Purified compounds and extracts from Euclea species with antimycobacterial activity against Mycobacterium bovis and fast-growing mycobacteria

A Review of the Potential of Poly-(lactide-co-glycolide) Nanoparticles as a Delivery System for an Active Antimycobacterial Compound, 7-Methyljuglone

7-Methyljuglone (7-MJ) is a pure compound isolated from the roots of Euclea natalensis A. DC., a shrub indigenous to South Africa. It exhibits significant promise as a potential treatment for the highly communicable disease tuberculosis (TB), owing to its effective antimycobacterial activity against Mycobacterium tuberculosis. Despite its potential therapeutic benefits, 7-MJ has demonstrated in vitro cytotoxicity against various cancerous and non-cancerous cell lines, raising concerns about its safety for consumption by TB patients. Therefore, this review focuses on exploring the potential of poly-(lactide-co-glycolic) acid (PLGA) nanoparticles as a delivery system, which has been shown to decrease in vitro cytotoxicity, and 7-MJ as an effective antimycobacterial compound.

Ethnobotanical uses, phytochemistry and biological activity of the genus Euclea: A review

Euclea (Ebenaceae) is a genus of flowering shrubs and trees widely distributed in Africa, the Comoro Islands, and Arabia. This review aimed to evaluate the ethnobotanical uses, phytochemistry, and biological activities of the genus Euclea on available research reports. This was achieved through PubMed, Medline, Google Scholar, Science Direct, Taylor and Francis Online, Wiley Online Library which provides access to scientific and medical research. The extensive literature survey revealed that plants that belong to this genus are used as folkloric medicine for the treatment of diabetes mellitus, toothache, diarrhea, cancer, malaria, leprosy, and genital and oral diseases in the case of HIV/AIDS-related diseases. To date, more than 40 secondary metabolites have been isolated and identified from these plants, especially from E natalensis and E. divinorum. Among these, naphthoquinones, terpenes, and flavonoids are potential secondary metabolites with profound biological activities. Euclea plant extracts and their bioactive compounds possess outstanding pharmacological properties, especially antimalarial, antidiabetic, anticancer, antimicrobial, and antioxidant properties.

The use of chemometric modelling to determine chemical composition-antimicrobial activity relationships of essential oils used in respiratory tract infections

The antimicrobial effects of essential oils are commonly cited within aromatherapeutic texts for use in respiratory tract infections. These essential oils are inhaled or applied to the skin to treat infections and manage symptoms associated with these conditions. A limited number of these essential oils have been scientifically studied to support these claims, specifically, against respiratory pathogens. This study reports on the minimum inhibitory concentration (MIC) of 49 commercial essential oils recommended for respiratory tract infections, and identifies putative biomarkers responsible for the determined antimicrobial effect following a biochemometric workflow. Essential oils were investigated against nine pathogens. Three essential oils, Amyris balsamifera (amyris), Coriandrum sativum (coriander) and Santalum austrocaledonicum (sandalwood) were identified as having greater activity (MIC value = 0.03-0.13 mg/ml) compared to the other essential oils investigated. The essential oil composition of all 49 oils were determined using Gas Chromatography coupled to Mass Spectroscopy (GC-MS) analysis and the GC-MS data analysed together with the antimicrobial data using chemometric tools. Eugenol was identified as the main biomarker responsible for antimicrobial activity in the majority of the essential oils. The ability of a chemometric model to accurately predict the active and inactive biomarkers of the investigated essential oils against pathogens of the respiratory tract was 80.33%.

Antimycobacterial cycloartane derivatives from the roots of Trichilia welwistchii C. DC (Meliaceae)

Chemical investigation of the roots of Trichilia welwitschii yielded a cycloartane type terpenoid 28,29-bis-norcycloart-24-en-3β,4α,6α-triol (1), isolated as pure compound for the first time, three coumarins and three sterols. New cycloartane derivatives (1a) and (1b+1c) were obtained by hemi-synthetic reaction of compound 1. The structures of 1a–c were established by spectroscopic methods including 1D and 2D-NMR analysis, HR-EIMS, chemical transformations and by comparison of these data with those of related compounds. Evaluated for their antimycobacterial potential, compound 1 and 1b+1c were determined to show significant activities against Mycobacterium tuberculosis MIC values of 6.25 μg mL−1 while compound 1a displayed weak activity showing MIC > 100 μg mL−1. Compounds 2–4 displayed moderate activity with MIC values range from 12.5 to 50 μg mL−1.

