Phytochemical Screening and Antioxidant and Cytotoxic Effects of Acacia macrostachya

In-vitro antioxidant, antimicrobial and phytochemical properties of extracts from the pulp and seeds of the African baobab fruit (Adansonia digitata L.)

Adansonia digitata, commonly known as the African Baobab plant is used widely in traditional medicine for treating of many diseases. The current study investigates the antioxidant and antimicrobial properties, and nutritional composition of the pulp and seeds from the fruit of African Baobab plant. Matured fruits were harvested and processed by separating the fruit pulp and seeds. Water, 70 % Ethanol/water mixture, and Hexane were used as solvents for extraction. Antioxidant properties of extracts in this study were investigated using the 2,2-diphenyl-1-picrylhydrazyl, hydrogen peroxidescavenging assays., Total Flavonoid Content, Total Phenolic Content, Total Tannin Content, and Total Antioxidant Capacity were also investigated. Agar Well Diffusion and Broth Dilution methods were used to estimate the antimicrobial properties of the extracts. The proximate composition of the seeds and fruit pulps was also determined. GC-MS was employed to determine the fatty acid composition. Results obtained showed the presence of Total phenolics (range 4.1-5.5 mg GAE/g), Total flavonoids (range 10.1-16.5 mg QE/g), Total Tannins (range 1.7-15.6 mg CE/g), and Antioxidants (range 2.0-14.5 mg AAE/g). The H2O2 and DPPH assays gave IC50s in the ranges of 300-1800 mg/L and 700-1600 mg/L respectively. Extract from the fruit pulp was found to inhibit the growth of a panel of 2 g-positive bacteria, 2 g-negative bacteria, and two fungi microorganisms. Fatty acids such as myristic acid, palmitic acid, and stearic acid were found to be present in oil from the seeds. Proximate components such as crude protein, crude fat, and crude fibre were found to be high. From the results, seeds and the fruit pulp of the African Baobab plant have significant antioxidant properties and can inhibit microbial growth.

Phenolic compounds as Nrf2 inhibitors: potential applications in cancer therapy

Cancer is a leading cause of death worldwide and involves an oxidative stress mechanism. The transcription factor Nrf2 has a crucial role in cytoprotective response against oxidative stress, including cancer growth and progression and therapy resistance. For this reason, inhibitors of Nrf2 are new targets to be studied. Traditional plant-based remedies rich in phytochemicals have been used against human cancers and phenolic compounds are known for their chemopreventive properties. This comprehensive review offers an updated review of the role of phenolic compounds as anticancer agents due to their action on Nrf2 inhibition. In addition, the role of naturally-occurring bioactive anticancer agents are covered in the clinical applications of polyphenols as Nrf2 inhibitors. Video Abstract.

Pharmacological properties and preliminary phytochemical analysis of Pseudocaryopterisfoetida (D.Don) P.D. Cantino leaves

Medicinal plants have significant contribution in pharmaceutical industries being producers of compounds utilized as precursors for drug development. A plant of Lamiaceae family; Pseudocaryopteris foetida had not been investigated for its biomedical potential. Current research was aimed to investigate phytochemical analysis, cytotoxic potential and antioxidant activity of crude methanolic extract and fractions of Pseudocaryopteris foetida (leaves). The preliminary phytochemical analysis of crude methanolic extracts and fractions of Pseudocaryopteris foetida revealed that plant is rich in phenolic and flavonoid classes of secondary metabolites while presence of tannin was observed only in crude methanolic extract. The cytotoxicity was determined using brine shrimp lethality test. Different concentrations (25, 50, 100, 150, 200 and 250 µg/mL) of crude methanolic extract and fractions exhibited dose dependent cytotoxicity. However, The LD₅₀ for all the extracts was more than 200 µg/mL indicating weak cytotoxic potential of Pseudocaryopteris foetida. The antioxidant capabilities of crude methanolic extract and fraction of Pseudocaryopteris foetida were analyzed by in vitro bio assays including DPPH, ABTS, Reducing power and phosphomolybdate antioxidant assays using ascorbic acid as standard. The crude methanolic extract showed IC₅₀ (256.38 ± 0.6 and 314.95 ± 1.1 µg/mL) for DPPH and ABTS respectively, while total antioxidant capacity was calculated as 55.79 ± 0.5 µg/mL for crude methanolic extract of Pseudocaryopteris foetida while ascorbic acid indicated total antioxidant capacity of 71.89 ± 2.3 µg/mL. Study concluded that leaves of Pseudocaryopteris foetida were the rich source of antioxidant phytochemicals. Based on preliminary investigations further research should be focused to isolate bioactive phytochemicals as leading source of clinical medicines in future.

Antibacterial, Antibiofilm, and Efflux Pump Inhibitory Properties of the Crude Extract and Fractions from Acacia macrostachya Stem Bark

Microbial infections remain a public health problem due to the upsurge of bacterial resistance. In this study, the antibacterial, antibiofilm, and efflux pump inhibitory activities of the stem bark of Acacia macrostachya, an indigenous African medicinal plant, were investigated. In traditional medicine, the plant is used in the treatment of microbial infections and inflammatory conditions. A crude methanol extract obtained by Soxhlet extraction was partitioned by column chromatography to obtain the petroleum ether, ethyl acetate, and methanol fractions. Antibacterial, efflux pump inhibition and antibiofilm formation activities were assessed by the high-throughput spot culture growth inhibition (HT-SPOTi), ethidium bromide accumulation, and the crystal violet retention assay, respectively. The minimum inhibitory concentrations (MICs) of the crude extract and major fractions ranged from 250 to ≥500 μg/mL. At a concentration of 3.9–250 μg/mL, all extracts demonstrated >80% inhibition of biofilm formation in S. aureus. In P. aeruginosa, the EtOAc fraction showed the highest antibiofilm activity (59–69%) while the pet-ether fraction was most active against E. coli biofilms (45–67%). Among the test samples, the crude extract, methanol, and ethyl acetate fractions showed remarkable efflux pump inhibition in S. aureus, E. coli, and P. aeruginosa. At ½ MIC, the methanol fraction demonstrated significant accumulation of EtBr in E. coli having superior efflux inhibition over the standard EPIs: chlorpromazine and verapamil. Tannins, flavonoids, triterpenoids, phytosterols, coumarins, and saponins were identified in preliminary phytochemical studies. Stigmasterol was identified in the EtOAc fraction. This study justifies the use of A. macrostachya in the treatment of infections in traditional medicine and highlights its potential as a source of bioactive compounds that could possibly interact with some resistance mechanisms in bacteria to combat antimicrobial resistance.