In vitro antibacterial activities of methanol and aqueous leave extracts of selected medicinal plants against human pathogenic bacteria

People use medicinal plants as diet, and for treatment of infectious and noninfectious diseases and they use brief procedures like frying and cooking to do so. Medicinal plants; Moringa oleifera, Azadirachta indica, and Lepidium sativum which is believed to have active components that help to treat and manage various diseases were investigated for their antibacterial activities against Staphylococcus aureus, Salmonella Typhi, Streptococcus agalactiae and Shigella boydii. Solvent methanol and aqueous were used for extraction of crudes by means of maceration. Susceptibility testing was determined by using disc diffusion method and Minimum inhibitory concentration was determined by broth dilution method. Heat treated plant material activity against test pathogen was aimed to identify resistance capacity of plant material at different interval of time and temperature. All plant extracts under study was active against all tested pathogen after exposure to 45 °C for 30 min. The antibacterial activities of the non-heat-treated extracts of Azadirachta indica were relatively low; the results of this study show that extracts of Azadirachta indica have better residual antibacterial activities. Methanol extracts of all plant leaves showed highest activity as compared to the aqueous extracts. This is probably assigning the choice of extraction solvent for extracting desired active phytochemical from plants. Many of the people in the study area were illiterate and they did not have awareness about the ways use of medicinal plants. They use the medicinal plants by cooking and frying for different purposes. In the main, plant material can be affected as the temperature of treatment is increases with respect to various times of exposures.     

Bioactive potential of Streptomyces associated with marine sponges

The present work deals with isolation of Streptomyces associated with marine sponges and its bioactive potential. Streptomyces sp. were isolated from the marine sponges Callyspongia diffusa, Mycale mytilorum, Tedania anhelans and Dysidea fragilis. From the initial screening, 94 cultures of Streptomyces were obtained and from these 58 cultures exhibited antagonism against bacteria, 36 strains against fungi and 27 strains exhibited broad spectrum activity against both. The submerged culture extracts of the 58 anti-bacterial isolates were analysed and of these 58 strains, 37 strains showed positive inhibition against Bacillus subtilis, 43 against Staphylococcus aureus, 10 against Vibrio cholerae and 10 against Escherichia coli. The antifungal activities of the 36 strains were also evaluated and 27 strains showed positive inhibition against Aspergillus niger, 23 against Saccharomyces cerevisiae and 16 against Candida albicans. The production of polyene substances from the active extracts was confirmed by UV spectral analysis by the absorbance peaks that ranged from 225 to 262 nm and the TLC (R _f values) ranging from 0.40 to 0.78. The results indicate that Streptomyces strains isolated from marine sponges produce potential antibacterial, antifungal and broad spectrum antibiotic compounds.     

Inhibitory Effects of Some Spice and Herb Extracts Against Arcobacter butzleri, A. cryaerophilus, and A. skirrowii

Seventeen spice and medicinal plant extracts (methanol and chloroform) were assayed for their antimicrobial activity against Arcobacter butzleri, A. cryaerophilus, and A. skirrowii. In general, all of the tested extracts were able, to a different extent, to inhibit the growth of the selected Arcobacter species. Cinnamon, bearberry, chamomile, sage and rosemary extracts showed strong antimicrobial activity toward arcobacter strains tested. Overall, the methanol extracts showed better activity than the chloroform extracts (P < 0.05); however, enhanced antibacterial activity of chloroform extracts of cinnamon and rosemary has been observed in comparison with their methanol counterparts. The inhibitory dose of the most active extracts (the diameter of zone of inhibition ≥ 20 mm) was determined using the disc-diffusion method as well.     