Chemical, Bioactivity, and Biosynthetic Screening of Epiphytic Fungus Zasmidium pseudotsugae

We report the first secondary metabolite, 8,8′-bijuglone, obtained from pure cultures of the slow growing Douglas fir- (Pseudotsuga menziesii var. menziesii) foliage-associated fungus Zasmidium pseudotsugae. The quinone was characterized using extensive LC/MS and NMR-based spectroscopic methods. 8,8′-Bijuglone exhibited moderate antibiotic activity against Gram-positive pathogens and weak cytotoxic activity in the NCI-60 cell line panel and in our in-house human colon carcinoma (HCT-116) cell line. An analysis of the fungal genome sequence to assess its metabolic potential was implemented using the bioinformatic tool antiSMASH. In total, 36 putative biosynthetic gene clusters were found with a majority encoding for polyketides (17), followed by non-ribosomal peptides (14), terpenes (2), ribosomal peptides (1), and compounds with mixed biosynthetic origin (2). This study demonstrates that foliage associated fungi of conifers produce antimicrobial metabolites and suggests this guild of fungi may present a rich source of novel molecules.

Exploring how structural changes to new Licarin A derivatives effects their bioactive properties against rapid growing mycobacteria and biofilm formation

Several species of rapidly growing mycobacteria (RGM) have been associated with biofilms in areas such as biomedical devices, water distribution systems, cosmetic surgery, and catheter-related blood infections. Biofilms which exhibit antimicrobial resistance such as those formed by the genus Mycobacterium pose a significant risk to health and are of particular interest to researchers. Licarin A (a neolignan found in numerous plant species e.g. nutmeg) has been reported to show a wide range of biological actions including anti-inflammatory, antioxidant, and antibacterial properties. The aim of this study was to prepare a set of Licarin A derivatives and investigate the impact of specific structural changes on its antimycobacterial ability, and its effect on the biofilm formation of RGM species. Initially, the phenolic sub-unit and alkenyl side chain of Licarin A were modified to create derivatives with a higher partition coefficient; as the activity of a compound against mycobacteria seems to be strongly influenced by its hydrophobicity. Further, polar groups were inserted into the side chain to change the hydrophilic-lipophilic profile of the molecules. Results showed variability in the susceptibility profile of mycobacteria against the Licarin A derivatives under analysis. A number of the derivatives showed significant inhibitory activity of planktonic growth of the three strains of mycobacteria used, with even lower MIC values than those observed with reference drugs and Licarin A itself. Cytotoxicity assays showed they also have low toxicity, confirming that structural modifications to the Licarin A have made improvements to its antimycobacterial properties.

Review: Southern African medicinal plants used as blood purifiers

ETHNOPHARMALOGICAL RELEVANCE

Blood purification practices, also referred to as blood cleansing or detoxification, is an ancient concept which is widespread amongst African traditional medicine, but for which no modern scientific basis exists. There prevails considerable ambiguity in defining what a blood purifier is.

AIM OF THE STUDY

The purpose of this review is to firstly define what a blood purifier is in the context of African traditional medicine and compare to other cultural and westernized interpretations. Thereafter, this study identifies traditionally used medicinal plants used as blood purifiers in southern Africa and correlates these species to scientific studies, which may support evidence for these "blood purifying plant species".

MATERIALS AND METHODS

Ethnobotanical books and review articles were used to identify medicinal plants used for blood purification. Databases such as Scopus, ScienceDirect, PubMed and Google Scholar were used to source scientific articles. An evaluation was made to try correlate traditional use to scientific value of the plant species.

RESULTS

One hundred and fifty nine plant species have been documented as traditional remedies for blood purification. Most of the plant species have some pharmacological activity, however, very little link to the traditional use for blood purification. There has been some justification of the link between blood purification and the use as an antimicrobial and this has been explored in many of the plant species identified as blood purifiers. Other pharmacological studies specifically pertaining to the blood require further attention.

CONCLUSION

Irrespective of the ambiguity of interpretation, medicinal plants used to "cleanse the blood", play an important holistic role in traditional medicine and this review with recommendations for further study provides some value of exploring this theme in the future.

Effect of 3-O-acetylaleuritolic acid from in vitro-cultured Drosera spatulata on cancer cells survival and migration

BACKGROUND

Drosera spatulata is a source of many compounds such as naphthoquinones, phenolic acids, flavonoids, anthocyanins, and naphthalene derivatives. Unfortunately, the information regarding the biological activity and chemical profile of those compounds is still incomplete. Herein, we investigated the biological activity of 3-O-acetylaleuritolic acid (3-O-AAA) in cancer cell lines.

