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Background: Cancer is a major cause of death worldwide. Limitations of current cancer therapies necessitate the search for new anticancer drugs. Plants represent an immeasurable source of bioactive compounds for drug discovery. The objective of this study was to assess the anti-proliferative and antioxidant potential of four indigenous South African plants commonly used in traditional medicine. Materials and Methods: The anti-proliferative activity of the plant extracts were assessed by the 2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2 H -Tetrazolium-5-Carboxanilide (XTT) assay on A431; HaCat; HeLa; MCF-7 and UCT-Mel 1 cells and sulforhodamine-B (SRB) assay on HCT-116 and HCT-15 cell lines. Antioxidant activity was determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO) and superoxide scavenging assays. Results: Three of the plant extracts ( Combretum mollefruit , Euclea crispa subsp. crispa leaves and stems and Sideroxylon inerme leaves and stems showed anti-proliferative activity on the A431 cells with IC 50 values ranging between 26.9 - 46.7 μg/ml. The Euclea crispa subsp. crispa extract also showed anti-proliferative activity on the MCF-7 cell line (45.7 μg/ml). All of the plant extracts ( Combretum molle leaves and fruit, Euclea crispa subsp. crispa leaves and stems, Sideroxylon inerme leaves and stems and Terminalia prunioides leaves and stems) showed DPPH scavenging activity with IC 50 values ranging from 1.8 μg/ml to 11.5 μg/ml. Conclusion: These results indicate that the active extracts of Combretum molle , Euclea crispa subsp. Crispa and Sideroxylon inerme warrant further investigation to determine the mechanism of anti-proliferative activity against cancerous cells. These plant extracts also show potential for further evaluation in the prevention and treatment of cancer. Keywords: South African plants, Traditional medicine, Anti-proliferative activity, Antioxidant activity

In subtropical coastal dune forests of South Africa, the microenvironment of tree seedlings is largely influenced by a pervasive understorey woody herb, Isoglossa woodii . We examined whether the additional shading by I. woodii explains the competitive response of tree seedlings from these forests. Seedlings of four common mid- to late-successional tree species ( Diospyros natalensis , Euclea racemosa , Sideroxylon inerme and Apodytes dimidiata ) were grown at three densities of I. woodii in a common garden experiment under greenhouse conditions. The seedlings were grown at 1.6% and 13.5% of full sunlight and supplied with 1% and 10% nitrogen in half-strength Hoagland's nutrient solution. Total biomass and biomass allocation parameters were used to measure the competitive response of the seedlings. Seedlings attained maximum biomass at high light and high nutrient levels and showed species- and light-specific responses to biomass of I. woodii neighbours. Seedlings' allocation to roots increased with increasing light levels but decreased at higher nutrient levels. The leaf mass fraction (LMF) response to light and nutrient levels was opposite to that shown by root allocation. Specific leaf area (SLA) and leaf area ratio (LAR) decreased with increasing light conditions but were not responsive to manipulation of nutrients. The presence of I. woodii neighbours reduced LMF whilst the responses of SLA to neighbours depended on the light level and species. Leaf trait responses to manipulation of light conditions, I. woodii neighbour density and soil nutrient concentration are complex but overall demonstrate an overwhelming role of light in influencing seedling establishment in coastal dune forests. The competitive response of these seedlings to low irradiance reiterates the notion of phenotypic clustering at the seedling stage amongst shade tolerant tree species, which promotes seedling persistence and gradual transition into the tree layer. Our results highlight the role of additional understorey shading by the herb stratum in influencing tree recruitment dynamics and ultimately tree community structure in many of Africa's tropical lowland forests.

