Dissotis Rotundifolia Research Articles

Phytoremediation Potential of Weeds in Heavy Metal Contaminated Soils of the Bassa Industrial Zone of Douala, Cameroon

Phytoremediation is a promising option for reclaiming soils contaminated with toxic metals, using plants with high potentials for extraction, stabilization and hyperaccumulation. This study was conducted in Cameroon, at the Bassa Industrial Zone of Douala in 2011, to assess the total content of 19 heavy metals and 5 other elements in soils and phytoremediation potential of 12 weeds. Partial extraction was carried out in soil, plant root and shoot samples. Phytoremediation potential was evaluated in terms of the Biological Concentration Factor, Translocation Factor and Biological Accumulation Coefficient. The detectable content of the heavy metals in soils was Cu:70–179, Pb:8–130, Zn:200–971, Ni:74–296, Co:31–90, Mn:1983–4139, V:165–383, Cr:42–1054, Ba:26–239, Sc:21–56, Al:6.11–9.84, Th:7–22, Sr:30–190, La:52–115, Zr:111–341, Y:10–49, Nb:90–172 in mg kg−1, and Ti:2.73–4.09 and Fe:12–16.24 in wt%. The contamination index revealed that the soils were slightly to heavily contaminated while the geoaccumulation index showed that the soils ranged from unpolluted to highly polluted. The concentration of heavy metals was ranked as Zn > Ni > Cu > V > Mn > Sc > Co > Pb and Cr in the roots and Mn > Zn > Ni > Cu > Sc > Co > V > Pb > Cr > Fe in the shoots. Dissotis rotundifolia and Kyllinga erecta had phytoextraction potentials for Pb and Paspalum orbiculare for Fe. Eleusine indica and K. erecta had phytostabilisation potential for soils contaminated with Cu and Pb, respectively.

Antidiarrhoea and toxicological evaluation of the leaf extract of Dissotis rotundifolia triana (Melastomataceae)

BackgroundThe leaves of Dissotis rotundifolia are used ethnomedically across Africa without scientific basis or safety concerns. Determination of its phytochemical constituents, antimicrobial activity, effects on the gastrointestinal tract (GIT) as well as toxicological profile will provide supportive scientific evidence in favour of its continous usage.MethodChemical and chromatographic tests were employed in phytochemical investigations. Inhibitory activity against clinical strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhi were compared with Gentamycin. Our report includes minimum inhibitory concentration (MIC) against the tested organisms. The effect of the ethanol extract on the motility of the GIT in mice using the charcoal plug method and castor oil induced diarrhoea in rats was evaluated. Toxicological evaluation was determined by administering 250 mg/kg and 500 mg/kg of extracts on male Wistar rats for 14 days with normal saline as control. The tissues of the kidneys, liver, heart and testes were examined.ResultsPhytochemical studies revealed the presence of alkaloids, saponin and cardiac glycosides. The crude ethanol extract and fractions inhibited the growth of E. coli, P. aeruginosa, S. aureus and S. typhi to varying extents. The degree of transition exhibited by the charcoal meal was dose-dependent. In the castor oil induced diarrhoea test, all the doses showed anti-spasmodic effects. The LD50 in mice was above 500 mg/kg body weight. Toxicological evaluation at 500 mg/kg showed increased cytoplasmic eosinophilia and densely stained nuclei of the liver, tubular necrosis of the kidney, presence of ill-defined testes with indistinct cell outlines and no remarkable changes in the heart.ConclusionEthanol extracts of Dissotis rotundifolia have demonstrated antimicrobial activity against clinical strains of selected microorganisms. The plant showed potential for application in the treatment of diarrhoea, thereby justifying its usage across Africa. It also demonstrated toxicity in certain organs at the dose of 500 mg/kg, and it will be necessary to fully establish its safety profile.