METHODS

The cell viability of HeLa, HT-29, MCF7, and MCF12A cells was assessed using MTT assay. Proliferation potential was assessed using the clonogenic assay and flow cytometry. Migration modulation was tested using a scratch assay. Protein expression was analyzed by immunoblotting.

RESULTS

3-O-AAA significantly inhibited the growth of all tested tumor cells. The results of the colony formation assay suggested cytostatic properties of the studied compound. The scratch assay showed that 3-O-AAA was an efficient migration inhibitor in a dose-dependent manner. Moreover, it caused modulation of mTOR, beclin1, and Atg5 proteins suggesting a possible role of the compound in autophagy induction.

CONCLUSION

Collectively, these results demonstrated that 3-O-AAA inhibited the proliferation and migration of cancer cell lines as well as contributed to autophagy induction showing some anticancer properties.

Antibacterial and Antimycobacterial Activity of Crude Extracts, Fractions, and Isolated Compounds From Leaves of Sneezewood, Ptaeroxylon obliquum (Rutaceae)

Ptaeroxylon obliquum (Thunb.) Radlk. (Rutaceae) is traditionally used to treat human and animal diseases in South Africa. In this study, the activity of leaf extracts, fractions, and isolated compounds was determined against nonpathogenic mycobacterial species and nosocomial bacterial pathogens. An acetone leaf extract was partitioned by liquid-liquid fractionation, and obliquumol, a mixture of lupeol and β-amyrin, and eranthin were isolated. Antimicrobial activity was determined using a serial microdilution assay against Mycobacterium smegmatis (American Type Culture Collection [ATCC] 1441), M. bovis (BCG P1172), M. aurum (NCTC 10437), M. fortuitum (ATCC 6841), Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 25922), and Escherichia coli (ATCC 27853). The n-hexane fraction had minimal inhibitory concentration (MIC) values as low as 20 and 40 µg/mL against M. fortuitum and S. aureus, respectively. The chloroform fraction also had promising activity with an MIC value of 80 µg/mL against both P. aeruginosa and M. fortuitum. Obliquumol had excellent activity (MIC 8 µg/mL) against M. fortuitum. Fractionation of the crude extract potentiated the antimicrobial activity of the nonpolar fractions. The isolated compound, obliquumol, had good antimicrobial and excellent antimycobacterial activities. The antimicrobial activity provides some scientific rationale for the use of P. obliquum against infectious diseases and related symptoms. This is the first report on the antibacterial activity of obliquumol.

Scientific rationale for traditional use of plants to treat tuberculosis in the eastern region of the OR Tambo district, South Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Tuberculosis (TB) remains a major health problem for humans worldwide, and was responsible for 1.4 million human deaths in 2015 alone. Although there is treatment for TB, emerging multi-drug, extensively drug and totally drug resistant forms of this disease, as well as co-infection with human immunodefiency virus (HIV) continue to worsen the situation. South Africa is among countries with reported traditional use and published documentation of such knowledge concerning the use of plants against TB. Based on a previous study where plants used traditionally for treating TB in the eastern region of OR Tambo district, South Africa, were documented, the present study aimed to determine the antimycobacterial effect, cytotoxicity and genotoxicity of plants selected from that list.

MATERIAL AND METHODS

Acetone, 70% ethanol, cold and hot water extracts were tested for antimycobacterial activity against saprophytic Mycobacterium species including M. aurum, M. bovis BCG, M. gordonae, M. fortuitum, and M. smegmatis using a microdilution method. Extracts with MIC values less than 1 mg/ml against at least three Mycobacterium strains were evaluated for antimycobacterial activity against pathogenic Mycobacterium strains including M. tuberculosis H37RV, M. tuberculosis and M. bovis, cytotoxicity (against Vero monkey kidney and bovine dermis cells), and genotoxicity (against Salmonella typhimurium TA98 and TA100).

RESULTS

The MIC values of the extracts ranged from 0.02 to 2.50 mg/ml, LC₅₀ values of twenty-nine extracts ranged from 0.001 to > 1 mg/ml and the highest selectivity index was 79.50, an extremely promising value. Phymaspermum acerosum roots and leaves (ethanol and water) extracts had the best MIC value (0.02 mg/ml) against at least one Mycobacterium strain. It was interesting to note the lack of cytotoxicity of these extracts with the highest selectivity index value of 39.75. Pterocelastrus echinatus bark acetone and Protorhus longifolia leaf hot water extracts were the most cytotoxic with LC₅₀ = 0.001 and 0.008 mg/ml, respectively, whereas Pittosporum viridiflorum bark water extract was genotoxic. Among non-pathogenic strains, M. gordonae, M. aurum, M. smegmatis showed good correlation of activity with pathogenic M. tuberculosis H37Rv, M. tuberculosis and M. bovis, however, M. aurum was the best predictor with Mycobacterium tuberculosis H37Rv (correlation coefficient value = 0.73).

