Optimization of Antioxidant Synergy in a Polyherbal Combination by Experimental Design.

Culinary herbs and spices are known to be good sources of natural antioxidants. Although the antioxidant effects of individual culinary herbs and spices are widely reported, little is known about their effects when used in combination. The current study was therefore undertaken to compare the antioxidant effects of crude extracts and essential oils of some common culinary herbs and spices in various combinations. The antioxidant interactions of 1:1 combinations of the most active individual extracts and essential oils were investigated as well as the optimization of various ratios using the design of experiments (DoE) approach. The 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays were used to determine the antioxidant activity, and MODDE 9.1® software (Umetrics AB, Umea, Sweden) was used to determine the DoE. The results revealed synergism for the following combinations: Mentha piperita with Thymus vulgaris methanol extract (ΣFIC = 0.32 and ΣFIC = 0.15 using the DPPH and FRAP assays, respectively); Rosmarinus officinalis with Syzygium aromaticum methanol extract (ΣFIC = 0.47 using the FRAP assay); T. vulgaris with Zingiber officinalis methanol extracts (ΣFIC = 0.19 using the ABTS assay); and R. officinalis with Z. officinalis dichloromethane extract (ΣFIC = 0.22 using the ABTS assay). The DoE produced a statistically significant (R2 = 0.905 and Q2 = 0.710) model that was able to predict extract combinations with high antioxidant activities, as validated experimentally. The antioxidant activities of the crude extracts from a selection of culinary herbs and spices were improved when in combination, hence creating an innovative opportunity for the future development of supplements for optimum health.

Three-Dimensional Printability of an ECM-Based Gelatin Methacryloyl (GelMA) Biomaterial for Potential Neuroregeneration.

The current study introduces two novel, smart polymer three-dimensional (3D)-printable interpenetrating polymer network (IPN) hydrogel biomaterials with favorable chemical, mechanical, and morphological properties for potential applications in traumatic brain injury (TBI) such as potentially assisting in the restoration of neurological function through closure of the wound deficit and neural tissue regeneration. Additionally, removal of injury matter to allow for the appropriate scaffold grafting may assist in providing a TBI treatment. Furthermore, due to the 3D printability of the IPN biomaterials, complex structures can be designed and fabricated to mimic the native shape and structure of the injury sight, which can potentially assist with neural tissue regeneration after TBI. In this study, a peptide-only approach was employed, wherein collagen and elastin in a blend with gelatin methacryloyl were prepared and crosslinked using either Irgacure or Irgacure and Genipin to form either a semi or full IPN hydrogel 3D-printable neuromimicking platform system, respectively. The scaffolds displayed favorable thermal stability and were amorphous in nature with high full width at half-maximum values. Furthermore, no alteration to the peptide secondary structure was noted using Fourier transform infrared spectroscopy. The IPN biomaterials have a stiffness of around 600 Pa and are suitable for softer tissue engineering applications-that is, the brain. Scanning electron micrographs indicated that the IPN biomaterials had a morphological structure with a significant resemblance to the native rat cortex. Both biomaterial scaffolds were shown to support the growth of PC12 cells over a 72 h period. Furthermore, the increased nuclear eccentricity and nuclear area were shown to support the postulation that the IPN biomaterials maintain the cells in a healthy state encouraging cellular mitosis and proliferation. The Genipin component of the full IPN was further shown to exhibit antimicrobial properties and this suggests that Genipin can prevent the growth of pathogens associated with postsurgical brain infections. In addition to these findings, the study presents an anomaly, wherein the full IPN is found to be more brittle than the semi IPN, a finding that is in contradiction with the literature. This research, therefore, contributes to the collection of potential biomaterials for TBI applications coupled with 3D printing and can assist in the progression of neural treatments toward patient-specific scaffolds through the development of custom scaffolds.

South Africa's Best BARK Medicines Prescribed at the Johannesburg Muthi Markets for Skin, Gut, and Lung Infections: MIC's and Brine Shrimp Lethality.

