In vitro antimalarial activity of traditionally used Western Ghats plants from India and their interactions with chloroquine against chloroquine-resistant Plasmodium falciparum

An insight into the potent medicinal plant Phyllanthus amarus Schum. and Thonn

Phyllanthus amarus Schum. and Thonn., a globally distributed herb is known for its several therapeutic potentials. P. amarus has a long history of use in the traditional system of medicine for over 2000 years owing to its wide array of secondary metabolites that confer significant medicinal attributes. Research on various aspects including ethnobotany, phytochemistry to bioactivity, or pharmacological studies has been conducted over the past several decades on this potent herb. P. amarus extracts have shown a broad range of pharmacological activities like hepatoprotective, antioxidant, antiviral, antimicrobial, antidiabetic, anti-inflammatory, anticancer, antimalarial, nephroprotective, diuretic, and several other properties. The present review compiles and covers literature and research of several groups across past decades to date and focuses on how the therapeutic significance of this plant can be further explored for future research either as herbal formulations, alternative medicine, or in the pharmaceutical industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13237-022-00409-z.

Antimalarial Efficacy and Toxicological Assessment of Extracts of Some Ghanaian Medicinal Plants

The economic costs associated with morbidity and mortality due to malaria and malaria associated complications in many sub-Saharan countries and other malaria endemic regions of the world are huge. Reports of emergence of parasite resistance to current malaria drugs have complicated malaria treatment and require the development of new therapeutic agents. The folkloric use of medicinal plants for the management of malaria is well documented. This work evaluated the antiplasmodial activities and toxicity of some medicinal plants used to treat malaria and malaria-like symptoms in Ghana. Plant extracts were obtained by cold maceration in 70% ethanol. Antiplasmodial efficacies were assessed in vitro against 3 strains of Plasmodium falciparum strains (FCM, W2, and CAM06) and in vivo via the 4-day suppressive test in Plasmodium berghei infected mice. Cytotoxicity and acute toxicity were assessed in mammalian cells and mice, respectively. All extracts were active against at least one of the Plasmodium falciparum strains in in vitro evaluations with IC50's in the range of 4-116 μg/mL, whereas Bidens pilosa extracts, with a chemosuppression rate of 75%, was the most active plant in the in vivo experiments. All plant extracts displayed very weak to no cytotoxicity against the mammalian cell line used and exhibited very good selectivity towards the Plasmodium parasites. Syzygium guineense and Parinari congensis extracts were the most toxic in the acute toxicity tests. Altogether, the results indicate that the medicinal plants do possess impressive antiplasmodial properties and provide scientific basis for their use in traditional herbal medicine.

Anti-infective activities of 11 plants species used in traditional medicine in Malaysia

Treatment of drug resistant protozoa, bacteria, and viruses requires new drugs with alternative chemotypes. Such compounds could be found from Southeast Asian medicinal plants. The present study examines the cytotoxic, antileishmanial, and antiplasmodial effects of 11 ethnopharmacologically important plant species in Malaysia. Chloroform extracts were tested for their toxicity against MRC-5 cells and Leishmania donovani by MTT, and chloroquine-resistant Plasmodium falciparum K1 strain by Histidine-Rich Protein II ELISA assays. None of the extract tested was cytotoxic to MRC-5 cells. Extracts of Uvaria grandiflora, Chilocarpus costatus, Tabernaemontana peduncularis, and Leuconotis eugenifolius had good activities against L. donovani with IC₅₀ < 50 μg/mL. Extracts of U. grandiflora, C. costatus, T. peduncularis, L. eugenifolius, A. subulatum, and C. aeruginosa had good activities against P. falciparum K1 with IC₅₀ < 10 μg/mL. Pinoresinol isolated from C. costatus was inactive against L. donovani and P. falciparum. C. costatus extract and pinoresinol increased the sensitivity of Staphylococcus epidermidis to cefotaxime. Pinoresinol demonstrated moderate activity against influenza virus (IC₅₀ = 30.4 ± 11 μg/mL) and was active against Coxsackie virus B3 (IC₅₀ = 7.1 ± 3.0 μg/mL). β-Amyrin from L. eugenifolius inhibited L. donovani with IC₅₀ value of 15.4 ± 0.01 μM. Furanodienone from C. aeruginosa inhibited L. donovani and P. falciparum K1 with IC₅₀ value of 39.5 ± 0.2 and 17.0 ± 0.05 μM, respectively. Furanodienone also inhibited the replication of influenza and Coxsackie virus B3 with IC₅₀ value of 4.0 ± 0.5 and 7.2 ± 1.4 μg/mL (Ribavirin: IC₅₀: 15.6 ± 2.0 μg/mL), respectively. Our study provides evidence that medicinal plants in Malaysia have potentials as a source of chemotypes for the development of anti-infective leads.

