Bacillus velezensis: A Valuable Member of Bioactive Molecules within Plant Microbiomes.

Bacillus velezensis is an aerobic, gram-positive, endospore-forming bacterium that promotes plant growth. Numerous strains of this species have been reported to suppress the growth of microbial pathogens, including bacteria, fungi, and nematodes. Based on recent phylogenetic analysis, several Bacillus species have been reclassified as B. velezensis. However, this information has yet to be integrated into a well-organized resource. Genomic analysis has revealed that B. velezensis possesses strain-specific clusters of genes related to the biosynthesis of secondary metabolites, which play significant roles in both pathogen suppression and plant growth promotion. More specifically, B. velezensis exhibits a high genetic capacity for synthesizing cyclic lipopeptides (i.e., surfactin, bacillomycin-D, fengycin, and bacillibactin) and polyketides (i.e., macrolactin, bacillaene, and difficidin). Secondary metabolites produced by B. velezensis can also trigger induced systemic resistance in plants, a process by which plants defend themselves against recurrent attacks by virulent microorganisms. This is the first study to integrate previously published information about the Bacillus species, newly reclassified as B. velezensis, and their beneficial metabolites (i.e., siderophore, bacteriocins, and volatile organic compounds).

Antimelanogenic Effects of Picrionoside A Isolated from the Leaves of Korean Ginseng.

This study was initiated to isolate active metabolites from the leaves of Panax ginseng. Among them, picrionoside A, a megastigmane glucoside, was isolated from the leaves of P. ginseng C. A. MAYER and its chemical structure was determined based on spectroscopic methods, including FAB-MS, one-dimensional (1D)-NMR, 2D-NMR, and IR spectroscopy. Picrionoside A from P. ginseng has not been investigated previously, and its biological or pharmaceutical activities have not been reported elsewhere. The IC50 value of mushroom tyrosinase-inhibitory activity of picrionoside A was 9.8 µM, and the rate of inhibition of synthesized melanin content in melan-a cells was 17.1% at a concentration of 80 µM without cytotoxicity. Furthermore, picrionoside A dramatically reduced body pigmentation in the zebrafish model. Taken together, the results suggest that picrionoside A isolated from the leaves of P. ginseng may be an effective skin-whitening agent that could be a potent candidate material in the cosmetic industry.

Immune-modulating activities of polysaccharides extracted from brown algae Hizikia fusiforme.

The immuno-modulating activities of seaweed (Hizikia fusiforme) extracts on murine macrophage and splenocyte were studied in vitro. Polysaccharide (HFP) exhibited the potential macrophage stimulating effects than water extract (HFW) such as NO production and enhanced pro-inflammatory cytokines on the Raw 264.7 cells and splenocytes. From the mono-sugar composition, HFP-associated fucose based on HFP of H. fusiforme acts as immune modulator.

Modulation of melanin synthesis by rengyolone isolated from the root of Eurya emarginata in melan-a cells.

In the course of screening for the melanogenesis inhibitors, rengyolone was isolated from Eurya emarginata (Thumb) Makino. Its chemical structure was determined on the basis of spectroscopic analysis including mass spectroscopy and nuclear magnetic resonance analysis. Rengyolone inhibited potent melanogenesis in melan-a cells with an IC50 value of 65 µM without cytotoxicity. Also, rengyolone showed a melanin biosynthesis inhibition zone in a culture plate of Streptomyces bikiniensis, which is commonly used as an indicator organism. Moreover, rengyolone dramatically reduced protein expression of melanogenic enzyme, tyrosinase. Furthermore, rengyolone presented inhibition on the body pigmentation in zebrafish model system and decreased melanin contents and tyrosinase activity. These results suggest that rengyolone isolated from E. emarginata may be an effective skin-whitening agent that regulates the expression of melanogenic enzymes.

Antioxidant and immunomodulating activities of exo-and endopolysaccharide fractions from submerged mycelia cultures of culinary-medicinal mushrooms.

