Effect of Mexican medicinal plant used to treat trichomoniasis on Trichomonas vaginalis trophozoites

Crude methanolic extracts from 22 Mexican medicinal plants were screened for antitrichomonal activity against Trichomonas vaginalis, which is the etiological agent of trichomoniasis. Among the plants tested Carica papaya and Cocos nucifera showed the best antitrichomonal activity with IC(50) values of 5.6 and 5.8 microg/ml, respectively. The extracts of Bocconia frutescens, Geranium mexicanum, and Lygodium venustum showed moderate activity with IC(50) values ranging from 30.9 to 60.9 microg/ml. All the other plant extracts were inactive (IC(50)>100 microg/ml). All extracts tested were less active than metronidazole (IC(50) 0.037 microg/ml), an antiprotozoal drug used as positive control. The results of the antiprotozoal screening support the popular uses of five of the plants tested for the treatment of some urogenital tract disorders in Mexican traditional medicine. However, seeds of Carica papaya and aerial parts of Bocconia frutescens should be used in herbal medicine with care to avoid toxicity.     

贯叶金丝桃化学成分研究

目的:研究贯叶金丝桃Hypericum perforatum的化学成分。方法:通过各种柱色谱进行分离纯化,根据理化性质和波谱数据对所得化合物进行结构鉴定;测定化合物对基因重组人PTP1B的抑制率。结果:从中分离并鉴定了10个化合物:D-甘露醇(1),邻苯二甲酸二异丁酯(2),(7E,6R,9S)-9-hydroxy-4,7-megastigmadien-3-one(3),(6S,9R)-roseoside(4),2,6-dim-ethoxy-4-hydroquinone-1-O-β-D-glucopyranoside(5),2,6-dimethoxy-4-hydroxybenzyl alcohol 1-O-β-D-glucopyranoside(6),syringate4-O-β-glucopyranoside(7),金丝桃素(8),skyrin-6-O-β-D-glucopyranoside(9),(R)-3,4-二羟基-苯甲酸-1’-丙三醇酯(10)。在2μmol.L-1时,化合物9对基因重组人PTP1B的抑制率为96.4%,IC50为2.5μmol.L-1。结论:化合物10为新化合物,化合物2～4,7为首次从该属中分离得到,化合物5,6从该植物中首次得到。体外活性筛选表明化合物8具有显著的PTP1B抑制作用。     

In vitro antiplasmodial activity of plants used in Benin in traditional medicine to treat malaria

Aim of the study

The aim of the study was to evaluate the in vitro antiplasmodial activity of crude extracts of 12 plant species traditionally used in Benin for the treatment of malaria in order to validate their use.

Materials and methods

For each species, dichloromethane, methanol and total aqueous extracts were tested. The antiplasmodial activity of extracts was evaluated using the measurement of the plasmodial lactate dehydrogenase activity on chloroquine-sensitive (3D7) and resistant (W2) strains of Plasmodium falciparum. The selectivity of the different extracts was evaluated using the MTT test on J774 macrophage-like murine cells and WI38 human normal fibroblasts.

Results

The best growth inhibition of both strains of Plasmodium falciparum was observed with the dichloromethane extracts of Acanthospermum hispidum DC. (Asteraceae) (IC₅₀ = 7.5 μg/ml on 3D7 and 4.8 μg/ml on W2), Keetia leucantha (K. Krause) Bridson (syn. Plectronia leucantha Krause) (Rubiaceae) leaves and twigs (IC₅₀ = 13.8 and 11.3 μg/ml on 3D7 and IC₅₀ = 26.5 and 15.8 μg/ml on W2, respectively), Carpolobia lutea G.Don. (Polygalaceae) (IC₅₀ = 19.4 μg/ml on 3D7 and 8.1 μg/ml on W2) and Strychnos spinosa Lam. (Loganiaceae) leaves (IC₅₀ = 15.6 μg/ml on 3D7 and 8.9 μg/ml on W2). All these extracts had a low cytotoxicity.

