Shakira Shaik

Impact of spiked concentrations of Cd, Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress).

abstract This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.

Phytochemical Analysis with Antioxidant and Cytotoxicity Studies of the Bioactive Principles from Zanthoxylum Capense (Small Knobwood).

BACKGROUND Zanthoxylum capense (small knobwood) is a South African species known for a wide range of anecdotal uses. However, there is a dearth of information on its phytoconstitutional make-up, specifically its knobs, with only a few reports on the bioactive compounds that could justify its ethnomedicinal use. OBJECTIVES This work aimed to identify the active principles in Z. capense and evaluate their cytotoxicity against breast cancer tumor cells. METHOD Extracts from the stem bark, knobs and leaves were purified using chromatographic methods and characterized using spectroscopic techniques. Cytotoxicity of isolated compounds was evaluated on mammalian MCF-7, Caco-2 tumor cell lines and HEK295, a normal kidney cell line. RESULTS The following compounds were isolated from the plant: a quaternary benzophenanthridine-type alkaloid (chelerythrine) along with its alkanoamine derivative (6-hydroxydihydrochelerythrine), an indolopyridoquinazoline alkaloid (rutaecarpine), an alkyl p-coumaric acid ester (dodecyl-trans-p-coumarate), a lignan (sesamin), a flavanol (catechin), two triterpenoids (lupeol and sitosterol) and two pigments (pheophytin a and lutein). In the cytotoxicity study, all tested samples decreased the viability of the MCF-7 tumor cells by at least 23% at concentration 1 μg mL-1 and Caco-2 tumor cells by at least 15% at concentration 5 μg mL-1 but a mild toxic effect on HEK295 across the tested samples. RESULTS The following compounds were isolated from the plant: a quaternary benzophenanthridine-type alkaloid (chelerythrine) along with its alkanoamine derivative (6-hydroxydihydrochelerythrine), an indolopyridoquinazoline alkaloid (rutaecarpine), an alkyl p-coumaric acid ester (dodecyl-trans-p-coumarate), a lignan (sesamin), a flavanol (catechin), two triterpenoids (lupeol and sitosterol) and two pigments (pheophytin a and lutein). In the cytotoxicity study, all tested samples decreased the viability of the MCF-7 tumor cells by at least 23% at concentration 1 μg mL-1 and Caco-2 tumor cells by at least 15% at concentration 5 μg mL-1 but a mild toxic effect on HEK295 across the tested samples.

Phytochemical, elemental and biotechnological study of Cryptocarya latifolia

Background: Existing populations of Cryptocarya latifolia (Lauraceae) are rapidly declining as a consequence of their substitutive use for Ocotea bullata. The uncontrolled and excessive removal of the bark and roots of this species has led to the death of many of these plants and may eventually result in its depletion in the natural habitat. Materials and Methods: The secondary metabolites from the leaves and fruits of C. latifolia were extracted using solvents of various polarities, isolated using column chromatography and identified using spectroscopic techniques. The in vitro free radical scavenging activity (antioxidant capacity) of selected phytocompounds at varied concentrations was determined by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. A propagation study of the species was also conducted. Results: The compounds isolated from the plant were the novel compound, α-pyrone (5-hexyltetrahydro-2H-pyran-2-one) and known compounds quercetin-3-O-rhamnoside, β-sitosterol, copaene and nerolidol. The radical scavenging activity of the isolated compounds indicated moderate to good anti-oxidant activity. Treatment of explants with BAP: NAA at 1.0:0.01 mg L-1 produced the highest percentage of shoots (94%) and longest shoot length (8.06 mm). Conclusion: This study validates the ethno-medicinal use of the plant and supports the replacement of bark and roots by leaves and fruits for the management and conservation of this declining plant species. The benefits of consuming the fruits are two-fold as they can also contribute to the recommended dietary allowances of most essential elements for the majority of individuals.

Establishment of seed germination and micropropagation protocols for Senegalia nigrescens, a potential anti-virulent species

ABSTRACT This study describes seed germination and micropropagation of Senegalia nigrescens, an economic, medicinal and nitrogen-fixing species of South Africa. Seeds of S. nigrescens were subjected to pre-sowing treatments including soaking in cold water for 24 h, sulphuric acid (H2SO4) or hydrochloric acid (HCl) for 4, 8 and 12 min and mechanically scarifying seeds before sowing on Petri plates with wet filter paper. Mechanically-scarified seeds were also sown aseptically on a filter paper bridge, plain agar, ½ or full strength Murashige and Skoog (MS) basal medium. Single nodal explants from MS-derived seedlings were grown on MS media supplemented with 0.0, 0.5, 1.0 and 2.0 mg L−1 of benzylaminopurine (BAP) or kinetin (KIN) and a combination of 0.5 mg L−1 of BAP and KIN to investigate shoot multiplication. No significant differences were observed in the number of shoots produced across all treatments. However, the treatment containing 1.0 mg L−1 KIN produced a significantly higher shoot length (14.17 ± 5.20 mm) than 0.5, 1.0 and 2.0 mg L−1 BAP (7.67 ± 3.87, 6.75 ± 2.93 and 8.70 ± 3.56 mm, respectively). The highest rooting rate (16.7%) was obtained on ¼ strength MS supplemented with either indole-3-acetic acid (IAA) or indole-3-butyric acid (IBA) at concentrations 1.0 and 0.5 mg L−1, respectively. Rooted plantlets were successfully acclimatised with a 66.7% survival rate. The findings from this study would be of great benefit for the commercial propagation of S. nigrescens.