Evaluation of Alstonia scholaris leaves for broncho-vasodilatory activity

Evaluation of Antidiarrheal Activity of 80% Methanolic Extract of the Leaves of Cordia africana (Lamiaceae) in Mice

Background

Diarrheal disease is a major cause of morbidity and mortality throughout the world, particularly in developing countries. Currently available drugs are linked with adverse effects, contraindications, and risk of resistance. Traditionally, the leaf concoction of Cordia africana is claimed to be used for diarrhea. However, the safety and efficacy of the leaf extract have not been scientifically approved yet. Therefore, the study was conducted to validate its antidiarrheal activity and safety profile in mice.

Method

The hydromethanolic extract was obtained by the cold maceration technique in 80% methanol. Phytochemical screening tests were done for secondary metabolites by using standard tests. The antidiarrheal activity of the test extract at the doses of 100, 200, and 400 mg/kg was evaluated by using castor oil-induced diarrheal, gastrointestinal transit, and enteropooling models in mice.

Result

In an acute toxicity study, there were no visible signs of toxicity and mortality following a single oral administration of 2000 mg/kg. Phytochemical screening tests revealed the presence of alkaloids, saponins, flavonoids, terpenoids, phenols, and tannins. The hydromethanolic extract significantly prolonged the onset of diarrhea and reduced the weight of wet and total feces at 100 (P < 0.01), 200 (P < 0.001), and 400 mg/kg (P < 0.001) in the castor oil-induced diarrheal model. However, in the gastrointestinal transit model, a significant (P < 0.001) reduction in the charcoal meal travel was observed in the middle (200 mg/kg) and higher (400 mg/kg) test doses. Similarly, the extract produced a significant (P < 0.001) reduction in the weight and volume of intestinal contents at the aforementioned doses.

Conclusion

The study demonstrated that the test extract showed promising antidiarrheal activity. Hence, this study supports its antidiarrheal use in Ethiopian folklore medicine.

Secondary Metabolites of Plants as Modulators of Endothelium Functions

According to the World Health Organization, cardiovascular diseases are the main cause of death worldwide. They may be caused by various factors or combinations of factors. Frequently, endothelial dysfunction is involved in either development of the disorder or results from it. On the other hand, the endothelium may be disordered for other reasons, e.g., due to infection, such as COVID-19. The understanding of the role and significance of the endothelium in the body has changed significantly over time—from a simple physical barrier to a complex system encompassing local and systemic regulation of numerous processes in the body. Endothelium disorders may arise from impairment of one or more signaling pathways affecting dilator or constrictor activity, including nitric oxide–cyclic guanosine monophosphate activation, prostacyclin–cyclic adenosine monophosphate activation, phosphodiesterase inhibition, and potassium channel activation or intracellular calcium level inhibition. In this review, plants are summarized as sources of biologically active substances affecting the endothelium. This paper compares individual substances and mechanisms that are known to affect the endothelium, and which subsequently may cause the development of cardiovascular disorders.

Therapeutic potential of medicinal plants against COVID-19: The role of antiviral medicinal metabolites

There are numerous trials underway to find treatment for the COVID-19 through testing vaccines as well as existing drugs. Apart from the many synthetic chemical compounds, plant-based compounds could provide an array of \suitable candidates for testing against the virus. Studies have confirmed the role of many plants against respiratory viruses when employed either as crude extracts or their active ingredients in pure form. The purpose of this review article is to highlight the importance of phytomedicine against COVID-19. The main aim is to review the mechanistic aspects of most important phytochemical compounds that have showed potential against coronaviruses. Glycyrrhizin from the roots of Glycyrrhiza glabra has shown promising potential against the previously epidemic coronavirus, SARS-CoV. Other important plants such as Artemisia annua, Isatis indigotica, Lindera aggregate, Pelargonium sidoides, and Glychirrhiza spp. have been employed against SARS-CoV. Active ingredients (e.g. emodin, reserpine, aescin, myricetin, scutellarin, apigenin, luteolin, and betulonic acid) have shown promising results against the coronaviruses. Phytochemicals have demonstrated activity against the coronaviruses through mechanisms such as viral entry inhibition, inhibition of replication enzymes and virus release blockage. However, compared to synthetic drugs, phytomedicine are mechanistically less understood and should be properly evaluated before application. Nonetheless, phytochemicals reduce the tedious job of drug discovery and provide a less time-consuming alternative for drug testing. Therefore, along with other drugs currently tested against COVID-19, plant-based drugs should be included for speedy development of COVID-19 treatment.