Conclusion

Our study gives some justifications for the traditional uses of some investigated plants.     

Antimicrobial activity of Ulopterol isolated from Toddalia asiatica (L.) Lam.: a traditional medicinal plant

Ethnopharmacological relevance

The leaves of Toddalia asiatica (L.) Lam. (Rutaceae) are widely used in folk medicine in India to treat various ailments like cough, malaria, indigestion, influenza lung diseases and rheumatism, fever, stomach ailments, cholera and diarrhea. In our earlier communication we have reported the antimicrobial study on the various extracts of the leaves and the isolation and identification of Flindersine, a quinolone alkaloid as the major active principle. In the present study, we report the antibacterial and antifungal activities of Ulopterol, a coumarin isolated as another major active antimicrobial principle.

Materials and methods

The leaves were successively extracted with hexane, chloroform, ethyl acetate, methanol and water. The extracts were studied for their antimicrobial activity against selected bacteria and fungi by using disc-diffusion method. The ethyl acetate extract which was found to possess highest antimicrobial activity was subjected to activity guided fractionation by column chromatography over silica gel. This resulted in the isolation of the coumarin, Ulopetrol, an active principle besides Flindersine which was reported by us earlier. The structure of the compound was elucidated using physical and spectroscopic data. Flindersine and Ulopterol were quantified by HPLC.

Results

Ulopterol showed activity against the bacteria viz. Staphylococcus epidermidis, Enterobacter aerogenes, Shigella flexneri, Klebsiella pneumoniae (ESBL-3967), Escherichia coli (ESBL-3984) and fungi viz. Aspergillus flavus, Candida krusei and Botrytis cinerea. Quantification by HPLC showed the content of Flindersine and Ulopterol to be 0.361% and 0.266% respectively on dry weight basis of the leaves.

Conclusions

Ethyl acetate extract (successive extraction) contained Ulopterol, a coumarin, besides Flindersine, a quinolone alkaloid, as a major active principle in the antimicrobial studies. This is the first report of the antimicrobial activity of Ulopterol and also its first report from the plant.     

Antiulcer effects of Achyrocline satureoides (Lam.) DC (Asteraceae) (Marcela), a folk medicine plant,in different experimental models

Ethnopharmacological relevance

Achyrocline satureoides is a medium-sized South American indigenous herb, commonly known as “Marcela” or “Macela”. The infusion obtained from inflorescences of this plant is widely used in Brazilian folk medicine as an antispasmodic, anti-inflammatory, hypoglycemic, and hypocholesterolemic, mainly to treat gastrointestinal disorders such as gastric ulcers and dyspepsia. However, the antiulcer properties of this species have not yet been fully studied.

Aim of the study

This study was conducted to evaluate and contribute to validating the antiulcer activity of hydroalcoholic extract of inflorescences of Achyrocline satureoides.

Materials and methods

The antiulcer assays were performed using the ethanol-induced ulcer, and nonsteroidal anti-inflammatory drug (NSAID)-induced ulcer protocols. Gastric secretion parameters were also evaluated (volume, pH and total acidity) by the pylorus ligated model, and the mucus in the gastric content was determined.

Results

In the ethanol-induced ulcer model, it was observed that the treatment with Achyrocline satureoides extract significantly reduced the lesion index by 75.1 ± 8.6, 85.0 ± 9.2, 86.6 ± 7.4 and 75.5 ± 5.3 for the groups treated with 100, 250 and 500 mg/kg of extract of inflorescences of Achyrocline satureoides and the positive control (omeprazole 30 mg/kg), respectively. Significant inhibition was also observed in the lesion index in the indomethacin-induced ulcer model, with decreases of 62.5 ± 7.1, 62.5 ± 6.1, 63.6 ± 5.5 and 96.2 ± 3.6 for the groups treated with 100, 250 and 500 mg/kg of extract and the positive control (cimetidine 100 mg/kg), respectively. The parameters of gastric secretion (pH, volume, [H⁺]) showed no alteration in the different doses of the treatment. On the other hand the treatment with the hydroalcoholic extract of Achyrocline satureoides (100, 250 and 500 mg/kg), significantly increased mucus production (p < 0.01), when compared with the groups treated with indomethacin (100 mg/kg), cimetidine (100 mg/kg) and negative control (vehicle). No signs of toxicity was observed in the acute toxicity study.

