Inhibitory Effect Of Crude Extract Research Articles

Inhibition potential of n-hexadecanoic and oleic acids from edible insects against α-glucosidase, α-amylase, tyrosinase, and acetylcholinesterase: in vitro and in silico studies.

Edible insects are used for consumption and traditional medicine due to their rich bioactive compounds. This study examined the bioactive compounds and inhibitory effects of crude extracts from Bombyx mori and Omphisa fuscidentalis on α-glucosidase, α-amylase, acetylcholinesterase (AChE), and tyrosinase. Fatty acids, including n-hexadecanoic acid and oleic acid, were identified in the extracts and evaluated for their inhibitory potential against the enzymes in vitro and in silico. The total phenolic content of the edible insect extracts correlated with enzyme inhibitory activity. The quercetin and kaempferol content of B. mori ethyl acetate (EtOAc) extract was also closely related to α-amylase inhibitory activity. The EtOAc and hexane extracts of B. mori showed similar inhibition potential to acarbose and tacrine against α-amylase and AChE, respectively. The hexane extract of O. fuscidentalis exhibited comparable tyrosinase inhibitory activity to kojic acid. n-Hexadecanoic acid and oleic acid were the predominant bioactive compounds in all of the extracts. A kinetic study revealed that n-hexadecanoic acid acted as a mixed-type inhibitor against α-amylase, similar to acarbose, whereas oleic acid showed non-competitive inhibition against AChE, unlike tacrine. Docking studies suggested that these fatty acids bind to the active sites of α-amylase and AChE. The findings suggest that n-hexadecanoic acid and oleic acid from edible insects could be potential candidates for treating diabetes mellitus and Alzheimer's disease. An animal model might be used for further examination to confirm these findings. © 2025 Society of Chemical Industry.

Exploring the antimicrobial and anti-HIV-1 properties of Anthocleista djalonensis, Vernonia cinerea, and Pycnanthus angolensis extracts

This study examined the anti-HIV-1 integrase, protease, and antimicrobial properties of crude extracts from three traditional Nigerian medicinal plants: Anthocleista djalonensis, Vernonia cinerea, and Pycnanthus angolensis. Fluorometric assays were utilized to assess the inhibitory effects of crude extracts produced through maceration on HIV-1 integrase and HIV-1 protease. The samples' antimicrobial activity was measured using microdilution methods. The results showed that all three crude plant extracts significantly inhibited HIV-1 integrase activity with IC50 values of 0.01891, 0.709, and 5.21 μg/mL for A. djalonensis, V. cinerea, and P. angolensis respectively. IC50 value of 0.006992 μM was recorded for chicoric acid used as the reference medication for anti-HIV-1 integrase activity. This allowed for comparison with the crude extracts from V. cinerea, P. angolensis, and A. djalonensis. Conversely, the methanol crude extract from A. djalonensis, V. cinerea, and P. angolensis did not show a dose response since none of the extracts could reduce a specific percentage of viable cells in the HIV-1 protease assay. This data provides vital information on the preference for A. djalonensis, V. cinerea, and P. angolensis extracts towards HIV-1 integrase rather than protease even though it may initially seem unexpected. A. djalonensis, V. cinerea, and P. angolensis extracts exhibited antibacterial activities against all pathogens with the minimum inhibitory concentrations (MIC) ranging between 8 and 67 μg/mL. The study underscores the potential of plant extracts as innovative treatments for HIV-1 infection, as they can provide anti-HIV-1 integrase inhibitors. The ethnopharmacological perspective thus confirms the significance of African traditional medicines.

EVALUATION OF ANTIMICROBIAL PROPERTY OF EXTRACT OF PUNICA GRANATUM (L.) ON ORAL PATHOGENS

The aim of the present research was the examination of the potential activity of various organic solvent extracts of Punica granatum on the important microbiota harbouring in the oral cavity. The dried peels and seeds of P. granatum were extracted using chloroform, methanol and nbutanol and their potential activity were studied. The inhibitory effect of crude extracts were observed on various microbial plates which were incubated with different bacterial species in terms of zone of inhibition as mm in diameter. The data was analysed by One Way Analysis of Variance for significance. The peel extract was more potent in inhibiting the microbial population growth as compared to seed extract. While all the four solvents were effective in case of peel extracts, the bioactivity was much higher in species such as Streptococcus mutants, Streptococcus sanguis, Staphylococcus aureus, Lactobacillus acidophilus and Actinomyces viscosus, among 8 species evaluated in the present investigation. The peel extract of P. granatum contains active biomolecule(s) against important oral microbial pathogens and thus holds promise as a potential bioactive molecule against Dental Caries. Based on the bioactivity analysis, the peel extract of P. granatum may further be subjected to purification and characterization of the bioactive compound(s) for regulating oral microbial contamination.