Traditional medicinal plants used for respiratory disorders in Pakistan: a review of the ethno-medicinal and pharmacological evidence

Respiratory disorders are a common cause of malady and demise in Pakistan due to its remoteness, cold and harsh climatic conditions as well as scarce health care facilities. The people rely upon the indigenous plant resources to cure various respiratory disorders. The primary objective of this review was to assemble all available ethno-medicinal data of plants used for respiratory disorders in Pakistan. Pharmacological activity of these plants (based upon published scientific research), distribution, diversity, use, preparation methods, economical value, conservation status and various available herbal products of some plants have also been explored. This study scrutinized various electronic databases for the literature on medicinal plants used in Pakistan to treat respiratory disorders. A total of 384 species belonging to 85 families used to treat respiratory disorders in Pakistan has been documented. Cough was the disorder treated by the highest number of species (214) followed by asthma (150), cold (57) and bronchitis (56). Most of the plants belongs to Asteraceae (32) and Solanaceae family (32) followed by moraceae (17), Poaceae (13), and Amaranthaceae (13) with their habit mostly of herb (219) followed by Shrub (112) and tree (69). Traditional healers in the region mostly prepare ethno medicinal recipes from leaves (24%) and roots (11%) in the form of decoction. Among the reported conservation status of 51 plant species, 5 were endangered, 1 critically endangered, 11 vulnerable, 14 rare, 16 least concern, 3 infrequent and 1 near threatened. We found only 53 plants on which pharmacological studies were conducted and 17 plants being used in herbal products available commercially for respiratory disorders. We showed the diversity and importance of medicinal plants used to treat respiratory disorders in the traditional health care system of Pakistan. As such disorders are still causing several deaths each year, it is of the utmost importance to conduct phytochemical and pharmacological studies on the most promising species. It is also crucial to increase access to traditional medicine, especially in rural areas. Threatened species need special attention for traditional herbal medicine to be exploited sustainably.

Cytotoxic monoterpenoid indole alkaloids from Alstonia yunnanensis Diels

The ethanol extract of the aerial parts of Alstonia yunnanensis Diels afforded five new monoterpenoid indole alkaloids, alstiyunnanenines A-E (1-5), along with one known compound, alstoniascholarine I (6). The structures of the isolated compounds were established based on 1D and 2D (¹H-¹H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential using eight tumor cell lines. As a result, alkaloids 4-6 exhibited cytotoxicities against all tested tumor cell lines, especially against osteosarcoma cell lines (SOSP-9607, MG-63, Saos-2, M663) with IC₅₀ values<6μM.

Anticarcinogenic and antimutagenic activity of Alstonia scholaris on the albino mice bone marrow cells and peripheral human lymphocyte culture against methyl methane sulfonate induced genotoxicity

Background:

The use of medicinal plants in modern medicine for the prevention and treatment of cancer is an important aspect. For this reason, it is important to identify antitumor promoting agents present in medicinal plants commonly used by the human population.

Materials and Methods:

We used in vivo and in vitro methods using chromosomal aberrations (CAs), sister chromatid exchange (SCE) and replication index (RI) as markers, exposed by methyl methanesulfonate (MMS) as well as alcoholic extract of Alstonia scholaris in five increasing concentrations (200, 250, 300, 350 and 400 mg/kg body weight for in vivo and 150, 200, 250 and 300 μg/ml of culture) and of three different durations of 24, 48 and 72 h in the presence as well absence of S₉ mix.

Results:

Extracts of Alstonia reduces the total aberrant cells ranges from 10.0% to 41.84% and frequencies of aberration in the aberrant cells ranges from 220 to 124 against 290 aberrations causes due to MMS in vivo. Similarly in the in vitro, it reduces CAs (39.62%, 32.83%, and 38.48%) and (45.31%, 44.46%, and 38.34%) at 24, 48, and 72 h of exposure respectively; in the absence as well as presence of liver S₉ fraction. It also reduces SCE from 7.70 to 4.20 per cell and enhances RI from 1.45 to 1.64.

Conclusion:

Extracts of Alstonia significantly reduces the number of aberrant cells and frequency of aberration per cell at each concentration and duration of exposure in vivo; and CAs and SCE in vitro and enhances RI.

Mechanisms underlying the antihypertensive effect of Alstonia scholaris

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris has a long history of use in the Ayurveda traditional treatment of various ailments including hypertension. We have reported the blood pressure lowering activity of the extract of A. scholaris. The following research aim to delineate the pharmacological mechanism involve in the antihypertensive action.

MATERIALS AND METHOD

Vasorelaxant effect of the n-butanol fraction of A. scholaris (NBF-ASME) was evaluated on rat aorta pre-contracted with phenyelphrine (PE, 1 µM). Aortic rings preparation were pre-incubated with various antagonists like 1H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ 10 μM), methylene blue (MB 10 μM), Nω-nitro-L-arginine methyl ester hydrochloride (l-NAME 10 μM), atropine (10 μM), indomethacin (1 μM), ML-9 and various K(+) channel blockers such as glibenclamide (10 μM) and tetraethyl ammonium (TEA 10 μM) for mechanism study.