A number of mushrooms are known to possess pharmacological activities. In this study, the phenolic and flavonoid contents of extracts of exo- and endopolysaccharide fractions obtained from submerged mycelia cultures of 7 edible or medicinal mushroom species, as well as their antioxidant and immunomodulatory properties, were evaluated. The exo- and endopolysaccharide yields were 0.576-1.950 and 0.438-0.933 g/L, respectively. The sugar and protein contents of these fractions were analyzed and contained predominantly sugars (52.3-87.6%). The exo- and endopolysaccharide fractions contained appreciable amounts of phenolics and flavonoids. The highest flavonoid contents were found in Cryptosporus volvatus (349.6 mg/g), followed by Cordyceps militaris (312.6 mg/g). The antioxidant activities were evaluated by 4 assays: biological assay using Saccharomyces cerevisiae, DPPH radical scavenging activity, chelating ability for ferrous ions and ferric reducing antioxidant power. The mycelia polysaccharide fractions had more ferric reducing antioxidant power than other antioxidant activities. Both exo- and endo polysaccharides of C. volvatus inhibited production of the T lymphocyte Th1 cytokines interferon (IFN)-γ and interleukin (IL)-2, the Th2 cytokines IL-4 and IL-5, and macrophage enzyme activity. Although those from C. militaris had similar inhibitory effects on cytokine production, the exopolysaccharides stimulated macrophage enzyme activity. The other exopolysaccharides (Pleurotus citrinopileatus, P. australis, and P. pulmonarius) inhibited IFN-γ and IL-5 production, but they had varying effects on IL-2 and IL-4 production. Only 3 exopolysaccharides (P. pulmonarius, Tremella mesenterica, and Cordyceps sinensis) also stimulated macrophage enzyme activity to the same extent as lipopolysaccharides. All of them reduced IL-5 production, but those from T. mesenterica also inhibited IFN-γ, IL-2, and IL-4 production. Thus the polysaccharide fractions from the mushrooms studied have antioxidant activities and general immunomodulating effects in vitro.

Antioxidant and anti-inflammatory activities of selected Chinese medicinal plants and their relation with antioxidant content.

BACKGROUND: The main aim of this study is to evaluate the antioxidant and anti-inflammatory properties of forty four traditional Chinese medicinal herbal extracts and to examine these activities in relation to their antioxidant content. METHODS: The antioxidant activities were investigated using DPPH radical scavenging method and yeast model. The anti-inflammatory properties of the herbal extracts were evaluated by measuring their ability to inhibit the production of nitric oxide and TNF-α in RAW 264.7 macrophages activated by LPS and IFN- γ, respectively. The cytotoxic effects of the herbal extracts were determined by Alomar Blue assay by measuring cell viability. In order to understand the variation of antioxidant activities of herbal extracts with their antioxidant contents, the total phenolics, total flavonoids and trace metal (Mg, Mn, Cu, Zn, Se and Mo) quantities were estimated and a correlation analysis was carried out. RESULTS: Results of this study show that significant levels of phenolics, flavonoids and trace metal contents were found in Ligustrum lucidum, Paeonia suffuticosa, Salvia miltiorrhiza, Sanguisorba officinalis, Spatholobus suberectus, Tussilago farfara and Uncaria rhyncophylla, which correlated well with their antioxidant and anti-inflammatory activities. Some of the plants displayed high antioxidant and anti-inflammatory activities but contained low levels of phenolics and flavonoids. Interestingly, these plants contained significant levels of trace metals (such as Zn, Mg and Se) which are likely to be responsible for their activities. CONCLUSIONS: The results indicate that the phenolics, flavonoids and trace metals play an important role in the antioxidant activities of medicinal plants. Many of the plants studied here have been identified as potential sources of new antioxidant compounds.

Ganoderma applanatum: a promising mushroom for antitumor and immunomodulating activity.

The antitumor effect of exo-biopolymer (EXP) produced by Ganoderma applanatum was investigated using sarcoma-180 bearing mice. EXP, when administered (10-80 mg/kg body weight: BW) intraperitoneally, significantly inhibited the growth of solid tumor and increased the natural killer (NK) cell activity. A dose of 40 mg/kg BW was found to be highly effective, as it reduced the tumor formation by 39.7%, and increased the NK cell activity of splenocytes by 51.6% compared with the control group. The complement activity of EXP was increased in accordance with an increase in concentration. The phosphatase activity of macrophages was increased by 0.7-fold (200 microg/mL) compared with the control group. This EXP contained 58.9% carbohydrate and 17.1% protein. The major sugar of EXP was composed of mannose and glucose, while the protein mainly consisted of serine, glycine and aspartic acid.

Taxonomic and Functional Changes of Bacterial Communities in the Rhizosphere of Kimchi Cabbage After Seed Bacterization with Proteus vulgaris JBLS202.