Conclusions

The results of the present study show that hydroalcoholic extract of Achyrocline satureoides displays antiulcer activity, as demonstrated by the significant inhibition of the formation of ulcers induced using different models. However, this activity appears not be related to the antisecretor mechanisms. Moreover, this work suggests that preparations obtained from Achyrocline satureoides could be used for the development of new phytotherapic drugs for the treatment of gastric ulcer.     

Hypoglycaemic activity of four plant extracts traditionally used in South Africa for diabetes

Aim

To validate plant species for hypoglycaemic activity.

Materials and methods

Four plants were investigated for hypoglycaemic activity by evaluating inhibiting effects on carbohydrate-hydrolising enzymes: α-glucosidase and α-amylase. Acetone plant extracts were screened against C2C12 myocytes, 3T3-L1 preadipocytes and Chang liver cells by measuring glucose uptake. Cytotoxicity was done in preadipocytes and hepatocytes.

Results

Extract of Euclea undulata rootbark exhibited highest activity, displaying a glucose uptake of 162.2% by Chang liver cells at 50 μg/ml. An inhibition concentration of 50% for Euclea undulata was found to be 49.95 μg/ml for α-glucosidase and 2.8 μg/ml for α-amylase. No cytotoxicity was recorded for Euclea undulata, while Schkuhria pinnata and Elaeodendron transvaalense exhibited cytotoxicity at 12.5 μg/ml. α-Glucosidase and α-amylase assays showed inhibitory activity on enzymes for three plant extracts.

Conclusion

Euclea undulata, Schkuhria pinnata and Elaeodendron transvaalense showed in vitro hypoglycaemic activity. Schkuhria pinnata and Elaeodendron transvaalense indicated cytotoxicity on 3T3-L1 preadipocytes and Chang liver cells. Euclea undulata, Pteronia divaricata and Elaeodendron transvaalense inhibited α-glucosidase and α-amylase enzymes.

Ethnopharmacological relevance

Screening of plant extracts scientifically validated traditional use of Euclea undulata for treatment of diabetes. Cytotoxicity results revealed that acetone extracts of Schkuhria pinnata and Elaeodendron transvaalense are toxic and raise concern for chronic use.     

Ethnobotanical survey and antibacterial activity of plants used in the Altiplane region of Mexico for the treatment of oral cavity infections

Ethnopharmacological relevance

The ethnobotanical survey conducted in this study showed 47 plant species used in the Altiplane region of Mexico for the treatment of dental diseases such as toothache, dental caries, periodontal disease and gingivitis.

Materials and methods

Information was collected by performing interviews. The following data were recorded: name of the patients or herbalists with their age, sex; date and place of gathering information; pathology of persons interviewed; name of the drug (vernacular name); parts used (leaves, bark, fruits, seeds, aerial parts), mode of preparation and administration, and possible combinations.The inhibitory effects of the aqueous and ethanolic extracts of the medicinal plants detected during the survey the on the growth of Streptococcus mutans and Phrophyromonas gingivalis were determined using microdilution method. The minimum bactericidal concentrations (MBC) were determined from the wells of microplate with no visible bacterial growth.

