A new protoberberine alkaloid from Meconopsis simplicifolia (D. Don) Walpers with potent antimalarial activity against a multidrug resistant Plasmodium falciparum strain

One-pot synthesis of magnetic sulfonated covalent organic polymer for extraction of protoberberine alkaloids in herbs and human plasma

A novel magnetic sulfonated covalent organic polymer was prepared for magnetic solid-phase extraction of protoberberine alkaloids. The magnetic sulfonated covalent organic polymer was rapidly synthesized under mild conditions. The physicochemical properties of the prepared materials were characterized by Fourier-transform infrared spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy. Several extraction parameters were systematically investigated, including desorption time, pH of sample solution, acetonitrile content, acetic acid content in the eluent, extraction time, and sample volume. By coupling magnetic solid-phase extraction and high-performance liquid chromatography, an efficient and sensitive method for the extraction and determination of protoberberine alkaloids in complex samples was developed. The proposed method showed great linearity (r > 0.9989), low limits of detection (0.2-0.3 ng/ml), and high precision (relative standard deviations ≤ 5.74%). The proposed method was further applied to the analysis of protoberberine alkaloids in Cortex phellodendri and human plasma samples. The recoveries were 91.50%-110.31% with relative standard deviations less than 6.63% in Cortex phellodendri and 96.12%-111.20% with relative standard deviations lower than 5.56% in plasma samples.

Antinociceptive and gastroprotective activities of Bocconia arborea S. Watson and its bioactive metabolite dihydrosanguinarine in murine models

ETHNOPHARMACOLOGICAL RELEVANCE

Bocconia arborea S. Watson (Papaveraceae) is known as "palo llora sangre" and is used in Mexican traditional medicine for the treatment of infections, it is also used as anxiolytic, analgesic, and antidiabetic, among others.

AIM OF THE STUDY

to evaluate the antinociceptive and gastroprotective activities of extracts from B. arborea and dihydrosanguinarine (DHS) in murine models.

MATERIALS AND METHODS

Organic extracts [hexane (HEX), dichloromethane (DCM) and methanol (MeOH)] were obtained by maceration. DHS was isolated and purified from HEX and DCM by precipitation and chromatographic column, respectively. Organic extracts and DHS were evaluated to determine their antinociceptive effect using formalin test in murine model. Also, the ambulatory effect of the HEX and DHS was determined in Open field test. The possible mechanism of action of DHS was explored in the presence of naltrexone (NTX, 1 mg/kg, i.p.), and picrotoxin (PTX, 1 mg/kg, i.p.). Gastric damage as possible adverse effect or gastroprotection were also investigated. Whereas DHS acute toxicological study was done, and 100 mg/kg of DHS was examined by electroencephalographic (EEG) analysis to discard neurotoxic effects.

RESULTS

The B. arborea extracts significantly showed effects in both neurogenic and inflammatory phases of the formalin test, where the HEX extract reached the major antinociceptive effect. A significant and dose-response (10, 30, and 100 mg/kg) antinociceptive activity was observed with the HEX (ED₅₀ = 69 mg/kg) and DHS (ED₅₀ = 85 mg/kg) resembling the effect of the reference analgesic drug tramadol (30 mg/kg). The significant effect of DHS was inhibited in the presence of NTX and PTX. Neither the extracts or DHS produced sedative effects or gastric damage per se at antinociceptive doses. The EEG analysis demonstrated central depressant activity but not sedative or neurotoxic effects at the highest antinociceptive dosage tested, and LD₅₀ is higher than 2000 mg/kg.

CONCLUSIONS

HEX, DCM, and MeOH extracts showed significant antinociceptive activity, and DHS was identified as one of bioactive compounds without producing sedative, neurotoxic or gastric damage effects, as possible adverse effects reported for analgesic drugs. A role of opioid and GABA_A neurotransmission appears to be involved as mechanisms of action of DHS, suggesting its potential for pain therapy and reinforcing the traditional use of B. arborea.

