ACACIA ATAXACANTHA (BARK): CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF THE EXTRACTS

Objective: The present work aimed to investigate the phytochemical constituents and antibacterial activity of several extracts of Acacia ataxacantha bark on pathogenic microbes. Methods: The phytochemical study was performed using tube test and Thin layer chromatography methods. The growth inhibitory effect and the Minimum Inhibitory Concentration of hexane, dichloromethane, ethyl acetate, methanol and hydroalcolic extracts were determined using the microplate dilution method. Results: Phytochemical screening revealed the presence of alkaloid, tannins, lignan, triterpenoids, anthracene derivatives, flavonoids, saponins and coumarins at different level. The extracts exhibited different effect against the tested bacteria. The minimum inhibitory concentrations of extracts ranged from 325 µg/ml to 5 mg/ml. Ethyl acetate extract was more potent than other extracts with the MIC values of 325 µg/ml against S. aureus and 625 µg/ml against all other tested bacteria. Escherichia coli was resistant to all extracts. Conlusion: These findings suggest that the rich phytochemical content of Acacia ataxacantha and its good antibacterial activity may be responsible for its popular and wide traditional use

Antimicrobial activity of Crataeva religiosa Forst against bacteria isolated from Thryonomys swinderianus Temminck

An attempt has been made to carry out a screening on the antibacterial activity of leaves of Crateva religiosa Forst used in Benin traditional veterinary medicine against bacterial infection of Thryonomys swinderianus (class of Mammalia, family of Thryonomyidae) commonly called agouti or kholan. The aim of this study was to select the most active extracts and fractions which may be useful to combat these bacterial infections. Seven extracts from C. religiosa were screened for their antibacterial. The antibacterial activity was evaluated by both microtest method using p-iodonitrotetrazolium and bioautography against five microorganisms obtained from T. swinderianus (Escherichia coli, Shigella sonei, Staphylococcus aureus, Pasteurela pestis and Yersinia enterocolitica). The minimum inhibitory concentration (MIC) and the total activity (TA) were determined. All extracts were effective against tested microorganisms at different levels (0.31 ≤ MIC ≤ 10 mg/ml). The screening experiment revealed that ethyl acetate extract was more potent than other extracts with the MIC values of 0.62 mg/ml against E. coli and 0.31 mg/ml against S. aureus, S. sonei, P. pestis and Y. enterocolitica. The results provide an evidence for the traditional use of C. religiosa for the treatment of infective diseases of T. swinderianus Temminck.Key words: Crataeva religiosa, Thryonomys swinderianus Temminck, ethnomedicine, Republic of Benin

ANTIPROTOZOAL ACTIVITIES OF COMPOUNDS ISOLATED FROM CROTON LOBATUS L

In a preliminary evaluation of ethnobotanically selected Beninese medicinal plants for their in vitro antiplasmodial activity, the methanolic extract of the aerial parts of C. lobatus was found to have significant activity against P. falciparum, antileishmainal and antiprotoazoal assays carried out on some of the isolated compounds. Phytochemical investigation of this extract resulted in the isolation of five compounds: tiliroside (kaempferol-3-O-β-D-(6-E-p-coumaroyl) glycopyranoside) (1), isovitexin (apigenin-6-C-β-D-glucopyranoside) (2), vitexin (apigenin-8-C- β-D-glucopyranoside) (3), chlorogenic acid (acid-5-O-cafféoylquinic) (4) and 4,5-O-dicaffeoylquinic acid (5). Vitexin and tiliroside showed the best in vitro antiplasmodial activity against P. falciparum, with IC50 values of 4.4 and 7.1 µM, respectively. Vitexin also exhibited strong in vitro leishmanicidal and antitrypanosomal activities against Leishmania donovani amastigotes and Trypanosoma brucei rhodensiense trypomastigotes, with IC50 values of 0.6 and 0.1 µM, respectively

Bumble bee parasite strains vary in resistance to phytochemicals

Nectar and pollen contain diverse phytochemicals that can reduce disease in pollinators. However, prior studies showed variable effects of nectar chemicals on infection, which could reflect variable phytochemical resistance among parasite strains. Inter-strain variation in resistance could influence evolutionary interactions between plants, pollinators, and pollinator disease, but testing direct effects of phytochemicals on parasites requires elimination of variation between bees. Using cell cultures of the bumble bee parasite Crithidia bombi, we determined (1) growth-inhibiting effects of nine floral phytochemicals and (2) variation in phytochemical resistance among four parasite strains. C. bombi growth was unaffected by naturally occurring concentrations of the known antitrypanosomal phenolics gallic acid, caffeic acid, and chlorogenic acid. However, C. bombi growth was inhibited by anabasine, eugenol, and thymol. Strains varied >3-fold in phytochemical resistance, suggesting that selection for phytochemical resistance could drive parasite evolution. Inhibitory concentrations of thymol (4.53-22.2 ppm) were similar to concentrations in Thymus vulgaris nectar (mean 5.2 ppm). Exposure of C. bombi to naturally occurring levels of phytochemicals—either within bees or during parasite transmission via flowers—could influence infection in nature. Flowers that produce antiparasitic phytochemical, including thymol, could potentially reduce infection in Bombus populations, thereby counteracting a possible contributor to pollinator decline

In vitro antileishmanial, antiplasmodial and cytotoxic activities of a new ventiloquinone and five known triterpenes from Parinari excelsa

Context: Parinari excelsa Sabine (Chrysobalanaceae) is an indigenous tree from West and Eastern Africa. This tree is used in Ivory Coast as an antimalaria remedy. Objective: The in vitro antiplasmodial and antileishmanial activities of the stem bark, the leaf and the major compounds from the stem bark were investigated. Materials and methods: The leaves and stem bark from P. excelsa were separately collected, air-dried and powdered. Two extracts (methylene chloride and methanol) were realized for both powders. Every extract was tested for its antiplasmodial and antileishmanial activities. Only the stem bark crude extracts were fractionated by column chromatography and their major components were analyzed by NMR, HRESIMS and IR methods. The compounds were tested for their antiplasmodial and antileishmanial activities. Results: The comparison of the IC(50) values of the crude extracts were in this ordrer: 3.41 (IC(50) of PeBMc) >4.10 (IC(50) of PeBMc) >4.42 (IC(50) of PeLMe) against P. falciparum and 5.19 (IC(50) of PeBMc) >12.32 (IC(50) of PeBMe) >19.33 (IC(50) of PeLMc) >32.37 (IC(50) of PeLMe) against L. donovani. The stem bark crude extracts were the most active against both parasites. Their fractionation leaded to a new ventiloquinone, five triterpenes and one chlorogenic acid. All these compounds were isolated for the first time from P. excelsa. High activities were observed with (3beta)-3-hydroxyolean-12-en-28-oic acid (IC(50) = 8.2 microM) and 3beta-hydroxyolean-5,12-dien-28-oic acid (IC(50) = 7.7 microM) against L. donovani. With the antiplasmodial activity, the best activity was observed with 16beta-hydroxylupane-1,20(29)-dien-3-one (IC(50) = 28.3 microM). Discussion and conclusion: These findings demonstrated that the constituents of P. excelsa stem bark have in vitro antiplasmodial and antileishmanial activitie