RESULT

The results showed that pre-incubation of aortic rings with the extract (0.5, 1 and 2mg/mL) significantly inhibit the contractile response of the rings to phenylephrine-induced contraction (p<0.05-0.001). Removal of endothelium, incubation with L-NAME, indomethacin, atropine and propranolol did not significantly affect the relaxation effect of NBF-ASME. Furthermore, the K(+) channel blockers, TEA and glibenclamide showed no inhibitory effect. However, aortic rings pretreated with ODQ and ML-9 showed a significant suppression of the relaxation curve of NBF-ASME (p<0.01-0.001). In Ca(2+)-free solution, NBF-ASME inhibits the release of intracellular Ca(2+) from the sarcoplasmic reticulum. NBF-ASME also inhibits calcium chloride (CaCl2)-induced contraction in endothelium-denuded aortic rings.

CONCLUSION

The results from this study suggests that A. scholaris exerts vasodilation via calcium channels blockade, direct activation of soluble guanylate cyclase and possibly by also inhibiting the formation of inositol 1, 4, 5-triphosphate.

Monoterpenoid Indole Alkaloids from Inadequately Dried Leaves of Alstonia scholaris

Six new indole alkaloids, named alstoniascholarines L-Q (1-6), together with nineteen known analogues were isolated from the inadequately dried leaves of Alstonia scholaris. Their structures were elucidated on the basis of extensive analysis of spectroscopic data and by comparison of their physical and spectroscopic data with the literature values. In addition, the new alkaloids were tested for their cytotoxic and neurite outgrowth-promoting activities.

Ethnobotanical study of Loloh: Traditional herbal drinks from Bali (Indonesia)

ETHNOPHARMACOLOGICAL RELEVANCE

Loloh are herbal drinks produced and consumed exclusively in Bali (Indonesia) to prevent and treat different ailments. This is the first study to document plants species used as Loloh, reporting the phytochemical components and pharmacological properties of the most cited plants. Documenting the plants used in herbal drinks in Bali by local communities to treat various ailments (providing some information on phytochemistry and pharmacology of the most interesting plants).

MATERIALS AND METHODS

Ethnobotanical data were obtained through semi-structured interviews (individual and group discussions) and questionnaires. Plant specimens were collected, identified and made into herbarium vouchers.

RESULTS

A total of 51 plants species (belonging to 32 families) have been documented for their use in the various preparation of Loloh. Different plants and plant parts are used to prepare Loloh to treat heartburn, fever, diarrhea, hypertension, aphthous stomatitis (canker sores), and other minor health problems. These plants are mainly prepared as decoctions, are juiced or simply added to the preparation. The most cited plants (>30 informants) are Alstonia scholaris (L.) R. Br., Blumea balsamifera (L.) DC., Cinnamomum burmanni Nees ex Bl., and Piper betle L. These plants are well studied with multiple demonstrated pharmacological activities (e.g., antimicrobial, anticancer, antidiabetic).

CONCLUSION

The Balinese communities still preserve a rich ethnobotanical knowledge. Several species are well known for their pharmacological properties, but some [such as Pneumatopteris callosa (Blume) Nakai and Dendrocnide stimulans (L. f.) Chew] are understudied and could be promising candidates for further research.

Antibacterial monoterpenoid indole alkaloids from Alstonia scholaris cultivated in temperate zone

Three new monoterpenoid indole alkaloids, named normavacurine-21-one (1), 5-hydroxy-19, 20-E-alschomine (2), and 5-hydroxy-19, 20-Z-alschomine (3), together with thirteen known indole alkaloids (4-16) were isolated from the leaves of Alstonia scholaris cultivated in Kunming. Their structures were elucidated on the basis of extensive spectroscopic analysis, as well as by comparison with the reported spectroscopic data. The leaves of A. scholaris cultivated in Kunming, contained picrinine-type alkaloids, scholaricin-type alkaloids and nareline as major alkaloids. New compounds 1-3 might be derived from a common biogenetic precursor (5). Compounds 1, 5 and 10 exhibited significant antibacterial activity against Enterococcus faecalis, and 3, 9 and 14 against Pseudomonas aeruginosa with an MIC value of 0.781 μg/mL, while 14 showed moderate activity against Klepsiella pneumonia with an MIC value of 1.56 μg/mL.

