In Vitro Antimicrobial Studies of Some Major Bioactive Compounds Isolated from Strychnos innocua (Delile) Root Bark

Plant based therapies are very essential in modern medicine, and have long been used to cure and prevent chronic diseases in many parts of the world. Medicinal herbs have been shown to have biological properties due to the presence of active compounds. Strychnos innocua, a medicinal plant from Loganiaceae, is commonly consumed for medicinal purposes in various African countries. The need to assess the usefulness of the plant's root bark in the treatment of disease spurred this study, which involved the isolation of six bioactive compounds and screening for antimicrobial properties against some pathogens using the agar well diffusion method. Chromatography separation led to first time isolation of Umbelliferone (1), Linalool (2), Nerolidol (3), Campesterol (4), β-sitosterol (5), and 2,13-Octadecadien-1-ol (6). GC-MS and NMR spectra, as well as comparisons with published data, were used to determine their structures. The compounds exhibited strong antimicrobial activity comparable to ciprofloxacin and fluconazole against MRSA, B. subtilis, S. pyogenes, S. aureus, K. pneumoniae, E. coli, P. aeruginosa, S. typhii, A. fumigatus, C. albicans, C. krusei, and A. nigre. The MIC as well as the MBC/MFC were determined. In conclusion, the compounds (1 - 6) isolated from S. innocua root bark have remarkable antibacterial action against pathogenic microbes.

In silico modelling and NMR Characterization of some steroids from Strychnos innocua (Delile) root bark as potential antifungal agents

The root bark of Strychnos innocua has long been employed by traditional healers to treat a variety of ill health conditions including fungal infections. The objective of this study was to isolate, characterized and evaluate the antifungal potential (insilico approach) of some steroids from root bark of S. innocua. Conventional method of column chromatography was carried out on the ethyl acetate root bark extract of S. innocua, leading to the isolation of two steroids. On the basis of 1D NMR, 2D NMR, GC-ESI/MS analyses, and literature comparisons, the compounds were characterized as Stigmast-5-en-3β-ol (1) and Campest-5-en-3β-ol (2). This is the first time these compounds have been isolated from the plant. The results of the in silico modelling of the compounds 1, 2, and fluconazole (control drug) with the binding sites of SAP2 from Candida albicans (PDB: 1EAG) demonstrated that the binding energies were -8.3, -8.0, and -7.1 kcal/mol, respectively. However, the modelling with binding sites of a deglycating enzyme fructosamine oxidase from Aspergillus fumigatus (PDB: 3DJE) demonstrated that the binding energies were -5.9, -7.2, and -8.0 for Stigmast-5-en-3β-ol (1) and Campest-5-en-3β-ol (2), and fluconazole, respectively. In conclusion, the study found that Stigmast-5-en-3-ol and Campest-5-en-3-ol are both present in the root bark of S. innocua. The compounds exhibited promising interaction with the binding sites of the protein target (SAP2 from C. albicans) compare to fluconazole.

Isolation, characterization, and docking studies of campesterol and β-sitosterol from Strychnos innocua (Delile) root bark

Objectives

Phytosterols obtained from medicinal plants are well known for their anti-diabetic, anti-cardiovascular, anti-cancer, and anti-microbial properties. Strychnos innocua (a member of the Loganiaceae family) grows in several African nations and is frequently used for medicinal purposes.

Methods

The chromatographic separation of S. innocua (root bark) ethyl acetate extract resulted in the isolation of campesterol (1) and β-sitosterol (2).

Results

The structures of 1 and 2 were confirmed by mass spectrometry, nuclear magnetic resonance (1D and 2D NMR), and literature data. This is a novel report of campesterol and β-sitosterol from S. innocua. Docking studies revealed that the binding affinities of 1 with the binding sites of Staphylococcus aureus pyruvate carboxylase (PDB: 3HO8) and Pseudomonas aeruginosa virulence factor regulator (PDB: 2OZ6) were -7.8 and -7.9 kcal/mol, respectively. Furthermore, 2 had binding affinities of -7.6 and -7.7 kcal/mol with binding sites of S. aureus and P. aeruginosa, respectively, whereas ciprofloxacin (a standard drug) had binding affinities of -6.6 and -8.7 kcal/mol.

Conclusion

This study indicated that S. innocua root bark is rich in campesterol and β-sitosterol. In silico molecular docking demonstrated that the compounds interact well with the binding sites of S. aureus and P. aeruginosa.

Gas chromatography–mass spectrometry (GC–MS) analysis of ethyl acetate root bark extract of Strychnos innocua (Delile)

Background

Majority of phytochemicals have been known to bear valuable therapeutic activities such as insecticidal, antibacterial, antifungal, anticonstipative, spasmolytic, antiplasmodial and antioxidant activities. Strychnos innocua is straight-stemmed tree belonging to the family Loganiaceae and can grow up to 18 m tall. The plant is used for various pharmacological purposes. The aim of this study was to determine the chemical composition of the ethyl acetate extract of root bark of S. innocua using GC–MS analysis. The root bark was collected, air-dried and then crushed to powder. Standard extraction method (maceration) was used to obtain the ethyl acetate extract. The GC–MS was carried out on the extract using GC 7890B, MSD 5977A, Agilent Tech.

Results

Thirty-seven compounds were identified among which dibutyl benzene-1,2-dicarboxylate showed the highest peak area (31.03%) and monomethyl pimelate showed the lowest peak area (0.39%). The major compounds identified were cyclooctane (methoxymethoxy), 2,4-dimethylheptanedioic acid dimethyl ester, azelaic acid, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, dibutyl benzene-1,2-dicarboxylate, butyl 8-methylnonyl benzene-1,2-dicarboxylate, 9,15-octadecadienoic acid, methyl ester, cis-vaccenic acid, linoleic acid ethyl ester and ethyl oleate.

Conclusions

In conclusion, these phytoconstituents might be responsible for the medicinal efficacy of the root bark of S. innocua and can be used as a source therapeutic drug.