CONCLUSION

The results indicate that Heteromorpha trifoliata and Phymaspermum acerosum should be investigated further for antimycobacterial efficacy against drug resistant strains of Mycobacterium.

A comprehensive study of the potential phytomedicinal use and toxicity of invasive Tithonia species in South Africa

BACKGROUND

Tithonia diversifolia and T. rotundifolia belong to the Asteraceae family and are native to Mexico and Central America. These plants have become invasive in parts of tropical Africa and Asia where they have become an ecological, agricultural and economic burden. Tithonia diversifolia is exploited by locals in its native and most parts of its invasive range as a source of medicines; however, T. rotundifolia is only used for medicinal purposes in one country in the native range (Venezuela) and none in the invasive range. Although T. diversifolia has been studied for different biological activities, little or no attention has been given to T. rotundifolia. This study compared the antimicrobial activity, phytochemistry, identification of bioactive compound(s) and toxicity levels of different leaf extracts and fractions of T. diversifolia and T. rotundifolia.

METHODS

Antimicrobial activity was evaluated against seven pathogenic bacteria, four non-pathogenic Mycobacterium species and three fungal species using serial microdilution assays. Phytochemical contents were determined through standard methods of analysis. UPLC/MS was used to analyse the fractions to identify possible bioactive compounds that may be responsible for bioactivity, while toxicity tests were carried out using the colorimetric MTT assay and the Ames test.

RESULTS

Both species had a range of antimicrobial activity against bacterial, mycobacterial and fungal species. However, T. rotundifolia displayed better activity against most of the strains tested with minimum inhibitory concentration values ranging between 0.01 and 0.07 mg/ml. Both species were rich in phenolics, flavonoids and tannins. Tagitinin A was identified as the main compound present in both species, and this compound may be responsible for the antimicrobial activity displayed. Toxicity tests showed that T. diversifolia was cytotoxic at concentrations used in this study, while T. rotundifolia was not. Both species did not show any mutagenic/genotoxic effects.

CONCLUSION

The above results suggest that both species may be further developed as a source of antimicrobials for the treatment of infections caused by opportunistic pathogens. They may also serve as alternatives to highly exploited plant species with the same medicinal properties. However, T. diversifolia should be used with caution as it may be toxic.

Review of Ethnomedicinal Uses, Phytochemistry and Pharmacological Properties of Euclea natalensis A.DC

Euclea natalensis is traditionally used as herbal medicine for several human diseases and ailments in tropical Africa. This study reviews information on ethnomedicinal uses, botany, phytochemical constituents, pharmacology and toxicity of E. natalensis. Results of this study are based on literature search from several sources including electronic databases, books, book chapters, websites, theses and conference proceedings. This study showed that E. natalensis is used as traditional medicine in 57.1% of the countries where it is indigenous. Euclea natalensis has a high degree of consensus on abdominal pains, antidote for snake bites, diabetes, diarrhoea, malaria, roundworms, stomach problems, toothache, venereal diseases and wounds. Several ethnopharmacological studies have shown that crude extracts and chemical compounds from E. natalensis demonstrated many biological activities both in vitro and in vivo, which included antibacterial, antidiabetic, antifungal, antimycobacterial, antiviral, antioxidant, antiplasmodial, larvicidal, antischistosomal, molluscicidal, dentin permeability and hepatoprotective activities. Future studies should focus on the mechanism of biological activities of both crude extracts and chemical compounds from the species, as well as structure-function relationships of bioactive constituents of the species.

Acetone leaf extracts of some South African trees with high activity against Escherichia coli also have good antimycobacterial activity and selectivity index

Background

Tuberculosis is a world-wide problem affecting humans and animals. There is increasing development of resistance of the pathogens to current antimycobacterial agents. Many authors have investigated activities of extracts and isolated compounds from plants. The traditional uses of plants have frequently been the criterion to select plants investigated. In this contribution, we investigate whether plant extracts with very good activity against Escherichia coli may also be active against mycobacteria.