Indigenous trade of medicinal plants in South Africa is a multi-million-rand industry and is still highly relevant in terms of primary health care. The purpose of this study was to identify today's most traded medicinal barks, traditionally and contemporaneously used for dermatological, gastrointestinal, and respiratory tract infections; then, to investigate the antimicrobial activity and toxicity of the respective extracts and interpret outcomes in light of pharmacokinetics. Thirty-one popularly traded medicinal barks were purchased from the Faraday and Kwa Mai-Mai markets in Johannesburg, South Africa. Information on the medicinal uses of bark-based medicines in modern commerce was recorded from randomly selected traders. The minimum inhibitory concentration (MIC) method was used for antimicrobial screening, and brine shrimp lethality was used to determine toxicity. New medicinal uses were recorded for 14 bark species. Plants demonstrating some broad-spectrum activities against tested bacteria include Elaeodendron transvaalense, Erythrina lysistemon, Garcinia livingstonei, Pterocelastrus rostratus, Rapanea melanophloeos, Schotia brachypetala, Sclerocarya birrea, and Ziziphus mucronata. The lowest MIC value of 0.004 mg/mL was observed against Staphylococcus epidermidis for a dichloromethane bark extract of E. lysistemon. The tested medicinal barks were shown to be non-toxic against the Artemia nauplii (brine shrimp) bioassay, except for a methanol extract from Trichilia emetica (69.52% mortality). Bacterial inhibition of bark extracts with minimal associated toxicity is consistent with the safety and valuable use of medicinal barks for local muthi market customers. Antimicrobial outcomes against skin and gastrointestinal pathogens are feasible because mere contact-inhibition is required in vivo; however, MIC values against respiratory pathogens require further explaining from a pharmacokinetics or pharmacodynamics perspective, particularly for ingested rather than smoked therapies.

The traditional use of southern African medicinal plants in the treatment of viral respiratory diseases: A review of the ethnobotany and scientific evaluations.

ETHNOPHARMACOLOGICAL RELEVANCE: Viral respiratory infections are amongst the most common infections globally, with most of the world's population contracting at least one infection annually. Numerous plant species are used in traditional southern African healing systems to treat these diseases and to alleviate the symptoms. Despite this, the therapeutic potential of these plants against viral respiratory diseases remains poorly explored. AIM OF THE STUDY: The aim of this study was to document the southern African plant species used in traditional medicine to treat viral respiratory infections. We also examined the extent of scientific evaluations of southern African plant species against the respiratory-infective viruses, with the aim of stimulating interest in this area and focusing on future studies. MATERIALS AND METHODS: We undertook an extensive review of ethnobotanical books, reviews and primary scientific studies to identify southern African plants which are used in traditional southern African medicine to treat viral respiratory diseases. This information was used to identify gaps in the current research that require further study. RESULTS: Two hundred and fifty-seven southern African plant species were identified as traditional therapies for viral respiratory diseases. Surprisingly, only one of those species (as well as twenty-one other species not recorded for these purposes) has been evaluated for the ability to block respiratory virus production. Furthermore, most of these studies screened against a single viral strain and none of those studies examined the mechanism of action of the plant preparations. CONCLUSIONS: Despite well documented records of the use of southern African plants to treat respiratory viral diseases, the field is poorly explored. Nearly all of the plant species used in traditional healing systems to treat these diseases are yet to be tested. Substantial further work is required to verify the efficacy of these traditional medicines.

The traditional use of southern African medicinal plants for the treatment of bacterial respiratory diseases: A review of the ethnobotany and scientific evaluations.

ETHNOPHARMACOLOGICAL RELEVANCE: Multiple plant species were used traditionally in southern Africa to treat bacterial respiratory diseases. This review summarises this usage and highlights plant species that are yet to be verified for these activities. AIM OF THE STUDY: This manuscript reviews the traditional usage of southern African plant species to treat bacterial respiratory diseases with the aim of highlighting gaps in the literature and focusing future studies. MATERIALS AND METHODS: An extensive review of ethnobotanical books, reviews and primary scientific studies was undertaken to identify southern African plants which are used in traditional southern African medicine to treat bacterial respiratory diseases. We also searched for southern African plants whose inhibitory activity against bacterial respiratory pathogens has been conmfirmed, to highlight gaps in the literature and focus future studies. RESULTS: One hundred and eighty-seven southern African plant species are recorded as traditional therapies for bacterial respiratory infections. Scientific evaluations of 178 plant species were recorded, although only 42 of these were selected for screening on the basis of their ethnobotanical uses. Therefore, the potential of 146 species used teraditionally to treat bacterial respiratory diseases are yet to be verified. CONCLUSIONS: The inhibitory properties of southern African medicinal plants against bacterial respiratory pathogens is relatively poorly explored and the antibacterial activity of most plant species remains to be verified.