Evaluation of Estrogenic Activity of Licorice Species in Comparison with Hops Used in Botanicals for Menopausal Symptoms

The increased cancer risk associated with hormone therapies has encouraged many women to seek non-hormonal alternatives including botanical supplements such as hops (Humulus lupulus) and licorice (Glycyrrhiza spec.) to manage menopausal symptoms. Previous studies have shown estrogenic properties for hops, likely due to the presence of 8-prenylnarigenin, and chemopreventive effects mainly attributed to xanthohumol. Similarly, a combination of estrogenic and chemopreventive properties has been reported for various Glycyrrhiza species. The major goal of the current study was to evaluate the potential estrogenic effects of three licorice species (Glycyrrhiza glabra, G. uralensis, and G. inflata) in comparison with hops. Extracts of Glycyrrhiza species and spent hops induced estrogen responsive alkaline phosphatase activity in endometrial cancer cells, estrogen responsive element (ERE)-luciferase in MCF-7 cells, and Tff1 mRNA in T47D cells. The estrogenic activity decreased in the order H. lupulus > G. uralensis > G. inflata > G. glabra. Liquiritigenin was found to be the principle phytoestrogen of the licorice extracts; however, it exhibited lower estrogenic effects compared to 8-prenylnaringenin in functional assays. Isoliquiritigenin, the precursor chalcone of liquiritigenin, demonstrated significant estrogenic activities while xanthohumol, a metabolic precursor of 8-prenylnaringenin, was not estrogenic. Liquiritigenin showed ERβ selectivity in competitive binding assay and isoliquiritigenin was equipotent for ER subtypes. The estrogenic activity of isoliquiritigenin could be the result of its cyclization to liquiritigenin under physiological conditions. 8-Prenylnaringenin had nanomolar estrogenic potency without ER selectivity while xanthohumol did not bind ERs. These data demonstrated that Glycyrrhiza species with different contents of liquiritigenin have various levels of estrogenic activities, suggesting the importance of precise labeling of botanical supplements. Although hops shows strong estrogenic properties via ERα, licorice might have different estrogenic activities due to its ERβ selectivity, partial estrogen agonist activity, and non-enzymatic conversion of isoliquiritigenin to liquiritigenin.     

GC/MS and LC/MS analysis,and antioxidant and antimicrobial activities of various solvent extracts from Mirabilis jalapa tubers

The antioxidant and antimicrobial activities of various solvent extracts from Mirabilis jalapa tubers (MJT) were investigated using various in vitro assays. The total phenolic and flavonoid contents varied from 21.45 to 364.6 mg gallic acid equivalent (GAE)/g dried extract and 5.2 to 71.6 mg quercetin/g dried extract, respectively. Water extract of MJT was the most potent antioxidant in all assays used, followed by methanol extract. The five solvent extracts were screened for antibacterial and antifungal activities. Water extract was the most effective with minimum inhibitory concentration <200 μg/ml against Staphylococcus aureus, Micrococcus luteus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus cereus and Enterococcus faecalis. Only water extract showed antifungal activity against Aspergillus niger, Fusarium solani, Fusarium oxysporium and Fusarium granularium. GC/MS analysis of MJT dichloromethane and methanol extracts showed that oleic acid and β-sitosterol were, respectively, the major compounds. LC/MS analysis of the aqueous extract showed a high content of flavanol and flavonol compounds. Phenolic acids such as ferulic and caffeic acid were also detected.To our knowledge, this is the first report on the chemical composition, and antioxidant and antimicrobial activities of phenolic extracts from M. jalapa tubers (MJT). The results of the present work indicate that MJT extracts could be used as natural antioxidant and antimicrobial agents in the food preservation and human health.     

Antimicrobial activity of selected extracts from Hakea salicifolia and H. sericeae (Proteaceae) against Staphylococcus aureus multiresistant strains

The antimicrobial activity of several plant extracts obtained from aerial parts of two invasive plants, Hakea sericeae and Hakea salicifolia, was evaluated against both Gram-positive and Gram-negative bacteria, including resistant strains of Staphylococcus aureus and assayed at different minimum inhibitory concentrations (MIC), ranging between 3.5 and 500 μg/mL. The twigs' aqueous extract showed the strongest antimicrobial activity (MIC 7.5–62 μg/mL) against the tested methicilin and vancomycin resistant strains of S. aureus.     

Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I

Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol.     