Methods

The antimycobacterial activity of eight South African tree leaf extracts with high activity against Escherichia coli were determined in vitro against Mycobacterium smegmatis, M. fortuitum and M. aurum, using a serial microdilution method. The cellular cytotoxicity was also determined by the MTT assay using Vero monkey kidney cells. The selectivity index was determined by dividing the cytotoxicity of extracts by MIC.

Results

The antimycobacterial activity of the extracts ranged from 0.02 to 2.5 mg/ml. Mycobacterium smegmatis was more sensitive to the extracts (Average MIC = 0.96 mg/ml) and Mycobacterium aurum was comparatively resistant (Average MIC = 2.04 mg/ml). The extracts of Cremaspora triflora had strong antimycobacterial activity with a MIC of 0.05 mg/ml that compared reasonably well with that of streptomycin (0.01 mg/ml) and rifampicin (0.03 mg/ml), p > 0.05. Cremaspora triflora had the best selectivity index of 2.87 against Mycobacterium fortuitum.

Conclusion

The high activity of C. triflora extracts against the fast-growing mycobacteria and good cellular safety is promising. It may be interesting to investigate extracts against pathogenic M. tuberculosis, M. bovis and M. avium cultures and to isolate active antimycobacterial compounds.

The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts

Background

The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells.

Results

The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC₅₀ > 20 μg/ml. Cremaspora triflora had the best selectivity index (SI) against S. aureus and E. coli of 2.87 and 1.15 respectively. Hypericum roeperianum had a SI of 1.10 against B. cereus. Bioautography revealed 1–6 visible antimicrobial compounds that were generally non-polar.

Conclusions

There was a weak positive, but statistically non-significant correlation between the potency of the extracts and their cytotoxicity (R = 0.45, ρ > 0.05). The activity of the extracts on the test bacteria was in some cases not correlated with cytotoxicity, as shown by selectivity indices >1. This means that cellular toxicity was probably not due to compounds with antibacterial activity. Some of the extracts had a good potential for therapeutic use against the bacterial pathogens or for application in treating diarhoea. It does not appear that activity against E. coli is a good predictor of activity against Gram-negative rather than Gram-positive bacteria. Further investigation is in progress on C. triflora and H. roeperianum, both of which had promising activities and potential safety based on cytotoxicity.

Anti-mycobacteria potential and synergistic effects of combined crude extracts of selected medicinal plants used by Bapedi traditional healers to treat tuberculosis related symptoms in Limpopo Province, South Africa

Background

Tuberculosis is an infectious communicable disease and the causative agent of the disease has over the years developed resistance to streamline chemotherapeutic agents with dire consequences and there is a need for development of new and more potent alternatives.

Methods

Constituents of leaves material of Combretum heroroense, Citrus lemon and Apodytes dimidiata were serially extracted using solvents of varying polarity. TLC finger print profile of the different extracts were determined by spraying eluted plates with vanillin sulphuric acid and 2, 2- diphenylpicryl hydrazyl (DPPH) for the presence of antioxidant constituents. Presence of different phytochemicals was determined using standard chemical test. Bioautography was used to determine the number of compounds present in sub-fractions active against Mycobacterium smegmatis. Minimum inhibitory concentration (MIC) values extract and sub-fractions were determined using serial microplate dilution method against M. smegmatis (ATCC 1441), M. tuberculosis (ATCC H37Rv) and multi-drug resistant TB (MDR-TB) field strain. Synergy of the crude extracts of the three plants was determined using microplate dilution method against M. smegmatis.

Results

Mass extracted by different solvents was less than 6% dry weight for all the plants. Phlobatannins were not detected in A. dimidiata, C. heroroense and C. lemon as well as cardiac glycosides in C. lemon and A. dimidiata, and saponins in C. heroroense. Sub-fractions of the different plants were shown to contain constituents with antioxidant activity with the highest number detected in C. heroroense. Bioautography results reveal the presence of a compound(s) in the ethyle acetate sub-fraction of C. heroroense and butanol, methanol/water, ethyl acetate and water no.2 subfractions of A. dimidiata, active against M. smegmatis that were not shown to have antioxidant capacity. MIC results for different crude extracts of the three plants against M. smegmatis ranges from 0.1 to 3 mg/ml. The average MIC for the synergistic effect of the plants ranged from 0.04 mg/ml to 1.25 mg/ml. An activity greater than that obtained for the reference drugs was shown for the butanol and hexane fractions of A. dimidiata (0.47 mg/ml) against the field strain of MDR-TB while that obtained for the M.TB (ATCC H37Rv) was 0.31 mg/ml.