Odoriferous Therapy: A Review Identifying Essential Oils against Pathogens of the Respiratory Tract.

This review explores the body of scientific information available on the antimicrobial properties of essential oils against pathogens responsible for respiratory infections and critically compares this to what is recommended in the Layman's aroma-therapeutic literature. Essential oils are predominantly indicated for the treatment of respiratory infections caused by bacteria or viruses (total 79.0 %), the efficacy of which has not been confirmed through clinical trials. When used in combination, they are often blended for presumed holistic synergistic effects. Of the essential oils recommended, all show some degree of antioxidant activity, 50.0 % demonstrate anti-inflammatory effects and 83.3 % of the essential oils showed antihistaminic activity. Of the essential oils reviewed, 43.8 % are considered non-toxic while the remaining essential oils are considered slightly to moderately toxic (43.7 %) or the toxicity is unknown (12.5 %). Recommendations are made for further research into essential oil combinations.

Carrier oils in dermatology.

Wounds are a common medical infliction. With the increase in microbial resistance and a shift of interest towards complementary medicines, essential oils have been shown to be beneficial in suppressing microbial growth. However, in practice, essential oils are more often diluted into a base due to the risk of topical adverse effects, such as dermatitis. There is a lack of collated evidence-based information on toxicity and efficacy of carrier oils. The current information on the subject matter is restricted to generic, aroma-therapeutic books and pamphlets, based on anecdotal evidence rather than an experimental approach. Therefore, this review aimed at identifying the recommended carrier oils used in dermatology and thereafter collating the scientific evidence to support the use of carrier oils together with essential oils recommended for dermatological use. Aloe vera gel had multiple studies demonstrating the ability to enhance wound healing; however, several other carrier oils have been largely neglected. It was observed that the extracts for certain plant species had been used to justify the use of the carrier oils of the same plant species. This is an inaccurate cross assumption due to the difference in chemical composition and biological activities. Lastly, despite these carrier oils being recommended as a base for essential oils, very little data was found on the interactive profile of the carrier oil with the essential oil. This review provides a platform for further studies, especially if essential oils are to receive credence in the scientific field.

The Influence of Carrier Oils on the Antimicrobial Activity and Cytotoxicity of Essential Oils.

The topical use of essential oils requires dilution into a carrier oil; however, scientific evidence regarding the antimicrobial efficacy and cytotoxicity when a carrier oil is combined with an essential oil is lacking. This study sets out to determine the antimicrobial activity and cytotoxicity of 23 essential oils combined with six known carrier oils. Gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID) was used to characterize the methyl esters of the carrier oils. The antimicrobial activity of the carrier oils alone and in combination with the essential oils was investigated using the broth microdilution assay against 11 skin pathogens and the cytotoxicity was determined using the brine shrimp lethality assay. The interactive profiles of the combinations for both antimicrobial activity and the cytotoxicity were analysed and calculated using the fractional inhibitory concentration index (ΣFIC). The carrier oils demonstrated no antimicrobial antagonism when combined with the essential oils and the overall cytotoxicity of the majority of the combinations was decreased. The carrier oils that could be identified as enhancing the antimicrobial activity and decreasing the cytotoxicity were Aloe vera Mill. and Simmondsia chinensis C.K.Schneid (Jojoba oil), with an overall reduction in essential oil cytotoxicity of 87.5% at 24 hrs and 85% at 48 hrs by A. vera. Five of the essential oils (when diluted in A. vera and S. chinensis carrier oils) demonstrated enhanced antimicrobial activity against pathogens such as Brevibacterium epidermidis, B. linens, and P. aeruginosa with MIC values ranging from 0.09 to 0.50 mg/mL (and ΣFIC 0.14-0.39). The study could conclude that the carrier oils are complementary to essential oil formulations, mostly reducing cytotoxicity and in some cases enhancing the antimicrobial activity.

Synthesis of silver nanoparticles from a Desmodium adscendens extract and its antibacterial evaluation on wound dressing material.

