A review on extraction techniques and therapeutic value of polar bioactives from Asian medicinal herbs: Case study on Orthosiphon aristatus,Eurycoma longifolia and Andrographis paniculata

Medicinal plants have gained much interest in the prevention and treatment of common human disease such as cold and fever, hypertension and postpartum. Bioactive compounds from medicinal plants were synthesised using effective extraction methods which have important roles in the pharmaceutical product development. Orthosiphon aristatus (OA), Eurycoma longifolia (EL) and Andrographis paniculata (AP) are among popular medicinal herbs in Southeast Asia. The major compounds for these medicinal plants are polar bioactive compounds (rosmarinic acid, eurycomanone and andrographolide) which have multiple benefits to human health. The bioactive compounds are used as a drug to function against a variety of diseases with the support of scientific evidence. This paper was intended to prepare a complete review about the extraction techniques (e.g. OA, EL and AP) of these medicinal plants based on existing studies and scientific works. Suitable solvents and techniques to obtain their major bioactive compounds and their therapeutic potentials were discussed.     

Styrylpyrone-class compounds from medicinal fungi Phellinus and Inonotus spp., and their medicinal importance

Members of the genera Phellinus and Inonotus, including P. linteus, P. igniarius, P. ribis, I. obliquus and I. xeranticus are well-known medicinal fungi (mushrooms) and have been used in treatment of cancer, diabetes, bacterial and viral infections and ulcer. Adverse effects of these medicinal mushrooms have not yet been reported, indicating the safe nature of these mushrooms. Polysaccharides, particularly β-glucan, are considered the compounds responsible for the biological activity of medicinal mushrooms. However, there is only a limited amount of evidence to indicate that polysaccharides are in fact responsible for the biological effects of these medicinal mushrooms. Recently, many research groups have begun identification of active low-MW compounds in medicinal mushrooms, with a focus on the yellow polyphenol pigments, which are composed of a styrylpyrone class of compounds. Interestingly, a representative group of medicinal fungi, including P. linteus, P. igniarius, P. ribis, I. obliquus and I. xeranticus were shown to produce a large and diverse range of styrylpyrone-type polyphenol pigments that exhibited various biological activities, including anti-oxidative, anti-inflammatory, cytotoxic, anti-platelet aggregation, anti-diabetic, anti-dementia and anti-viral effects. Styrylpyrone pigments in mushrooms are thought to have a role similar to that of flavonoids in plants. The unique and unprecedented carbon skeleton of fused styrylpyrone might be an attractive molecular scaffold for pharmacological applications. In this review, the structural diversity, biological effects and biogenesis of styrylpyrone-class polyphenols from medicinal fungi are described.     

Cadmium as a testicular toxicant: A Review

Cadmium (Cd) is a toxic heavy metal with no known biological functions in the human body. Due to a considerably long biological half‐life and very low rate of excretion, accumulation of Cd in different body organs (eg, liver, kidney, and testes) over time is associated with perturbed functioning of these organs. Recent studies have shown the extreme sensitivity of the testes to Cd toxicity. In testes, Cd has been reported to induce oxidative stress, apoptosis of spermatogenic cells, reduction in androgen production and sperm functions. Moreover, Cd in combination with other environmental toxicants may be responsible for the declining fertility of males in both animals and humans. Pinpointing how Cd toxicity affects various testicular processes will be imperative for the development of preventative measures to promote fertility among males. Therefore, in the present review, we summarize the recent findings related to the Cd‐induced oxidative toxicity, apoptotic toxicity, steroidogenic toxicity, and spermatotoxicity, along with their possible mechanisms in testicular tissue of different animal species. In addition, the utilization of various antioxidant compounds, medicinal plants and other compounds for the management of Cd toxicity in testes is discussed.     

Bitter substances from plants used in traditional Chinese medicine exert biased activation of human bitter taste receptors

The number and variety of bitter compounds originating from plants are vast. Whereas some bitter chemicals are toxic and should not be ingested, other compounds exhibit health beneficial effects, which is manifest in the cross‐cultural believe that the bitterness of medicine is correlated with the desired medicinal activity. The bitter taste receptors in the oral cavity serve as sensors for bitter compounds and, as they are expressed in numerous extraoral tissues throughout the body, may also be responsible for some physiological effects exerted by bitter compounds. Chinese herbal medicine uses bitter herbs since ancient times for the treatment of various diseases; however, the routes by which these herbs modify physiology are frequently not well understood. We therefore screened 26 bitter substances extracted from medical herbs for the activation of the 25 human bitter taste receptors. We identified six receptors activated by in total 17 different bitter compounds. Interestingly, we observed a bias in bitter taste receptor activation with 10 newly identified agonists for the broadly tuned receptor TAS2R46, seven agonists activating the TAS2R14 and two compounds activating narrowly tuned receptors, suggesting that these receptors play dominant roles in the evaluation and perhaps physiological activities of Chinese herbal medicines.     

