Screening of traditional medicinal plant extracts and compounds identifies a potent anti-leishmanial diarylheptanoid from Siphonochilus aethiopicus.

Available anti-leishmanial drugs are associated with toxic side effects, necessitating the search for safe and effective alternatives. This study is focused on identifying traditional medicinal plant natural products for anti-leishmanial potential and possible mechanism of action. Compounds S and T. cordifolia residual fraction (TC-5) presented the best anti-leishmanial activity (IC50: 0.446 and 1.028 mg/ml) against promastigotes at 48 h and less cytotoxicity to THP-1 macrophages. These test agents elicited increased expression of pro-inflammatory cytokines; TNFα and IL-12. In infected untreated macrophages, NO release was suppressed but was significantly (p < 0.05) increased in infected cells treated with compound S. Importantly, Compound S was found to interact with LdTopoIIdimer in silico, resulting in a likely reduced ability of nucleic acid (dsDNA)-remodelling and, as a result, parasite proliferation in vitro. Thereby, Compound S possesses anti-leishmanial activity and this effect occurs via a Th1-mediated pro-inflammatory response. An increase in NO release and its inhibitory effect on LdTopoII may also contribute to the anti-leishmanial effect of compound S. These results show the potential of this compound as a potential starting point for the discovery of novel anti-leishmanial leads.Communicated by Ramaswamy H. Sarma.

Marmesin isolated from Celtis durandii Engl. root bioactive fraction inhibits ß-hematin formation and contributes to antiplasmodial activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Malaria is a leading cause of death in many developing countries, especially in sub-Saharan Africa. Nigeria is endowed with an abundance of medicinal plants, many of which are used to treat malaria. Celtis durandii Engl. is one such plant used as a traditional antimalarial remedy in southeast Nigeria. However, its antiplasmodial potential is poorly explored. AIM OF THE STUDY: The study aimed at identifying the antiplasmodial components of C. durandii root extract through antiplasmodial activity-guided fractionation. MATERIALS AND METHODS: Dichloromethane/methanol mixture extract (1:1 v/v) of C. durandii root was prepared and partitioned against water to obtain the organic phase, which was further separated by column chromatography into nine (C1 - C9) fractions. The antiplasmodial activity was evaluated by in vitro screening of the different fractions against drug-sensitive and drug-resistant Plasmodium falciparum strains. Further purification of the active column fractions resulted in a potent anti-Plasmodial compound that was subsequently investigated for its effect on ß-hematin formation. Additionally, the isolated compound was characterized and identified as marmesin using mass spectrometry and nuclear magnetic resonance spectroscopy. RESULTS: Celtis durandii root extract exhibited promising antiplasmodial activity {IC50 (µg/ml) 5.92, 6.04, and 6.92} against PfW2mef, PfINDO, and Pf3D7 respectively. Pooled fractions with good antiplasmodial activity {IC50 (µg/ml) Pf3D7: 3.99; PfINDO: 2.24} and selectivity for the parasites (SI: 21) yielded a compound that was fourteen-fold potent in antiplasmodial activity against Pf3D7(IC50: 0.28 µg/ml). It also inhibited ß-hematin formation with an IC50 = 150 µM. Further studies using spectral data, literature, and chemical databases identified the purified compound as marmesin. CONCLUSION: This work has demonstrated that Celtis durandii root extract has good antiplasmodial activity against drug-sensitive and drug-resistant P. falciparum. The inhibition of ß-hematin formation by marmesin accounts in part for this activity.

Assessment of antimalarial medicinal plants used in Nigerian ethnomedicine reveals antimalarial potential of Cucurbita pepo leaf extract.

Medicinal plants are often used to treat malaria in different parts of Nigeria and exploiting these can unravel new therapeutic leads. This study evaluated the antiplasmodial potential of selected plants used to treat malaria in Nsukka, Enugu state, Nigeria. Leaves of three different plants (Cucurbita pepo, Hibiscus rosa-sinensis and Pennisetum purpureum) were collected for screening and two extracts viz., 70%v/v ethanol and dichloromethane/methanol (1:1 v/v), were prepared for each. An acute toxicity test was done in mice and cytotoxicity was assessed using human hepatoma cell line (HUH). The extracts were screened against chloroquine-sensitive P. falciparum (Pf3D7) in vitro, and chloroquine-resistant P. berghei ANKA in vivo using a 4 day-suppressive test in mice. Cucurbita pepo ethanol extract was further tested for hemolytic effect on human erythrocytes and in established infection in mice. Parameters assessed were post-treatment parasitemia, hematological indices, organ (brain, kidney, liver, and spleen) weights, and survival. The extracts were non-cytotoxic up to a test dose of 100 µg/ml and 2000 mg/kg fed - mice did not show acute or delayed toxicity. Cucurbita pepo ethanol extract (CpE) displayed excellent in vitro antiplasmodial activity with IC50 of 3.05 µg/ml. At an oral dose of 500 mg/kg, mice were observed to display significant (p < 0.01) ∼51% suppression of parasitemia. The extract did not produce any significant hemolytic effect up to a test concentration of 1 mg/ml. In established infection, a dose of 300 mg/kg significantly (p < 0.01) protected mice from anemia caused by low hematocrit. The extract produced significant (p < 0.05) elevation in red blood cells and platelet counts, and an increase in hemoglobin was evident at 100 and 300 mg/kg. Further, CpE in a dose-dependent manner, reversed liver and spleen weight increase seen in untreated, infected mice. These findings show C. pepo as a potential candidate for further studies to identify its bioactive principle(s) and possible mechanism(s) of antimalarial action.