Results

In total, tree places of the Altiplane region of Mexico were visited and five healers and 100 patients were questioned. 47 wild and cultivated species were recorded. The most frequent uses were to treat tooth pain, gum diseases, bad breath and cavities. Infusions were the most frequently prepared formulation. Other applied preparations mentioned with decreasing frequency were decocts, syrups, tinctures, direct application of the plant material without prior preparation and finally macerations.The ethanolic extracts of Haematoxylon brasiletto, Punica granatum, Iostephane heterophyla, Bursera simaruba, Cedrela odorata and Rhus standleyi (12.5–65.0 μg/mL) as well as water extracts of Haematoxylon brasiletto, Punica granatum, Iostephane heterophyla, Amphipterygium adstringens, Argemone mexicana, Cedrela odorata, Eysenhardtia polystachya, Persea americana, Syzygium aromaticum, Cinnamomun zeylanicum, Cnidoscolus multilobus and Rhus standleyi (10.5–78.0 μg/mL) showed the highest inhibitory effect against Streptococcus mutans and Porphyromonas gingivalis.

Conclusions

Many plants are used in the Mexican traditional medicine to treat oral bacterial diseases by the healers or patients. Our study demonstrated that most of the medicinal plants showed an antibacterial effect in vitro, and justified at least in part their use in traditional medicine. These results encourage further investigations to extract and identify the active chemical compounds responsible for the antibacterial effect observed.     

Antibacterial, antisecretory and antihemorrhagic activity of Azadirachta indica used to treat cholera and diarrhea in India

Indigenous uses of Azadirachta indica A. juss (Maliaceae) (locally known as neem) leaves in different parts of India for curing gastrointestinal disorder such as diarrhea and cholera is wide spread. The objective of the present study was to evaluate the antibacterial and antisecretory activity of neem extract against Vibrio cholerae, a causative agent of watery diarrhea such as cholera. The methanol extract of neem leaf was tested for its antibacterial, antisecretory and antihemorrhagic activity against Vibrio cholerae. Azadirachta indica extract had significant antibacterial activity against the multi-drug-resistant Vibrio cholerae of serotypes O1, O139 and non-O1, non-O139. The minimum inhibitory concentration reached by 50% (MIC50) and 90% (MIC90), and minimum bactericidal concentration for the extract were 2.5, > 5, and 10 mg/ml, respectively. Neem extract showed antisecretory activity on Vibrio cholerae induced fluid secretion in mouse intestine with inhibition values of 27.7%, 41.1%, 43.3%, 57.0%, and 77.9% at doses of 100, 200, 300, 450 and 1800 mg/kg, respectively. Oral administration of the extract inhibited hemorrhage induced by Vibrio cholerae in mouse intestine at a dose > or = 300 mg/kg. The results obtained in this study give some scientific support to the uses of neem employed by the indigenous people in India employed for the treatment of diarrhea and dreadful disease cholera.     

Evaluation of mechanism for antihypertensive action of Clerodendrum colebrookianum Walp., used by folklore healers in north-east India

Ethnopharmacological relevance

The present investigation was aimed to justify the pharmacological basis in traditional use of Clerodendrum colebrookianum as antihypertensive agent in north-east India.

Materials and Methods

The aqueous extract (AECc), its aqueous, n-butanol (nBFCc), Ethyl-acetate (EtFCc) and Chloroform fractions of C. colebrookianum leaves were evaluated for antihypertensive potential by using fructose-induced hypertension model in rats and in isolated frog heart. The ex-vivo muscarinic action in isolated rat ileum, in-vitro assay for Rho-kinase (ROCK –II), phosphodiesterase-5 (PDE-5) and angiotension converting enzyme (ACE) were also carried out to establish the mechanism of action of samples. The total phenolic and flavonoied contents in test samples were estimated to establish phyto–pharmacological relationship.

Results

The 100 μg/mL test samples were showed calcium antagonism in rat ileum and at 50 μg/mL and 75 μg/mL doses exhibited ROCK-II and PDE-5 inhibition respectively where, EtFCc was caused maximum 68.62% (ROCK-II) and 52.28% (PDE-5) inhibition, but none of the sample was exhibit effect in ACE at 100 μg/mL. The test samples also showed negative inotropic and chronotropic effect on isolated frog heart and significant (P<0.001) reduction in systolic blood pressure and heart rate in hypertensive rats compared to control. The total phenolic content maximum 80 μg gallic acid equivalents in nBFCc and flavonoids content maximum 69.57 μg Quercetin equivalent in AECc were estimated.

