Antimicrobial activities of Tephrosia vogelii against selected pathogenic fungi and bacteria strains

In vitro antibacterial and antioxidant activity of flavonoids from the roots of Tephrosia vogelii: a combined experimental and computational study

Tephrosia vogelii is a traditional medicinal plant used to treat hypertension, diarrhea and urinary disorders. Silica gel chromatographic separation of CH2Cl2/MeOH (1:1) roots extract of T. vogelii afforded seven compounds namely; β-sitosterol (1a), stigmasterol (1b), 6a, 12a-dehydro-deguelin (2), tephrosin (3), maackiain (4), obovatin (5) and 6-oxo, 6a, 12a-dehydro-deguelin (6). GC-MS analysis of essential oils from the root of T. vogelii displayed a total of 17 compounds of which cis-nerolidol (41.7 %) and cadinol (19.7 %) were the major constituents. CH2Cl2/MeOH (1:1) extract, MeOH extract, maackiain (4) and obovatin (5) showed moderate inhibitory activity against Pseudomonas aeruginosa with MIC value of 0.5, 0.66, 0.83 and 0.83 mg/mL, respectively, compared to ciprofloxacin (MIC of 0.078 μg/mL). 6a, 12a-dihydro-deguelin (2), and 6-oxo, 6a, 12a-dehydro-deguelin (6) displayed significant activity against S. epidermis with MIC values of 0.66 mg/mL. Tephrosin (3) and maackiain (4) also showed moderate antibacterial activity against Staphylococcus aureus and Proteus mirabilis with MIC values of 0.83 and 0.5 mg/mL, respectively, compared to ciprofloxacin (0.312 μg/mL). The radical scavenging activity results indicated that tephrosin (3), obovatin (5) and 6-oxo, 6a, 12a-dehydro-deguelin (6) showed potent DPPH scavenging activity with IC50 values of 10.97, 10.43 and 10.73 μg/mL, respectively, compared to ascorbic acid (IC50 of 5.83 μg/mL). The docking prediction results revealed that 6a, 12a-dehydro-deguelin (2) displayed the best binding energy of -8.1 kcal/mol towards pyruvate kinase of S. aureus (PDB ID: 3T07) and -7.9 kcal/mol towards P. mirabilis urease (PDB ID: 1E9Y) and DNA gyrase B of Escherichia coli (PDB: 4F86) receptors compared to ciprofloxacin (-7.2 to -8.0 kcal/mol). Maackiain (4) and obovatin (5) displayed the minimum binding energy of -7.9 and -8.2 kcal/mol towards the LasR protein of P. aeruginosa (PDB: ID 2UV) and S. epidermidis FtsZ (PDB: ID 4M8I), respectively. The SwissADME drug-likeness and Pro Tox II toxicity prediction results indicated that compounds (2-6) obeyed Lipinski's rule of five with 0 violations and none of them were found to be hepatotoxic, mutagenic, and cytotoxic, respectively. The in vitro assessment results supported by the in silico analysis revealed that crude extracts and isolated compounds showed promising antibacterial and antioxidant activity, which proves the therapeutic potential of the roots of T. vogelii.

In vitro evaluation of the herbal cream formulation from methanolic leaf extracts of Tephrosia vogelii Hook.f for topical application

Background

Topical infectious are among of global challenges which propelled up with antimicrobial resistances. This scenario compels for drug discovery and development. Herbal formulation is one of important struggle in the drug development with the purpose of overcoming various diseases distressing health care settings. Thus, this study aimed to formulate and evaluate herbal cream from leaf methanolic extracts of Tephrosia vogelii Hook.f for topical therapies.

Methods

Herbal cream was prepared by homogeneously mixing up cream base and methanolic leaf extracts of Tephrosia vogelii. Physicochemical properties and in vitro antimicrobial activities of the cream were evaluated. The stability, colour change, washability and texture were parameters used evaluate physicochemical properties of cream. Disc diffusion method was employed to evaluate antimicrobial activities of the cream against Candida albicans (ATCC 90,028), Escherichia coli (ATCC29953) and Staphylococcus aureus (ATCC25923).

Results

Formulated herbal creams; CBTV1, CBTV2 and CBTV3 with methanolic extracts concentrations content of Tephrosia vogelii 0.05%, 0.10% and 0.25%, respectively, were prepared. All cream formulations were stable, washable by water, green in colour and soft. The CBTV3 product exhibited with high prominent antimicrobial activity compared to the rest, henceforth promisingly to be effective for topical skin therapy.

Conclusion

The herbal cream formulation of methanolic leaf extract of Tephrosia vogelii at 0.25% appeared to have more antimicrobial performance. Therefore, it is considered as minimal concentration for the herbal cream formulation in future for clinical trials as a potential antifungal and antibacterial agent product for treatment of skin infections.

