Evaluation of the immunomodulatory activity of ethanolic extract of the stem bark ofBauhinia variegataLinn

Anti-Biofilm, Antibacterial, and Anti-Quorum Sensing Activities of Selected South African Plants Traditionally Used to Treat Diarrhoea

The development of resistance of microorganisms to conventional antibiotics is a major global health concern; hence, there is an increasing interest in medicinal plants as a therapeutic option. This study aimed to evaluate the antibacterial, anti-biofilm, and anti-quorum activities of crude extracts prepared using various solvents of nine indigenous South African plants used locally for the treatment of diarrhoea. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method and the crystal violet assay was used to test the anti-biofilm activity of the extracts against a panel of bacteria. Anti-quorum sensing activity of the extracts was assessed via inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Preliminary screening of extracts against E. coli ATCC 25922 revealed that the acetone extracts had significant activity, with MIC values ranging from 0.04 to 0.63 mg/mL. Further screening against a panel of bacterial pathogens showed that the acetone extract of Bauhinia bowkeri was the most active with MIC of 0.01 mg/mL against Salmonella enteritidis, followed by Searsia lancea with MIC of 0.03 mg/mL against Bacillus cereus. All the plant extracts prevented the attachment of biofilms by more than 50% against at least one of the tested bacteria. However, only the mature biofilm of B. cereus was susceptible to the extracts, with 98.22% eradication by Searsia pendulina extract. The minimum quorum sensing inhibitory concentration of the extracts ranged from 0.08 to 0.32 mg/mL with S. lancea having the most significant activity. The extract of S. lancea had the best violacein production inhibitory activity with IC₅₀ value of 0.17 mg/mL. Overall, the results obtained indicate that acetone extracts of S. leptodictya, S. lancea, S. batophylla, S. pendulina, B. galpinii, and B. bowkeri possess antibacterial and anti-biofilm activities and can modulate quorum sensing through the inhibition of violacein production. Therefore, these results signify the potential of the selected plant extracts in treating diarrhoea through inhibition of bacterial growth, biofilm formation inhibition, and quorum sensing antagonism, supporting their medicinal use.

Invasive alien plants and weeds in South Africa: A review of their applications in traditional medicine and potential pharmaceutical properties

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional pharmacopoeias are constantly evolving and adapting, hence the assimilation of alien plants and weeds into traditional systems of healing. Invasive plants are detrimental to the ecosystem, however they are also potential sources of secondary metabolites with useful biological activities.

AIM OF THE REVIEW

The aim of this review was to investigate published reports of traditional use and biological activity of declared invasive alien plants and other weeds in South Africa.

MATERIALS AND METHODS

Information was retrieved from scientific databases including Scopus, Web of Science, ScienceDirect, Google Scholar, PubMed, Chemical Abstracts Services and books, theses, dissertations and technical reports. Keywords used for the search engines were "South Africa" or "southern Africa" in conjunction with "(native weeds OR alien invasive)" AND "medicinal". Separate searches were conducted on the individual invasive plant species recorded as having been used in ethnobotanical surveys to determine their known biological activities and chemical components.

RESULTS

A total of 89 plant species regarded as invasive species or weeds in South Africa were identified as being used in traditional medicine. The most commonly mentioned plant family was the Asteraceae with a total of 15 species followed by the Fabaceae and Solanaceae with 6 species each. Of the 89 species recorded, 68% were reported to have traditional usage with both phytochemical and biological data available. A history of traditional usage coupled with biological data was available for 12% of species. Records of traditional usage alone were linked to 11% of species. Invasive alien species comprised 61% of recorded species, while native and non-invasive alien weeds formed the remaining 39%.

CONCLUSIONS

The exploration of alternative uses for weeds and particularly invasive plants, whether native or alien, as medicines for possible commercialisation may lead to innovative mechanisms for putting such species to good use.

A semi-synthetic flavonoid from Bauhinia pulchella stem attenuates inflammatory osteolysis in periodontitis in rats: Impact on cytokine levels, oxidative stress, and RANK/RANKL/OPG pathway

OBJECTIVES

Many species of theBauhinia genus have been widely used in folk medicine as analgesic, anti-inflammatory and antioxidant agents. (-)-Fisetinidol palmitate is a semi-syntetic flavonoid obtained from the ethanolic extract of the stem of Bauhinia pulchella. This study aimed to evaluate the antiresorptive effect of the semi-syntetic (-)-fisetinidol palmitate in ligature-induced periodontitis in rats. Also, it evaluated the mechanism of action of (-)-fisetinidol palmitate and its toxicity.

DESIGN

Periodontitis was inducedvia a nylon thread ligature (3.0) around the second upper left molars. Rats were treated (oral gavage) once a day for 11 days with (-)-fisetinidol palmitate (0.01 or 0.1 mg/kg) or saline vehicle.

RESULTS

(-)-Fisetinidol palmitate (0.1 mg/kg) reduced alveolar bone loss, increased bone alkaline phosphatase (BALP), superoxide dismutase (SOD), and catalase (CAT) activity; also, it decreased IL1-β, IL-8/CINC-1, nitrite/nitrate levels and myeloperoxidase activity. (-)-Fisetinidol palmitate reduced the mRNA levels of IL1-β, IL-6, RANK, and RANK-L, while it increased the OPG ones. No statistical differences (P > 0.05) were observed in the transaminases (ALT, AST) and Total Alkaline Phosphatase (TALP) levels among groups.