Conclusions

These observations established the traditional claim and thus C. colebrookianum could be a potent antihypertensive agent for use in future. The antihypertensive effect mediated by cholinergic action and following ROCK – II, PDE-5 inhibition of C. colebrookianum.     

Lysosomal membrane stabilization and anti-inflammatory activity of Clerodendrum phlomidis L.f., a traditional medicinal plant

Ethnopharmacological relevance Clerodendrum phlomidis L.f., is used to treat several inflammatory diseases and arthritis in Indian traditional system and folk medicine.Aim of the study The aim of the present study was to evaluate the scientific basis of antiinflammatory activity of different organic solvent extracts of Clerodendrum phlomidis and to evaluate the active crude extract for its antiarthritic activity in FCA induced animal model.Materials and methods The antiinflammatory activity of Clerodendrum phlomidis was studied using the carrageenan and cotton pellet induced inflammatory models. The crude ethanol extract was standardized with the known standard using HPLC. The antiarthritic activity was studied using Freund's complete adjuvant induced rat model. For antiarthritic activity, the active crude extract was administered at the concentrations of 100, 200 and 400 mg/kg body weight. The effect of the ethanol extract on serum SGOT, SGPT, ALP, levels of pro-inflammatory cytokines, plasma lysosomal enzymes and protein bound carbohydrates of FCA arthritic animals were studied.Results The ethanol extract at 100, 200, and 400 mg/kg, showed maximum inhibition of inflammation induced by carrageenan (100 mg/kg - 47.73%; 200 mg/kg - 54.00% and 400 mg/kg - 65.15%). In cotton pellet induced granuloma, the ethanol extract at different concentrations showed significant reduction in granuloma weight. In FCA induced arthritis, the ethanol extract showed a significant reduction in paw thickness (100 mg/kg - 51.71%; 200 mg/kg - 57.58% and 400 mg/kg - 62.48%). The levels of lysosomal enzymes and protein bound carbohydrates were significantly decreased in the ethanol extract treated groups compared with the arthritic control. The pro-inflammatory cytokine levels were significantly decreased in a dose dependent manner in all the Clerodendrum phlomidis treated groups.Conclusion Clerodendrum phlomidis displays considerable potency in antiinflammatory action and has prominent antiarthritic effect on adjuvant induced arthritis. Future studies will provide new insights into the antiinflammatory activity of Clerodendrum phlomidis and isolation of compound from it may eventually lead to development of a new class of antiinflammatory agent.     

Kaempferia parviflora, a plant used in traditional medicine to enhance sexual performance contains large amounts of low affinity PDE5 inhibitors

Aim of the study

A number of medicinal plants are used in traditional medicine to treat erectile dysfunction. Since cyclic nucleotide PDEs inhibitors underlie several current treatments for this condition, we sought to show whether these plants might contain substantial amounts of PDE5 inhibitors.

Materials and methods

Forty one plant extracts and eight 7-methoxyflavones from Kaempferia parviflora Wall. ex Baker were screened for PDE5 and PDE6 inhibitory activities using the two-step radioactive assay. The PDE5 and PDE6 were prepared from mice lung and chicken retinas, respectively. All plant extracts were tested at 50 μg/ml whereas the pure compounds were tested at 10 μM.

Results

From forty one plant extracts tested, four showed the PDE5 inhibitory effect. The chemical constituents isolated from rhizomes of Kaempferia parviflora were further investigated on inhibitory activity against PDE5 and PDE6. The results showed that 7-methoxyflavones from this plant showed inhibition toward both enzymes. The most potent PDE5 inhibitor was 5,7-dimethoxyflavone (IC₅₀ = 10.64 ± 2.09 μM, selectivity on PDE5 over PDE6 = 3.71). Structure activity relationship showed that the methoxyl group at C-5 position of 7-methoxyflavones was necessary for PDE5 inhibition.

