Characterization, Anti-glycation, Anti-inflammation, and Lipase Inhibitory Properties of Rauvolfia vomitoria Leaf Extract: In Vitro and In Silico Evaluations for Obesity Treatment

Pancreatic lipase (PLP) is an enzyme responsible for the catalytic hydrolysis of fats and its inhibition is relevant for obesity management. Side effects linked with orthodox inhibitors have, however, paved the way for an increased search for safe natural sources. The present study investigated the anti-glycation, anti-inflammatory, and anti-lipase properties of Rauvolfia vomitoria aqueous (ARV), ethanolic (ERV), and methanolic (MRV) leaf extracts coupled with the molecular interactions of selected bioactive compounds with PLP using in vitro and in silico techniques. Phytochemical constituents were characterized using spectroscopic techniques. Drug-likeness and chemical reactivity profile of selected bioactive compounds were analyzed using SwissADME and quantum chemical calculations. FT-IR and GC-MS affirmed the presence of phenolic compounds including 3-phenyl-2-ethoxypropylphthalimide and 5-methyl-2-phenyl-1H-indole. All extracts showed moderate anti-glycation, anti-inflammatory, and lipase inhibitory capacities relative to standard controls. However, MRV exhibited the highest lipase inhibition (IC50, 0.17 ± 0.01 mg/mL), using a mixed-inhibition pattern. MRV interaction with PLP resulted in decreased secondary structure components of PLP (α-sheet, β-turn). MRV compounds (MCP20, MCP28, etc.) exhibited low chemical hardness, EHOMO-ELUMO energy gap, and high chemical reactivity. Foremost MRV compounds obeyed Lipinski's rule of five for drug-likeness and interacted with PHE-78 amongst others at PLP catalytic domain with high binding affinity (≥ - 9.3 kcal/mol). Pi-alkyl hydrophobic interaction and hydrogen bonding were predominantly involved. Our findings provide scientific insights into the ethnotherapeutic uses of R. vomitoria extracts for the management of obesity and related complications, plus useful information for optimizable drug-like candidates against obesity.

Cytotoxicity, Antimicrobial, Antioxidant, Anthelmintic, and Anti-Inflammatory Activities and FTIR Analysis of Combretum nioroense Stem Bark

Combretum nioroense is widely used in the folkloric treatment of a variety of bacterial and helminthic infections. The decoction of its leaves is traditionally fed to newborn babies in some rural parts of Ghana. The study focused on identifying the prime components of petroleum ether and ethanolic extracts of the stem bark using standard phytochemical screening protocols and chromatographic and spectroscopic techniques. The activities (cytotoxicity, antimicrobial, antioxidant, anthelmintic, and anti-inflammatory) of the extracts of C. nioroense were also investigated. Preliminary phytochemical analysis of the extracts revealed the presence of glycosides, saponins, phenols, coumarins, alkaloids, flavonoids, tannins, steroids, phytosterols, flavanols, terpenoids, and cardiac glycosides. The action of the extracts of C. nioroense on Milsonia ghanensis worms was concentration-dependent, with the least concentration (0.75 mg/mL) paralyzing and killing M. ghanensis after the maximal exposure time. The IC50 values for petroleum ether and ethanol extracts in the DPPH assay were >100.0 and 27.940 ± 1.005 μg/mL and those of the H2O2 assay were 400.900 ± 3.400 and 322.500 ± 1.005 μg/mL, respectively. The total antioxidant capacities (TACs) for petroleum ether and ethanol extracts were 47.197 ± 0.533 and 57.968 ± 0.560 gAAE/100 g, respectively. The IC50 value for ethanol extract in the cytotoxicity studies was 115.4 ± 1.332 μg/mL. The MICs of the extracts against the test organisms were within the range of 0.0122–25.0 mg/mL. The extracts (petroleum ether and ethanol) showed a concentration-dependent increase in anti-inflammatory activity with IC50 values of 31.254 ± 0.359 and 24.402 ± 0.569 μg/mL, respectively. Chromatographic separations of the ethanol extract gave three fractions. FTIR analysis of the extracts and purified fractions revealed the presence of functional groups, confirming the presence of the phytochemicals identified in the screening test. The results indicate that both extracts of C. nioroense exhibit cytotoxicity, antimicrobial, antioxidant, anthelmintic, and anti-inflammatory activities, thereby proving the folkloric use to treat ailments caused by worms and microorganisms.

Isolation and Identification of Flavanone Derivative Eriodictyol from the Methanol Extract of Afzelia africana Bark and Its Antimicrobial and Antioxidant Activities

Background

Afzelia africana is a plant species with well-documented ethnobotanical and medicinal properties. The plant is reported to have various secondary metabolites and had been applied for the treatment of various diseased conditions.

Objectives

The study objectives include fractionation, isolation, purification, and characterization of eriodictyol from the bark of A. africana, and the determination of its antimicrobial and antioxidant activities. Methodology. The series of methodologies that were employed include fractionations and purification (column chromatography), characterization (HPLC, LC-MS, IR, ¹H, ¹³C, DEPT-135, HSQC, and HMBC), antimicrobial assays (microbroth dilution and checkerboard assay), and antioxidant activities assays (ABTS and DPPH scavenging capacity).

Results

The study reports the identification and characterization of eriodictyol from the bark of A. africana which exhibited potent antioxidant activities against ABTS and DPPH radicals with scavenging capacities (SC₅₀) of 2.14 ± 0.05 and 2.51 ± 0.06 µg/mL, respectively. The compound exhibited its antimicrobial activity by reporting good bacteriostatic activities (MBC/MIC > 4) against Staphylococcus aureus (SA), methicillin-resistant Staphylococcus aureus (MRSA), and fluconazole-resistant Candida albicans (CA2). Moreover, a broad spectrum of bactericidal effects (MBC/MIC ≤ 4) was reported against Streptococcus mutans (SM), Escherichia coli (EC), Bacillus subtilis (BS), Klebsiella pneumonia (KP), Pseudomonas aeruginosa (PA), Salmonella typhi (ST), and standard Candida albicans (CA1). The compound further exhibited synergistic effects against EC, KP, ST, and MRSA; ST; and CA2 when combined with ciprofloxacin, tetracycline, and nystatin, respectively. However, antagonistic effects were observed against PA and CA1 when combined with ciprofloxacin and ketoconazole, respectively.

Conclusion

The study reports for the first time the identification of eriodictyol from the bark of A. africana which exhibited significant antioxidant and antimicrobial properties.