Conclusion

A significant finding shown in this study reveals the potent anti-mycobacteria potential of sub-fractions of A. dimidiata against MDR-TB field strain that can lead to the isolation of compounds that can be used to counter resistant strains of tuberculosis.

Aqueous extracts of Mozambican plants as alternative and environmentally safe acid-base indicators

Indicators are substances that change color as the pH of the medium. Many of these substances are dyes of synthetic origin. The mulala plant (Euclea natalensis), which roots are commonly used by rural communities for their oral hygiene, and roseira (Hibiscus rosa-sinensis), an ornamental plant, are abundant in Mozambique. Currently, synthetic acid-base indicators are most commonly used but have environmental implications and, on the other hand, are expensive products, so the demand for natural indicators started. This study investigated the applicability of aqueous extracts of H. rosa-sinensis and E. natalensis as acid-base indicators. Ground on this work, the extracts can be used as acid-base indicators. On the basis of the absorption spectroscopy in both the UV-Vis region and previous studies, it was possible to preliminarily pinpoint anthocyanins and naphthoquinones as responsible for the shifting of colors depending on the pH range of aqueous extracts of H. rosa-sinensis and E. natalensis. These natural indicators are easily accessible, inexpensive, easy to extract, environmentally safe, and locally available.

Anti-mycobacterial activity of polyketides from Penicillium sp. endophyte isolated from Garcinia nobilis against Mycobacteriumsmegmatis

OBJECTIVE/BACKGROUND

According to estimates by the World Health Organization, there were 9.6 million new tuberculosis (TB) cases in 2014: 5.4 million among men, 3.2 million among women, and 1.0 million among children. There were also 1.5 million TB deaths. Although there are potent anti-TB molecules, the misuse of these drugs in addition to inconsistent or partial treatment have led to the development of multidrug-resistant TB and extensively drug-resistant TB. It is established that plants harbor microorganisms, collectively known as endophytes, which also produce metabolites. Exploring the as-yet untapped natural products from the endophytes increases the chances of finding novel and active compounds. The present study was aimed to investigate the antimycobacterial activity of the crude extract and compounds isolated from Penicillium sp. endophyte associated with Garcinia nobilis against Mycobacterium smegmatis.

METHODS

Liquid culture obtained from the fermentation of Penicillium sp. was extracted using ethylacetate and the liquid chromatography-mass spectrometry monitored fractionation of crude extracts yielded six compounds. Their structures were elucidated with spectroscopic analyses including two-dimensional nuclear magnetic resonance, high resolution mass spectrometry by dereplication using Antibase, and by comparison to literature data. All compounds and the crude extract from the liquid medium were evaluated for their antimycobacterial activity against M. smegmatis.

RESULTS

In this study, the activity of penialidins A-C (1-3), citromycetin (4), p-hydroxy phenyl glyoxalaldoxime (5), and Brefeldin A (6) were tested against nonpathogenic M. smegmatis. Penialidin C was the most active compound with a minimum inhibitory concentration of 15.6μg/mL.

CONCLUSION

Isolated compounds from Penicillium sp. harbored in G. nobilis exhibited promising antimycobacterial activity against M. smegmatis thus supporting the immensity of the potential of antimycobacterial drug discovery from endophytes from medicinal plants. Penialidin C could further be investigated for antimycobacterial drug development.

The antibacterial, phytochemicals and antioxidants evaluation of the root extracts of Hydnora africanaThunb. used as antidysenteric in Eastern Cape Province, South Africa

Background

To determine the anti-dysenteric, phytochemicals and antioxidative properties of the root extracts of Hydnora africana. The use of plants for the treatment of dysentery and other diseases in traditional medicine has increased on the basis of these rich traditional medicine systems. Series of pharmacological tests are recommended since the aetiology of many diseases may be due to more than one factor.

Methods

The agar well diffusion method was used to determine the susceptibility of bacterial strains to crude extracts of the plant. The minimum inhibitory concentration was determined by the microdilution test. The presence of phytochemicals and antioxidant was also assessed using standard methods.

Results

The antimicrobial activity of H. africana against all the tested organisms demonstrated a mean zone diameter of inhibition ranging from 0 to 25 mm. The MIC of the extracts ranged from 0.071 to 5.0 mg/mL. Antioxidant activity showed lower ferric reducing activities, moderate nitric oxide, moderate DPPH and higher ABTS scavenging activities of the plant. Phytochemical assay revealed the presence and equivalent quantity of alkaloids, tannins, flavonoids, saponins and phenolic acid in the extracts. The water and methanol extracts were also shown as the best solvents of extraction for the phytochemicals.