Conclusions

Kaempferia parviflora rhizome extract and its 7-methoxyflavone constituents had moderate inhibitory activity against PDE5. This finding provides an explanation for enhancing sexual performance in the traditional use of Kaempferia parviflora. Moreover, 5,7-dimethoxyflavones should make a useful lead compound to further develop clinically efficacious PDE5 inhibitors.     

In vivo and in vitro anti-hepatitis B virus activity of total phenolics from Oenanthe javanica

The traditional Chinese medicine Oenanthe javanica (OJ) has been used for many years, mainly for the treatment of inflammatory conditions including hepatitis. In this study, human hepatoma Hep G2.2.15 cells culture system and duck hepatitis B virus (DHBV) infection model were used as in vivo and in vitro models to evaluate the anti-HBV effects of total phenolics from Oenanthe javanica (OJTP). The HBeAg and HBsAg concentrations in cell culture medium were determined by using the enzyme immunoassay kit after Hep G2.2.15 cells were treated with OJTP for 9 d. DHBV-DNA in duck serum was analyzed by dot blot hybridization assay. In the cell model, OJTP could dose-dependently inhibit the production of the HBeAg and HBsAg, and the inhibition rates of OJTP on HBeAg and HBsAg in the Hep G2.2.15 cells were 70.12% and 72.61% on day 9, respectively. In the DHBV infection model, OJTP also reduced HBV DNA level in a dose-dependent manner. The DHBV-DNA levels decreased significantly after the treatment with 0.10 g kg(-1)d(-1) and 0.20 g kg(-1)d(-1) OJTP. The inhibition of the peak of viremia was at the maximum at the dose of 0.20 g kg(-1)d(-1) and reached 64.10% on day 5 and 66.48% on day 10, respectively. Histopathological evaluation of the liver revealed significant improvement by OJTP. In conclusion, our results demonstrate that OJTP can efficiently inhibit HBV replication in Hep G2.2.15 cells line in vitro and inhibit DHBV replication in ducks in vivo. OJTP therefore warrants further investigation as a potential therapeutic agent for HBV infections.     

Ability of certain plant extracts traditionally used to treat ciguatera fish poisoning to inhibit nitric oxide production in RAW 264.7 macrophages

Aim of the study

Ciguatera fish poisoning (CFP) is an intertropical ichthyosarcotoxism that manifests in complex assortment of symptoms in humans. Ciguatoxins (CTXs), issued from Gambierdicus spp., are causative agents of this intoxication. We have recently demonstrated that a Pacific CTX (P-CTX-1B) strongly modulated iNOS expression, leading to overproduction of nitric oxide (NO) in RAW 264.7 murine macrophage cells. NO produced in large amounts is involved in a wide range of pathophysiological processes. Many traditional remedies are commonly used in the Pacific against CFP. In this context, bioassay-guided screening was carried out to study NO inhibiting capacity of 28 selected plant extracts.

Materials and methods

We prepared aqueous extracts of plants used in New Caledonia in the treatment of CFP and screened their NO inhibitory activity in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages.

Results

Among 28 plants tested, Euphorbia hirta (Euphorbiaceae), Syzygium malaccense (Myrtaceae), Schinus terebenthifolius (Anacardiaceae), Punica granatum (Punicaceae), Cerbera manghas (Apocynaceae), Vitex trifolia (Labiateae) and Ximenia americana (Olacaceae) showed inhibitory activity, validating their use as traditional remedies in CFP, and the potential for use in the treatment of conditions accompanied by NO overproduction.

Conclusion

These plants are promising candidates for further screening of their active compounds through activity-guided fractionation.     

Consequences of subchronic exposure to ethanolic extract from fruits and leaves of Schinus molle var. areira L. in mice

Aim of the study

Several extracts of Schinus molle var. areira L. plant proved to be useful for the treatment of different pathologies and for the control of insect pest. Due to these potential uses, it is necessary to study their safety. In this work, we evaluated the effects of subchronic exposure to ethanolic extracts from leaves and fruits of Schinus molle var. areira in mice.