Combined in vitro and in silico approach to evaluate the inhibitory potential of an underutilized allium vegetable and its pharmacologically active compounds on multidrug resistant Candida species.

Candida infections and related mortality have become a challenge to global health. Nontoxic and natural bioactive compounds from plants are regarded as promising candidates to inhibit these multidrug resistant strains. In the present study, in vitro assays and in silico molecular docking approach was combined to evaluate the inhibitory effect of crude extracts from Allium ampeloprasum and its variety A. porrum on Candida pathogens. Phytochemical screening revealed the presence of phenolic acids and flavonoids in higher quantity. Spectral studies of the extracts support the presence of phenols, flavonoids and organosulfur compounds. Aqueous extract of A. ampeloprasum showed a total antioxidant capacity of 68 ± 1.7 mg AAE/ g and an IC50 value of 0.88 ± 2.1 mg/ml was obtained for DPPH radicals scavenging assay. C. albicans were highly susceptible (19.9 ± 1.1 mm) when treated with aqueous A. ampeloprasum extract. Minimum inhibitory concentrations were within the range of 19–40 μg/ml and the results were significant (p ≤ 0.05). In silico molecular docking studies demonstrated that bioactive phytocompounds of A. ampeloprasum and A. porrum efficiently interacted with the active site of Secreted aspartyl proteinase 2 enzyme that is responsible for the virulence of pathogenic yeasts. Rosmarinic acid and Myricetin exhibited low binding energies and higher number of hydrogen bond interactions with the protein target. Thus the study concludes that A. ampeloprasum and A. porrum that remain as underutilized vegetables in the Allium genus are potential anti-candida agents and their pharmacologically active compounds must be considered as competent candidates for drug discovery.

Selected Plant Extracts Show Antiviral Effects against Murine Norovirus Surrogate

Noroviruses are the most common cause of acute gastroenteritis. Annually, 21 million Americans are infected with norovirus. Recent advances in molecular diagnostics have helped to establish norovirus as the most common cause of outbreaks of acute gastroenteritis across all ages. However, there is no effective or efficient treatment/control against norovirus infection. Conventional intervention techniques used to inactivate norovirus have shown lack of efficacy against human norovirus. Currently, effective treatment or control measures against human norovirus have not been identified. In this study, murine norovirus acts as a model to human norovirus to evaluate the inhibitory effects of crude extracts of Zanthoxylum armatum and Hibiscus sabdariffa. The study also separated, identified and quantified the selected compounds using the ultra-liquid chromatography (UPLC). To study the antiviral activities of crude extracts and its fractionated portions of Z. armatum and H. sabdariffa against norovirus surrogate, RAW 264.7 cells were infected with Murine norovirus surrogate virus of human norovirus and incubated at 37˚C. Phytochemicals were extracted from the seeds and calyces of the plants using methanolic extraction. Fractionated portions of the crude extracts were subsequently used in both chromatographic and microbiological studies. Our data indicated that there was reduction of viruses, when treated with the 60% aqueous methanol extracts. Amongst the four selected phenolic compounds (myricetin, quercetin, kaempferol and luteolin), quercetin showed the most significant logarithmic viral reductions. These compounds were identified, purified and quantified using UPLC. Extracts of Zanthoxylum armatum and Hibiscus sabdariffa showed antiviral effects. Phenolic compounds are virucidal. Extracts of Hibiscus sabdariffa also exhibits anti-norovirus activities. The results are anticipated to control/prevent the human norovirus infections.