Anticancer bioactivity of compounds from medicinal plants used in European medieval traditions

Since centuries, natural compounds from plants, animals and microorganisms were used in medicinal traditions to treat various diseases without a solid scientific basis. Recent studies have shown that plants that were used or are still used in the medieval European medicine are able to provide relieve for many diseases including cancer. Here we summarize impact and effect of selected purified active natural compounds from plants used in European medieval medicinal traditions on cancer hallmarks and enabling characteristics identified by Hanahan and Weinberg. The aim of this commentary is to discuss the pharmacological effect of pure compounds originally discovered in plants with therapeutic medieval use. Whereas many reviews deal with Ayurvedic traditions and traditional Chinese medicine, to our knowledge, the molecular basis of European medieval medicinal approaches are much less documented.     

Effects of local administration of propolis and its polyphenolic compounds on tumor formation and growth

Many dietary constituents are chemopreventive in animal models, and experiments with cultured cells are revealing various potential mechanisms of action. Compounds classified as blocking agents can prevent, or greatly reduce, initiation of carcinogenesis, or suppressing agents can act on cell proliferation. Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE), members of the polyphenolic compounds, are present in high concentrations in medicinal plants and propolis, a natural beehive product. A water-soluble extract of propolis (WSDP) and two components of propolis, CA and CAPE were investigated for direct antitumor activity in vivo and in vitro. The local presence of CA and CAPE in the tissue caused a significant delay in tumor formation and increased life span 29.30 to 51.73%, respectively. CA and CAPE, but not WSDP, significantly suppressed human HeLa cervical carcinoma cell proliferation in vitro. Based on these results, we postulate that the antitumor activity of polyphenolic compounds includes direct cytotoxic effects on tumor cells.     

Cancer chemotherapy with novel bioactive natural products

Cancer is the primary cause of death on a global scale. Every year, 8.8 million people die because lung, prostate gland, colorectal, and hepatic cancers are more common in men. In contrast, mammary glands, large intestine, bronchi, cervix, and abdomen cancers are more common in women. The Food and Drug Administration of the United States of America has approved plant-based medications for cancer treatment. Examples include taxanes, such as paclitaxel, and vinca alkaloids, such as vincristine and...     

Actieve inhoudsstoffen der Amaryllidacee?nfamilie

Different aspects of the Amaryllidaceae family as medicinal plants are discussed. The botanical and chemical characteristics are presented as well as the use of these herbs as medicinal plants in the past. Subsequently, a review is given of the pharmacological effects of some compounds isolated from the Amaryllidaceae and of some crude extracts of these plants. The conclusion can be drawn that the alkaloids present in all the plants belonging to this family, are responsible for the toxic and for the therapeutically active effects attributed to the Amaryllidaceae.Samenvatting Een aantal aspecten van de Amaryllidaceae als familie van geneeskrachtige planten wordt belicht. Enkele botanische en chemische kenmerken worden gegeven, alsook het gebruik van deze planten in de volksgeneeskunde in het verleden. Vervolgens wordt een overzicht gegeven van de farmacologische effecten van enkele componenten geisoleerd uit deze Amaryllidaceae en van enkele ruwe extracten van planten uit deze familie. Als besluit kan worden gezegd dat de alkaloïden aanwezig in deze familie, verantwoordelijk zijn voor de toxische en de eventueel therapeutische activiteit die wordt toegeschreven aan deze familie.

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Voordracht gehouden op het Congres van de Nederlandse Vereniging voor Geneeskruidenonderzoek, Egmond aan Zee, 5–7 juni 1980.     