The one-pot synthesis of silver nanoparticles (AgNPs) using the medium-polar extract of Desmodium adscendens (Sw.) DC. is presented here as an alternative synthesis of metal NPs. Characterisation of the formed NPs showed polydispersed AgNPs ranging from 15 to 100 nm where the concentration of metal ions was found to play a role in the size and shape of the prepared NPs. It could be established that the flavonoids, saponins, and alkaloids present in the extract acted as both reducing and stabilising agents during the formation of the capped metal NPs. This means of NP synthesis was also employed during the in situ immobilisation of AgNPs on gauze and plaster. An evaluation of the antibacterial activity of the medium-polar D. adscendens extract, AgNPs suspended in solution, and the immobilised AgNPs against Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 11778), and Escherichia coli (ATCC 25922) showed high efficacy against the latter in particular. This suggests that gauze, dilute silver nitrate solutions, and D. adscendens extract could be used successfully in the simple in situ preparation of effective antibacterial wound dressings.

Labdane and Clerodane Diterpenoids from Colophospermum mopane.

Five labdane (1-5), an isolabdane (6), and five clerodane diterpenoids (7-11), were isolated from seeds, husks, and leaves of Colophospermum mopane. Compounds 1-3 and 6-9 are new, and their structures were elucidated by means of physical data analysis (1D and 2D NMR, HRESIMS). The absolute configurations of 1, 7, and 10 were determined by single-crystal X-ray diffraction with Cu Kα radiation. For compounds 2 and 6, the absolute configurations were established by the modified Mosher's method and corroborated by comparison of experimental and calculated electronic circular dichroism spectra of their 3-p-bromobenzoate derivatives. The crude extracts and compounds were evaluated for antimicrobial activity. The leaf extract was the most active against Staphylococcus aureus (125 µg/mL). Compound 11 showed the best inhibitory activity, with minimum inhibitory values of 15.6 µg/mL against Escherichia coli and Staphylococcus aureus and 31.3 µg/mL against Enterococcus faecalis.

Antimicrobial evaluation of plants used for the treatment of diarrhoea in a rural community in northern Maputaland, KwaZulu-Natal, South Africa.

BACKGROUND: Zulu people living in the rural area of Maputaland (KwaZulu-Natal, South Africa) rely heavily on medicinal plants for the treatment of diarrhoea. Abundant availability of medicinal plants in the study area offers low cost health care, but scientific validation is needed in order to lend credibility to the traditional use against many ailments including diarrhoeal infections. With this in mind a study was designed to test the in vitro antimicrobial efficacy of 23 plant species which are used for the treatment of diarrhoea in rural Maputaland. Four 1:1 plant combinations were also evaluated to determine their interactive effects against seven diarrhoea-related bacterial pathogens. METHODS: Minimum inhibitory concentration (MIC) assays were undertaken on dichloromethane-methanol (CH2Cl2: MeOH) and aqueous crude extracts. The following micro-organisms were selected for this study and were tested based on their association with stomach ailments and diarrhoea; Bacillus cereus (ATCC 11778), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739), Proteus vulgaris (ATCC 33420), Salmonella typhimurium (ATCC 14028), Shigella flexneri (ATCC 25875) and Staphylococcus aureus (ATCC 12600). The fractional inhibitory concentration index (ΣFIC) was determined for plants traditionally used in combination. RESULTS: Shigella flexneri proved to be the most susceptible pathogen, where the organic extract of Terminalia sericea showed the most prominent noteworthy antibacterial activity (mean MIC value of 0.04 mg/mL). The aqueous extracts generally showed poorer antimicrobial activity with some exceptions i.e. Acacia burkei, Brachylaena transvaalensis against B. cereus and B. transvaalensis against S. flexneri. In the combination studies, synergy was predominant with mean (across all pathogens) ΣFIC values of 0.30 for Acanthospermum glabratum with Krauseola mosambicina; ΣFIC values of 0.46 for A. glabratum with Psidium guajava; ΣFIC values of 0.39 for B. transvaalensis with P. guajava and ΣFIC values of 0.88 (additive) for the combination of B. transvaalensis with Sclerocarya birrea. CONCLUSION: This study provided some insight into the bacterial in vitro efficacies of plants traditionally used to treat diarrhoea by the people of Northern Maputaland. Very little connection was observed between frequency of use and efficacy. Plant combinations demonstrated favourable efficacy with mostly synergistic effects noted, lending some credibility to their use in combination.

The acid-catalysed synthesis of 7-azaindoles from 3-alkynyl-2-aminopyridines and their antimicrobial activity.