Pharmacological activity of Curarea toxicofera in combination with classical antimalarial treatments

ETHNOPHARMACOLOGICAL RELEVANCE

In the Leticia-Amazonas area, Uitoto indigenous people use a preparation of Curarea toxicofera (Wedd) Barneby & Krukoff (Menispermaceae) alone or combined with prescribed medications to prevent and treat malaria.

AIM OF STUDY

To determine the in vitro and in vivo antiplasmodial activity of traditional preparations of Curarea toxicofera alone and in combination with classical antimalarials.

MATERIAL AND METHODS

The traditional preparation was evaluated in vitro against P. falciparum FCR3 CQ resistant strain, alone and combined. The preparation was further administered orally alone or combined with chloroquine and artesunate in mice infected with Plasmodium berghei ANKA strain on the four-day antimalarial test model.

RESULTS

The herbal remedy used alone was able to significantly decrease the parasitemia both in vitro (IC₅₀ 7.3 µg/ml) and in vivo (ED₅₀ 328 mg/Kg) but it was less active than chloroquine (IC₅₀ 0.29 µg/ml in vitro and ED₅₀ 2.3 mg/Kg/day in vivo), and than artesunate (IC₅₀ 0.002 µg/ml and ED₅₀ 3.7 mg/Kg/day). Interestingly it presented synergism with chloroquine in vitro (Combination Index: 0.39) and in vivo; and was additive with artesunate in vitro (Combination Index: 0.94) and in vivo.

CONCLUSION

The traditional preparation showed potential as an antimalarial and, when used in combination, does not negatively affect the efficacy of the drugs evaluated. Pre-clinical studies should be conducted with a standardized preparation to confirm its efficacy and safety alone and in combination with chloroquine and artesunate.

Cytotoxicity and anti-Leishmania amazonensis activity of Citrus sinensis leaf extracts

CONTEXT

Leishmania amazonensis is the main agent of diffuse cutaneous leishmaniasis, a disease characterized by lesional polymorphism and the commitment of skin surface. Previous reports demonstrated that the Citrus genus possess antimicrobial activity.

OBJECTIVE

This study evaluated the anti-L. amazonensis activity of Citrus sinensis (L.) Osbeck (Rutaceae) extracts.

MATERIALS AND METHODS

Citrus sinensis dried leaves were subjected to maceration with hexane (CH), ethyl acetate (CEA), dichloromethane/ethanol (CD/Et - 1:1) or ethanol/water (CEt/W - 7:3). Leishmania amazonensis promastigotes were treated with C. sinensis extracts (1-525 μg/mL) for 120 h at 27 °C. Ultrastructure alterations of treated parasites were evaluated by transmission electron microscopy. Cytotoxicity of the extracts was assessed on RAW 264.7 and J774.G8 macrophages after 48-h treatment at 37 °C using the tetrazolium assay. In addition, Leishmania-infected macrophages were treated with CH and CD/Et (10-80 μg/mL).