Medicinal plants for the prevention and treatment of bacterial infections

Infectious diseases are a significant cause of morbidity and mortality worldwide, accounting for approximately 50% of all deaths in tropical countries and as much as 20% of deaths in the Americas. Despite the significant progress made in microbiology and the control of microorganisms, sporadic incidents of epidemics due to drug resistant microorganisms and hitherto unknown disease-causing microbes pose an enormous threat to public health. These negative health trends call for a global initiative for the development of new strategies for the prevention and treatment of infectious disease. For over 100 years chemical compounds isolated from medicinal plants have served as the models for many clinically proven drugs, and are now being re-assessed as antimicrobial agents. The reasons for this renaissance include a reduction in the new antibacterial drugs in the pharmaceutical pipeline, an increase in antimicrobial resistance, and the need of treatments for new emerging pathogens. Literally thousands of plant species have been tested against hundreds of bacterial strains in vitro and many medicinal plants are active against a wide range of gram positive and gram negative bacteria. However, very few of these medicinal plant extracts have been tested in animal or human studies to determine safety and efficacy. This review focuses on the medicinal plants and bacteria for which there is significant published in vitro, in vivo and clinical data available. The examples provided in this review indicate that medicinal plants offer significant potential for the development of novel antibacterial therapies and adjunct treatments (i.e. MDR pump inhibitors).     

Anti-HIV activity of Indian medicinal plants

Acquired immunodeficiency syndrome patients face great socio-economic difficulties in obtaining treatment. There is an urgent need for new, safe, and cheap anti-HIV agents. Traditional medicinal plants are a valuable source of novel anti-HIV agents and may offer alternatives to expensive medicines in future. Various medicinal plants or plant-derived natural products have shown strong anti-HIV activity and are under various stages of clinical development in different parts of the world. The present study was directed towards assessment of anti-HIV activity of various extracts prepared from Indian medicinal plants. The plants were chosen on the basis of similarity of chemical constituents with reported anti-HIV compounds or on the basis of their traditional usage as immunomodulators. Different extracts were prepared by Soxhlet extraction and liquid-liquid partitioning. Ninety-two extracts were prepared from 23 plants. Anti-HIV activity was measured in a human CD4+ T-cell line, CEM-GFP cells infected with HIV-1NL4.3. Nine extracts of 8 different plants significantly reduced viral production in CEM-GFP cells infected with HIV-1NL4.3. Aegle marmelos, Argemone mexicana, Asparagus racemosus, Coleus forskohlii, and Rubia cordifolia demonstrated promising anti-HIV potential and were investigated for their active principles.     

Effect of altitude on picroside content in core collections of Picrorhiza kurrooa from the north western Himalayas

Picrorhiza kurrooa Royle ex Benth (Scrophulariaceae), commonly known as Kutki, is a major ingredient of many ayurvedic preparations prescribed in the treatment of various diseases. Picrosides I and II are the active agents responsible for the medicinal effects of Kutki, and the variation in content of these compounds in plants at different altitudes is a major question to be addressed. The picroside I and II content in various plant parts of P. kurrooa collected from different altitudes, viz. Sonemarg (2,740 m a.s.l.), Tangmarg (2,690 m a.s.l.), and Pulwama (1,630 m a.s.l.) in the north-western Kashmir Himalayas was analyzed by HPLC. A considerable degree of variation in picroside content was observed. Picroside I and II was highest in populations collected from Sonemarg followed by Tangmarg, suggesting that picroside accumulation is directly correlated with altitudinal change. More picroside I was found in the rhizome and roots of the Pulwama population as compared to Tangmarg samples, whereas the quantity of Picroside II was reduced in plants from Pulwama compared to the Tangmarg population, suggesting that cultivation of P. kurroa at lower altitude reduces the picroside content. The quantities of picrosides also varied spatially, being highest in rhizome followed by roots, inflorescence and leaves in the populations from all three locations. The study concludes that picroside I and II accumulation depends on altitude, which could help in the selection and collection of superior genotypes with uniform effects for utilization by the pharmaceutical industry.     

Safety and tolerability of available drugs for hyperuricemia: a critical review and an update on recent developments

Hyperuricemia (HUA) is a metabolic disease caused by excessive production of serum uric acid (sUA) or decreased excretion of sUA in the body. HUA is an independent risk factor for chronic kidney disease, hypertension, cardiovascular and cerebrovascular diseases, and diabetes mellitus. Timely and effective treatment for reducing sUA plays a key role in reducing urate deposition, preventing gout attacks, and reducing kidney damage and the occurrence of other accompanying diseases. Four pharmacological methods can be used to treat HUA: decrease urate production, increase urate excretion, prevent urate formation, and catabolize urate. To provide a reference for clinical treatment and new medical research for HUA, the drugs and potential drugs for HUA were reviewed in the present work.     