Natural Products Useful in Respiratory Disorders: Focus on Side-Effect Neutralizing Combinations

This review summarizes literature related to medicinal plants reputed in traditional medical systems for treatment of asthma and coughs. The plants that are pharmacologically investigated for their effectiveness in such conditions, along with respective experimental protocol details, are also discussed. Some of plant origin compounds, which are considered useful as antitussive and antiasthmatic agents, are described as well. Chrysoeriol, a constituent of Aspalathus linearis (Fabaceae) was observed to be selective for relaxant effect in airways (through K⁺ channel activation), compared with other smooth muscles. We reported that Hypericum perforatum (Hyperieaceae), Andropogon muricatus (Poaceae), Juniper excelsa (Coniferae) and Nepeta cataria (Lamiaceae) exhibit bronchodilatory action, mediated through combination of Ca⁺⁺ antagonist and phospohodiesrase inhibitory mechanisms, which scientifically explains their medicinal use in asthma. Hyocyamus niger (Solanaceae), Artemisia vulgaris (Compositae), Fumaria parviflora (Fumariaceae) and Terminalia bellerica (Combretaceae) caused bronchodilation via dual blockade of muscarinic receptors and Ca⁺⁺ influx. Acorus calamus (Araceae), Carum roxburghianum (Apiaceae), Lens culinaris (Fabaceae) and Lepidium sativum (Cruciferae) mediate bronchodilatation through multiple pathways: anticholinergic and inhibition of Ca⁺⁺ channels and PDE enzyme(s). In conclusion, this review presents an analysis of different novel combinations of pharmacological activities in medicinal plants with side effect-neutralizing/synergistic potential, setting new trends in the therapeutic options for hyperactive respiratory disorders such as asthma and cough. Copyright © 2015 John Wiley & Sons, Ltd.

Alstonia scholaris (L.) R. Br. and Alstonia macrophylla Wall. ex G. Don: A comparative review on traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (L.) R. Br. and Alstonia macrophylla Wall. ex G. Don are two vital medicinal plant species (family: Apocynaceae). In India, the therapeutic use of Alstonia scholaris has been described in both codified and non-codified drug systems for the treatment of malaria, jaundice, gastrointestinal troubles, cancer and in many other ailments. Other species, Alstonia macrophylla has been used in conventional medicines in Thailand, Malaysia and Philippines as a general tonic, aphrodisiac, anticholeric, antidysentery, antipyretic, emmenagogue, and vulnerary agents. In India, Alstonia macrophylla is used as a substitute for Alstonia scholaris in various herbal pharmaceutical preparations. However, one certainly cannot evaluate the truthfulness of a practice (i.e. in scientific terms). In this article we discuss and summarize comparative data about traditional uses, phytochemistry, pharmacology and toxicity of Alstonia scholaris and Alstonia macrophylla. Moreover, in order to unfold future research opportunities, lacunae in the present knowledge are also highlighted.

MATERIALS AND METHODS

Literature about Alstonia scholaris and Alstonia macrophylla was collected by using electronic and library search. Additionally, referred books on traditional medicine and ethnopharmacology were also utilized for receiving traditional records about both the plant species.

RESULTS

Both Alstonia scholaris and Alstonia macrophylla are rich in different types of bioactive alkaloids. So far, broad spectrum of in vitro and in vivo biological and pharmacological activities have been reported to both the species. Amongst them, antimicrobial and anticancer activities were promising.

CONCLUSIONS

The use of Alstonia macrophylla as a substitute for Alstonia scholaris is not at all justifiable as both the species are distinct from each other in their phytochemistry and pharmacology. Further detail chemical fingerprinting and metabolic studies of these two species are warranted to prevent their mutual adulteration most importantly in the context of commercial preparations.

Aerobiological, clinical, and immunobiochemical studies on Alstonia scholaris pollen from Eastern India

Alstonia scholaris or Indian devil tree is a common, evergreen, tropical tree of the Apocynaceae family. The objectives of this study were (a) to observe the seasonal variation of A. scholaris pollen in the atmosphere of an industrial and rural area of West Bengal, India by conducting a 2-year aerobiological survey with a Burkard personal volumetric sampler, (b) to study its allergenicity in the local population by in vivo (skin-prick test) and in vitro tests (enzyme-linked immunosorbent assay and dot blotting), (c) to identify the immunoglobulin E (IgE)-binding proteins present in the pollen extract (sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblotting), (d) to study its chemical composition. A. scholaris pollen were present in the air from September until November. They contained 14.3 % carbohydrate, 9.2 % lipid, and 4.3 % protein. Among 140 respiratory allergic local patients, 28.57 % showed positive skin reaction to A. scholaris pollen extract. Twelve protein bands in the range of 94.4-13.3 kDa were observed in the pollen extract. Seven IgE-binding proteins were found. Among them, one component of 29.9 kDa was the most important in A. scholaris pollen extract. This component could be purified and would be helpful in the diagnosis and therapy of A. scholaris pollen-susceptible patients.