The synthesis of 7-azaindoles from 3-alkynyl-2-aminopyridines using acidic conditions, namely, a mixture of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA), is described. This methodology resulted in the synthesis of fifteen 7-azaindoles, with most containing substituents at the 2- and 5-positions. The majority of these were tested for antimicrobial activity against a range of bacteria and yeasts. The 7-azaindoles displayed the best activity against the yeasts, particularly against Cryptococcus neoformans, where activities as low as 3.9 µg ml(-1) were observed.

Medicinal plants used for the treatment of various skin disorders by a rural community in northern Maputaland, South Africa.

BACKGROUND: Skin diseases have been of major concern recently due to their association with the Human Immunodeficiency Virus and Acquired Immunity Deficiency Syndrome (HIV/AIDS). The study area (northern Maputaland) has the highest HIV infection rate in South Africa, which made them more prone to a wide range of skin conditions. Fungal infections due to the hot climate and overcrowding households are common in this area, as well as burn accidents due to the use of wood as the major fuel for cooking. It is known that the lay people in this area depend on medicinal plants for their primary health care. However no survey has been done in northern Maputaland to document the medicinal plants used to treat various skin disorder. METHODS: Interviews were undertaken at 80 homesteads, using structured questionnaires. The focus was on plants used for dermatological conditions and information regarding vernacular plant names, plant parts used, preparation (independently and in various combinations) and application was collected. RESULTS: A total of 87 lay people, both male (22%) and female (78%) were interviewed on their knowledge of medicinal plants used to treat disorders of the skin. Forty-seven plant species from 35 families were recorded in the present survey for the treatment of 11 different skin disorders including abscesses, acne, burns, boils, incisions, ringworm, rashes, shingles, sores, wounds and warts. When searching the most frequently used scientific databases (ScienceDirect, Scopus and Pubmed), nine plant species (Acacia burkei, Brachylaena discolor, Ozoroa engleri, Parinari capensis, subsp. capensis, Portulacaria afra, Sida pseudocordifolia, Solanum rigescens, Strychnos madagascariensis and Drimia delagoensis) were found to be recorded for the first time globally as a treatment for skin disorders. Fourteen plant combinations were used. Surprisingly, the application of enema's was frequently mentioned. CONCLUSIONS: The preference of traditional medicine over allopathic medicine by most of the interviewees strengthens previous studies on the importance that traditional medicine can have in the primary health care system in this rural community. Studies to validate the potential of these plants independently and in their various combinations is underway to provide insight into the anti-infective role of each plant.

The synthesis of xanthones, xanthenediones, and spirobenzofurans: their antibacterial and antifungal activity.

Exposure of the phenol, (5-bromo-2-hydroxyphenyl)(2,4,5-trimethoxyphenyl)methanone 18 to ceric ammonium nitrate (CAN) resulted in the formation of 7-bromo-3,4a-dimethoxy-2H-xanthene-2,9(4aH)-dione 19 and 5-bromo-2',5'-dimethoxy-3H-spiro[benzofuran-2,1'-cyclohexa[2,5]diene]-3,4'-dione 20. The brominated spirobenzofuran 20 was then subjected to Suzuki-Miyaura reactions to give six derivatives 22a-f. These compounds, related diones and xanthones displayed mostly noteworthy antimicrobial activity, particularly towards the yeasts Cryptococcus neoformans and Candida albicans. Diones 15 and 30 displayed significant activity (7.8 µg/mL) against C. albicans and C. neoformans, respectively. Furthermore, dione 10 displayed the most significant activity (3.6 µg/mL) against both yeasts.

Potential interaction between the volatile and non-volatile fractions on the in vitro antimicrobial activity of three South African Pelargonium (Geraniaceae) species.