Metabolic disturbance and phytochemical changes in Andrographis paniculata and possible action mode of andrographolide

Objective: To explore the effect of gibberellic acid (GA3) and its inhibitor paclobutrazol (PBZ) on chemical composition and their pharmacological effects on Andrographis paniculata (Burm. f.) Wall. ex Nees, and to clarify action mode of andrographolide. Methods: The chemical composition was extracted by sequential extraction with hexane, dichloromethane, ethyl acetate and methanol, respectively. Andrographolide and its derivatives were evaluated by HPLC. Moreover, the metabolic profiling was analyzed by GC-MS. Inhibitory effect of crude extracts was tested against Staphylococcus aureus using agar well diffusion method. Mode of action was tested against mutant yeast by spotting assay. Andrographolide were tested for their mode of action against eukaryotes. Results: Among different solvents, dichloromethane gave the highest yield of crude (3.58% DW), with the highest andrographolide content (8.3 mg/g DW). The effect of plant hormone (10 mg/L GA3 or PBZ) on phytochemical variations and bioactivity of Andrographis paniculata was demonstrated. It was found that PBZ promoted sesquiterpene compounds about 3.5 times over than GA3 treatment. But inhibitory effect of extracts against Staphylococcus aureus was highest in GA3 treated plants; andrographolide and 14-deoxy-11,12-didehydroandrographolide contents were significantly higher than those of water or PBZ. It was found that there were 11 strains involving in ergosterol biosynthesis, V-ATPase activity and homeostasis, and superoxide detoxification process. In this regard, andrographolide might cause the damage on the lipid bilayer of yeast cell and plasma membrane by interfering ergosterol biosynthesis. Conclusions: It is found that GA3 promotes andrographolide and 14-deoxy-11,12-didehydroandrographolide content while PBZ promotes sesquiterpene content. Andrographolide might cause the damage on the lipid bilayer of yeast cell and plasma membrane by interfering ergosterol biosynthesis. It might also affect mitochondria electron transport chain, leading to the occurrence of ROS, which can further harm cell organelles. However, the library screening is the first step to investigate mode of action of andrographolide.

In vivo antiplasmodial activity and toxicological assessment of hydroethanolic crude extract of Ajuga remota

BackgroundMalaria is one of the most life-threatening health problems worldwide and treatment has been compromised by drug resistance. Identifying lead molecules from natural products might help to find better anti-malarial drugs, since those obtained from natural sources are still effective against malarial parasites. This study aimed at investigating the in vivo antiplasmodial activity of crude extract of the leaves of Ajuga remota together with its safety in mice models.MethodsIn vivo parasite growth inhibitory effect of crude extract was assessed in mice inoculated with Plasmodium berghei (ANKA strain). The in vivo antiplasmodial activity of the test extract was performed against early infection (4-day suppressive test), curative effect against established infection and prophylactic effect against residual infection. Acute and sub-acute toxicity were carried out according to OECD guidelines.ResultsIn vivo parasite growth inhibition effect of hydroethanolic crude extract of A. remota was evaluated at 30, 50 and 100 mg/kg dose levels. It suppressed parasitaemia by 77.34% at 100 mg/kg dose level in the 4-day test. In curative and prophylactic potential tests, it suppressed parasitaemia by 66.67 and 59.66% at 100 mg/kg dose level, respectively. In vivo toxicity tests revealed no toxicity. All parasitaemia suppressions were statistically significant at P < 0.05 as compared to the vehicle-treated group. The crude extract also prolonged survival time in a dose dependent manner.ConclusionsThe investigation results suggest that the leave extract of Ajuga remota possesses antimalarial activity.

A-Amylase and a-Glucosidase Inhibition by Brown Seaweed (Sargassum sp) Extracts

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to control post-prandial hyperglycemia associated with diabetes mellitus. In vitro inhibitory effects of crude extracts of seaweed against α-amylase and α-glucosidase were studied. Crude ethyl acetate extracts of Sargassum aquifolium were the stronger inhibitor to α-amylase and α-glucosidase than others. Furthermore, Sargassum aquifolium ethyl acetate extract significantly suppressed the rise in postprandial glucose level after oral administration of glucose in normal rats. The results of this study suggest that the crude Sargassum aquifolium extract may suppress the rise in postprandial hyperglycemia in vivo in part, through inhibition of alpha amylase and glucosidase.