A combination of alkaloids and triterpenes of Alstonia scholaris (Linn.) R. Br. leaves enhances immunomodulatory activity in C57BL/6 mice and induces apoptosis in the A549 cell line

Experiments were conducted to evaluate the induction of apoptosis and the immunomodulatory activities of alkaloids and triterpenes of Alstonia scholaris (Linn.) R. Br. leaves (ASL). Importantly, their possible synergistic properties were also explored in this study. Human lung adenocarcinoma cell line A549 and Lewis tumor-bearing C57BL/6 mice were used for the evaluation of their activities. A MTT assay was used to determine the proliferation inhibition in A549 cells. Annexin-V/PI double staining as well as flow cytometry was performed to detect apoptosis and cell cycle status. Enzyme-linked immunosorbent assay (ELISA) was conducted to determine the levels of inflammatory mediators interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum. Furthermore, western blot analysis was applied to evaluate the expressions of proteins associated with cell death. Alkaloids or triterpenes showed a high anti-proliferative activity in A549 cells, with IC₅₀ values of 14.4 µg/mL and 9.3 µg/mL, respectively. The alkaloids and triterpenes combination could significantly inhibit tumor growth in tumor-bearing C57BL/6 mice, compared with alkaloids or triterpenes alone (7.5, 15, 30 g raw material/kg). The immune organs indexes including spleen index and thymus index were increased remarkably by the combination of alkaloids and triterpenes, whereas the levels of IL-6 and TNF-α were up-regulated significantly. Moreover, Annexin-V/PI double staining and flow cytometry showed that the combination of alkaloids and triterpenes (1, 2 and 3 mg raw material/kg) could induce apoptosis and cause S cell cycle arrest in A549 cells. Western blot analysis also showed that their combination (2 mg raw material/kg) significantly down-regulated Bcl-2 expression and pro-casp8 level, whereas it remarkably increased the level of cleaved caspase-8 leading to apoptosis in A549 cells. These observations provide preliminary evidence that both alkaloids and triterpenes possess immune regulation and induction apoptosis activities. Their combination has a stronger activity than that of either class alone. Our findings suggested that these components might be beneficial for the prevention and treatment of NSCLC through a significant synergy effect.

Calcium antagonistic activity of Bacopa monniera in guinea-pig trachea

OBJECTIVE

To demonstrate the calcium antagonistic property of ethanol extract of Bacopa monniera in guinea-pig trachea.

MATERIALS AND METHODS

The dose response curves of CaCl(2) (1 × 10(-5) to 1 × 10(-1) M) were constructed in the absence and presence of ethanol extract of Bacopa monniera (100, 500 and 700 μg/ml) or nifedipine (1 × 10(-6) M) in guinea-pig trachea in calcium free high K(+)-MOPS-PSS (3-(N-morpholino)-propanesulphonic acid physiological salt solution). The data was analyzed by ANOVA followed by least significant difference test or by Student's 't' test for unequal variance when appropriate. A probability of at least P < 0.05 was considered statistically significant.

RESULTS

The plant extract (500 and 700 μg/ml) significantly (P < 0.05) depressed and shifted the calcium concentration-response curves (1 × 10(-3)- 1 × 10(-1) M) to rightward similar to that of nifedipine.

CONCLUSIONS

Bacopa monniera extract exhibited calcium channel blocking activity in guinea-pig tracheal smooth muscles that may rationalize its relaxant action on guinea-pig trachea and its traditional use in respiratory disorders.

Monoterpenoid indole alkaloids from Alstonia rupestris with cytotoxic, anti-inflammatory and antifungal activities

Phytochemical investigation of the 70% EtOH extract of the leaves of Alstonia scholaris afforded seven new monoterpenoid indole alkaloids: scholarisins I-VII (1-7), and three known compounds: (3R,5S,7R,15R,16R,19E)-scholarisine F (8), 3-epi-dihydro- corymine (9), and (E)-16-formyl-5α-methoxystrictamine (10). Structural elucidation of all the compounds was accomplished by spectral methods such as 1D- and 2D-NMR, IR, UV, and HRESIMS. The isolated compounds were tested in vitro for cytotoxicity against seven tumor cell lines, anti-inflammatory activities against Cox-1 and Cox-2, and antifungal potential against five species of fungi. Compounds 1, 6, and 10 exhibited significant cytotoxicities against all the tested tumor cell lines with IC₅₀ values of less than 30 μM and selective inhibition of Cox-2 comparable with the standard drug NS-398 (>90%). Additionally, 1, 2, 3 and 8 showed antifungal activity against two fungal strains (G. pulicaris and C. nicotianae).