(-)- CONCLUSIONS

Fisetinidol palmitate did not result in any signs of toxicity and had anti-resorptive effects in a pre-clinical trial of periodontitis, showing antioxidant activity with the involvement of the RANK/RANKL/OPG pathway.

The antimicrobial, antioxidative, anti-inflammatory activity and cytotoxicity of different fractions of four South African Bauhinia species used traditionally to treat diarrhoea

ETHNOPHARMACOLOGICAL IMPORTANCE

Many Bauhinia species, including those indigenous to South Africa, are used in traditional medicine across the world for treating ailments such as gastrointestinal tract (GIT) disorders, diabetes, infectious diseases and inflammation.

AIMS

Several relevant aspects of different fractions of leaf extracts of Bauhinia bowkeri (BAB), Bauhinia galpinii (BAG), Bauhinia petersiana (BAP), and Bauhinia variegata (BAV) used in South African traditional medicine to alleviate diarrhoea related symptoms were evaluated.

MATERIALS AND METHODS

The antioxidative activities of the extracts were determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS(+)) radical scavenging and ferric reducing antioxidant power (FRAP) methods. In vitro antimicrobial activities of the extracts were determined against bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis) and clinical isolates of the opportunistic fungal strains (Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans) using a serial dilution microplate method. The polyphenolic contents were quantified using standard methods, and anti-inflammatory activities of the crude extracts were determined using the cyclooxygenase and soybean 15-lipoxygenase enzyme inhibitory assays. The safety of the extracts was evaluated by determining the cytotoxicity against Vero cell lines.

RESULTS

The acidified 70% acetone crude extract and their fractions had good antiradical potency against the DPPH and ABTS radicals. The methanol soluble portions of the butanol fractions were more potent (EC(50) ranges from 0.64 ± 0.05 to 1.51 ± 0.07 and 0.88 ± 0.18 to 1.49 ± 0.09 μg/ml against DPPH and ABTS radical respectively) compared to the standard, trolox and ascorbic acid (EC(50) ranges from 1.47 ± 0.24 to 1.70 ± 0.27 μg/ml) for both DPPH and ABTS. The crude extracts contained variable quantities of phenolic content. The crude extracts and their fractions had weak to good antimicrobial activities, inhibiting the growth of the organisms at concentrations ranging from 39 to 2500 μg/ml. The BAG crude extract and its fractions were the most active against the fungi (MICs ranging from 39 to 625 μg/ml) while the BAB extract and its fractions were the least active with the MICs ranging between 39 and 2500 μg/ml. Aspergillus fumigatus was the least susceptible fungus while Cryptococcus neoformans was the most susceptible. The phenolic-rich crude extracts of BAB, BAG, and BAP had moderate to good dose-dependent cyclooxygenase-1 enzyme inhibitory activity with inhibitions between 22.8% and 71.4%. The extracts were however, inactive against cyclooxygenase-2. The extracts had some level of cytotoxicity towards Vero cell lines, reducing cell viability to less than 10% at concentrations more than 50 μg/ml.

CONCLUSION

The biological activities observed in Bauhinia species provide a scientific basis for the use of the plants in traditional medicines to treat diseases with multi-factorial pathogenesis such as diarrhoea, with each aspect of activity contributing to the ultimate therapeutic benefit of the plants. However, the use of the phenolic-rich extracts of these plants to treat diarrhoea or any other ailments in traditional medicine needs to be monitored closely because of potential toxic effects and selective inhibition of COX-1 with the associated GIT injury.

Immunomodulatory and antioxidant effect of Leptadenia reticulata leaf extract in rodents: possible modulation of cell and humoral immune response

CONTEXT

Leptadenia reticulata Linn. (Asclpiadaceae) commonly known as "dodi," is an Indian medicinal plant which is known to have ethno-medical uses such as stimulant, tonic, immunostimulant and is one of the ingredient in ayurvedic formulation called as "Chawanprash," which is widely used in India to increase the strength of immune system.

OBJECTIVE

The aim of present study is to evaluate immunomodulatory and antioxidant activity of ethanolic extract of L. reticulata L. leaves in rodents.

METHODS

Haemagglutinating antibody (HA) titre, haematological profile (Hb, WBC, RBC), lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), delayed type of hypersensitivity (DTH) response, neutrophil adhesion test and carbon clearance assay were determined by in vivo experiments.

RESULTS

The evaluation of immunomodulatory potential of L. reticulata (100, 200 mg/kg, p.o.) evoked a significant dose-dependent increase in antibody titre values; DTH reaction induced by SRBC and potentiated percentage neutrophil adhesion to nylon fibers as well as phagocytosis in carbon clearance assay. Also it caused significant increase in haematological profile, GSH, SOD, CAT activity and significantly decreased LPO levels in cyclophosphamide-induced immunosuppressed rats.

CONCLUSION

The results obtained in this study indicate that L. reticulata possesses potential immunomodulatory and antioxidant activity and can play a major role in reducing the risk to develop immunodeficiency disorders.