Ethno-medicinal, phytochemistry, and pharmacological importance of Hunteria umbellate (K. Schum.) Hallier f. (Apocynaceae): a useful medicinal plant of sub-Saharan Africa

Background

Hunteria umbellate (K. Schum.) Hallier f. (Apocynaceae) is a tropical rainforest tree commonly found in sub-Saharan region of Africa. It is a useful and very popular plant among the locals due to the outstanding anti-diabetic activity of the seeds.

Methods

A comprehensive literature search on articles published on phytochemical analysis and various pharmacological activities of Hunteria umbellate was carried out using search engines such as Google Scholar, PubMed and Science Direct.

Results

In this review, it was deduced that H. umbellate is employed in folk medicine as an elixir for obesity, fever, leprosy sores, menstrual pain, infertility, yaws, intestinal worms, abdominal discomfort and stomach ache. Due to their durability and immunity against termites, the stems are coveted and desired as timbers in the construction of houses, while the bark has been reportedly exported to Europe for medicinal uses. Pharmacological activities such as fertility enhancing, aphrodisiac, hypoglycemic, anti-inflammatory, has been ascribed to the different morphological organs of H. umbellate. Moreover, compounds belonging to important classes of secondary metabolites with biological activities such as triterpenoids, flavonoids, tannins, alkaloids, quinic acids have been identified and characterized from the plant.

Conclusion

From this review, it can be inferred that, numerous and bioactive principles with known biological usefulness are present in the extracts of H. umbellate and might be responsible for the observed biological and pharmacological activities.

Alkaloids from Plants with Antimalarial Activity: A Review of Recent Studies

Malaria is one of the major health problems in developing countries. The disease kills a large number of people every year and also affects financial status of many countries. Resistance of the plasmodium parasite, the causative agent, to the existing drugs, including chloroquine, mefloquine, and artemisinin based combination therapy (ACT), is a serious global issue in malaria treatment and control. This warrants an urgent quest for novel compounds, particularly from natural sources such as medicinal plants. Alkaloids have over the years been recognized as important phytoconstituents with interesting biological properties. In fact, the first successful antimalarial drug was quinine, an alkaloid, which was extracted from Cinchona tree. In the present review work, the alkaloids isolated and reported recently (2013 till 2019) to possess antimalarial activity are presented. Several classes of alkaloids, including terpenoidal, indole, bisindole, quinolone, and isoquinoline alkaloids, were identified with a promising antimalarial activity. It is hoped that the reports of the review work will spur further research into the structural modification and/or development of the interesting compounds as novel antimalarial drugs.

Antiplasmodial natural products: an update

Background

Malaria remains a significant public health challenge in regions of the world where it is endemic. An unprecedented decline in malaria incidences was recorded during the last decade due to the availability of effective control interventions, such as the deployment of artemisinin-based combination therapy and insecticide-treated nets. However, according to the World Health Organization, malaria is staging a comeback, in part due to the development of drug resistance. Therefore, there is an urgent need to discover new anti-malarial drugs. This article reviews the literature on natural products with antiplasmodial activity that was reported between 2010 and 2017.

Methods

Relevant literature was sourced by searching the major scientific databases, including Web of Science, ScienceDirect, Scopus, SciFinder, Pubmed, and Google Scholar, using appropriate keyword combinations.

Results and Discussion

A total of 1524 compounds from 397 relevant references, assayed against at least one strain of Plasmodium, were reported in the period under review. Out of these, 39% were described as new natural products, and 29% of the compounds had IC₅₀ ≤ 3.0 µM against at least one strain of Plasmodium. Several of these compounds have the potential to be developed into viable anti-malarial drugs. Also, some of these compounds could play a role in malaria eradication by targeting gametocytes. However, the research into natural products with potential for blocking the transmission of malaria is still in its infancy stage and needs to be vigorously pursued.