Antiplasmodial, antinociceptive and antipyretic potential of the stem bark extract of Burkea africana and identification of its antiplasmodial-active fraction.

BACKGROUND AND AIM: Burkea africana stem bark is used as a remedy for malaria in north-central and southern Nigeria. Based on its traditional use, this study was conducted to investigate the antiplasmodial, antinociceptive and antipyretic potential of an extract of B. africana stem bark. EXPERIMENTAL PROCEDURE: A 70% v/v ethanol extract of stem bark of B. africana was prepared by cold maceration. Fractions (dichloromethane, ethyl acetate, and residual) were also prepared. The extract was screened for hemolytic, cytotoxic and antiplasmodial activity effects. The effect of the extract and fractions against chloroquine-sensitive (3D7) and multi-drug resistant (W2mef) P. falciparum was assessed. Acute toxicity test, acetic acid-induced abdominal writhing in mice, and lipopolysaccharide-induced fever in rats were also employed to screen the extract. Chromatographic fingerprints of the extract and active fraction were obtained. RESULTS: B. africana extract showed no cytotoxic or significant hemolytic effects and did not cause acute toxicity or mortality. The ethanol extract exhibited moderate antiplasmodial activity while the dichloromethane fraction showed high activity against P. falciparum 3D7 (IC50 = 6.44 µg/ml) and W2mef (IC50 = 6.30 µg/ml) respectively. The extract elicited significant (p < 0.05) attenuation of acetic acid-induced writhing and significantly (p < 0.05) ameliorated lipopolysaccharide-induced pyrexia at 300 mg/kg. The HPLC profile of the dichloromethane fraction showed peaks with retention times that corresponded with those of rutin and caffeic acid. CONCLUSION: Burkea africana extract has antiplasmodial, antinociceptive and antipyretic potential and its antiplasmodial constituents are concentrated in its dichloromethane fraction.

Lophira alata Suppresses Phorbol Ester-Mediated Increase in Cell Growth via Inhibition of Protein Kinase C-α/Akt in Glioblastoma Cells.

BACKGROUND: Medicinal plants serve as sources of compounds used to treat other types of cancers. The root of the plant Lophira alata (Ochnaceae) has been used as a component of traditional herbal decoctions administered to cancer patients in southwestern Nigeria. However, the mechanism of the cytotoxic effects of Lophira alata alone or in the presence of phorbol ester has not been investigated in brain tumor cells. OBJECTIVE: This study aimed to examine the cytotoxic potential of the methanolic fraction of Lophira alata root on malignant glioma invasive cellular growth and survival. METHODS: The methanolic fraction of Lophira alata (LAM) was subjected to high-performance liquid chromatography to determine the fingerprints of the active molecules. The antiproliferative effects of Lophira alata were assessed using the MTT and LDH assays. Protein immunoblots were carried out to test the effects of Lophira alata, alone or in the presence of phorbol ester, on survival signaling pathways, such as Akt, mTOR, and apoptotic markers such as PARP and caspases. RESULTS: The methanolic fraction of Lophira alata (LAM) induced a concentration-dependent and time-dependent decrease in glioma cell proliferation. In addition, LAM attenuated phorbol ester-mediated signaling of downstream targets such as Akt/mTOR. Gene silencing using siRNA targeting PKC-alpha attenuated LAM-mediated downregulation of Akt. In addition, LAM induced both PARP and caspase cleavages. The HPLC fingerprint of the fraction indicates the presence of flavonoids. CONCLUSION: LAM decreases cell proliferation and induces apoptosis in glioma cell lines and thus could serve as a therapeutic molecule in the management of gliomas.

Antiplasmodial activity of a novel diarylheptanoid from Siphonochilus aethiopicus.

The Nigerian and South African varieties of Siphonochilus aethiopicus were examined for their phytochemical constituents. The ethyl acetate extract of the rhizomes of the South African variety yielded a novel diarylheptanoid, 2,3-diacetoxy-7-(3'',4''-dihydroxy-5''-methoxyphenyl)-1-(4'-hydroxy-3'-methoxyphenyl)-5-heptene and the flavonoid 3,7-dimethoxyquercetin. From the hexane extract of the Nigerian variety, siphonochilone and another flavonoid, 3,4',7-trimethylkaempferol were isolated. The isolated compounds were characterised by NMR spectroscopic techniques and mass spectrometry. The diarylheptanoid was then assayed for antiplasmodial activity in vitro using a Plasmodium falciparum growth inhibition assay. At the concentrations tested, the compound inhibited parasite growth by 69 - 74%, without producing cytotoxic or significant haemolytic effects. The antiplasmodial activity of the compound is likely mediated by direct mechanism(s) in erythrocytic - stage parasites.