Materials and methods

The plant extract was added to the diet at 1 g/kg body weight/day for 90 days. At the end of the exposure, behavioral and functional parameters in a functional observational battery and motor activity in an open field were assessed. Finally, several biochemical and histopathological studies were realized.

Results

The exposure to extract from leaves produced an increase in the number of rearings in the open field and of urine pools in the functional observational battery. On the other hand, the exposure to extract from fruits produced an increase in the neutrophil count and a decrease in the lymphocyte count and in the total cholesterol levels. None of the exposures affected the different organs evaluated.

Conclusions

Our results suggest that subchronic exposure to ethanolic extracts from leaves and fruits of Schinus molle var. areira should be potentially useful in the treatment of lipid pathologies and safe to use.     

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Ethnopharmacological importance

Gastrointestinal disorders and infections are the major pathoaetiologies of diarrhoea causing many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat infectious diseases including diarrhoea and many other ailments by rural people in Africa and Asia. Much of the work done to date on this genus was on the non-polar or intermediate polarity components. Some parameters that may cause diarrhoea and the evaluation of more polar extracts have apparently not been investigated.

Aims

The polar components were extracted and fractionated by solvent–solvent fractionation to yield fractions with different polarities. The activity of these fractions on different parameters that could be involved in factors associated with diarrhoea was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals.

Materials and methods

Phenolic-enriched leaf extracts of Combretum bracteosum (COB), Combretum padoides (COP), Combretum vendae (COV) and Combretum woodii (COW) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. Acetone was removed from a portion of the 70% acetone extract and it was sequentially treated by solvent–solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures The antioxidant activities were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH); 2,2′-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid (ABTS⁺) radical scavenging, ferric reducing antioxidant power (FRAP) methods and lipid peroxidation inhibitory capacity standard methods. The ferric reducing antioxidant activities of the fractions were also determined. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method. Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.

Result

Some of the fractions had much higher antioxidant activity than the positive controls. The average EC₅₀ values of the extracts for the DPPH and ABTS antioxidant assays were 0.21–12 µg/ml (COP), 0.25–16 µg/ml (COV), 0.33–9.41 µg/ml (COW) and 4.97–85 µg/ml (COB) respectively while the mean EC₅₀ values for the positive controls ascorbic acid and trolox were 1.28–1.51 and 1.02–1.19 µg/ml respectively. All the crude extracts inhibited lipid peroxidation of linoleic acid by more than 80% at a concentration of 64 µg/ml. COP had the highest antibacterial activity with MICs ranging between 19–2500 µg/ml, followed by COV with MICs ranging between 39–625 µg/ml; COW and COB had similar MICs ranging between 39–2500 µg/ml. COP also had the highest antifungal activity with MICs between 19–625 µg/ml. The MIC for COW and COV ranged from 19 to 1250 µg/ml. COB had the lowest antifungal activity (MIC values were between 39 and 625 µg/ml). In general non-polar fractions had a high antimicrobial activity and polar fractions had a high antioxidant activity. The extracts had no activity against COX 1 and 2 enzymes in the anti-inflammatory assay but had good lipoxygenase inhibition. The crude extracts had high concentration of hydrolysable tannin (gallotannin). A good correlation (R²= 0.99) was found between the antioxidant activity and total tannin content indicating that, gallotannins may be responsible for the antioxidant activity.

Conclusion

The results obtained in this study with more polar extracts indicate that the use of extracts of these plant species as antidiarrhoeal agents may have a scientific basis. The extractant used here extracted a much higher percentage of the phytochemicals than acetone. It was better for isolating antioxidant compounds (polar) but not good for isolating antimicrobial compounds (non-polar) from the same species compared to acetone, ethyl acetate, dichloromethane, and hexane.