RESULTS

CH, CD/Et and CEA displayed antileishmanial activity with 50% inhibitory activity (IC₅₀) of 25.91 ± 4.87, 54.23 ± 3.78 and 62.74 ± 5.04 μg/mL, respectively. Parasites treated with CD/Et (131.2 μg/mL) presented severe alterations including mitochondrial swelling, lipid body formation and intense cytoplasmic vacuolization. CH and CD/Et demonstrated cytotoxic effects similar to that of amphotericin B in the anti-amastigote assays (SI of 2.16, 1.98 and 1.35, respectively). Triterpene amyrins were the main substances in CH and CD/Et extracts. In addition, 80 μg/mL of CD/Et reduced the number of intracellular amastigotes and the percentage of infected macrophages in 63% and 36%, respectively.

CONCLUSION

The results presented here highlight C. sinensis as a promising source of antileishmanial agents.

Antimalarial efficacy of Pongamia pinnata (L) Pierre against Plasmodium falciparum (3D7 strain) and Plasmodium berghei (ANKA)

Background

The objective of the current study was to assess the in vitro antiplasmodial activities of leaf, bark, flower, and the root of Pongamia pinnata against chloroquine-sensitive Plasmodium falciparum (3D7 strain), cytotoxicity against Brine shrimp larvae and THP-1 cell line. For in vivo study, the plant extract which has shown potent in vitro antimalarial activity was tested against Plasmodium berghei (ANKA strain).

Methods

The plant Pongamia pinnata was collected from the herbal garden of Acharya Nagarjuna University of Guntur district, Andhra Pradesh, India. Sequentially crude extracts of methanol (polar), chloroform (non-polar), hexane (non-polar), ethyl acetate (non-polar) and aqueous (polar) of dried leaves, bark, flowers and roots of Pongamia pinnata were prepared using Soxhlet apparatus. The extracts were screened for in vitro antimalarial activity against P. falciparum 3D7 strain. The cytotoxicity studies of crude extracts were conducted against Brine shrimp larvae and THP-1 cell line. Phytochemical analysis of the plant extracts was carried out by following the standard methods. The chemical injury to erythrocytes due to the plant extracts was checked. The in vivo study was conducted on P. berghei (ANKA) infected BALB/c albino mice by following 4-Day Suppressive, Repository, and Curative tests.

Results

Out of all the tested extracts, the methanol extract of the bark of Pongamia pinnata had shown an IC₅₀ value of 11.67 μg/mL with potent in vitro antimalarial activity and cytotoxicity evaluation revealed that this extract was not toxic against Brine shrimp and THP-1 cells. The injury to erythrocytes analysis had not shown any morphological alterations and damage to the erythrocytes after 48 h of incubation. Because methanolic bark extract of Pongamia pinnata has shown good antimalarial activity in vitro, it was also tested in vivo. So the extract had exhibited an excellent activity against P. berghei malaria parasite while decrement of parasite counts was moderately low and dose-dependent (P < 0.05) when compared to the control groups, which shown a daily increase of parasitemia, unlike the CQ-treated groups. The highest concentration of the extract (1000 mg/kg b.wt./day) had shown 83.90, 87.47 and 94.67% of chemo-suppression during Suppressive, Repository, and Curative tests respectively which is almost nearer to the standard drug Chloroquine (5 mg/kg b.wt./day). Thus, the study has revealed that the methanolic bark extract had shown promisingly high ((P < 0.05) and dose-dependent chemo-suppression. The phytochemical screening of the crude extracts had shown the presence of alkaloids, flavonoids, triterpenes, tannins, carbohydrates, phenols, coumarins, saponins, phlobatannins and steroids.

Conclusions

The present study is useful to develop new antimalarial drugs in the scenario of the growing resistance to the existing antimalarials. Thus, additional research is needed to characterize the bioactive molecules of the extracts of Pongamia pinnata that are responsible for inhibition of malaria parasite.