Albany Coastal Forests are subtropical vegetation type occurring in the western part of the Eastern Cape Province of South Africa. Alexandria Forest is the largest complex of forest patches of this type. Smaller, numerous patches of the Albany forests occur in deeply incised valleys of the rivers in the Albany region. These forests are in contact with the matrix zonal vegetation of the subtropical Albany thickets. This chapter reports on survey (based on full-floristic vegetation plots) of these forests and the classification which yielded six forest (habitat-level) communities, grouped into three Forest Subtypes. The major tree dominants in these forests are Celtis africana, Afrocarpus falcatus, Mimusops obovata, Erythrina caffra, Apodytes dimidiata, Maytenus undata and Sideroxylon inerme. Canonical correspondence analysis was used to characterise major environmental drivers underpinning the revealed vegetation patterns. An identification key assisting in field recognition of forest subtypes and communities is also presented.

Electracma minyops sp. n. (Lepidoptera: Tortricidae: Chidanotini) is described and illustrated from South Africa. The larvae form galls on white milkwood (Sideroxylon inerme L., Sapotaceae). The galls, situated about 3 to 5 cm from the tip of young shoots, cause the tips to wilt and die. About 50 % of the observed galls are also inhabited by larvae of Cecidomyidae (Diptera). Larvae of E. minyops were found in galls from July to November, whereas larvae of cecidomyids were present from August to November. Adults of the tortricid were relatively abundant from April to July.

Suppression of tree seedlings by the understory is an important ecological filter with implications for tree diversity and dynamics. In a greenhouse competition experiment, we used seedlings of four canopy species from coastal dune forest (Diospyros natalensis, Euclea racemosa, Sideroxylon inerme and Apodytes dimidiata) to examine the relative competitive effects of the dominant understory herb Isoglossa woodii on seedling performance. We manipulated I. woodii density, light and nutrient levels and measured growth responses. Total seedling biomass decreased with density of I. woodii. The magnitude of biomass suppression with competitor density was similar among tree species. Consequently there was no discernable hierarchy of competitive ranking among tree species. The relative growth rate of seedlings decreased at higher densities of I. woodii and increased at higher nutrient levels but was unaffected by variation in light conditions. Aboveground biomass decreased at higher densities of I. woodii and at higher light levels but increased at higher nutrient levels. Size asymmetric competition for light and nutrients may be the major driver of aboveground interactions between tree seedling and I. woodii. While tree species showed no hierarchy of competitive ability their seedlings exhibited equivalent responses to competition from an understory dominant, permitting species coexistence and the maintenance of species diversity.

We investigated the plasticity of seedlings to shade in six shrub species common in subtopical thicket, in order to assess their microhabitat preferences for regeneration. Cassine peragua and Sideroxylon inerme , which also occur in adjacent forests, were the most shade tolerant and would be unlikely to require canopy gaps for recruitment: their relative reduction in growth in dense shade was slight, as was their increase in leaf weight ratio (LWR); leaf inclination was adjusted to near horizontal in dense shade and maximum net photosynthetic rate ( A max ) remained fairly low in sun-acclimated plants. Rhus glauca , which also occurs on forest margins, demonstrated the highest growth rates, especially in the open, and together with its high potential A max is well-equipped as a pioneer, and would benefit from canopy gaps for establishment. Cassine aethiopica , which is also common in coastal forests, was slower growing than Rhus , but less shade tolerant than C. peragua and Sideroxylon and would probably benefit from canopy gaps for establishment. Pappea capensis and Schotia afra , which also occur in open savanna vegetation, demonstrated a growth and morphological pattern indicative of species adapted to periodic drought, in having a high ratio of woody conductive tissue to leaf tissue with accompanying slow growth. Their relatively poor performance in deep shade suggests that canopy gaps would benefit their recruitment. We concluded that canopy gaps may be essential for recruitment of the full species complement in sub-tropical thickets.

