Browsing by Author "Yalo, Masande"

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    Characterization of four new compounds from protea cynaroides leaves and their tyrosinase inhibitory potential
    (MDPI, 2022) Yalo, Masande; Makhaba, Masixole; Hussein, Ahmed A.
    Protea cynaroides (king protea) is a flowering plant that belongs to the Proteaceae family. This multi-stemmed shrub is the national flower of South Africa and has important economic and medicinal values. Traditionally, the main therapeutic benefits of this plant species include the treatment of cancer, bladder, and kidney ailments. There are very limited reports on the isolation of phytochemicals and their biological evaluation from P. cynaroides. In this study, the leaves of P. cynaroides were air-dried at room temperature, powdered, and extracted with 80% methanol followed by solvent fractionation (hexane, dichloromethane, ethyl acetate, and butanol). The ethyl acetate and butanol extracts were chromatographed and afforded four new (1–4) and four known (5–8) compounds, whose structures were characterized accordingly as 3,4-bis(4-hydroxybenzoyl)-1,5-anhydro-D-glucitol (1), 4-hydroxybenzoyl-1,5-anhydro-D-glucitol (2), 2-(hydroxymethyl)-4-oxo-4H-pyran-3-yl-6-O-benzoate-β-D-glucopyranoside (3), 3-hydroxy-7,8-dihydro-β-ionone 3-O-β-D-glucopyranoside (4), 4-hydroxybenzoic acid (5), 1,5-anhydro-D-glucitol (6), 3,4-dihydroxybenzoic acid (7), and 3-hydroxykojic acid (8).
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    Characterization of new pyrone-containing flavones from Helichrysum petiolare Hilliard & B.L. Burtt
    (Elsevier B.V., 2025) Makhaba, Masixole; Yalo, Masande; Koki, Mkhuseli; Nako, Ndikho; Mabusela, Wilfred T.; Pearce, Keenau; Benjeddou, Mongi
    Helichrysum petiolare Hilliard & B.L. Burtt. (Asteraceae), native to the Cape Floral Region of South Africa, is traditionally used in the management of wounds, respiratory complaints, and diabetes. Although extensive studies on its extracts, few have focused on the bioactivity of the individual phytochemicals. In this study, chromatographic processing of the H. petiolare leaf total extract led to the isolation and identification of ten compounds C1–C10) using NMR, FTIR, and HRESIMS spectroscopy. Two pyrone-containing flavones (C1 and C2) are reported for the first time from natural sources. The known compounds identified included flavonoids (C3–C5), phenolics (C6–C9), and a sterol (C10). The MTT assay revealed dose-dependent cytotoxicity of C1–C4 only against MDA-MB-231 (breast cancer), HeLa (cervical cancer), and HEK-293 (non-cancerous kidney) cell lines after 24 h exposure. Notably, C4 demonstrated selective activity toward HeLa cells (45 % viability reduction at 100 µM; IC₅₀ = 89.19 µg/mL). This is the first report of compounds C1–C10 from H. petiolare and their in vitro cytotoxic profile. Despite moderate activity, this work provides a foundation for further pharmacological investigations of derivatives of these metabolites in cancer management.
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    Phytochemistry, anti-tyrosinase, and anti-diabetes studies of extracts and chemical constituents of dicerothamnus rhinocerotis leaves
    (Multidisciplinary Digital Publishing Institute (MDPI), 2024) Watti, Olusola Ifedolapo; Mabusela, Wilfred T.; Yalo, Masande
    Dicerothamnus rhinocerotis (L.f.) Koekemoer, also known as rhinoceros bush and previously called Elytropappus rhinocerotis (L.f.) Less., is from the Asteraceae plant family. The plant is traditionally used to treat indigestion, stomach ulcers, influenza, and diarrhea. This study was aimed at investigating the phytochemistry, anti-glucosidase, anti-amylase, and anti-tyrosinase effects of D. rhinocerotis as research in this area is limited. The air-dried plant materials were macerated in 80% methanol (MeOH) and fractionated between hexane, dichloromethane (DCM), ethyl acetate (EtOAc), and butanol (BuOH). Column chromatography on silica gel was employed for the isolation of the compounds. A total of six compounds (1–6) were isolated from the fractions viz. acacetin (1), 15-hydroxy-cis-clerodan-3-ene-18-oic-acid (2), acacetin-7-glucoside (3), pinitol (4), apigenin (5), and β-sitosterol-3-O-glycoside (6). Compounds 2–4 and 6 are reported for the first time from this plant. Among the different fractions, the BuOH and EtOAc fractions had strong tyrosinase inhibitory activities with IC50 values of 13.7 ± 1.71 and 11.6 ± 2.68 µg/mL, respectively, while among the isolated compounds, apigenin (5) had the strongest inhibitory activity, with an IC50 of 14.58 µM, which competes favorably with Kojic acid (17.26 µM). The anti-glucosidase assay showed good activity in three of the fractions and compound 5, while the anti-amylase assays did not show significant inhibition activity.