Graphical Abstract

Tephrosia toxicaria (Sw.) Pers. extracts: Screening by examining aedicidal action under laboratory and field conditions along with its antioxidant, antileishmanial, and antimicrobial activities

An increase in the incidence of arboviral, microbial and parasitic infections, and to disorders related to oxidative stress has encouraged the development of adjuvant therapies based on natural formulations, such as those involving plant extracts. Thus, to expand the repertoire of the available therapeutic options, this study aimed to describe the versatility of Tephrosia toxicaria (Sw.) (Pers., 1807) extracts for the control of arbovirus vectors, as well as their antioxidant, antileishmanial, and antimicrobial potential. Among the aqueous and hydroethanolic extracts obtained, the hydroethanolic extract from roots (RHA) was identified as the most active larvicide extract demonstrating, respectively, the lowest lethal concentration (mg/mL) for 50%, 90% and 99% of Aedes aegypti (L., 1762) and Aedes albopictus (S., 1894) larvae, observed at 24 h (0.33, 0.84 and 1.80; 0.32, 0.70 and 1.32) and 48 h (0.17, 0.51 and 1.22; 0.26, 0.47 and 0.78) post-exposure. Field assays revealed that RHA (0.84 mg/mL) is a potential oviposition deterrent, reducing egg-laying by approximately 90%. RHA (0.1 mg/mL) also exhibited antioxidant activity for the following tests: total antioxidant capacity (286.86 mg AAE/g), iron (87.16%) and copper (25.64%) chelation, and superoxide scavenging (10%). In the cell culture assays, RHA (0.1 mg/mL) promoted regeneration of metabolic activity (92% cell viability) in cells exposed to oxidative stress. Furthermore, RHA displayed weak antileishmanial activity (IC50 = 3.53 mg/mL) against Leishmania amazonensis and not exhibit antimicrobial activity. The extraction favored the concentration of carbohydrates in RHA, in addition to lectins and protease inhibitors, with molecular masses estimated between 10 and 24 kDa. Cytotoxicity and phytotoxicity analyses of RHA suggested its biosecurity. Thus, RHA is a multivalent extract with insecticide and antioxidant properties at low and safe concentrations. However, others studies on its indirect toxic effects are ongoing to ensure the complete safety of RHA.

The Anti-Candida Activity of Tephrosia apollinea Is More Superiorly Attributed to a Novel Steroidal Compound with Selective Targeting

Tephrosia is widely distributed throughout tropical, subtropical, and arid regions. This genus is known for several biological activities, including its anti-Candida activity, which is mainly attributed to prenylated flavonoids. The biological activities of most Tephrosia species have been studied, except T. apollinea. This study was conducted to investigate the underlying anti-Candida activity of T. apollinea, wildly grown in the United Arab Emirates (UAE). The T. apollinea plant was collected, dried, and the leaves were separated. The leaves were ground and extracted. The dried extract was subjected to successive chromatography to identify unique phytochemicals with a special pharmacological activity. The activity of the compound was validated by homology modeling and molecular docking studies. A novel steroidal compound (ergosta-6, 8(14), 22, 24(28)-tetraen-3-one) was isolated and named TNS. In silico target identification of TNS revealed a high structural similarity with the Candida 14-α-demethylase enzyme substrate. The compound exhibited a significant anti-Candida activity, specifically against the multi-drug-resistant Candida auris at MIC₅₀, 16 times less than the previously reported prenylated flavonoids and 5 times less than the methanol extract of the plant. These findings were supported by homology modeling and molecular docking studies. TNS may represent a new class of Candida 14-α-demethylase inhibitors.

Lycorine Alkaloid and Crinum americanum L. (Amaryllidaceae) Extracts Display Antifungal Activity on Clinically Relevant Candida Species

Candida species are the main fungal agents causing infectious conditions in hospital patients. The development of new drugs with antifungal potential, increased efficacy, and reduced toxicity is essential to face the challenge of fungal resistance to standard treatments. The aim of this study is to evaluate the in vitro antifungal effects of two crude extracts of Crinum americanum L., a rich alkaloid fraction and lycorine alkaloid, on the Candida species. As such, we used a disk diffusion susceptibility test, determined the minimum inhibitory concentration (MIC), and characterized the components of the extracts using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI FT-ICR MS). The extracts were found to have antifungal activity against various Candida species. The chemical characterization of the extracts indicated the presence of alkaloids such as lycorine and crinine. The Amaryllidaceae family has a promising antifungal potential. Furthermore, it was found that the alkaloid lycorine directly contributes to the effects that were observed for the extracts and fraction of C. americanum.

The in vivo toxicity evaluation of leaf and root methanolic extracts of Tephrosia vogelii Hook.f using animal model

Background

Traditionally, herbal medicines are commonly used to cure several diseases since immemorial of human life. Nevertheless, the safety of some traditionally used medicinal plants is uncertain. Since Tephrosia vogelii Hook.f is a traditionally used medicinal plant, the effects of its extracts were evaluated on lethality (LD50) and sub-acute toxicity in this study.

Methods

Phytochemistry screening and an in vivo toxicity evaluation of leaf and root methanolic extracts of T. vogelii using laboratory albino rats were conducted. Methanolic extracts of doses 600, 1200, 2000 and 5000 mg/kg body weights were administered single dose in rats to observe deaths within 72 h in order to determine the LD50. Methanolic extracts doses of 600, 1200 and 2000 mg/kg body weights were consecutively administered for 14 days in order to evaluate sub-acute toxicity.

Results

Tannins, steroids, terpenoids, flavonoids and saponins were identified in the phytochemical screening. The LD50 experiments revealed zero deaths of rats for the administered doses, 600 to 5000 mg/kg body weight. Histopathological examination of liver and kidney for sub-acute toxicity test showed safety at all doses except root methanolic extracts dose of 2000 mg/kg which exhibited necrosis and vacuolation of liver cells on the 14th day. Nonetheless, hepatic necrosis and hepatic vacuolation disappeared upon time elongation without dose administration to 28th day.

Conclusion

The conducted toxicity evaluation of methanolic leaf and root extracts in albino rats revealed no deleterious effects, henceforth, suggesting that T. vogelii could be safe to users using it as a medicinal plant.