Previous studies have reported promising antimicrobial efficacy for the essential oils and solvent extracts of several indigenous Pelargonium species. This study aimed to determine if any pharmacological interaction (e.g. synergism or antagonism) exists between the volatile and non-volatile components when the different fractions were investigated. The antimicrobial activity of the following fractions were tested; the essential oil prepared by hydrodistillation (EO), non-volatile fraction (NV), prepared by extraction of plant material remaining in the distilling apparatus (having no or negligible volatile constituents) and solvent extracts prepared from fresh (FC) and dried (DC) plant material containing both volatile and non-volatile constituents. Pelargonium quercifolium oil was dominated by p-cymene (42.1%) and viridiflorol (16.9%), while P. graveolens and P. tomentosum oil had high levels of isomenthone (84.0 and 58.8%, respectively). Menthone was noted as a major constituent in the P. tomentosum EO sample. It was evident from the results that the presence of volatile constituents in the three species; P. graveolens, P. quercifolium and P. tomentosum is generally not a pre-requisite for antimicrobial activity. The most significant variations of antimicrobial activity were noted for P. tomentosum where poorer activity was noted for the FC and EO fractions against Bacillus cereus and Candida albicans. Studies on Staphylococcus aureus, however, showed the converse, where best activity was noted for the FC fraction (3.0 mg/mL). For P. quercifolium, the DC fraction indicated a notable increase in anti-staphylococcal activity (2.0 mg/mL) when compared with the FC (8.0 mg/mL) and EO (16.0 mg/mL) fractions. For P. tomentosum, the FC fraction indicated much lower antimicrobial activity (against both B. cereus and C. albicans) when compared with all other fractions, suggesting that the essential oils may impact negatively on the antimicrobial activity when tested against these two pathogens.

Encapsulation of essential oils within a polymeric liposomal formulation for enhancement of antimicrobial efficacy.

Essential oils and their constituents are known to possess antimicrobial activity; however, their inherent volatility is a limiting factor. In order to exploit the antimicrobial efficacy of essential oils, encapsulation within polymeric liposomal systems was undertaken. The liposomes were subsequently polymer-coated in order to further enhance the stability of the formulations. Essential oils distilled from Artemisia afra, Eucalyptus globulus and Melaleuca alternifolia were encapsulated into diastearoyl phosphatidylcholine and diastearoyl phosphatidylethanolamine liposomes employing a reverse phase evaporation methodology. A polyelectrolyte coating was then applied via the layer-by-layer self-deposition technique. A batch of the liposomes was polymer-coated with a 0.15%w/v chitosan solution. Using the minimum inhibitory concentration assay, the liposome-encapsulated, unencapsulated and polymer-coated liposome-encapsulated essential oils were compared in order to observe whether the antimicrobial efficacy was improved with encapsulation and polymer coating. Fractional inhibitory concentrations (FICs) were calculated in order to determine the antimicrobial interactions amongst the lipoid components, polymer coating and essential oils (synergistic, additive, indifferent and antagonistic interactions). With the exception of A. afra, microbial growth was inhibited at lower concentrations for the encapsulated formulations in comparison with the nonencapsulated oils. Synergistic to additive interactions were noted for encapsulated E. globulus (sigmaFIC values 0.25-0.45) and M alternifolia (sigmaFIC values 0.26-0.52) formulations. The addition of the polymer coating did not enhance antimicrobial activity, but owing to their positive effects on membrane stability, its presence is important as a means of extending the shelf life of these formulations. Additionally, the presence of the polymeric coating availed the essential oil at a slower rate. This investigation is a stepping stone towards the promotion of the antimicrobial use of essential oils. The added benefits are that essential oils not only provide effective antimicrobial efficacy, but also promote a "greener" consumerism. Within liposomes, they will enhance dermato-cosmetic properties and increase the marketing image of the final product.

The anti-diarrhoeal properties of Breonadia salicina, Syzygium cordatum and Ozoroa sphaerocarpa when used in combination in Swazi traditional medicine.