Objective To investigate the stem bark of Sideroxylon inerme L. and its compounds for tyrosinase-inhibition activity and to evaluate the mechanism involved of the most potent compounds in tyrosinase inhibition. Materials and methods Three different extracts (acetone, methanol and dichloromethane) of Sideroxylon inerme L. were evaluated for their inhibitory effect in vitro on the monophenolase and diphenolase activated forms of tyrosinase, using a colorimetric procedure. This test was used for bioactivity-guided isolation of two active compounds using column chromatography and TLC. Active extracts were also investigated for their inhibitory effect on melanogenesis in cultured B16 melanoma cells. Antioxidant activities of the methanolic extract of Sideroxylon inerme and purified compounds were investigated using the 1,2-diphenyl-2-picrylhydrazyl (DPPH) antioxidant assay. The inhibition of tyrosinase activity relative to the inhibition of its activity at the transcriptional level was also studied by determination of the degree of expression of mRNAs for this gene by using extract of Sideroxylon inerme-treated cells (B16F10) and semi-quantitative RT-PCR. Results Methanolic and acetonic extracts of the stem bark of Sideroxylon inerme showed significant inhibition of monophenolase activity (IC50 values of 63 μg/ml and 82 μg/ml, respectively). The methanolic extract also exhibited 37% reduction of melanin content at 6.2 μg/ml in melanocytes without being significantly toxic to the cells. Examination for inhibition of monophenoloxidase in situ on TLC, followed by column chromatographic purification of the stem bark extract of Sideroxylon inerme, resulted in the isolation of two active compounds, epigallocatechin gallate and procyanidin B1, with IC50 values against monophenolase of 30 μg/ml and >200 μg/ml, respectively. Epigallocatechin gallate exhibited a greater anti-tyrosinase activity than arbutin. Sideroxylon inerme bark extracts, epigallocatechin gallate and procyanidin B1 exhibited antioxidant DPPH radical scavenging activities with EC50 values of 1.54 μg/ml, 1.33 μg/ml and 1.68 μg/ml, respectively and were not particularly cytotoxic. During mechanism studies it was evident that at the transcription level, Sideroxylon inerme (25 μg/ml) was acting as a potent tyrosinase inhibitor compared to controls (untreated cells and kojic acid). Conclusion The bark extract of Sideroxylon inerme and the two isolated compounds warrant further investigation in clinical studies to be considered as skin-depigmenting agents.

Sideroxylon inerme Linnaeus, Species Plantarum 1: 192. 1753. "Habitat in Aethiopia." RCN: 1543. Lectotype (Meeuse in Bothalia 7 : 325. 1960): Herb. Linn. No. 261.1 (LINN). Generitype of Sideroxylon Linnaeus (vide Baillon, Bull. Mens. Soc. Linn. Paris 114: 908. 1891). Current name: Sideroxylon inerme L. (Sapotaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part S), pp. 806-877 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 849, DOI: 10.5281/zenodo.291971

Sideroxylon inerme, spec. nov. 1. Sideroxylon inerme. Hort. cliff. 69. Sideroxylon primum s. dein Coriae indorum nomine data arbor. Dill. elth. 357. t.265. f.344. Padus foliis oblongis, fructu solitario. Burm. afric. 238. t.84. f.2. Habitat in AEthiopia . ���, Published as part of Linnaeus, Carolus, 1753, Species plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas, Stockholm :Laurentius Salvius on pages 192-193, DOI: 10.5281/zenodo.3931989

A unique specimen of Viscum obscurum on the succulent Euphorbia polygona is described and its structure compared with that of specimens of similar size on two woody hosts, Brachylaena elliptica and Sideroxylon inerme . On Euphorbia , the primary haustorium was embedded in host wood, but it was ribbed and had produced narrow branches at various points. The structure can be related to the normal types on woody hosts as the response of the parasite to initially separate bundles, by production of branches growing along them inwards. The cambial activity of the host was greatly stimulated, groups of bundles united to form steles, these merged more or less as they increased in diameter. At the margin of contact in the cambial region, protrusions formed the ribs, more or less embedded in host xylem. Some of these extended inwards along the host cambium; a few were separated from the main cortex as lateral branches of the haustorium, with separate cortical tips and cambium. Against the haustorium and its branches internal patches of periderm were frequent and the extent of periderm at the surface was greatly increased. Comparison of the different specimens and of a range of seedling forms leads to an emphasis of the dorsiventral character of the haustorial system and an attempt to distinguish the reactions expressed in its structure.