The Parotoid Gland Secretion of Bufonids Inhibits the Activity of the Multidrug Resistance Target Pdr5p from Yeast Plasma Membranes

Aims: Considering the well known biological effects of secretion of cutaneous glands in anurans and that Pdr5p belongs to the ATB-Binding Cassette (ABC) superfamily of membrane transporters, which efflux a large variety of xenobiotic compounds, and play an important role in the multidrug resistance (MDR), the parotoid gland of two bufonids were used in order to evaluate their secretion activity on Pdr5p of plasma membranes of the yeast Saccharomyces cerevisiae as a potential inhibitor of MDR. Place and Duration of Study: Laboratory of Integrative Histology and Laboratory of Microbian Biochemistry, Federal University of Rio de Janeiro, between September 2009 and October 2011. Methodology: Five male bufonids of Rhinella icterica and of R. ornata were used, and the parotoid gland secretion was obtained after manual gland comprehension and by dissection. ATPase assays as well as SDS-PAGE were performed, besides immunohistochemical analysis at light microscopy. Results: Pdr5p ATPase activity was inhibited when the crude extract was obtained by Original Research Article Annual Research & Review in Biology, 4(2): 378-391, 2014 379 manual compression from the parotoid gland in contrast to the isolated intake of the large granular alveoli, which showed no enzymatic activity. Moreover, the Pgp expression in acinar cells of both mixed and small granular glands as well as in a myoepithelial cells was visualized by immunohistochemistry, suggesting its participation in tissue defense against toxic compounds. Conclusion: The inhibitory effect of crude extract obtained by manual comprehension was detected, while the isolated intake showed no effect on the Pdr5p ATPase activity. Both bufonid represent an important source of biomolecules, opening new perspectives of research on natural products.

Algicidal effects of Zostera marina L. and Zostera noltii Hornem. extracts on the neuro-toxic bloom-forming dinoflagellate Alexandrium catenella

The inhibitory effects of crude extracts of Zostera marina L. and Zostera noltii Hornemann on the growth of the toxic red tide dinoflagellate Alexandrium catenella were investigated through bio-assays. Methanolic and aqueous extracts were prepared from fresh and detrital leaves of Z. marina and Z. noltii collected in the Thau lagoon and Arcachon bay (France). All the extracts exhibited significant inhibition of A. catenella growth, whatever the species and without the need of continuous addition of extracts. The effective concentrations (EC50) varied in the range 0.036–0.199gL−1 for Z. noltii and 0.036–0.239gL−1 for Z. marina. Methanolic extracts prepared from fresh plant tissues were the most potent, with EC50 of 0.036–0.039 and 0.036–0.045gL−1, for Z. noltii and Z. marina, respectively. After exposure to the extracts, Alexandrium cells exhibited severe morphological anomalies. Hence many cells exhibited a lytic membrane and became necrotic. Cellular degradation appeared dose- and time-dependent. The observed algicidal activities demonstrated the existence of bioactive molecules in the tissues of Zostera leaves, which were stable in the culture medium. The chemical contents of the crude extracts were determined by NMR, LC/MS, and quantitative HPLC. Results showed the predominance of flavonoids and phenolic acids. The total phenolics concentrations correlated negatively with the EC50 values, suggesting that these secondary metabolites might be responsible for the observed algicidal effects.

Anti-Inflammatory Components of the Starfish Astropecten polyacanthus

Inflammation is important in biomedical research, because it plays a key role in inflammatory diseases including rheumatoid arthritis and other forms of arthritis, diabetes, heart disease, irritable bowel syndrome, Alzheimer’s disease, Parkinson’s disease, allergies, asthma, and even cancer. In the present study, we describe the inhibitory effect of crude extracts and steroids isolated from the starfish Astropecten polyacanthus on pro-inflammatory cytokine (Interleukin-12 (IL-12) p40, interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α)) production in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs). Among those tested, compounds 5 and 7 showed potent inhibitory effects on the production of all three pro-inflammatory cytokines with IC50 values ranging from 1.82 ± 0.11 to 7.00 ± 0.16 μM. Potent inhibitory activities were also observed for compound 1 on the production of IL-12 p40 and IL-6 with values of 3.96 ± 0.12 and 4.07 ± 0.13 μM, respectively, and for compounds 3 and 4 on the production of IL-12 p40 with values of 6.55 ± 0.18 and 5.06 ± 0.16 μM, respectively. Moreover, compounds 2 (IC50 = 34.86 ± 0.31 μM) and 6 (IC50 = 79.05 ± 2.05 μM) exhibited moderate inhibitory effects on the production of IL-12 p40, whereas compounds 3 (IC50 = 22.80 ± 0.21 μM) and 4 (IC50 = 16.73 ± 0.25 μM) moderately inhibited the production of TNF-α and IL-6, respectively.