AIM OF THE STUDY: The aim of the study was to determine in vitro activity of the bark of Ozoroa sphaerocarpa R. Fern & A. Fern (Anacardiaceae), Breonadia salicina (Vahl) Hepper & J.I.R. Wood (Rubiaceae) and Syzygium cordatum Hochst ex C Krauss (Myrtaceae) against a diarrhoea-causing pathogen, Escherichia coli; as well as the pharmacological interactions present in their combination. MATERIALS AND METHODS: In consultation with traditional healers, the plants were collected from the wild, dried and extracted with dichloromethane:methanol (1:1). Thereafter, antimicrobial activity of the individual plants and their different combinations was tested using a common diarrhoea pathogen, Escherichia coli by employing the minimum inhibitory concentration assay. RESULTS: Ozoroa sphaerocarpa was the most potent inhibitor of antimicrobial growth (MIC value of 1.2 mg/ml), followed by Syzygium cordatum (MIC value of 1.44 mgl/ml) and lastly Breonadia salicina (MIC value of 10.89 mg/ml). The combination between Syzygium cordatum and Ozoroa sphaerocarpa gave the strongest synergistic interaction (MIC value of 0.33 mg/ml); whilst that between Syzygium cordatum and Breonadia salicina was mildly synergistic (MIC value of 1.00 mg/ml). The triple combination (1:1:1) was also very effective in inhibiting microbial growth (MIC value of 0.44 mg/ml). The combined effect of these plants on toxicity was predominantly synergistic except for the combination of Ozoroa sphaerocarpa and Syzygium cordatum which was predominantly antagonistic (ΣFIC value of 1.48 ± 0.25). The triple combination had a favourable toxicity profile with an IC(50) value of 155.76 ± 11.86 µg/ml. CONCLUSION: This study supports the rationale by traditional healers to use the bark of Syzygium cordatum, Breonadia salicina and Ozoroa sphaerocarpa in combination for the treatment of diarrhoea.

The synthesis of 2- and 3-aryl indoles and 1,3,4,5-tetrahydropyrano[4,3-b]indoles and their antibacterial and antifungal activity.

A series of 2- and 3-aryl substituted indoles and two 1,3,4,5-tetrahydropyrano[4,3-b]indoles were synthesized from indole and 5-methoxyindole. The 2-aryl indoles were synthesized from the 1-(phenylsulfonyl)indole derivatives using magnesiation followed by iodination. The 2-iodinated compounds were then subjected to Suzuki-Miyaura reactions. In addition, the 3-aryl indoles were made from the corresponding 3-bromoindoles using Suzuki-Miyaura reactions. The 1,3,4,5-tetrahydropyrano[4,3-b]indoles were also synthesized from 1-(phenylsulfonyl)indole by magnesiation followed by treatment with allylbromide. The product was then converted into [2-allyl-1-(phenylsulfonyl)-1H-indol-3-yl]methanol which upon exposure to Hg(OAc)(2) and NaBH(4) afforded tetrahydropyrano[4,3-b]indoles. A number of the 2- and 3-aryl indoles displayed noteworthy antimicrobial activity, with compound 13a displaying the most significant activity (3.9 microg/mL) against the Gram-positive micro-organism Bacillus cereus.

Antimicrobial acylphloroglucinols and dibenzyloxy flavonoids from flowers of Helichrysum gymnocomum.

From the dichloromethane extract of the flowers of Helichrysum gymnocomum (Asteraceae) two known flavonoids, 4 and 5, and a known acylphloroglucinol, 3B, were isolated. In addition to 1 and 2, the 4',6'-dibenzyloxy-2'-hydroxy derivative of 2',4',6'-trihydroxychalcone and 5,7-dibenzyloxy derivative of pinocembrin, respectively, are reported in Nature for the first time. A compound 3A, related to 3B has the structure 2-methyl-1-[2,4,6-trihydroxy-3-(2-hydroxy-3-methyl-3-butenyl)phenyl]-1-propanone. Compounds 1, 2, 3A, 3B, 4 and 5 have MIC values below 64microg/ml against a selection of pathogens, with 3B having the highest sensitivity (6.3-45microg/ml) for eight of the ten pathogens tested, including Staphylococcus aureus (6.3microg/ml) and methicillin and gentamycin resistant strain of S. aureus (7.8microg/ml). With the exception of 2, the other compounds had notable activity (45-63microg/ml) towards Pseudomonas aeruginosa.

Antimicrobial monomeric and dimeric diterpenes from the leaves of Helichrysum tenax var tenax.

The hexane extract of fresh air-dried leaves of Helichrysum tenax (Asteraceae) afforded ent-beyer-15-en-19-ol (1), its 4-epimer ent-beyer-15-en-18-ol (2), 15beta,16beta-epoxide-ent-beyeran-19-ol (3), as well as (4) consisting of two units of (1) linked as a diester of malonic acid, and (5), a compound. Its constituents are (1) and (3) also linked as a diester of malonic acid. The leaves of the plant are densely covered in fine glandular trichomes. These are extremely sticky and exude a mixture of the above diterpenes. Antimicrobial tests showed that (1), in particular, was highly active (3.1 and 3.6 microg/ml) against Bacillus cereus and Staphylococcus epidermidis, respectively.