Psidium guajava L., from ethnobiology to scientific evaluation: Elucidating bioactivity against pathogenic microorganisms

ETHNOPHARMACOLOGICAL RELEVANCE

The use of popular plants has guided pharmaceutical research aimed at combating pathogenic microorganisms. Psidium guajava L. is a plant of great versatility and it has been used both as food and as a therapeutic agent. Root, bark, leaves, fruits, flowers and seeds are used for medicinal purposes, especially in infusions and decoctions for oral and topical use. P. guajava is utilized in symptomatology treatment related to organ malfunction and of diseases caused by the action of pathogenic and/or opportunistic microorganisms. Many pharmacological studies have been conducted to scientifically assess its therapeutic potential.

AIMS OF STUDY

The aim of the current study is to relate the popular use of this plant and its bioscientific assessment as a therapeutic agent in the treatment of diseases and symptoms caused by the action of protozoa, fungi, bacteria and viruses, and also evaluate the safety for the usage and the interaction with drugs.

MATERIALS AND METHODS

A bibliographic database the ethnobiology of Psidium guajava (2005-2015) and the pharmacological infections and parasitic diseases (2010-2015). Searches were done in scientific disclosure databases such as PubMed, Web of Science, and Scopus.

RESULTS

P. guajava leaf extracts were scientifically investigated for the treatment of diseases caused by protozoa (leishmaniasis, malaria, giardiasis, amoebiasis and trichomoniasis), fungi (dermatosis, systemic and mucocutaneous diseases), bacteria (respiratory, mucocutaneous and gastrointestinal infections, cholera, gastritis and stomach ulcers, oral and periodontal infections, venereal diseases and urinary infections) and viruses (herpes, influenza, rotavirus disease and AIDS). The toxicity assays indicates the safet for usage.

CONCLUSIONS

Highlight and elucidate the therapeutic potential and versatility of P. guajava. They also justify using ethnobiology efficiency to guide pharmacological studies. Some limitations can be observed in this kind of study, as the lack for ethnobiological informations and the absence of some controls in the assays.

An ethnobotanical study of anti-malarial plants among indigenous people on the upper Negro River in the Brazilian Amazon

BACKGROUND

In this article we present the plants used for the treatment of malaria and associated symptoms in Santa Isabel do Rio Negro in the Brazilian Amazon. The region has important biological and cultural diversities including more than twenty indigenous ethnic groups and a strong history in traditional medicine.

OBJECTIVE

The aims of this study are to survey information in the Baniwa, Baré, Desana, Piratapuia, Tariana, Tukano, Tuyuca and Yanomami ethnic communities and among caboclos (mixed-ethnicity) on (a) plant species used for the treatment of malaria and associated symptoms, (b) dosage forms and (c) distribution of these anti-malarial plants in the Amazon.

METHODS

Information was obtained through classical ethnobotanical and ethnopharmacological methods from interviews with 146 informants in Santa Isabel municipality on the upper Negro River, Brazil.

RESULTS

Fifty-five mainly native neotropical plant species from 34 families were in use. The detailed uses of these plants were documented. The result was 187 records (64.5%) of plants for the specific treatment of malaria, 51 records (17.6%) of plants used in the treatment of liver problems and 29 records (10.0%) of plants used in the control of fevers associated with malaria. Other uses described were blood fortification ('dar sangue'), headache and prophylaxis. Most of the therapeutic preparations were decoctions and infusions based on stem bark, root bark and leaves. These were administered by mouth. In some cases, remedies were prepared with up to three different plant species. Also, plants were used together with other ingredients such as insects, mammals, gunpowder and milk.