Inhibitory effects of crude extracts from some edible Thai plants against replication of hepatitis B virus and human liver cancer cells

BackgroundEdible plants such as Cratoxylum formosum (Jack) Dyer, Curcumin longa Lin, Momordica charantia Lin and Moringa oleifera Lam have long been believed in Thai culture to relieve ulcers and the symptoms of liver disease. However, little is known about their anti-liver cancer properties and antiviral activity against hepatitis B virus (HBV). The aim of this study was to investigate the anti-liver cancer and anti-HBV activities of crude extracts from these edible plants on human liver cancer cells.MethodsPlant samples were prepared and extracted using buffer and hydro-alcoholic solvents. The MTT assay was performed to investigate the effects of the plant extracts on the cell viability of HepG2 cells. The inhibitory effect on replication of HBV was analysed by determining the level of HBV covalently closed circular DNA (cccDNA) in transiently transfected HepG2 cells with the DNA expression plasmid of the HBV genome using a quantitative real-time PCR.ResultsBuffer and hydroalcoholic extracts from C. formosum (leaf) reduced cell viability of HepG2 cells and they also inhibited HBV cccDNA. Crude extracts from C. longa (bulb) in both solvents did not have any cytotoxic effects on the HepG2 cells, but they significantly decreased the level of HBV cccDNA. Buffer extracts from the leaves of M. charantia and the fruits of M. oleifera showed to have anti-HBV activity and also a mild cytotoxicity effect on the HepG2 cells. In addition, leaves of M. Oleifera extracted by hydroalcoholic solvent drastically decreased the level of cccDNA in transiently transfected HepG2 cells.ConclusionSome crude extracts of edible plants contain compounds that demonstrate anti-liver cancer and anti-HBV activities.

Effect of Alpinia zerumbet components on antioxidant and skin diseases-related enzymes

BackgroundThe skin is chronically exposed to endogenous and environmental pro-oxidant agents, leading to the harmful generation of reactive oxygen species. Antioxidant is vital substances which possess the ability to protect the body from damage cause by free radicals induce oxidative stress. Alpinia zerumbet, a traditionally important economic plant in Okinawa, contains several interesting bioactive constituents and possesses health promoting properties. In this regard, we carried out to test the inhibitory effect of crude extracts and isolated compounds from A. zerumbet on antioxidant and skin diseases-related enzymes.MethodsThe antioxidant activities were examined by DPPH, ABTS and PMS-NADH radical scavenging. Collagenase, elastase, hyaluronidase and tyrosinase were designed for enzymatic activities to investigate the inhibitory properties of test samples using a continuous spectrophotometric assay. The inhibitory capacity of test samples was presented at half maximal inhibitory concentration (IC50).ResultsThe results showed that aqueous extract of the rhizome was found to have greater inhibitory effects than the others on both of antioxidant and skin diseases-related enzymes. Furthermore, 5,6-dehydrokawain (DK), dihydro-5,6-dehydrokawain (DDK) and 8(17),12-labdadiene-15,16-dial (labdadiene), isolated from rhizome, were tested for antioxidant and enzyme inhibitions. We found that DK showed higher inhibitory activities on DPPH, ABTS and PMS-NADH scavenging (IC50 = 122.14 ± 1.40, 110.08 ± 3.34 and 127.78 ± 4.75 μg/ml, respectively). It also had stronger inhibitory activities against collagenase, elastase, hyaluronidase and tyrosinase (IC50 = 24.93 ± 0.97, 19.41 ± 0.61, 19.48 ± 0.24 and 76.67 ± 0.50 μg/ml, respectively) than DDK and labdadiene.ConclusionOur results indicate that the rhizome aqueous extract proved to be the source of bioactive compounds against enzymes responsible for causing skin diseases. Moreover, DK could be used as a potent inhibitor and be further exploited to be used in anti-skin disease formulations.