In vitro enzyme inhibitory properties,antioxidant activities,and phytochemical profile of Potentilla thuringiaca

The genus Potentilla is interesting for the pharmaceutical field due to its valuable medicinal properties, which have been observed in complementary and alternative medicine. In recent years, studies conducted to estimate the biological activity of several of the Potentilla species have shown a wide spectrum of therapeutic properties. In particular, in the present paper, different extracts obtained from the herb P. thuringiaca were analysed for antioxidant and enzyme inhibitory activities. The UHPLC-DAD-MS³ hyphenated techniques reported herein allow for the identification of phytoconstituents. The analyses showed the presence of flavonoids and ellagitannins as major components. Furthermore, the data demonstrated that the analysed extracts revealed a high total antioxidant capacity in the phosphomolybdenum assay. The free radical scavenging activity of the extracts was evaluated using DPPH and ABTS assays. The reducing power activity of P. thuringiaca was also determined by FRAP and CUPRAC assays, as well as metal chelating activity. In addition, the total extracts and the different fractions of P. thuringiaca revealed potent inhibitory activities against α-amylase and α-glucosidase, AChE, tyrosinase and lipase. Surprisingly, no activity against BChE was shown. P. thuringiaca could be a valuable natural source of antioxidants with interesting inhibitory actions against the key enzymes involved in several human diseases, and could represent a valid starting point for the development of new treatment and management strategies, including its use as a food supplement.     

Evaluation of antibacterial activity of crude protein extracts from seeds of six different medical plants against standard bacterial strains

A huge group of natural antimicrobial compounds are active against a large spectrum of bacterial strains causing infectious threat. The present study was conducted to investigate the crude extracts of antimicrobial protein and peptide efficacy from six medicinal plant seeds. Extraction was carried out in Sodium phosphate citrate buffer, and Sodium acetate buffer using different pH. Antimicrobial activities of these plants were determined by the microbiological technique using Agar well diffusion Assay. Extremely strong activity was observed in the seed extracts of Allium ascolinicum extracted in sodium phosphate citrate buffer at pH (5.8) against Proteus vulgaris, Escherichia coli and Staphylococcus aureus with zone of inhibition 17 mm, 17 mm and 15 mm and Rumex vesicarius at pH (7.6), Ammi majus at pH (6.8), Cichorium intybus at pH (7.4) and Cucumis sativus at pH (7.8) also showed better sensitivity against the bacterial strains with zone of inhibition ranges 16–10 mm and some of the strains were found to be resistant. Antibacterial activity pattern of different plant extracts prepared in sodium acetate buffer pH (6.5), among all the plant seed extracts used Foeniculum vulgare had shown good inhibition in all the bacterial strains used, with zone of inhibition ranges 11–12.5 mm, The extracts of C. intybus and C. sativus were found to be effective with zone of inhibition 11–6 mm and some of the strains were found to be resistant. Most of the strains found to have shown better sensitivity compared with the standard antibiotic Chloramphenicol (25 mcg). Our results showed that the plants used for our study are the richest source for antimicrobial proteins and peptides and they may be used for industrial extraction and isolation of antimicrobial compounds which may find a place in medicine industry as constituents of antibiotics.     

Functional constituents of wild and cultivated Goji (L. barbarum L.) leaves: phytochemical characterization,biological profile,and computational studies

Goji (Lycium barbarum L.) leaves are emphasized as a functional tea or as dietary supplements. The phenolic compound profile, antioxidant, enzyme inhibitory, antimicrobial, and antimutagenic activities of leaf extracts from two selected cultivars in comparison with wild-growing plants have been evaluated. HPLC-DAD/ESI-ToF-MS analysis revealed the presence of phenolic acids and flavonoids with chlorogenic acid and rutin being the dominant compounds in the cultivated plants, whereas rutin and kaempeferol-3-O-rutinoside for wild growing ones. In particular, cv. Erma contained the highest amount of chlorogenic acid and showed a strong tyrosinase-inhibitory effect. Staphylococcus aureus, Listeria monocytogenes, and Penicillium funiculosum were the most sensitive strains when exposed to extracts from cultivated plants. Antimutagenic activity was evaluated by Ames' test. The tested extracts provided high protection against mutagenicity induced by 2-anthramine (2-AA) to Salmonella typhimurium strains TA 98 and TA 100 (max. inhibition (%) 88% and 74.2%, respectively). Overall, Goji leaves are a rich source of bioactive compounds with functional properties that need further risk/benefit evaluation when used in foods or health-promoting formulations.     

