Publications by authors named "Nneka Augustina Akwu"

2 Publications

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Foliar microstructure and histochemical analysis of the lavender tree (Heteropyxis natalensis Harv.).

Micron 2022 Feb 18;153:103184. Epub 2021 Nov 18.

School of Biological and Marine Sciences, Faculty of Science and Engineering, University of Plymouth, Drake Circus, PL4 8AA, United Kingdom.

Heteropyxis natalensis Harv. is a native South African tree used in traditional medicine among Venda and Zulu communities. In this study, micromorphological investigations using light and scanning electron microscopy identified long, tapered non-glandular trichomes on the abaxial and adaxial surfaces of the leaves. The total number of trichomes appeared to be greater on emergent leaves and decreased as leaves matured. In addition, schizolysigenous secretory cavities and druse crystals were found within the leaves. Swollen subdermal secretory cavities were also distributed in the midrib of the leaves. Transmission electron microscopy confirmed the presence of nuclei, plastids, mitochondria, vesicles, rough endoplasmic reticulum cisternae and Golgi bodies in the secretory epithelia of these cavities. Various histochemical tests revealed the presence of alkaloids, phenolics, lipids, proteins, essential oils, resin acids and trace amounts of unesterified pectins and polysaccharides in the leaves. This study provides new findings and contributes to the existing research regarding H. natalensis with respect to the micromorphology, ultrastructure and histochemical composition of this species.
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February 2022

The essential oils of Grewia Lasiocarpa E. Mey. Ex Harv.: chemical composition, in vitro biological activity and cytotoxic effect on Hela cells.

An Acad Bras Cienc 2021 28;93(2):e20190343. Epub 2021 May 28.

School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa.

The chemical composition and biological activity of the essential oil extracted from the fresh leaves and stem bark of Grewia lasiocarpa was determined for the first time in this study. The essential oils were extracted by hydrodistillation and identified by GC-MS and FTIR. The antibacterial, antioxidant activity and total phenolic content of essential oils were determined. The major compounds identified were phytol (22.6%); α-farnesene (8.62%); n-hexadecanoic acid (7.24%); farnesol (4.61%) in the leaves, and 2-methylheptadecane (7.24%); heptacosane (7.60%); heptadecane, 2,6,10,14-tetramethyl (7.30%). The presence of aromatic, alkanes and phenolic compounds were revealed by FTIR analysis. The in silico oral prediction shows that some of the components are orally safe. The essential oil from the leaves showed cytotoxic activity at 1mg/mL(IC50 =555.70 μg/mL) against HeLa cells. The oils exhibited no significant antioxidant activity (IC50 >1 000 μg/mL) with <100 mg/g GAE of total phenol. The essential oils showed different degrees of activities against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 314588) at 10 μg/mL, 5 μg/mL and 2.5 μg/mL. These results might provide a future reference basis for further exploration of more of its medicinal application.
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June 2021