Antidiarrheal and antispasmodic activities of Salvia officinalis are mediated through activation of K+ channels

This study was conducted to provide pharmacological basis for the medicinal use of Salvia officinalis in diarrhea. The crude extract of S. officinalis was studied using the in vivo and in vitro assays. The crude extract inhibited castor oil-induced diarrhea in mice at the dose of 100 and 300 mg/kg. In isolated rabbit jejunum, it caused a dose-dependent (0.1-3 mg/mL) relaxation of spontaneous as well as low K+ (25 mM) and high K+ (80 mM)-induced contractions, being distinctly more potent on low K+. Pretreatment of tissue with 4-aminopyridine (1 mM) almost completely blocked the inhibitory effect of crude extract on low K+. These results indicate that the crude extract of S. officinalis possesses antidiarrheal and antispasmodic activities mediated possibly through the dominant activation of voltage-dependent K+ channels and this study provides sound pharmacological basis for its medicinal use in diarrhea and gut spasm.

Bioactivity of extracts from Jatropha curcas L. branches and leaves against plant pathogenic fungi.

The inhibitory effects of crude extracts from Jatropha curcas L. branches and leaves using six different solvents were tested against Fusarium graminearum,Pyricularia oryae Cav.,Phytophthora nicotianae Breda de Haan. and Phytophthora capsici Leon,using mycelium growth inhibition method. Then active component separation and bioactivity assay were conducted on the crude extracts with the highest bioactivity. The results showed that the most active extracts from J.curcas L. branches and leaves against four plant pathogenic fungi was alcohol extracts,the inhibition rate to the mycelial radial growth of four plant pathogenic fungi was 87.1%,90.3%,86.4% and 77.9% when concentration was 0.8g·L-1,there was no obvious difference when comparing to 10% difenoconazole. In the bioassays of alcohol crude extracts by partitively extracting of five different solvents against Pyricularia oryae Cav. and Phytophthora nicotianae Breda de Haan. We found that the antifungal activity of petroleum ether and water fractions were all higher,the inhibition rate to the mycelial radial growth of two plant pathogenic fungi were all higher than 50% at concentration of 0.8g·L-1. It is suggested that the branches and leaves of J.curcas L. contain abundant substances with antifungal activity,the active components with the inhibitory effect on plant pathogenic fungi mainly exit in petroleum ether and water fractions of alcohol extracts from J.curcas L. branches and leaves.

In vitro inhibitory effects of Hypoxis obtusa and Dicoma anomala on cyp450 enzymes and p-glycoprotein

Herbal medicines have been shown to cause clinically significant interactions with conventional medicines. Herbal medicines can alter the activity of drug-metabolizing enzymes and transporters, potentially resulting in herb-drug interactions. However, such information is generally not yet available for herbal medicines used only in developing nations. The inhibitory effects of crude extracts of Hypoxis obtusa andDicoma anomala on cytochrome P450 (CYP) isoforms 1A2, 2C9, 2C19, 2D6 and 3A4 were evaluated in vitro using human liver microsomes. Herbal extracts at concentrations of 50 and 250 μg/ml were tested for inhibition of P-glycoprotein (Pgp) transport across Caco-2 cell monolayers using 4.3 nM [3H]-digoxin as the substrate. Extracts of Hypoxis inhibited CYPs strongly, while extracts of Dicoma were moderate CYP inhibitors. The IC50 values for methanol and water extracts on CYP3A4 were 0.20 and 1.0 mg/ml for Hypoxis and 1.2 and 2.4 mg/ml for Dicoma. In the Pgp inhibition experiments, the (basolateral to apical) / (apical to basolateral) digoxin efflux ratios did not change significantly in the presence of the herbal extracts. Whilst, the extrapolation of the data to in vivo is rather speculative, there is need for assessment of the clinical significance of Hypoxis - drug interactions. Key words: Herb-drug interactions, cytochrome P450, P-glycoprotein, Hypoxis obtusa, Dicoma anomala.