Aqueous Extracts of the Marine Brown Alga Lobophora variegata Inhibit HIV-1 Infection at the Level of Virus Entry into Cells

In recent years, marine algae have emerged as a rich and promising source of molecules with potent activities against various human pathogens. The widely distributed brown alga Lobophora variegata that is often associated with tropical coral reefs exerts strong antibacterial and antiprotozoal effects, but so far has not been associated with specific anti-viral activities. This study investigated potential HIV-1 inhibitory activity of L. variegata collected from different geographical regions, using a cell-based full replication HIV-1 reporter assay. Aqueous L. variegata extracts showed strong inhibitory effects on several HIV-1 strains, including drug-resistant and primary HIV-1 isolates, and protected even primary cells (PBMC) from HIV-1-infection. Anti-viral potency was related to ecological factors and showed clear differences depending on light exposition or epiphyte growth. Assays addressing early events of the HIV-1 replication cycle indicated that L. variegata extracts inhibited entry of HIV-1 into cells at a pre-fusion step possibly by impeding mobility of virus particles. Further characterization of the aqueous extract demonstrated that even high doses had only moderate effects on viability of cultured and primary cells (PBMCs). Imaging-based techniques revealed extract effects on the plasma membrane and actin filaments as well as induction of apoptosis at concentrations exceeding EC₅₀ of anti-HIV-1 activity by more than 400 fold. In summary, we show for the first time that L. variegata extracts inhibit HIV-1 entry, thereby suggesting this alga as promising source for the development of novel HIV-1 inhibitors.     

Design,synthesis, antibacterial activity and physicochemical parameters of novel N-4-piperazinyl derivatives of norfloxacin

We report herein the synthesis of some N-Mannich bases in addition to different N-4 substituents of norfloxacin. The antibacterial activities of the newly synthesized compounds were evaluated and correlated with their physicochemical properties. Results revealed that some of the tested compounds exhibited better inhibitory activities than the reference antibiotic norfloxacin against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus strains. Correlation results showed that there is no single physicochemical parameter that can determine the effect of N-4 piperazinyl group on the activity of these fluoroquinolones, where lipophilicity, molecular mass and electronic factors may influence the activity.     

Antibacterial activities of the methanol extracts of Albizia adianthifolia,Alchornea laxiflora,Laportea ovalifolia and three other Cameroonian plants against multi-drug resistant Gram-negative bacteria

In the last 10 years, resistance in Gram-negative bacteria has been increasing. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of six Cameroonian medicinal plants Albizia adianthifolia, Alchornea laxiflora, Boerhavia diffusa, Combretum hispidum, Laportea ovalifolia and Scoparia dulcis against a panel of 15 multidrug resistant Gram-negative bacterial strains. The broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the reference qualitative phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols and triterpenes, other classes of chemicals being selectively distributed. The best antibacterial activities were recorded with bark and root extracts of A. adianthifolia as well as with L. ovalifolia extract, with MIC values ranging from 64 to 1024 μg/mL on 93.3% of the fifteen tested bacteria. The lowest MIC value of 64 μg/mL was recorded with A. laxiflora bark extract against Enterobacter aerogenes EA289.Finally, the results of this study provide evidence of the antibacterial activity of the tested plants and suggest their possible use in the control of multidrug resistant phenotypes.     

Antioxidant and antifungal potential of methanol extracts of Phellinus spp. from Sonora, Mexico