Conclusions

The methanol and acetone extracts of H. africana exhibited a significant antibacterial and antioxidant activities, suggesting the presence of either good bioactive potency or the high concentration of the active principle in the extracts which may serve as a guide for selecting bio- medicinal substances of plant origin in antidysenteric drugs.

The 15-lipoxygenase inhibitory, antioxidant, antimycobacterial activity and cytotoxicity of fourteen ethnomedicinally used African spices and culinary herbs

ETHNOPHARMACOLOGICAL RELEVANCE

Culinary herbs and spices are widely used ethnomedically across Africa. They are traditionally employed in the treatment of several ailments including inflammation disorders, pain alleviation and infectious diseases. Pharmacological studies are necessary to provide a scientific basis to substantiate their traditional use and safety. In this study, the 15-lipoxygenase inhibitory, antioxidant, antimycobacterial and the cytotoxic activities, total phenolic and flavonoid contents of fourteen edible plants were investigated.

MATERIALS AND METHODS

The 15-lipoxygenase inhibitory activity was evaluated by the ferrous oxidation-xylenol orange (FOX) assay method. The antioxidant activity was determined using free-radical scavenging assays. The antimycobacterial activity was determined by a broth microdilution method against three species of mycobacteria: Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium fortuitum using tetrazolium violet as growth indicator. The cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on Vero monkey kidney cells.

RESULTS

All the extracts tested had some 15-lipoxygenase inhibitory activity ranging from 32.9 to 78.64%. Adansonia digitata (fruit) had the highest antioxidant capacity (IC₅₀ values of 8.15 μg/mL and 9.16 μg/mL in the DPPH and ABTS assays respectively; TEAC of 0.75 in the FRAP assay) along with the highest amount of total phenolics (237.68 mg GAE/g) and total flavonoids (16.14 mg E/g). There were good correlations between DPPH and ABTS values (R(2) 0.98) and between total phenolics and total flavonoids (R(2) 0.94). Tamarindus indica had significant antimycobacterial activity against Mycobacterium aurum (MIC 78 μg/mL). As could be expected with edible plants, all the extracts had a relatively low cytotoxicity with LC₅₀ values higher than 102 μg/mL with the exception of the two Aframomum species (33 and 74 μg/mL).

CONCLUSIONS

This study provides scientific support for some of the the traditional uses and the pharmacological activities of the culinary herbs and spices investigated. The results suggest that increasing intake of some of these herbs may be useful in preventing or reducing the progression of lifestyle-related diseases. The diversity of the pharmacological activities of the extract from the fruit of Adansonia digitata suggested that this plant might be valuable for application in human and animal health.

Review of the chemistry and pharmacology of 7-Methyljugulone

BACKGROUND

Naphthoquinone is a class of phenolic compounds derived from naphthalene. 7-Methyljuglone (7-MJ) is a naphthoquinone also known as ramentaceone or 6-Methyl-8-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-1,4-naphthoquinone or 7-Methyl-5-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-,1,4-naphtoquinone or 7-Methyl-5-hydroxynaphthalene-1,4-dione. This compound is a biologically active naphtoquinone, with a molecular weight of 188 g/mol mostly isolated in the genus Diospyros and Euclea.

OBJECTIVES

This review was aimed at providing available chemically and pharmacological data on 7-MJ.

METHODS

The chemical and pharmacological data were retrieved from the well-known scientific websites such as Pubmed, Google Scholar, Reaxys, Scirus, Scopus, Sciencedirect, Web-of-knowledge and Scifinder.

RESULTS

7-MJ was reported to have a variety of pharmacological activities such as antibacterial, antifungal, anticancer, antitubercular, anti-inflammatory and antiviral activities. The hemi-synthesis of the compound have been described.

CONCLUSIONS

The present review pooled out together the knowledge on 7-MJ, and can serve as the start point for future research and valorization accomplishments.

Evaluation of anti-bacterial and anti-oxidant potential of andrographolide and echiodinin isolated from callus culture of Andrographis paniculata Nees

OBJECTIVE

To evaluate the anti-bacterial and anti-oxidant activity of andrographolide (AND) and echiodinin (ECH) of Andrographis paniculata.

METHODS

In this study, an attempt has been made to demonstrate the anti-microbial and anti-oxidant activity of isolated AND and ECH by broth micro-dilution method and 2,2-diphenyl-2-picryl-hydrazyl (DPPH) assay, respectively. Structure elucidation was determined by electro-spray ionization-MSD, NMR ((1)H and (13)C) and IR spectra.