Antidiarrhoeal properties of Syzygium guineense leaf extract and identification of chemical constituents in its active column fractions.

Background Syzygium guineense (Myrtaceae) has been used in traditional medicine against various ailments, including diarrhoea. This study was conducted to scientifically evaluate the antidiarrheal effects of S. guineense extract and fractions. Methods An ethanol extract of S. guineense leaves was prepared and tested for its effect on small intestinal propulsion in mice and castor oil-induced fluid accumulation in rats. The extract was also evaluated for its effect on itopride-induced small intestine propulsion in mice. Column fractions were also investigated in rats and sub-fractions were tested for activity on spontaneous contractions of isolated rabbit jejunum. Results The results showed that the extract significantly (p<0.05) inhibited intrinsic small intestinal propulsion and itopride-induced propulsive activity, similar to atropine (0.3 mg/kg) although its inhibitory effect against castor oil-induced intestinal fluid accumulation and diarrhoea was statistically insignificant (p>0.05). Column separation yielded 14 fractions, with three fractions producing significant (p<0.001) inhibition of small intestinal propulsion. Sub-fractions 1, 7 and 16 obtained from an active column fraction also exhibited relaxant effects on isolated rabbit jejunum. Spectral analysis (proton, 13C NMR) of sub-fractions 7 and 16 revealed the presence of betulinic acid, ursolic acid, oleanolic acid in 7 and a mixture of luteolin and friedelane-type triterpenes in 16. Conclusions These findings provide scientific evidence that S. guineense leaf extract possess antidiarrhoeal activity and may be potentially beneficial in treatment diarrhoeal disease. The identified compounds may also be implicated in its antidiarrhoeal effects.

Ocimum basilicum extract exhibits antidiabetic effects via inhibition of hepatic glucose mobilization and carbohydrate metabolizing enzymes.

AIM: Ocimum basilicum L (Lamiaceae) is used as a traditional remedy for different ailments, including diabetes mellitus. This study investigated the antidiabetic effects of an extract of aerial parts of O. basilicum. METHODS: Antihyperglycemic effect of the extract was determined by its effects on α-amylase and α-glucosidase in vitro, while antidiabetic properties were studied in alloxan induced diabetic rats treated for 28 days with extract and compared to those treated with oral metformin (150 mg/kg). The study and analysis was conducted between 2014 and 2015. RESULTS: The treatment with 100 and 200 mg/kg extract significantly (P < 0.05) reduced fasting blood glucose concentration and slightly increased mean body weight in treated groups. Oral glucose tolerance was also significantly (P < 0.05, 0.001) improved in 100 and 400 mg/kg extract-treated groups. The extract caused a dose-dependent increase in liver glycogen content, while it decreased alanine transferase (18.9-30.56%) and aspartate transferase (6.48-34.3%) levels in a non-dose-dependent manner. A dose of 100 mg/kg also reduced serum cholesterol and triglycerides by 19.3 and 39.54%, compared to a 2.6% reduction of cholesterol seen in the metformin-treated group. The extract was observed to produce significant (P < 0.001) concentration-dependent inhibition of α-glucosidase (35.71-100%) and also α-amylase (23.55-81.52%), with estimated inhibitory concentration values of 1.62 and 3.86 mg/mL, respectively. CONCLUSIONS: The antidiabetic properties of the extract may be due to its ability to suppress endogenous glucose release, inhibit glycogenolysis and/or stimulate glycogenesis.

Analgesic, anti-inflammatory, and heme biomineralization inhibitory properties of Entada africana ethanol leaf extract with antiplasmodial activity against Plasmodium falciparum.

BACKGROUND: Entada africana (EA) is a medicinal plant used in West Africa for the treatment of malaria fever, but its efficacy against malaria is yet to be scientifically validated. Our study explores the antimalarial potential of the ethanol leaf extract of EA. METHODS: The antiplasmodial activity of EA against chloroquine-sensitive (HB3) and chloroquine-resistant (FcM29) Plasmodium falciparum was determined as well as its peripheral antinociceptive and anti-inflammatory properties. The effect of the extract on human monocytic (THP-1) cells was recorded as a measure of cytotoxicity, whereas the inhibitory effect on heme detoxification was evaluated as a possible mechanism of antiplasmodial activity. RESULTS: At a concentration of 100 µg/mL, EA was noncytotoxic and displayed moderate antiplasmodial activity against HB3 and FcM29 (IC50=26.36 and 28.86 µg/mL, respectively). It also exhibited concentration-dependent inhibition of synthetic heme (IC50=16 mg/mL). The extract (200 mg/kg body weight) showed significant (p<0.05) inhibition of paw inflammation, and significantly (p<0.01, 0.05) reduced the number of abdominal writhes induced by acetic acid (58.62%-65.51%), which was higher compared to that of diclofenac (50%, p<0.05). CONCLUSIONS: These findings suggest that peripheral antinociceptive effects and parasiticidal activity of EA contribute to its antimalarial properties and it can be further explored as effective therapy against malaria infection.