Presence of phthalate derivatives in the essential oils of a medicinal plant Achillea tenuifolia

Background

Phthalate, esters of phthalic acid, are mainly applied as plasticizers and cause several human health and environment hazards. The essential oils of Achillea species have attracted a great concern, since several biological activities have been reported from varieties of these medicinal species. On the other side, due to the problems regarding the waste disposal in developing countries, phthalate derivatives can easily release from waste disposal to the water and soil resulting in probable absorption and accumulation by medicinal and dietary plants. As a matter of fact, although the toxicity of phthalate derivatives in human is well-known, food crops and medicinal plants have been exposing to phthalates that can be detected in their extracts and essential oils. Achillea tenuifolia (Compositea) is one of these herbaceous plants with traditional applications which widely growing in Iran.

Finding

The plant root was subjected to hydro-distillation for 4 h using Clevenger type apparatus to obtain its essential oil before and after acid treatment. Both of the hydro-distilled essential oils were analysed by GC-MS method resulted in recognition of their constituent. Phthalate contamination as (1, 2-benzenedicarboxylic acid, bis (2-methylpropyl) ester (5.4%) and phthalic acid (4.5%), were identified in the first and second extracted oils, respectively.

Conclusion

As a warning, due to the potential role of phthalates to cause reproductive toxicity, disturb of endocrine system and causing cancers, medicinal plants have to be considered through quality control for detection of these compounds.     

Pharmacological Evaluation of Bangladeshi Medicinal Plants for Antioxidant Activity

A growing body of evidence suggests that cellular damage or oxidative injury arising from production of free radicals or reactive oxygen species (ROS) are critical causative factors in the pathogenesis of many neurodegenerative disorders, inflammatory conditions, autoimmune diseases, diabetes, and gastrointestinal disorders. Results from biological and phytochemical studies indicate that medicinal plants have profound antioxidant potential that can be exploited further in the prevention and treatment of these devastating disorders. Here we have summarized the pharmacological and phytochemical investigations of 49 Bangladeshi medicinal plants representing 36 families with proven strong antioxidant properties. The medicinal plants were found to have profound antioxidant effect that can explain and justify some of their use in traditional medicine. These antioxidant medicinal plants may be considered as future leads to novel drug development for the management of various neurodegenerative and inflammatory disorders associated with oxidative cellular damage.     

Chemical constituents and biological activities of Vietnamese medicinal plants

Every country has its own traditional medicine system originated from ancient times. Vietnam, a Southeast Asian country, has a unique traditional medicine system. Several medicinal plants are still used by different ethnic societies of Vietnam for treating several diseases due to their easy availability. Combretum quadrangulare, Panax vietnamensis (Vietnamese Ginseng), Dracaena angustifolia (Nam Ginseng) and Orthosiphon stamineus are among the popular medicinal plants used in Vietnamese traditional medicine for curing various diseases and to improve physical strength. In this review article, we discuss the chemical analysis as well as biological activities of these Vietnamese medicinal plants in order to establish the relation between their therapeutic uses and scientific findings.     

Advances in bile acid medicinal chemistry

Bile acids (BAs) are a family of steroidal molecules derived from cholesterol and biosynthesised in the pericentral hepatocytes of the liver. Structurally they may be regarded as consisting of two components, a rigid steroid nucleus and a short aliphatic side chain terminating in an alcohol or carboxyl group. Traditionally BAs are known for their ability to act as solubilising agents in the gut, aiding in the absorption of dietary lipids through the formation of mixed micelles. However the identification of BAs as ligands of the farnesoid X receptor (FXR) has lead to the realisation that these molecules have a wider range of biological effects. BAs regulate lipid and glucose homeostasis through activation of the FXR and the G-protein coupled receptor, TGR5. They can activate apoptotic, inflammatory and carcinogenic signalling pathways. BAs have also been shown to have anti-inflammatory effects. Interestingly, BAs are not restricted to the hepatic-intestinal system. Plasma BAs regulate BA synthesis and metabolism. BAs have recently been identified in cerebrospinal fluid. The BA, ursodeoxycholic acid has a potential role as a neuroprotectant in Huntington's disease and its taurine conjugate exhibits neuro-protective effects in vitro that may be relevant to Alzheimer's disease. This renaissance in BA biology has lead to the development of numerous medicinal chemistry programmes with different therapeutic targets, using BAs as lead structures. BA derivatives with increased efficacy and potency for FXR and TGR5 hold significant promise for the treatment of metabolic disorders. The peculiar effects of BAs on cell viability have been exploited for the design of selective cytocidal agents for treatment of various cancers. BA derivatives have also been screened with much success for anti-microbial and antifungal properties. Other targets include carbonic anhydrase for treatment of glaucoma and the glucocorticoid receptor for antiinflammatory effects. In this review interesting recent developments in the medicinal chemistry of these eclectic substances will be discussed.     