Monoterpenoid indole alkaloids from Alstonia yunnanensis and their cytotoxic and anti-inflammatory activities

The 80% ethanol extract of Alstonia yunnanensis afforded five new monoterpenoid indole alkaloids: 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (1), 14-chloro-15-hydroxy-vincadifformine (2), perakine N₄-oxide (3), raucaffrinoline N₄-oxide (4), and vinorine N₁,N₄-dioxide (5), together with three known compounds: 11-methoxy-6,7-epoxy-8-oxo-vincadifformine (6), vinorine N₄-oxide (7) and vinorine (8). The structures of the isolated compounds were established based on 1D and 2D (¹H-¹H-COSY, HMQC, HMBC, and ROESY) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential against seven tumor cell lines and anti-inflammatory activities. Compounds 3, 4 and 7 exhibited weak cytotoxicity against the tested cell lines and selective inhibition of Cox-2 (>85%).

Review of the phytochemical, pharmacological and toxicological properties of Alstonia Scholaris Linn. R. Br (Saptaparna)

The use of ethnornedical information has immensely contributed to health care, and scientific studies have shown that the evaluation of traditionally used medicines may provide leads towards effective drug discovery. Since antiquity, Alstonia scholaris connmonly known as devil's tree has been used for the treatment of many human ailments. Literature suggests that Alstonia scholaris is useful in treating malaria, abdominal disorders, dyspepsia, leprosy, skin diseases, tumors, chronic and foul ulcers, asthma, bronchitis, helminthiasis, agalactia, and debility. Preclinical studies have shown that it possesses anti-microbial, anti-diarrhoeal, anti-plasmodial, anti-oxidant, anti-inflammatory hepatoprotective, nootrophic, anti-stress, anti-fertility, immunomodulatory, analgesic, anti-ulcer, wound healing, anti-cancer, chemopreventive, radiation protection, radiation sensitization, and chemosensitization activities. The diverse pharmacological observations are supposed to be due to the presence of alkaloids, flavonoids and phenolic acids. The bark and leaf extract when administered orally did not induce lethality or adverse affects at the limit doses of 2 000 mg/kg body weight. However when administered intraperitoneally at high concentrations, the extract showed systemic and developmental toxicities. This review addresses the experimentally authenticated facts and also suggests the need for research on chemical and pharmacological properties of Alstonia scholaris.

Pharmacological evaluation of Alstonia scholaris: anti-tussive, anti-asthmatic and expectorant activities

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (Apocynaceae) was documented as an effective herb for the treatment of chronic respiratory diseases in "dai" ethnopharmacy historically, and its leaf crude extract, used for releasing tracheitis and cold symptom, was approved to be a commercial formulation by State Food and Drugs Administration of China (SFDA).

AIM OF THE STUDY

The investigation evaluates the anti-tussive and anti-asthmatic activities of the ethanolic extract, fractions and main alkaloids of Alstonia scholaris leaf to provide experimental evidence for its traditional and modern clinical use. For our most interesting, is to reveal the active components for further new drug development.

MATERIALS AND METHODS

The leaf of Alstonia scholaris was extracted with ethanol and then separated into different fractions. Furthermore, alkaloids were isolated by phytochemical method. The anti-tussive activity was evaluated using three different models including ammonia or sulfur dioxide induced mice coughing, and citric acid induced guinea pigs coughing. The anti-asthmatic activity was investigated on guinea pigs bronchoconstraction induced by histamine. The expectorant activity was evaluated by volume of phenol red in mice's tracheas.

RESULTS

The alkaloids fraction significantly inhibited mice's frequency of cough induced by ammonia, increased mice's latent period of cough induced by sulfur dioxide, and increased guinea pigs' latent period of cough and inhibited frequency of cough. Besides, the alkaloids fraction increased delitescence of convulsion, and tumble of guinea pigs in anti-asthmatic test, and enhanced tracheal phenol red output in expectorant evaluation. Moreover, the main alkaloid, picrinine exhibited anti-tussive and anti-asthmatic activities in vivo.

CONCLUSIONS

The alkaloids fraction was anti-tussive, anti-asthmatic and expectorant activities component of Alstonia scholaris leaf, and it may also be a valuable lead material for respiratory diseases drug development. Picrinine, the main anti-tussive and anti-asthmatic compound, could be applied in quality control of products from Alstonia scholaris leaf.

Pharmacological evaluation of Alstonia scholaris: anti-inflammatory and analgesic effects

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (Apocynaceae) has been historically used in "dai" ethnopharmacy to treat chronic respiratory diseases. The leaf extract, developed as a commercially available traditional Chinese medicine, used to release tracheitis and cold symptom, has also been prescribed in hospitals and sold over the counter in drug stores.