CONCLUSION

This is the first study on the anti-malarial plants from this region of the Amazon. Aspidosperma spp. and Ampelozizyphus amazonicus Ducke were the most cited species in the communities surveyed. These species have experimental proof supporting their anti-malarial efficacy. The dosage of the therapeutic preparations depends on the kind of plant, quantity of plant material available, the patient's age (children and adults) and the local expert. The treatment time varies from a single dose to up to several weeks. Most anti-malarial plants are domesticated or grow spontaneously. They are grown in home gardens, open areas near the communities, clearings and secondary forests, and wild species grow in areas of seasonally flooded wetlands and terra firme ('solid ground') forest, in some cases in locations that are hard to access. Traditional knowledge of plants was found to be falling into disuse presumably as a consequence of the local official health services that treat malaria in the communities using commercial drugs. Despite this, some species are used in the prevention of this disease and also in the recovery after using conventional anti-malarial drugs.

Antimalarial evaluation of the leaf latex of Aloe citrina and its major constituent

Background:

Malaria is one of the major obstacles to the socioeconomic development of several developing countries. Adequate treatment of the disease is becoming increasingly difficult due to the worsening problems of drug resistance in many parts of the world. Therefore, increased efforts in antimalarial drug discovery are urgently needed.

Objectives:

This study was designed to evaluate the antimalarial activity of the leaf latex of Aloe citrina Carter and Brandham and its major constituent.

Materials and Methods:

The leaf latex of A. citrina was dissolved in methanol and subjected to preparative thin layer chromatography. Structure of the isolated compound was determined on the basis of its electrospray-ionization tandem mass spectrometry, ¹H, ¹³C NMR and DEPT spectral data. The latex and its isolated compound were tested for their in vivo antimalarial activity using a 4-day suppressive test against chloroquine sensitive ANKA strain of Plasmodium berghei in mice.

Results:

Homonataloin A/B was isolated as a major component of the latex. Both the latex and isolated compound exhibited significant (P < 0.001) antimalarial activity at a dose of 400 mg/kg with parasite suppression of 60.59% and 67.52%, respectively. No significant adverse signs of toxicity were observed in mice treated with the leaf latex up to the highest dose (5000 mg/kg).

Conclusion:

The results of this study indicate that the antimalarial activity of the plant is attributed in part or in full to the presence of homonataloin A/B in the latex. It also validates the traditional use of the plant as an antimalarial agent.

Antimalarial properties of SAABMAL (®): an ethnomedicinal polyherbal formulation for the treatment of uncomplicated malaria infection in the tropics

Background & objectives:

Malaria is a serious problem in the countries of the developing world. As the malaria parasite has become resistant to most of the antimalaria drugs available currently, there is a need to search for newer drugs. This study reports the pharmaceutical quality and in vivo antimalarial activities of a polyherbal formulation (SAABMAL^®) used as malarial remedy in Nigeria.

Methods:

The antiplasmodial activity of SAABMAL^® was determined by using the 4-day suppressive test in Plasmodium berghei-infected mice. The formulation was tried on three different experimental animal models for in vivo antimalarial activities, which are prophylactic, suppressive and curative in mice. Chloroquine and pyrimethamine were used as standard drugs for comparison.

Results:

The suppressive study showed that, SAABMAL^® (200 and 400 mg/kg/bw) significantly (P<0.01) produced a suppression (29.39 - 100%) of parasitaemia in a dose-dependent manner, while the curative study showed that SAABMAL^® at 400 mg significantly (P<0.01) reduced (95.80%) parasitaemia compared with controls. The mean survival time of SAABMAL^®-treated groups (100 and 200 mg/kg) was higher than that of the chloroquine-treated group. Histopathologically, no changes were found in the spleen of both untreated and treated groups. SAABMAL^® capsules were of good mechanical properties with low weight variation and high degree of content mass uniformity.

Interpretation & conclusions:

The results obtained in this study showed the efficacy of SAABMAL^®, a herbal antimalarial formulation against chloroquine sensitive malaria and its potential use in the treatment of uncomplicated malaria infection. Further studies need to be done in humans to test its efficacy and safety for its potential use as an antimalarial drug.