Streptomycessp. ST8 extracts attenuate growth, acid production, adhesion, biofilm formation, and water-insoluble glucan synthesis ofStreptococcus mutans

The purpose of this study was to evaluate the inhibitory effects of crude extract of endophytic Streptomyces sp . ST8 against Streptococcus mutan s, which is one of the major causes of dental caries and oral diseases. The extract from culture filtrate of endophytic Streptomyces sp. ST8 by ethylacetate has activity against S. mutans ATCC25175 and 104B. The extract at such concentrations (0.05-5 mg/ml) demonstrated inhibition of bacterial adherence on glass surfaces and saliva-coated hydroxyapatite. The crude extract also decreased the activity of glucosyltransferase and glucan-binding lectin from both strains. These results suggest that the crude extract of endophytic Streptomyces sp. ST8 may be a new potential source for pharmaceutical products used for prevention and/or treatment of dental caries and periodontal disease. Key words: adherence, biofilm production, glucan-binding lectin, glucosyltransferase, endophytic Streptomyces, Streptococcus mutans

Anti-HSV-1 activity of Euclea natalensis

The inhibitory effect of crude extracts of Euclea natalensis A. DC. and a naphthoquinone, diospyrin, isolated from this species, was investigated against herpes simplex virus Type 1 (HSV-1) for activity by in vitro studies on primary vervet monkey kidney (VK) cells. Cell toxicity was monitored by determining the effect of the extracts and diospyrin on the monolayers of VK cells. The dose of the plant samples that inhibited 50% cell growth (ID 50 ) after the incubation period was 0.1 mg ml -1 and 0.2 mg ml -1 for acetone and water extracts, respectively. Diospyrin exhibited an ID 50 of 0.02 mg ml -1 on VK cells. The water extract from the roots of the plant was the least toxic to cell cultures and inhibited the replication of HSV-1 moderately at a concentration of 0.2 mg ml –1 . Diospyrin had no inhibitory effect against the virus. However, acetone extracts inhibited the replication of the virus at concentrations ranging from 0.1 mg ml –1 to 0.02 mg ml –1 , as shown by the reduction of virus- induced cytopathogenic effects and the protection of cells in a cell viability assay

The in vitro inhibitory effects of crude extracts of traditional Chinese herbs on 3-hydroxy-3-methylglutaryl-coenzyme A reductase on Vero cells.

Cardiovascular disease is still the leading cause of death in Western countries. Epidemiological studies have shown that hypercholesterolemia is a major risk factor for coronary artery disease. Clinical trials of lipid lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme A (HMG Co-A) reductase inhibitor have been shown to decrease coronary events and mortality. Flavonoids are polyphenolic natural antioxidants occurring in natural products such as traditional Chinese herbs, fruits and beverages such as tea and wine. The aim of this study was to evaluate the effects of crude extracts from traditional Chinese herbs on HMG Co-A reductase. The methods for analysis of specific inhibitors of mevalonate biosynthesis have been well-established by using Vero cells, a cell line obtained from kidneys of African green monkeys. Crude extracts from different traditional Chinese herbs were dissolved in 1% Dulbecco's modified Eagle's medium and incubated with Vero cells with or without the addition of 1 mM mevalonate or 5 mM sodium acetate for 24 hours in order to observe cell growth. Pravastatin, a specific HMG Co-A reductase inhibitor, was used as a positive control which inhibits Vero cells growth effectively and cell growth inhibition was reversible after 1 mM mevalonate. Among 100 traditional Chinese herbs used for the study, only two herbs: Curcuma zedoaria Roscoe and Poncirus trifoliata Raf. showed significant growth inhibition of Vero cells. This study shows that some crude extracts isolated from traditional medicinal herbs were effective HMG Co-A reductase inhibitors which might be developed into new hypocholesterolemic agents.

Inhibitory effect of garlic, clove and carrot on growth ofAspergillus flavus and aflatoxin production

The inhibitory effect of crude extracts of garlic, clove and carrot at concentrations of 20,000, 40,000, 60,000, 80,000 and 100,000 μg/mL on growth ofAspergillus flavus and aflatoxin production in rice was investigated. The results showed that garlic, clove and carrot could inhibit the growth ofA. flavus and aflatoxin production. Garlic and clove at 100,000 μg/mL highly reduced the level of aflatoxin from 5.94 to 0.15 and 0.06 μg/g respectively whereas carrot at 20,000 μg/mL reduced the most level of aflatoxin from 5.94 to 0.03 μg/g. Garlic, clove and carrot at 100,000μg/mL also inhibited the mould growth. The most effective herb for inhibiting the growth ofA. flavus and aflatoxin production was garlic.