Identification of lead chemotherapeutic agents from medicinal plants against blood flukes and whipworms

Schistosomiasis and trichuriasis are two of the most common neglected tropical diseases (NTD) that affect almost a billion people worldwide. There is only a limited number of effective drugs to combat these NTD. Medicinal plants are a viable source of parasiticides. In this study, we have investigated six of the 19 phytochemicals isolated from two Bhutanese medicinal plants, Corydalis crispa and Pleurospermum amabile, for their anthelmintic properties. We used the xWORM technique and Scanning Electron Microscope-based imaging to determine the activity of the compounds. Of the six compounds tested, isomyristicin and bergapten showed significant anthelmintic activity against Schistosoma mansoni and Trichuris muris with bergapten being the most efficacious compound one against both parasites (S. mansoni IC₅₀ = 8.6 μg/mL and T. muris IC₅₀ = 10.6 μg/mL) and also against the schistosomulum stage of S. mansoni. These two compounds induced tegumental damage to S. mansoni and affected the cuticle, bacillary bands and bacillary glands of T. muris. The efficacy against multiple phylogenetically distinct parasites and different life stages, especially the schistosomulum where praziquantel is ineffective, makes isomyristicin and bergapten novel scaffolds for broad-spectrum anthelmintic drug development that could be used for the control of helminths infecting humans and animals.

Quality assurance of the university medical education, hospital services and traditional pharmaceutical products of the Bhutanese So-wa-rig-pa health care system

BACKGROUND

The Bhutanese So-wa-rig-pa medicine (BSM) was integrated with the allopathic (modern) health care system in 1967. Ever since the health care integration policy was implemented, the BSM has gone through many phases of quality improvement and changes including the establishment of one university-based institute, 58 hospitals and Basic Health Units (BHU)-based health care services, and one traditional medicine factory. The BSM provides primary health care services to more than 20-30 % of patients who visit hospitals and BHU on a daily basis. However, there has been no study covering the quality assurance system of BSM. Our paper addresses this information gap.

METHODS

This study was an observational ethnographic study supported by phenomenological understanding and content analysis of the data. The information was triangulated through consultation with the BSM practitioners (discussion (N = 8)) and personalized in-depth question-answer sessions using electronic protocols (N = 5). These participants comprised BSM educationists, clinical physicians, researchers, production and the quality assurance staff who were selected using convenience and purposive sampling method. The relevant So-wa-rig-pa information and literature were obtained from the government policy documents, official websites, scientific papers and the traditional medical texts. This study is enhanced by our practical observations and first-hand experience with BSM while working as the researchers at the Ministry of Health in Bhutan. In addition, the information in this paper is crosschecked and authenticated by five So-wa-rig-pa practitioners of Bhutan.

RESULTS

The study highlights the following: a) The BSM receives both the government and people's support, b) The quality assurance system have been developed by integrating the traditional empirical knowledge and modern scientific protocols, c) There exist three administrative and functional organizations responsible for providing the quality BSM health care services in Bhutan, d) Extensive standard treatment guidelines and Quality documentation system exist for BSM as required by the regulatory bodies in Bhutan. The paper also recommends appropriate future directions for BSM.

CONCLUSIONS

The BSM plays significant role in the primary health care system of the country. Consequently, the quality, safety and efficacy of BSM has been given priority by the Bhutan government. Many scientific protocols were integrated with the traditional quality approaches and further scientific studies are still required to improve its quality.

Compounds Derived from the Bhutanese Daisy, Ajania nubigena, Demonstrate Dual Anthelmintic Activity against Schistosoma mansoni and Trichuris muris

Background

Whipworms and blood flukes combined infect almost one billion people in developing countries. Only a handful of anthelmintic drugs are currently available to treat these infections effectively; there is therefore an urgent need for new generations of anthelmintic compounds. Medicinal plants have presented as a viable source of new parasiticides. Ajania nubigena, the Bhutanese daisy, has been used in Bhutanese traditional medicine for treating various diseases and our previous studies revealed that small molecules from this plant have antimalarial properties. Encouraged by these findings, we screened four major compounds isolated from A. nubigena for their anthelmintic properties.