An overview of important ethnomedicinal herbs of Phyllanthus species: present status and future prospects

The genus Phyllanthus consists of more than 1000 species, of which many are used as traditional medicines. The plant extracts have been used since ancient times, for treating hypertension, diabetes, hepatic, urinary, and sexual disorders, and other common ailments. Modern day scientific investigations have now confirmed pharmacognostic properties of Phyllanthus herbs. The phytochemicals attributing these medicinal properties have been identified in many of the Phyllanthus herbs. The morphologically similar herbs of Phyllanthus grow together and admixture of species during collection for manufacture of herbal medicines is quite common. Hence, along with pharmacognostic and phytochemical studies, appropriate protocols for correct identification of species are also important. As the use of these herbs as green medicines is becoming more popular, it is imperative to assess its genetic diversity and phylogenetic relatedness for future conservation strategies. This review is an attempt to present an overview of the existing studies on pharmacognostics, phytochemistry, species identification, and genetic diversity of Phyllanthus herbs and consequently (i) highlight areas where further research is needed and (ii) draw attention towards extending similar studies in underutilized but potentially important herbs such as P. maderaspatensis, P. kozhikodianus, P. rheedii, P. scabrifolius, and P. rotundifolius.

Ethnopharmacology guided screening of traditional Indian herbs for selective inhibition of Plasmodium specific lactate dehydrogenase

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants traditionally used to treat malaria can provide quality leads towards identifying novel anti-malarial drugs. Here we combined this approach with target based drug discovery and explored Plasmodium specific lactate dehydrogenase (LDH) inhibitory activity of 8 Indian plants which are ethnically used to treat malaria.

METHODS

LDH from Indian Plasmodium falciparum and Plasmodium vivax strains, were cloned and expressed in Escherichia coli, followed by purification of recombinant enzymes (rPfLDH and rPvLDH respectively). Extracts of 8 plants in different organic and aqueous solvents, were screened for their inhibitory activity on rPfLDH, rPvLDH and mammalian LDHs. Phyllanthus amarus aqueous extract was further tested for in vitro parasiticidal activity.

RESULTS

Aqueous extract of Phyllanthus amarus Schum. and Thonn. and chloroform extract of Murraya koenigii (L.) Spreng. exhibited profound and exclusive inhibitory effect on Plasmodium falciparum LDH (IC(50)=11.2 μg/ml ± 0.4) and Plasmodium vivax LDH (IC(50)=6.0 μg/ml ± 0.6) respectively. Moreover, Phyllanthus amarus aqueous extract also demonstrated antiplasmodial activity in vitro, on Chloroquine sensitive and resistant strains of Plasmodium falciparum (IC(50)=7.1 μg/ml ± 0.5 and 6.9 μg/ml ± 0.7 respectively).

CONCLUSION

Target specific screening of traditional herbs used in malaria treatment has proffered Phyllanthus amarus and Murraya koenigii extracts as hits which can optimistically provide novel antimalarial drugs.

In vitro and in vivo antiplasmodial activity of the root extracts of Brucea mollis Wall. ex Kurz