Pharmacognostic evaluation of the leaves of Dissotis rotundifolia Triana ( Melastomataceae )

Dissotis rotundifolia Triana (Melastomataceae), a native of tropical West Africa is known to have many uses in ethnomedicine. Establishment of pharmacognostic profile of the leaves will assist in standardization which can guarantee quality, purity and identification of samples. Evaluation of fresh, powdered and anatomical sections of the leaves was carried out to determine the macromorphological, micromorphological, chemomicroscopic, numerical and phytochemical profiles. Macroscopically, the leaf was linear in shape, with a glabrous texture, a short petiole, margin entire, apex and leaf base acute with pinnate venation. Microscopically, stomata was anomocytic, epidermal cells were straight and polygonal with uniseriate and multiseriate covering trichomes. Chemomicroscopic characters present included lignin, starch, mucilage and calcium oxalate crystals while phytochemical evaluation revealed the presence of alkaloids, cardiac glycosides and saponins. The investigations also included the moisture content, ash values as well as palisade ratio, stomata index, vein – islet and veinlet termination numbers. These findings should be suitable for inclusion in the proposed Pharmacopoeia of Nigerian medicinal plants.

Evaluation of Colletotrichum gloeosporioides for Biological Control of Miconia calvescens in Hawaii.

Miconia calvescens (Melastomataceae), from the Neotropics, is a noxious forest weed in Hawaii. We evaluated an isolate of Colletotrichum gloeosporioides that causes leaf spots on Miconia spp. in Brazil for its potential in biological control. Hawaii has no native Melastomataceae genera but does have members of 12 introduced genera. Following Wapshere's centrifugal phylogenetic method (2), eight species of Melastomataceae genera in Hawaii were inoculated in addition to Miconia spp. Naturalized and native Hawaiian members of the order Myrtales also were inoculated to determine host specificity, including Terminalia catappa (Combretaceae); Cuphea hysopifolia and C. ignea (Lythraceae); Arthrostema ciliatum, Clidemia hirta, Dissotis rotundifolia, Heterocentron subtriplinervium, Medinilla scortechenii, Melastoma candidum, Pterolepsis glomerata, and Tibouchina herbaceae (Melastomataceae); Eucalyptus grandis, Eucalyptus microcorys, Eugenia reinwardtiana, Eugenia uniflora, Leptospermum laevigatum, Melaleuca quinquenervia, Metrosideros polymorpha, Psidium guajava, and Syzgium malaccanse (Myrtaceae); Fuchsia magellanica and Oenothera stricta (Onagraceae); and Wikstroemia oahuensis and W. uva-ursi (Thymelaeaceae). All M. calvescens plants were grown from seed collected in Hawaii. Other test plants were grown from seeds or cuttings in artificial potting medium in a greenhouse. Plants had 6 to 8 mature leaves when inoculated. C. gloeosporioides was cultured on 10% potato dextrose agar supplemented with plain agar (35 g/liter) and incubated under constant fluorescent illumination at 20°C. Conidia were harvested by flooding 10-to 14-day-old cultures with sterile tap water, followed by light scraping with a scalpel. Conidial suspensions were adjusted to 106 conidia per ml and applied to both leaf surfaces with a hand-held sprayer. Inoculated plants were kept at 100% relative humidity and 16 to 25°C for 48 h. Four replicate plants and one plant of M. calvescens per species were inoculated. Plants were observed for symptom development for up to 6 weeks. The entire test was repeated once. Lesions were visible after 7 to 10 days. Young lesions had chlorotic halos and expanded in a roughly circular pattern to diameters of 5 to 10 mm. Mature lesions developed necrotic centers, coalesced, and became dry and brittle with age, resulting in extensive leaf necrosis. Defoliation of moderately to severely infected leaves occurred ≈ 30 days after inoculation. With the exception of M. calvescens, C. gloeosporioides did not produce visible symptoms on test plants. The failure of Clidemia hirta, the taxonomic species most closely related to M. calvescens, to become symptomatic was particularly significant relative to the centrifugal phylogenetic concept. The results demonstrate that our pathogen (VIC 19306) is distinct from C. gloeosporioides f. sp. clidemiae (1), which did not infect M. calvescens. We designate our pathogen C. gloeosporioides f. sp. miconiae. Voucher specimens (VIC 19306, Sana, RJ, 24.II.1998, and R. W. Barreto) and cultures are maintained at the Departamento de Fitopatologia, Universidade Federal de Viçosa MG, Brazil.

Phytosociological Observations on the Vegetation of Burnt and Unburnt Areas near Ibadan, Nigeria

Phytosociological Observations on the Vegetation of Burnt and Unburnt Areas near Ibadan, Nigeria