AIM OF THE STUDY

The investigation evaluated the anti-inflammatory and analgesic activities of the ethanolic extract, fractions and main alkaloids of Alstonia scholaris leaf to provide experimental evidence for its traditional and modern clinical use. Besides, to discover the active fraction and components for further better use in Chinese medicine is hopeful.

MATERIALS AND METHODS

The leaf of Alstonia scholaris was extracted with ethanol and then separated into different fractions. Furthermore, alkaloids were isolated by phytochemical method. The analgesic activities were investigated using acetic acid-induced writhing, hot-plate and formalin tests in mice. The anti-inflammatory activities were carried out in vivo and in vitro, including xylene-induced ear edema and carrageenan-induced air pouch formation in mice, and COX-1, -2 and 5-LOX inhibition.

RESULTS

It has been exhibited that the EtOAc and alkaloid fractions reduced acetic acid-induced writhing response in mice, significantly. The ethanolic extract, EtOAc and alkaloid fractions remarkably inhibited xylene-induced ear edema. Further investigation was focused on the alkaloids fraction and three main alkaloids isolated from the alkaloids fraction, in different animal models. Alkaloids reduced acetic acid-induced writhing response, and xylene-induced ear edema in mice. In the hot-plate test, alkaloids did not increase the latency period of mice obviously. In the formalin test, alkaloids did not inhibit the licking time in first phase, but significantly inhibited the licking time in second phase of mice. Alkaloids increased significantly SOD activity and decreased levels of NO, PGE2 and MDA significantly, in air pouch mice model. Moreover, some alkaloids isolated from the leaf of Alstonia scholaris exhibited inhibition of COX-1, COX-2 and 5-LOX in vitro anti-inflammatory assay, which supported alkaloids as the bioactive fraction.

CONCLUSIONS

The alkaloids fraction of Alstonia scholaris leaf, three main alkaloids, picrinine, vallesamine and scholaricine, may produce the anti-inflammatory and analgesic effect peripherally based on several in vivo assays. In in vitro tests, alkaloids exhibited inhibition of inflammatory mediators (COX-1, COX-2 and 5-LOX), which is accordant with results on animal models. Besides, COX-2/5-LOX dual inhibitors found in the experiment, such as 16-formyl-5alpha-methoxystrictamine, picralinal, and tubotaiwine might be valuable for further attention.

Antidiarrhoeal and spasmolytic activities of the methanolic crude extract of Alstonia scholaris L. are mediated through calcium channel blockade

This study was aimed to provide a pharmacological basis to the medicinal use of Alstonia scholaris as an antidiarrhoeal and antispasmodic by using in vivo and in vitro techniques. In the in vivo study the crude extract of Alstonia scholaris (As.Cr), which tested positive for the presence of alkaloids, provided 31-84% protection against castor oil-induced diarrhoea in mice at 100-1000 mg/kg doses, similar to loperamide. In isolated rabbit jejunum preparation, the As.Cr caused inhibition of spontaneous and high K(+) (80 mm)-induced contractions, with respective EC(50) values of 1.04 (0.73-1.48) and 1.02 mg/mL (0.56-1.84; 95% CI), thus showing spasmolytic activity mediated possibly through calcium channel blockade (CCB). The CCB activity was further confirmed when pretreatment of the tissue with the As.Cr (0.3-1 mg/mL) caused a rightward shift in the Ca(++) concentration-response curves similar to verapamil, a standard calcium channel blocker. Loperamide also inhibited spontaneous and high K(+) precontractions as well as shifted the Ca(++) CRCs to the right. These results indicate that the crude extract of Alstonia scholaris possesses antidiarrhoeal and spasmolytic effects, mediated possibly through the presence of CCB-like constituent(s) and this study provides a mechanistic base for its medicinal use in diarrhoea and colic.

Anticancer Activity of an Indian Medicinal Plant, Alstonia scholaris, on Skin Carcinogenesis in Mice

Alstonia scholaris, commonly known as sapthaparna, has been used for centuries in Ayurvedic medicine for treatment of various disorders. The objective of this study was to investigate the possible chemopreventive and anti-oxidative properties of this medicinal plant on two-stage process of skin carcinogenesis induced by a single application of 7, 12-dimethyabenz(a)anthrecene (100 lg/100 ll acetone), and two weeks later, promoted by repeated application of croton oil (1% in acetone/thrice a week) till the end of the experiment (16 weeks) in Swiss albino mice.The tumor incidence, tumor yield, tumor burden and cumulative number of papillomas were found to be higher in the carcinogen treated control (without ASE treatment) as compared to experimental animals (ASE treated). Furthermore, a significant increase in reduced glutathione, superoxide dismutase and catalase but decrease in lipid peroxidation was measured in ASE administered experimental groups than the carcinogen treated control. The present study demonstrates the chemopreventive potential of Alstonia scholaris bark extract in DMBA-induced skin tumorigenesis in Swiss albino mice.