Malaria control is compromised worldwide by continuously evolving drug-resistant strains of the parasite demanding exploration of natural resources for developing newer antimalarials. The northeastern region of India is endemic for malaria characterized by high prevalence of drug-resistant Plasmodium falciparum strains. Many plants are used by the indigenous communities living in the northeast India in their traditional system of medicine for the treatment of malarial fever. Folklore claim of antimalarial property of one such plant Brucea mollis was evaluated in vitro and in vivo for antiplasmodial activity. Crude extracts from dried B. mollis root powder were prepared through soxhlet extraction using petroleum ether, methanol, and water sequentially. Methanol extract was further partitioned between chloroform and water. These extracts were tested in vitro against laboratory-adapted chloroquine-sensitive and chloroquine-resistant strains of P. falciparum. In in vitro evaluation, extracts were found more active on the chloroquine-sensitive strain. Methanolic-chloroform (IC(50) 5.1 μg ml(-1)) and methanolic-aqueous (IC(50) 13.9 μg ml(-1)) extracts recorded significant in vitro antiplasmodial activity which was also supported by their promising in vivo activity (ED(50) 72 and 30 mg kg(-1) bw day(-1), respectively) against chloroquine-resistant Plasmodium yoelli N-67 strain in Swiss albino mice. Methanolic-aqueous extract-treated mice survived on average for 14 days that was comparable to the reference drug chloroquine. This is the first report of antiplasmodial activity of B. mollis validating the traditional use of this plant as antimalarial in the northeast India and calls for further detailed investigations.

Antimalarial activities of medicinal plants traditionally used in the villages of Dharmapuri regions of South India

ETHNOPHARMACOLOGICAL RELEVANCE

An ethnopharmacological investigation of medicinal plants traditionally used to treat diseases associated with fevers in Dharmapuri region of South India was undertaken. Twenty four plants were identified and evaluated for their in vitro activity against Plasmodium falciparum and assessed for cytotoxicity against HeLa cell line.

AIM OF THE STUDY

This antimalarial in vitro study was planned to correlate and validate the traditional usage of medicinal plants against malaria.

MATERIALS AND METHODS

An ethnobotanical survey was made in Dharmapuri region, Tamil Nadu, India to identify plants used in traditional medicine against fevers. Selected plants were extracted with ethyl acetate and methanol and evaluated for antimalarial activity against erythrocytic stages of chloroquine (CQ)-sensitive 3D7 and CQ-resistant INDO strains of Plasmodium falciparum in culture using the fluorescence-based SYBR Green I assay. Cytotoxicity was determined against HeLa cells using MTT assay.

RESULTS

Promising antiplasmodial activity was found in Aegle marmelos [leaf methanol extract (ME) (IC(50)=7 μg/mL] and good activities were found in Lantana camara [leaf ethyl acetate extract (EAE) IC(50)=19 μg/mL], Leucas aspera (flower EAE IC(50)=12.5 μg/mL), Momordica charantia (leaf EAE IC(50)=17.5 μg/mL), Phyllanthus amarus (leaf ME IC(50)=15 μg/mL) and Piper nigrum (seed EAE IC(50)=12.5 μg/mL). The leaf ME of Aegle marmelos which showed the highest activity against Plasmodium falciparum elicited low cytotoxicity (therapeutic index>13).

CONCLUSION

These results provide validation for the traditional usage of some medicinal plants against malaria in Dharmapuri region, Tamil Nadu, India.

Phyllanthus amarus: ethnomedicinal uses, phytochemistry and pharmacology: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus amarus Schum. & Thonn. belongs to the family Euphorbiaceae is a small herb well known for its medicinal properties and widely used worldwide. P. amarus is an important plant of Indian Ayurvedic system of medicine which is used in the problems of stomach, genitourinary system, liver, kidney and spleen. It is bitter, astringent, stomachic, diuretic, febrifuge and antiseptic. The whole plant is used in gonorrhea, menorrhagia and other genital affections. It is useful in gastropathy, diarrhoea, dysentery, intermittent fevers, ophthalmopathy, scabies, ulcers and wounds.

MATERIALS AND METHODS

The present review covers a literature across from 1980 to 2011. Some information collected from traditional Ayurvedic texts and published literature on ethanomedicinal uses of Phyllanthus amarus in different countries worldwide.

RESULTS

Phytochemical studies have shown the presence of many valuable compounds such as lignans, flavonoids, hydrolysable tannins (ellagitannins), polyphenols, triterpenes, sterols and alkaloids. The extracts and the compounds isolated from P. amarus show a wide spectrum of pharmacological activities including antiviral, antibacterial, antiplasmodial, anti-inflammatory, antimalarial, antimicrobial, anticancer, antidiabetic, hypolipidemic, antioxidant, hepatoprotective nephroprotective and diurectic properties.

