source of molecules with therapeutic potential, and nowadays still represent an important pool for the identification of novel drug leads. In the past decades, pharmaceutical industry focused mainly on libraries of synthetic compounds as drug discovery source. They are comparably easy to produce and resupply, and demonstrate good compatibility with established high throughput screening (HTS) platforms. However, at the same time there has been a declining trend in the number of new drugs reaching the market, raising renewed scientific interest in drug discovery from natural sources, despite of its known challenges. In this survey, a brief outline of historical development is provided together with a comprehensive overview of used approaches and recent developments relevant to plant-derived natural product drug discovery. Associated challenges and major strengths of natural product-based drug discovery are critically discussed. A snapshot of the advanced plant-derived natural products that are currently in actively recruiting clinical trials is also presented. Importantly, the transition of a natural compound from a "screening hit" through a "drug lead" to a "marketed drug" is associated with increasingly challenging demands for compound amount, which often cannot be met by re-isolation from the respective plant sources. In this regard, existing alternatives for resupply are also discussed, including different biotechnology approaches and total organic synthesis. While the intrinsic complexity of natural product-based drug discovery necessitates highly integrated interdisciplinary approaches, the reviewed scientific developments, recent technological advances, and research trends clearly indicate that natural products will be among the most important sources of new drugs also in the future.

Beverages of lemon juice and exotic noni and papaya with potential for anticholinergic effects

Lemon (Citrus limon (L.) Burm. f.) juice beverages enriched either with noni (Morinda citrifolia L.) (LN) or papaya (Carica papaya L.) (LP), were characterized by HPLC-DAD-ESI/MS(n), the antioxidant capacity was evaluated by (DPPH·), superoxide (O2(·-)), hydroxyl radicals (·OH) and hypochlorous acid (HOCl) assays, and their potential as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitors was also assessed. The fruits are rich in a wide range of bioactive phenolics. Regarding DPPH·, ·OH and HOCl assays, the LP displayed strong activity, and LN was the most active against O2(·-). Concerning cholinesterases, LP was the most active, mainly due to lemon juice contribution. The effect on the cholinesterases was not as strong as in previous reports on purified extracts, but the bioactive-rich beverages offer the possibility of dietary coadjutants for daily consumption of health-promoting substances by adults with aging-related cognitive or physical disorders.

Phytosynergy in some Hypoxis species and pharmacological properties of a Hypoxis-based phytopharmaceutical formula

ETHNOPHARMACOLOGY RELEVANCE

Hypoxis species are used extensively in traditional medicine in southern Africa for several ailments including tuberculosis, chest infections, and nervous and urinary disorders. Several other claims have been made for extracts emanating from Hypoxis species and have led to the production of several commercial products used as immunostimulants mostly for people living with HIV/AIDS and cancer. This study was aimed at investigating the biological activity of four Hypoxis species and a commercial herbal product, 'African potato extract' (APE).

MATERIALS AND METHODS

Antibacterial, antifungal, cyclooxygenase (COX) and acetylcholineasterase (AChE) inhibitory activities of four Hypoxis species (H. acuminata, H. colchicifolia, H. hemerocallidea and H. rigidula) and a popular Hypoxis-based herbal preparation, APE were tested. The phytoconstituents of the mixture were also profiled using TLC methods. Several combinations of the Hypoxis species were prepared and their synergism, additive, autonomic and antagonism effects investigated. As a quality control measure, batch to batch comparison in the phytoconstituents and biological activity of APE was carried out.

RESULTS

The results confirmed H. colchicifolia and H. hemerocallidea as the phytoconstituents of APE. The extracts showed a broad spectrum of activities against the bacterial and fungal strains used. Of particular interest were the activities exhibited by the APE and combinations of H. colchicifolia and H. hemerocallidea. The APE mixture exhibited good antibacterial activity (MIC values of 0.78mg/ml each) in all the tested batches against the bacterial strains used. The water extracts of all four Hypoxis species, three batches of APE and the combination (water extracts) of H. colchicifolia and H. hemerocallidea exhibited high COX-1 and moderate COX-2 inhibitory activity except for H. acuminata which showed low activity against COX-2. All the extract, batches of APE and combinations showed low to moderate AChE inhibitory activity. These results provided some evidence of phytosynergy in some extracts of H. hemerocallidea and H. colchicifolia except for a few extracts which act as additive, autonomous and antagonistic when used to inhibit some bacterial and fungal strains. However, this was not the case for COX and AChE inhibition, as only acetone extracts acted in a synergistic way to reduce the activity of the enzyme.

CONCLUSION

Even though the results give an indication of a positive interaction between some extracts of H. hemerocallidea and H. colchicifolia, the study was carried out on 1:1 v/v combinations only. It is therefore important to carry out isobologram studies, which considers more than one ratio of the combinations.

Antihyperalgesic and antiedematous activities of bisabolol-oxides-rich matricaria oil in a rat model of inflammation

From the dried flower heads of Matricaria recutita L., essential oil was isolated by hydrodistillation, and in the obtained blue oil, α-bisabolol oxide A (21.5%), α-bisabolol oxide B (25.5%) and (Z)-spiroether (cis-en-yn-spiroether) (10.3%) were identified as the main compounds, by gas chromatography (GC) and GC-mass spectrometry analyses. The antihyperalgesic effects of this oil were examined in a rat model of inflammation induced by carrageenan, through a modified 'paw-pressure' test. Antiedematous effects were examined in a rat model of inflammation induced by carrageenan, dextran and histamine, through plethysmometry. Matricaria oil (25, 50 and 100 mg/kg, p.o.) exhibited a significant dose-dependent reduction of hyperalgesia and edema induced by carrageenan in both prophylactic and therapeutic treatment schemes. It was more efficacious in the prophylactic treatment scheme, and the corresponding median effective dose (ED50 ) ± standard error of the mean (SEM) values were 49.8 ± 6.0 and 42.4 ± 0.2 mg/kg for antihyperalgesic and antiedematous effects, respectively. Prophylactic treatments with matricaria oil (25, 50 and 100 mg/kg, p.o.) caused a significant dose-dependent antiedematous effect in dextran-induced edema with lower efficacy than in the carrageenan model. In a dose of 100 mg/kg, p.o., matricaria oil caused a slight reduction of histamine-induced edema. These results suggest that bisabolol-oxide-rich matricaria oil may be effective against pain and edema present in various inflammatory conditions, which supports matricaria traditional uses.