Maintenance of a beneficial microbial community, especially in the rhizosphere, is indispensable for plant growth and agricultural sustainability. In this sense, plant growth-promoting rhizobacteria (PGPR) have been extensively studied for their role in plant growth promotion and disease resistance. However, the impact of introducing PGPR strains into rhizosphere microbial communities is still underexplored. We previously found that the Proteus vulgaris JBLS202 strain (JBLS202) promoted growth of Kimchi cabbage and altered the relative abundance of total bacteria and Pseudomonas spp. in the treated rhizosphere. To extend these findings, we used pyrosequencing to analyze the changes in bacterial communities in the rhizosphere of Kimchi cabbage after introduction of JBLS202. The alterations were also evaluated by taxon-specific real-time PCR (qPCR). The pyrosequencing data revealed an increase in total bacteria abundance, including specific groups such as Proteobacteria, Acidobacteria, and Actinobacteria, in the treated rhizosphere. Time-course qPCR analysis confirmed the increase in the abundance of Acidobacteria, Actinobacteria, Alphaproteobacteria, and Betaproteobacteria. Furthermore, genes involved in nitrogen cycling were upregulated by JBLS202 treatment indicating changes in ecological function of the rhizosphere soil. Overall, these results indicate that introduction of JBLS202 alters both the composition and function of the rhizosphere bacterial community, which can have direct and indirect effects on plant growth. Therefore, we propose that long-term changes in bacterial composition and community-level function need to be considered for practical use of PGPRs.

Effects of flaC Mutation on Stringent Response-Mediated Bacterial Growth, Toxin Production, and Motility in Vibrio cholerae.

The stringent response (SR), which is activated by accumulation of (p)ppGpp under conditions of growth-inhibiting stresses, plays an important role on growth and virulence in Vibrio cholerae. Herein, we carried out a genome-wide screen using transposon random mutagenesis to identify genes controlled by SR in a (p)ppGpp-overproducing mutant strain. One of the identified SR target genes was flaC encoding flagellin. Genetic studies using flaC and SR mutants demonstrated that FlaC was involved in bacterial growth, toxin production, and normal flagellum function under conditions of high (p)ppGpp levels, suggesting FlaC plays an important role in SR-induced pathogenicity in V. cholerae.

Isolation and characterization of biopolymers extracted from the bark of Acanthopanax sessiliflorus and their anticomplement activity.

The crude biopolymer (AS-S1) and endo-biopolymer (AS-S2) were isolated from the dry stem bark of Acanthopanax sessiliflorus and tested for anti complement activity. The two potent anticomplement biopolymers, AS-1 and AS-2-Fr.I, were isolated by the combination of ion-exchange chromatography and gel filtration methods from the endo-biopolymers (AS-S2). The anticomplement activity of AS-1 (MW 12 kDa) and AS-2-Fr.I (MW 180 kDa) were found to be 84.4% and 100.0%, respectively, at the concentration of 25 microg/ml. Activated pathway of the complement system occurred in both classical and alternative pathways, as evidenced by crossed immunoelectrophoresis (CIEP), where a major pathway was detected to be the classical one. It was found that the anticomplement activities of the periodate oxidized were decreased significantly, but those of pronase digested biopolymers of AS-1 and AS-2-Fr.I were decreased very little. The AS-1 contained 2,4,6-tri-O-methyl-D-glucitol, 2,3,6-tri-O-methyl-D-glucitol, and 2,3,6-tri-O-methyl-D-galacitol, which indicated that AS-1 contained a (1 --> 3), (1 --> 4)-linked glucopyranosyl residue and a (1 --> 4)-linked galactosyl residue. AS-2-Fr.I contained mainly 2,4-di-O-methyl-D-mannitol and 2,3,4-tri-O-methyl-D-galacitol, which contained (1 --> 3), (1 --> 6) linked mannosyl and (1 --> 6) linked galactosyl residues.

Chemical characteristics and immuno-stimulating properties of biopolymers extracted from Acanthopanax sessiliflorus.