Methodology/Principal Findings

Here we studied four major compounds derived from A. nubigena for their anthelmintic properties against the nematode whipworm Trichuris muris and the platyhelminth blood fluke Schistosoma mansoni using the xWORM assay technique. Of four compounds tested, two compounds—luteolin (3) and (3R,6R)-linalool oxide acetate (1)—showed dual anthelmintic activity against S. mansoni (IC₅₀ range = 5.8–36.9 μg/mL) and T. muris (IC₅₀ range = 9.7–20.4 μg/mL). Using scanning electron microscopy, we determined luteolin as the most efficacious compound against both parasites and additionally was found effective against the schistosomula, the infective stage of S. mansoni (IC₅₀ = 13.3 μg/mL). Luteolin induced tegumental damage to S. mansoni and affected the cuticle, bacillary bands and bacillary glands of T. muris. Our in vivo assessment of luteolin (3) against T. muris infection at a single oral dosing of 100 mg/kg, despite being significantly (27.6%) better than the untreated control group, was markedly weaker than mebendazole (93.1%) in reducing the worm burden in mice.

Conclusions/Significance

Among the four compounds tested, luteolin demonstrated the best broad-spectrum activity against two different helminths—T. muris and S. mansoni—and was effective against juvenile schistosomes, the stage that is refractory to the current gold standard drug, praziquantel. Medicinal chemistry optimisation including cytotoxicity analysis, analogue development and structure-activity relationship studies are warranted and could lead to the identification of more potent chemical entities for the control of parasitic helminths of humans and animals.

Schistosomiasis and trichuriasis affects millions of people worldwide and are caused by blood flukes and whipworms, respectively. Only a handful of anthelmintic drugs exist to treat these infections and the pipeline for the next generation of anthelmintic drugs is sparse, precipitating the need for new drug development. In this context, medicinal plants present a viable source of novel anthelmintic compounds. This inspired us to study the selected naturally occurring compounds derived from a Bhutanese daisy medicinal plant, Ajania nubigena for their anthelmintic activities. Here, using the xWORM motility assay, we demonstrate that two compounds, luteolin (3) and (3R,6R)-linalool oxide acetate (1), display significant broad-spectrum anthelmintic activity against two of the most important genera of human helminth parasites, the nematode whipworm and the platyhelminth blood fluke. Luteolin exhibited the best activities with IC₅₀ values of 5.8 μg/mL against schistosomes and 9.7 μg/mL against whipworms. Using scanning electron microscopy we showed that luteolin damages the tegument of blood flukes and induces abnormalities in the bacillary bands/glands and cuticles of whipworms. Intriguingly, our previous study showed that luteolin (3) was effective against multi-drug resistant Plasmodium falciparum malaria. Due to its broad-spectrum anti-parasitic activities, luteolin (3) is a desirable drug lead scaffold, which could be used for developing effective compounds to control and treat numerous tropical diseases.

Medicinal plants of Dagala region in Bhutan: their diversity, distribution, uses and economic potential

BACKGROUND

The traditional g.so-ba-rig-pa hospitals in Bhutan uses more than 100 polyingredient medicines that are manufactured by the Menjong Sorig Pharmaceuticals (MSP). The MSP has been collecting medicinal plants from Lingzhi region for about 48 years and therefore the ecological pressure on these plants have increased. It is MSP's top priority to identify an alternative collection site to ease the problem. Therefore, this study was carried out to determine whether Dagala region could potentially be an alternative collection site for MSP.