BackgroundAmong the potential natural sources of bioactive compounds, those of the macroscopic fungi Phellinus spp. have been identified by previous researches. Phenolic compounds are among the major antioxidant and antimicrobial contributors due to their bioactive properties.AimsThe goal of this study was to determine the total phenolic and flavonoid contents, and its relation with the antioxidant and antifungal activity of methanolic extracts of Phellinus gilvus, Phellinus rimosus and Phellinus badius, respectively.MethodsThe collected and identified organisms of Phellinus spp. were treated with methanol and the generated aqueous extract was analyzed to quantified total phenolic compounds, total flavonoids, radical scavenging activity against DPPH, trolox equivalent antioxidant capacity, and oxygen absorbance capacity. The antifungal property of the extracts was evaluated against Alternaria alternata.ResultsThe content of phenolic compounds was of 49.31, 46.51 and 44.7 mg of gallic acid equivalents/g, for P. gilvus, P. rimosus and P. badius, respectively. The total flavonoid content followed the same pattern with values of 30.58, 28, and 26.48 mg of quercetin equivalents/g for P. gilvus, P. rimosus and P. badius, respectively. The variation on the content of phenolic components was reflected on the antioxidant activity of every organism. The antioxidant activity ranked as follows: P. gilvus > P. rimosus > P. badius. The antifungal effect of the different extracts against A. alternata showed a significant effect, all of them, inhibiting the growth of this pathogen.ConclusionsP. gilvus showed the best potential to inactivate free radicals, being all the tested fungi effective to inhibit A. alternata growth.     

Phytochemical, antimicrobial, antioxidant and antigenotoxic potentials of Cyperus rotundus extracts

The aqueous, ethyl acetate, methanolic and Total Oligomer Flavonoids (TOF) enriched extracts, obtained from the aerial parts of Cyperus rotundus, were investigated for their contents in phenolic compounds. Antioxidative activity using the NBT/riboflavin assay system, antimicrobial activity against Gram positive and Gram negative bacterial reference strains as well as antigenotoxic activity tested with the SOS chromotest assay were also studied. Significant antibacterial activity against reference strains; Staphylococcus aureus, Enterococcus faecalis, Salmonella enteritidis and Salmonella typhimurium, was detected in the presence of ethyl acetate and TOF enriched extracts. In addition to their antimicrobial activity, the same extracts showed a significant ability to inhibit nitroblue tetrazolium reduction by the superoxide radical in a non enzymatic O₂^.− generating system, and were also able to reduce significantly the genotoxicity induced by nifuroxazide and Aflatoxin B1. The antioxidant, antimicrobial and antigenotoxic activities exhibited by C. rotundus depend on the chemical composition of the tested extracts.     

Laurus nobilis L. Extracts against Paenibacillus larvae: Antimicrobial activity,antioxidant capacity,hygienic behavior and colony strength

The aim of this work was to compare the antimicrobial activity against Paenibacillus larvae and the antioxidant capacity of two Laurus nobilis L. extracts obtained by different extraction methods. The hydroalcoholic extract was moreover added as supplementary diet to bees in field conditions to test behavioural effects and colony strength. Both laurel extracts were subjected to different phytochemical analysis to identify their bioactive compounds. Antimicrobial activity was analyzed by the minimal inhibitory concentration (MIC) determination by means the agar dilution method. The hydroalcoholic extract (HE) was able to inhibit the bacterial growth of all P. larvae strains, with 580 µg/mL mean value. This better antibacterial activity in relation to the essential oil (EO) could be explained by the presence of some phenolic compounds, such as flavonoids, evidenced by characteristic bands resulting from the Fourier Transform Infrared Spectroscopy (FTIR) analysis. Antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging ability and ferric reducing antioxidant power (FRAP) assays. The HE showed the highest antioxidant activity as measured by DPPH, with IC50 values of 257 ± 12 μg/mL. The FRAP assay method showed that the HE was 3-fold more effective reducing agent than the EO. When the bee colonies were supplied with laurel HE in sugar paste an improvement in their general condition was noticed, although neither the hygienic behavior nor the proportions of the breeding cells varied statistically due to the treatment. In conclusion, the inhibition power against P. larvae attributable to the phenolic compounds, the antioxidant capacity of the HE, and the non-lethal effects on adult honey bees on field trials suggest the HE of laurel as a promising substance for control American foulbrood disease.     

Phytochemicals,mineral contents,antioxidants, and antimicrobial activities of propolis produced by Brunei stingless bees Geniotrigona thoracica,Heterotrigona itama,and Tetrigona binghami

The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.     