During our search for macrophage stimulating compounds from medicinal plants, we isolated biopolymers from Acanthopanax sessiliflorus. Isolated fraction AS-5 showed maximum potential, and stimulated lysosonal enzymatic activity by 230% at 300 microg/ml. The nitric oxide (NO) producing ability of AS-5 100 microg/ml was 58 microM when treated with interferon-gamma and lipopolysaccharide 20 micro/ml. The lymphocyte proliferating effects of isolated biopolymer fractions were also investigated. Highest lymphoproliferative activity (a 2.8-fold enhancement compared to salines treated group was exhibited by AS-3 at 200 micro/ml followed by AS-5 and AS-6. The AS-3 fraction stimulated only T-lymphocytes and had little or no effect on B-lymphocyte proliferation. Partially methylated alditol acetates were prepared to elucidate the glycosyl linkage-compositions of the AS-3 and AS-5 biopolymers, and were analyzed by GC-MS. The AS-3 and AS-5 biopolymer fractions were found to contain 2,3,4-tri-O-methyl-D-glucitol, 2,3,4-tri-O-methyl-D-galacitol 3,4,6-tri-O-methyl-galacitol, 2-O-methyl-arabinitol and 2,4,6-tri-O-methyl-D-glucitol, 2,3,6-tri-O-methyl-D-galacitol linkages, respectively.

Macrophage-stimulating activity of polysaccharides extracted from fruiting bodies of Coriolus versicolor (Turkey Tail Mushroom).

The macrophage-stimulating effect of polysaccharides extracted from Coriolus versicolor (Turkey Tail mushroom) was investigated, and their effectiveness was compared with that of lipopolysaccharide (LPS). The purified polysaccharide (CV-S2-Fr.I) of C. versicolor obtained by Sepharose CL-6B gel chromatography stimulated macrophage lysosomal enzyme activity by 250% at a concentration of 100 microg/mL, which was higher than that of LPS at the same concentration. When CV-S2-Fr.I was used in combination with interferon-gamma, there was a marked cooperative induction of nitric oxide production. However, CV-S2-Fr.I had no effect on nitric oxide production by itself. The proportion of C3-positive macrophages in the CV-S2-Fr.I group increased by 7.2-fold compared with the control group.

Antidiabetic and hypolipidemic effects of Collybia confluens mycelia produced by submerged culture in streptozotocin-diabetic rats.

This investigation was undertaken to study the effects of oral administration (3 weeks) of Collybia confluens mycelial powder (CCMP) produced by a submerged culture on plasma glucose and other biochemical parameters in streptozotocin (STZ)-induced diabetic rats. Antidiabetic and hypolipidemic effects were proportionally increased with the increasing concentration of the CCMP for oral administration. The CCMP, at the dose of 400 mg/kg BW, substantially reduced the plasma glucose level by as much as 33.1% as compared to the STZ-induced diabetic rats group. It also lowered the plasma total cholesterol, triglyceride, and low density lipoprotein (LDL) cholesterol by 22.9%, 19.9%, and 37.3%, respectively. The levels of total cholesterol and triglyceride in liver were reduced to the extent of by 13.5% and 18.8%, and the activity of alanine transaminase (ALT) and aspartate transaminase (AST) was decreased by 48.8% and 37.2%, respectively, under the influence of CCMP. The general components of CCMP were found to contain 26.18% carbohydrate, 3.67% crude ash, 4.02% crude fat, 22.55% crude protein, and 43.58% dietary fiber. The amino acid composition of the CCMP was also analyzed in detail.

Antioxidant Capacities of Hot Water Extracts and Endopolysaccharides of Selected Chinese Medicinal Fruits.

Fruits are a rich source of antioxidants and traditional Chinese fruits have been studied for their chemopreventive and chemotherapeutic properties against cancers and other diseases. The total phenol and flavonoid contents of eleven Chinese fruits extracts were determined. Total phenolic and flavonoid contents were estimated by both the Folin-Ciocalteau and aluminium chloride methods. The antioxidant activities were evaluated by four assays: a biological assay using Saccharomyces cerevisiae, DPPH radical scavenging activity, chelating ability for ferrous ions and ferric reducing antioxidant power (FRAP). The phenols and flavonoids contents of the hot water extracts were in the range of 17.7 to 94.7 mg/g and 12.3 to 295.4 mg/g, whereas the endopolysaccharides lie in the range of 4.5 to 77.4 mg/g and 22.7 to 230.0 mg/g. Significant amounts of phenols and flavonoids were present in the majority of the fruit extracts and showed strong antioxidant activities. The antioxidant properties of the fruit extracts of Crataegus pinnatifida, Illicium verum, Ligustrum lucidum, Momordica grosvenori and Psoralea corylifolia as determined by the DPPH and FRAP methods, were significant compared to other fruit extracts. In the present study, we found that significant amounts of phenolic and flavonoid compounds were present in these fruit extracts and may contribute to in vitro antioxidant activities.