METHODS

First the multidisciplinary research team generated a tentative plant list by reviewing a body of ancient g.so-ba-rig-pa literature, current formulations, and the MSP medicinal plants inventory documents. Second, the research team visited the study areas in Dagala region for spot identification of medicinal plants. Third, we confirmed our traditional and botanical identification by crosschecking the descriptions with the series of books on traditional texts, Flora of Bhutan, scientific papers on medicinal plants, and the plant databases.

RESULTS

We have identified 100 species of high altitude medicinal plants from Dagala region. Of these, 24 species grow abundantly, 29 species grow in moderate numbers and 47 species were scarce. More than 85 species belonged to the herbaceous life form and 51 of them are used as a whole plant. A total of 68 species grow in between 4000 and 4999 meter above sea level. These 100 medicinal plants represented 39 different families and 80 genera and the maximum number of plants belonged to the family Asteraceae. Of 60 species that are currently used for formulating medicines at MSP, 16 species have economic importance with potential for commercial collection. Out of seven areas covered by the survey, Kipchen hosted maximum number of medicinal plants (21 species).

CONCLUSIONS

Our survey identified 100 medicinal plants from Dagala region and of these, 16 species has economic potential that could benefit both MSP and Dagala communities. It is feasible to establish an alternative medicinal plants collection center in Dagala Gewog.

An Ethnopharmacological, Phytochemical and Pharmacological Review of the Genus Meconopsis

The Meconopsis plants (Chinese: 绿绒篙), belonging to the family Papaveraceae, have been used as traditional Tibetan medicine (TTM) for thousands of years. Meconopsis has the effects of clearing heat, reducing swelling, and easing pain, and is mainly prescribed for heat syndromes, hepatitis, pneumonia, and pain in joints. Phytochemical studies have revealed the presence of major isoquinoline alkaloids and flavonoids. Modern pharmacological research has demonstrated its antitumor, hepatoprotective, analgestic, antimicrobial, anti-oxidant, antitussive, and anti-inflammatory activities. However, resource availability, in-depth in vivo pharmacological study and qualitative and quantitative analysis are still insufficient and deserve further efforts. This paper provides a comprehensive advance on the ethnopharmacological, phytochemical, and pharmacological studies of the genus, in hopes of promoting a better understanding of their medicinal values.

Contributions of medicinal plants to the Gross National Happiness and Biodiscovery in Bhutan

BACKGROUND

The medicinal plants and the associated Bhutanese traditional medicine (BTM) are protected by the country's constitution and receive both government support and acceptance by the wider public. More than 1000 medicinal plants are described in the BTM but currently collects only 300 species for daily formulations of BTM. These medicinal plants have been one of the drivers of the 'Gross National Happiness (GNH)' and biodiscovery projects in Bhutan. However, no review covering the systematic evaluations of the contributions of medicinal plants and the BTM to the GNH and biodiscovery exist till date.

METHODS

This paper, therefore addresses this information gap. It is based on the review of the existing traditional and scientific literature, government websites and policy documents. The descriptions and discussions of the paper is straightened, authenticated and enhanced by the data collected through the informal discussions with the BTM practitioners and also through the authors' many years of practical observations of the impact of the medicinal plants programs and the BTM practices in Bhutan.

RESULTS

This paper found the following: a) the medicinal plants generates income to the farmers elevating their living standard and the economic status, b) it serves as the bulk ingredients of the BTM facilitating the provision of free traditional health care services to the patients, c) helps the conservation of medicinal plants and their pristine environment through recognition of their spiritual, social and economic values, d) preserves the rich BTM cultural heritage, and e) guides the biodiscovery projects based on their ethnobotanical information. The paper also identified the challenges and research gaps, and recommends appropriate strategies that can help secure the sustainable future of the medicinal plants, the BTM and the biodiscovery projects.

CONCLUSIONS

The medicinal plants play significant role in the country's biodiscovery projects and the internationally renowned development policy of 'Gross National Happiness'.