Design,synthesis and molecular modeling studies of new series of s-triazine derivatives as antimicrobial agents against multi-drug resistant clinical isolates

Three novel series of s-triazine derivatives, including thirty-five new compounds 2a-d, 3a-3p, 4b-d, 5b-d, 6d-6d, and 7a-7f were synthesized comprising a diversity of substituents based on the structure of Astrazeneca arylaminotriazine DNA gyrase B inhibitor. The antimicrobial activity was determined for all compounds against Staphylococcus aureus, Escherichia coli and Candida albicans using the two-fold serial dilution technique and against reference standards Ampicillin for the antibacterial screening and Clotrimazole regarding the antifungal evaluation. The tested compounds showed strong to moderate antibacterial inhibitory action and weak antifungal activity. Compounds 3j and 6b were the most potent antibacterial agents against the tested strains and multi-drug resistant (MDR) clinical isolates of Klebsiella pneumoniae and methicillin resistant Staphylococcus aureus (MRSA1) with minimal toxicity in comparison to the reference drugs. In silico molecular properties calculations and molecular docking study for 3j and 6b revealed that both compounds could be considered as promising antibacterial DNA gyrase B inhibitors.     

Antibacterial activity of water extracts and essential oils of various aromatic plants against Paenibacillus larvae, the causative agent of American Foulbrood

Vegetal water extracts, namely the water remaining after hydro-distillation and decoctions, and essential oils of 10 plant species were tested as inhibitors for the growth of Paenibacillus larvae, the causative agent of American Foulbrood. Achyrocline satureioides, Chenopodium ambrosioide, Eucalyptus cinerea, Gnaphalium gaudichaudianum, Lippia turbinata, Marrubium vulgare,Minthostachys verticillata, Origanum vulgare, Tagetes minuta and Thymus vulgaris were included in the study. The water remaining after hydro-distillation showed the highest antibacterial activities, the growth of almost all the P. larvae strains tested was inhibited by these extracts. Regarding the plants tested, E. cinerea and M. verticillata were the plant species with the highest biological activity with 100% efficacy (all its extracts inhibited the growth of all P. larvae strains). Essential oils were less active for the inhibition of P. larvae growth.     

Antifungal, acetylcholinesterase inhibition, antioxidant and phytochemical properties of three Barleria species

This study was aimed at evaluating the antifungal, acetylcholinesterase inhibition and antioxidant activities of petroleum ether, dichloromethane, ethanol and methanol extracts from different parts of Barleria prionitis, Barleria greenii and Barleria albostellata. Their phytochemical properties and the possibility of plant-part substitution as a conservation strategy against destructive harvesting (use of aerial parts and roots) of these species for medicinal purposes were also investigated. Microtitre plate assays were used in determining their antifungal (against Candida albicans) and acetylcholinesterase inhibition activities. All the extracts demonstrated both fungistatic and fungicidal activities with the minimum inhibitory concentration ranging from 0.78 to 9.38 mg/ml and minimum fungicidal concentration ranging from 1.17 to 12.50 mg/ml. The higher inhibitory activity of B. greenii leaf extracts in most cases compared to similar extracts of the stems and roots suggest the potential of B. greenii leaves in plant-part substitution. At the lowest extract concentration (0.156 mg/ml), the leaf extract of B. greenii demonstrated a significantly higher acetylcholinesterase (AChE) inhibition than its stem and root extracts. In B. albostellata, the AChE inhibitory activity demonstrated by the stem was significantly greater than that recorded in its leaf extract. These findings suggest that the idea of plant part substitution may be species and/or biological activity dependent. In the DPPH radical scavenging assay, different parts of Barleria species showed free radical scavenging activity with EC₅₀ values ranging from 6.65 to 12.56 μg/ml. The ability of the extracts from different plant parts to reduce ferric ion/ferricyanide complex to the ferrous form and decrease carotenoid bleaching rate suggests the presence of antioxidant compounds capable of donating electrons and hydrogen atoms in their reaction mechanisms. Flavonoids, iridoids and tannins were detected in the different parts of these Barleria species. These phytochemicals might be responsible for the observed biological activities. The isolation of specific bioactive compounds through bioassay-guided fractionation and their characterization as well as studies evaluating their safety may be necessary in the exploration of these species for potential new therapeutic drugs or drug leads.