Osteoprotective Effects of Polysaccharide-Enriched Hizikia fusiforme Processing Byproduct In Vitro and In Vivo Models.

The traditional manufacturing method used to produce goods from Hizikia fusiforme, utilizes extraction steps with hot water. The byproduct (of hot water extraction) is rich in polysaccharide and is considered a waste. To evaluate the osteogenic effects of the byproduct of H. fusiforme (HFB), osteogenic cells and animal models were used to test it effects on osteogenesis. The HFB-treated mouse myoblast C2C12 cells exhibited significant dose dependently elevated alkaline phosphatase (ALP) activity and slightly increased bone morphogenetic protein-2 (BMP-2). HFB also suppressed the formation of tartrate-resistant acid phosphatase (TRAP) activity and TRAP staining in the bone marrow-derived macrophages (BMM) cells that had been stimulated with the receptor activator of the nuclear factor kB ligand/macrophage colony-stimulating factor kB ligand. In addition, HFB also increased the phosphorylation of extracellular signal-regulated protein kinase (p-ERK) level. Finally, osteogenic effects of HFB were clearly confirmed in the three in vivo models: zebrafish, ovariectomized mice, and mouse calvarial bones. HFB accelerated the rate of skeletal development in zebrafish and prevented much of the mouse femoral bone density loss of ovariectomized mice. Moreover, HFB enhanced woven bone formation over the periosteum of mouse calvarial bones. Our result showed that HFB functions as a bone resorption inhibitor as well as an activator of bone formation in vivo and in osteogenic in vitro cell systems.

Modulation effects of sweroside isolated from the Lonicera japonica on melanin synthesis.

In the course of screening for the melanogenesis inhibitors, sweroside was isolated from Lonicera japonica. Its chemical structure was determined on the basis of spectroscopic analysis, including mass spectroscopy and nuclear magnetic resonance analysis. Sweroside inhibited potent melanogenesis in melan-a cells at 300µM without cytotoxicity. Also, sweroside decreased tyrosinase, tyrosinase-related protein-1 (TRP-1) and TRP-2 protein production in melan a cells. To identify the signaling pathway of sweroside, the ability of sweroside to influence Akt and extracellular signal-regulated protein kinase (ERK) activation was investigated. Sweroside induced Akt and ERK in a dose-dependent manner. In addition, the specific inhibition of the Akt and ERK signaling pathways were studied by specific inhibitor LY294002 and U0126, respectively and it was causing the increased melanin synthesis. Furthermore, sweroside presented inhibition of the body pigmentation and tyrosinase activity in zebrafish in vivo model. These results suggest that sweroside isolated from L. japonica may be an effective skin-whitening agent through the regulates the expression of MAP kinase and melanogenic enzymes.

Melanin Biosynthesis Inhibition Effects of Ginsenoside Rb2 Isolated from Panax ginseng Berry.

Ginsenoside Rb2 (Gin-Rb2) was purified from the fruit extract of Panax ginseng. Its chemical structure was measured by spectroscopic analysis, including HR-FAB-MS, (1)H-NMR, and IR spectroscopy. Gin-Rb2 decreased potent melanogenesis in melan-a cells, with 23.4% at 80 µM without cytotoxicity. Gin-Rb2 also decreased tyrosinase and MITF protein expression in melan-a cells. Furthermore, Gin-Rb2 presented inhibition of the body pigmentation in the zebrafish in vivo system and reduced melanin contents and tyrosinase activity. These results show that Gin-Rb2 isolated from P. ginseng may be an effective skin-whitening agent via the in vitro and in vivo systems.

Hepatoprotective effect of water extract from Chrysanthemum indicum L. flower.