CONCLUSION

The present review summarizes information concerning the morphology, ecology, ethnopharmacology, phytochemistry, biological activities, clinical applications and toxicological reports of P. amarus. This review aims at gathering the research work undertaken till date on this plant in order to provide sufficient baseline information for future works and commercial exploitation.

Synergy of the antiretroviral protease inhibitor indinavir and chloroquine against malaria parasites in vitro and in vivo

Many malaria-endemic areas are also associated with high rates of human immunodeficiency virus (HIV) infection. An understanding of the chemotherapeutic interactions that occur during malaria and HIV co-infections is important. Our previous studies have demonstrated that some antiretroviral protease inhibitors are effective in inhibiting Plasmodium falciparum growth in vitro. Currently, studies examining the interactions between antiretroviral protease inhibitors and antimalarial drugs are being conducted, but the data are limited. In this study, we examined the synergistic interactions between the antiretroviral protease inhibitor indinavir and chloroquine (CQ) in chloroquine-resistant and chloroquine-sensitive malaria parasites in vitro and in vivo. In vitro, by using modified fixed-ratio isobologram method, fractional inhibitory concentrations index (FICI) was calculated to indicate the interaction between the two drugs. The results demonstrated that indinavir interacted synergistically with chloroquine against both chloroquine-sensitive P. falciparum clone 3D7 (mean FICI 0.784) and multidrug-resistant P. falciparum clone Dd2 (mean FICI 0.599). In vivo drug interactions were measured using a 4-day suppressive test in a rodent malaria model infected with Plasmodium chabaudi. We observed that indinavir enhanced the antimalarial activity of chloroquine against both the chloroquine-sensitive line P. chabaudi ASS and the chloroquine-resistant line P. chabaudi ASCQ. More importantly, chloroquine had a 100% clearance of asexual parasites when used in combination with indinavir at an appropriate dose ratio (10 mg/kg CQ + 1.8 g/kg indinavir) where there was no obvious toxicity. We conclude from this study that the combination of indinavir and chloroquine may become a novel antimalarial drug regimen.

Seaweeds as a source of lead compounds for the development of new antiplasmodial drugs from South East coast of India

The problems of resistant lines of Plasmodium falciparum are escalating. Twelve seaweeds species belong to five different families (Sargassaceae, Gracilariaceae, Hypneaceae, Corallinaceae and Halimedaceae) were collected from Mandapam coastal area, and the seaweeds extracts were tested for in vitro antiplasmodial activity against P. falciparum. Among the tested seaweeds, Gracilaria verrucosa (IC(50) 5.55 μg.ml(-1)) and Hypnea espera (IC(50) 8.94 μg.ml(-1)) showed good antiplasmodial activity, and these results are comparable with positive controls such as artemether (IC(50) 4.09 μg.ml(-1)) and chloroquine (IC(50) 19.59 μg.ml(-1)), respectively. Turbinaria conoides, Sargassum myriocystem, Hypnea valentiae and Jania rubens extracts showed IC(50) values between 5 to 50 μg.ml(-1). Sargassum sp., Turbinaria decurrens and Halimeda gracilis extracts showed IC(50) values between 50 to 100 μg.ml(-1). Gracilaria corticata, Jania adherens and Halimeda opuntia extracts showed IC(50) value of more than 100 μg.ml(-1). Statistical analysis reveals that significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out, and it shows that no morphological changes in erythrocytes by the ethanolic extract of seaweeds extracts after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of sugars, proteins, phenols and carboxylic acid in the ethanolic extracts of seaweeds. It is concluded from the present study that the ethanolic extracts of seaweeds of G. verrucosa and Hypnea espera possess lead compounds for development of antiplasmodial drugs.