Regulatory approach on environmental risk assessment. Risk management recommendations, reasonable and prudent alternatives

Current knowledge shows that residues of human medicinal products at trace quantities are widespread in aquatic systems. The sewage treatment plants are pointed out as the major source discharge of these compounds on the environment. In this context, it has been worldwide recognised that the environmental impact of medicinal products have to be evaluated, according to recent EU legislation and regulatory guidance. The strategy of the global risk assessment includes primarily a pre-screening based on the estimation of exposure concentrations of drugs in the wastewater. The present paper addresses the decision-maker frontier of the ecologically relevant endpoints. Risk management recommendation and reasonable and prudent alternatives are discussed to minimise the possible environmental impact.     

Insights into the search for new drugs from traditional knowledge: An ethnobotanical and chemical–ecological perspective

Context: The variety of pathways for the introduction of a species into the medical collection of traditional communities has led many researchers to question the processes of selection and the use of these resources. A better comprehension of these processes will allow us to understand the cultural dynamics that are related to traditional medical practices, as well as to provide us with new ways in which to facilitate the exploration of natural products.

Objective: This study aims to test the predictive power of the plant apparency hypothesis as it relates to medicinal plant selection by the rural communities of the Caatinga and the Atlantic Forest in northeast Brazil.

Material and methods: Initially, a survey of the medicinal plants used by these communities was conducted using semistructured interviews. Subsequently, data on the life strategies and the habits of each species were collected. More detailed data on the specific plant parts indicated in interviews were also collected. A phytochemical screening for seven classes of chemical compounds was carried out to test the predictions of the plant apparency hypothesis.

Results: The medicinal plants from the Caatinga (especially those that are considered to be trees in habit) have a strong ability to accumulate quantitative compounds, and these species are most likely to be plants with significant biological activity related to these compounds; the medicinal plants from the Atlantic Forest, on the other hand, tend to have a high occurrence of qualitative compounds, especially in herbaceous life forms.

Discussion and conclusion: It was concluded that the plant apparency hypothesis does not adequately explain the selection of medicinal plants in the two environments studied. Our findings highlight some important implications for bioprospecting that need to be further tested experimentally, and through systematic studies, in different regions.     

Medicinal plant extracts with efflux inhibitory activity against Gram-negative bacteria

It was hypothesised that extracts from plants that are used as herbal medicinal products contain inhibitors of efflux in Gram-negative bacteria. Extracts from 21 plants were screened by bioassay for synergy with ciprofloxacin against Salmonella enterica serotype Typhimurium, including mutants in which acrB and tolC had been inactivated. The most active extracts, fractions and purified compounds were further examined by minimum inhibitory concentration testing with five antibiotics for activity against Enterobacteriaceae and Pseudomonas aeruginosa. Efflux activity was determined using the fluorescent dye Hoechst 33342. Eighty-four extracts from 21 plants, 12 fractions thereof and 2 purified molecules were analysed. Of these, 12 plant extracts showed synergy with ciprofloxacin, 2 of which had activity suggesting efflux inhibition. The most active extract, from Levisticum officinale, was fractionated and the two fractions displaying the greatest synergy with the five antibiotics were further analysed. From these two fractions, falcarindiol and the fatty acids oleic acid and linoleic acid were isolated. The fractions and compounds possessed antibacterial activity especially for mutants lacking a component of AcrAB-TolC. However, no synergism was seen with the fractions or purified molecules, suggesting that a combination of compounds is required for efflux inhibition. These data indicate that medicinal plant extracts may provide suitable lead compounds for future development and possible clinical utility as inhibitors of efflux for various Gram-negative bacteria.