Clinical and Experimental Effectiveness of Astragali Compound in the Treatment of Chronic Viral Hepatitis B

Chinese herbs are widely used in the treatment of chronic viral hepatitis B. The effectiveness of 2 months' treatment with Astragali compound (AC), containing Radix Astragali and adjuvant components, was studied for the treatment of chronic viral hepatitis in 116 patients; 92 patients were given other drugs in regular clinical use for viral hepatitis (controls). The clinical efficacy of AC was significantly better in AC-treated patients than in controls. Negative seroconversions of hepatitis B virus (HBV) antigen e and HBV DNA were also significantly higher in AC-treated patients than in controls. Of eight duck viral hepatitis B models infected with duck hepatitis B virus (DHBV) and treated with AC, three showed negative seroconversion of DHBV DNA and serum DHBV DNA levels significantly decreased after AC administration compared with the controls; DHBV DNA was negative in biopsied liver tissue by in situ hybridization and immunohistochemistry in two ducks treated with AC. Pathological changes were milder in AC-treated ducks than in controls. These results indicate that AC may promote recovery from viral hepatitis and inhibit HBV replication.

Mechanisms underlying the antispasmodic and bronchodilatory properties of Terminalia bellerica fruit

AIM OF THE STUDY

The present investigation was carried out to provide the pharmacological basis for the medicinal use of Terminalia bellerica in hyperactive gastrointestinal and respiratory disorders.

MATERIALS AND METHODS

Crude extract of Terminalia bellerica fruit (Tb.Cr) was studied in in vitro and in vivo.

RESULTS

Tb.Cr caused relaxation of spontaneous contractions in isolated rabbit jejunum at 0.1-3.0mg/mL. Tb.Cr inhibited the carbachol (CCh, 1microM) and K(+) (80mM)-induced contractions in a pattern similar to that of dicyclomine, but different from nifedipine and atropine. Tb.Cr shifted the Ca(++) concentration-response curves to right, like nifedipine and dicyclomine. In guinea-pig ileum, Tb.Cr produced rightward parallel shift of acetylcholine-curves, followed by non-parallel shift at higher concentration with the suppression of maximum response, similar to dicyclomine, but different from nifedipine and atropine. Tb.Cr exhibited protective effect against castor oil-induced diarrhea and carbachol-mediated bronchoconstriction in rodents. In guinea-pig trachea, Tb.Cr relaxed the CCh-induced contractions, shifted CCh-curves to right and inhibited the contractions of K(+). Anticholinergic effect was distributed both in organic and aqueous fractions, while CCB was present in the aqueous fraction.

CONCLUSIONS

These results indicate that Terminalia bellerica fruit possess a combination of anticholinergic and Ca(++) antagonist effects, which explain its folkloric use in the colic, diarrhea and asthma.

A systematic review of mechanisms by which natural products of plant origin evoke vasodilatation

This article reviews the body of work aimed at elucidating the mechanisms of action by which natural products of plant origin exert a vasodilatory effect at the level of the vasculature. The search was restricted to 4 mechanisms: the nitric oxide system and (or) reactive oxygen species, the eicosanoid system, potassium channel function, and calcium channel function. The National Library of Medicine database was searched using "PubMed" without restriction to language. The search generated 266 references on 15 November 2005. Most studies were in vitro in nature and of these, most involved studies in the rat aorta. Many of the natural products evoked vasodilatation through an endothelium-dependent mechanism. The vasodilatation was attenuated or abolished by a nitric oxide synthase inhibitor and, in some of these studies, by an inhibitor of guanylate cyclase. A few studies reported a cyclooxygenase component, but most found no effect of the cyclooxygenase inhibitor, indomethacin. The vasorelaxation evoked by several natural products was attenuated by various potassium channel blocking agents, suggesting that some natural products exerted their effect either directly or indirectly through activation of potassium channels. Finally, a significant number of natural products evoked vasodilatation either through blockade of calcium channels or by inhibiting the release of calcium from intracellular stores. Many natural products evoked vasodilatation through multiple mechanisms. The information in this review on mechanisms of action should facilitate good clinical practice by increasing the predictive capabilities of the practitioner, notably the ability to predict adverse effects and interactions among medications. The knowledge should also help to provide leads to the ultimate goal of developing new therapeutic medications.