RESULTS

AND was effective against most of the strains tested including Mycobacterium smegmatis, showing broad spectrum of growth inhibition activity with Minimum inhibitory concentration values against Staphylococcus aureus (100 µg/mL), Streptococcus thermophilus (350 µg/mL) Bacillus subtilis (100 µg/mL), Escherichia coli (50 µg/mL), Mycobacterium smegmatis (200 µg/mL), Klebsiella pneumonia (100 µg/mL), and Pseudomonas aeruginosa (200 µg/mL). ECH showed specific anti-bacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa at a concentration higher than 225 µg/mL. Both AND and ECH were not effective against the two yeast strains, Candida albicans and Saccharomyces cerevisiae tested in this study.

CONCLUSION

This preliminary study showed promising anti-bacterial activity and moderate free radical scavenging activity of AND and ECH, and it may provide the scientific rationale for its popular folklore medicines.

Evaluation of an Experimental Gel Containing Euclea natalensis: An In Vitro Study

Objective. To evaluate the effect of an experimental gel containing Euclea natalensis extract on dentin permeability. Methods. Thirty-six dentin discs, 1-mm-thick. The discs were prepared from the coronal dentin of extracted human third molars that were divided into 3 groups (n = 10). The dentin discs in each group were treated with the groups following experimental materials: (FG): 1.23% fluoride gel, pH 4.1; (EG): Euclea natalensis extract gel, pH 4.1; (CG): control gel, pH 4.1. The gels were applied to the occlusal slide of the dentin under the following conditions: after 37% phosphoric acid and before 6% citric acid. The hydraulic conductance (HC) of each condition was determined four times using a fluid flow apparatus (Flodec). The data were analyzed using Two-way ANOVA and Tukey's test (P < 0.05). Results. The greatest mean reduction in HC was produced in group EG dentin discs (61.2%; P < 0.05). Even after acid challenge with 6% citric acid the great reduction occurred in group EG (66.0%; P < 0.05) than other groups (CG-77.1%, FG-90.8%). Conclusion. E. natalensis gel not only reduced dentin permeability, but also resisted posttreatment citric acid challenge without changing its permeability. Further research has to confirm this promising result in the clinical situation.

Antibacterial activity of two biflavonoids from Garcinia livingstonei leaves against Mycobacterium smegmatis

Amentoflavone and 4' monomethoxy amentoflavone were previously isolated from Garcinia livingstonei leaves. These compounds had good activities (MIC 6 and 8 μg/ml) against some nosocomial bacteria. In this study, the activity of these purified compounds were tested against fast-growing non-pathogenic Mycobacterium smegmatis. Amentoflavone was the most active compound, with an MIC of 0.60 ± 0.70 mg/ml. The MIC of 4' monomethoxy amentoflavone and the positive control isoniazid against Mycobacterium smegmatis were similar 1.40 ± 1.56 and 1.30 ± 1.70 mg/ml respectively. Although, Mycobacterium smegmatis is a non-pathogenic fast growing mycobacterium the activities of these compounds may also be useful in combating infections by pathogenic Mycobacterium spp.

The potential of South African plants against Mycobacterium infections

ETHNOPHARMACOLOGICAL RELEVANCE

In South Africa, tuberculosis (TB) caused by Mycobacterium tuberculosis is the most commonly notified disease and the fifth largest cause of mortality, with one in ten cases of TB resistant to treatment in some areas. Many plants are used locally in traditional medicine to treat TB-related symptoms.

AIM OF THE STUDY

The aim was to summarize currently available knowledge on South African plants used to treat TB symptoms, and antimycobacterial efficacy of plant-derived extracts and compounds.

MATERIALS AND METHODS

The traditional uses of plants for respiratory ailments and TB were collated and tabulated. The antimycobacterial activity tests of extracts and chemical constituents of several of these plants and others using different methods and target organisms were summarized.

RESULTS

Almost 180 plants used for TB-related symptoms in South African traditional medicine were documented. About 30% of these have been tested for antimycobacterial efficacy, mostly against fast-growing, non-pathogenic Mycobacterium species.

CONCLUSIONS

Many plant species are used in traditional South African medicine to alleviate symptoms of TB, and several interesting leads have originated for further inquiry following in vitro antimycobacterial activity evaluation. However, much work remains to be done on the systematic assessment of anti-TB efficacy of local plants against pathogenic Mycobacterium species, both in vitro and in vivo.