BACKGROUND: Chrysanthemum indicum L. flower (CIF) has been widely used as tea in Korea. This study aims to investigate the hepatoprotective effect of the hot water extract of CIF (HCIF) in in vitro and in vivo systems. METHODS: Hepatoprotective activities were evaluated at 250 to 1000 µg/mL concentrations by an in vitro assay using normal human hepatocytes (Chang cell) and hepatocellular carcinoma cells (HepG2) against CCl4-induced cytotoxicity. Cytochrome P450 2E1, which is a key indicator of hepatic injury, was detected by western blot analysis using rabbit polyclonal anti-human CYP2E1 antibody. An in vivo hepatoprotective activity assay was performed at 1000 to 4000 µg/mL concentrations on CCl4-induced acute toxicity in rats, and the serum levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were determined by standard enzyme assays. RESULTS: The hepatoprotective effects of HCIF significantly reduced the levels of GOT (60.1%, P = 0.000) and GPT (64.5%, P = 0.000) compared with the vehicle control group (CCl4 alone). The survival rates of HepG2 and Chang cells were significantly improved compared with the control group [82.1% (P = 0.034) and 62.3% (P = 0.002), respectively]. HCIF [50 mg/kg body weight (BW)] treatment significantly reduced the serum levels of GOT (49.5%, P = 0.00), GPT (55.5%, P = 0.00), ALP (30.8%, P = 0.000) and LDH (45.6%, P = 0.000) compared with the control group in this in vivo study. The expression level of cytochrome P450 2E1 (CYP2E1) protein was also significantly decreased at the same concentration (50 mg/kg BW; P = 0.018). CONCLUSION: HCIF inhibited bioactivation of CCl4-induced hepatotoxicity and downregulates CYP2E1 expression in vitro and in vivo.

Immunomodulatory activities of polysaccharides isolated from Taxillus chinensis and Uncaria rhyncophylla.

Taxillus chinensis and Uncaria rhyncophylla are the herbs used in traditional Chinese anticancer formulations. During the past decade, research on plant polysaccharides has gained importance due to their therapeutic value and minimum side effects. In this study, hot water extraction method was employed to isolate polysaccharides from the stems of T. chinensis and stems with hooks of U. rhyncophylla. Size-exclusion chromatography was then used for further fractionation. Separated fractions from T. chinensis were designated as TCP-1, TCP-2 and TCP-3 and those from U. rhyncophylla were termed UC-1 and UC-2. Their sugar compositions were estimated using gas chromatography that revealed the presence fructose, glucose, xylose, arbinose, and rhamnose. Amino acid analysis of these fractions has indicated that they are protein-bound polysaccharides. The antioxidant activities were investigated using DPPH and yeast assays. The ability of these polysaccharide fractions to stimulate mouse macrophages was measured using Griess reagent and ELISA test. The results revealed that some of the isolated fractions (TCP-2, TCP-3, UC-1 and UC-2) displayed significant antioxidant activities and were also found to be effective immunomodulators in a concentration-dependent manner. Outcomes of this research strongly indicate that U. rhyncophylla and T. chinensis have therapeutic potential to be used for the treatment of cancer.

Anti-fungal and anti-bacterial activities of ethanol extracts of selected traditional Chinese medicinal herbs.

OBJECTIVE: To evaluate in vitro antimicrobial activities of selected 58 ethno-medicinal plant extracts with a view to assess their therapeutic potential. METHODS: A total of 58 traditional Chinese medicinal plants were carefully selected based on the literature review and their traditional use. The antimicrobial activities of ethanol extracts of these medicinal plants were tested against fungi (Aspergillus fumigatus), yeast (Candida albicans), gram-negative (Acinetobacter baumannii and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus). The activities were tested at three different concentrations of 1.00, 0.10 and 0.01 mg/mL. The data was analysed using Gene data Screener program. RESULTS: The measured antimicrobial activities indicated that out of the 58 plant extracts, 15 extracts showed anti-fungal activity and 23 extracts exhibited anti-bacterial activity. Eight plant extracts have exhibited both anti-bacterial and anti-fungal activities. For instance, Eucommia ulmoides, Polygonum cuspidatum, Poria cocos and Uncaria rhyncophylla showed activity against both bacterial and fungal strains, indicating their broad spectrum of activity. CONCLUSIONS: The results revealed that the ethanol extracts of 30 plants out of the selected 58 possess significant antimicrobial activities. It is interesting to note that the findings from the current study are consistent with the traditional use. A clear correlation has also been found between the antimicrobial activity and the flavonoid content of the plant extracts which is in agreement with the literature. Hence, the results presented here can be used to guide the selection of potential plant species for the isolation and structure elucidation of novel antimicrobial compounds in order to establish the structure-activity relationship. This in turn is expected to lead the way to the discovery of novel antimicrobial agents for therapeutic use.