Expanding the reach: ethnobotanical knowledge and technological intensification in beekeeping among the Ogiek of the Mau Forest, Kenya.

BACKGROUND: Initiatives for beekeeping intensification across the tropics can foster production and income, but the changes triggered by the introduction of modern beehives might permeate traditional knowledge and practices in multiple ways, and as such should be investigated and understood. We conducted an ethnobotanical study in the Eastern part of the Mau Forest among Ogiek beekeepers who customarily practice forest beekeeping and who are involved in a project aimed at the modernization of their beekeeping activities. We aimed to document the beekeeping-associated ethnobotanical knowledge, exploring the relationships and complementarity between modern and traditional knowledge and practices. METHODS: Field research was carried out through semi-structured interviews with 30 Ogiek beekeepers and 10 additional stakeholders. We collected ethnobotanical data about plants used for beekeeping purposes, and ethnographic information on traditional and modern beekeeping systems. RESULTS: We report 66 plant species, distributed across 36 botanical families representing 58 genera, important as melliferous, for the construction and placing of hives, attracting bees, and harvesting and storing honey. Dombeya torrida (J.F.Gmel.) Bamps, Juniperus procera Hochst. ex Endl., and Podocarpus latifolius (Thunb.) R.Br. ex Mirb. are the species with the most mentions and the highest number of uses. Our study reveals that the Ogiek possess a detailed knowledge of the forest's flora, its importance and uses and that this knowledge underpins beekeeping practices. Under the influence of external actors, the Ogiek have progressively adopted modern versus traditional log hives and moved beekeeping out of the forest into open areas of pastures and crop fields. Beekeepers are also experimenting with combinations of practices borrowed from modern and traditional beekeeping systems, particularly in the field of hive construction and in the criteria to set up apiaries. CONCLUSIONS: The study indicates a complementarity and an incipient hybridization of traditional and modern beekeeping, in a way that suggests that modern beehives are instrumental in expanding the reach of beekeeping into deforested and cultivated areas. The study also points to the existence of a rift in the effects of beekeeping intensification on the livelihoods of the Ogiek and on their relationship with the forest. We argue that this intensification might be improving the former but weakening the latter, carrying the associated risk of erosion of traditional forest-based ethnobotanical knowledge.

Abyssinone V, a prenylated flavonoid isolated from the stem bark of Erythrina melanacantha increases oxidative stress and decreases stress resistance in Caenorhabditis elegans.

OBJECTIVES: Recent studies showed that distinct extracts of Erythrina species used in the traditional medicine of sub-Saharan Africa are protective against stress conditions. However, the underlying molecular mechanisms as well as relevant compounds remain unclear. METHODS: We used the model organism Caenorhabditis elegans to investigate compounds isolated from the stem bark of Erythrina melanacantha (abyssinone V (1), abyssinon-4'O-methylether (2), sigmoidin B-4'O-methylether (3), glabranin (4), 8-prenylnaringenin (5), citflavanone (6), exiguaflavanone (7) and homoeriodictyol (8)). Antioxidative capacity in vitro (trolox equivalent antioxidative capacity assay) and modulation of oxidative stress in vivo (2', 7'-dichlorofluorescein assay) were investigated; stress resistance was analysed using the nucleic acid stain SYTOX green. KEY FINDINGS: None of the prenylated flavonoids caused protection against thermal stress; in contrast, most of the compounds (1, 4, 5, 8) decreased stress resistance. None of the compounds decreased the accumulation of reactive oxygen species, but abyssinone V (1) caused an increase in oxidative stress. In line with these results, none of these compounds showed radical-scavenging effects in vitro. CONCLUSIONS: The stem bark of E. melanacantha contains various prenylated flavonoids, but no compound protected C. elegans against stress conditions. In contrast, abyssinone V increases oxidative stress and reduces stress resistance in this model organism.

Structure of constituents isolated from the bark of Cassipourea malosana and their cytotoxicity against a human ovarian cell line.

Three aromatic compounds, 2α,3α-epoxyflavan-5,7,4'-triol-(4ß â†’ 8)-afzelechin (1), 2ß,3ß-epoxyflavan-5,7,4'-triol-(4α → 8)-epiafzelechin (2), and methyl 4-ethoxy-2-hydroxy-6-propylbenzoate (3), as well as eight known compounds (4-11) were isolated from the bark of Cassipourea malosana (Rhizophoraceae). Their structures were determined on the basis of an analysis of spectroscopic data. The in vitro cytotoxic activities of these compounds against human ovarian cancer cell line TOV21G were evaluated. Most compounds showed little activity; however, the methyl derivatives of flavan dimers (1a and 2a) showed higher activity (IC50 value of 30.3 and 75.4 µM) than parent compounds 1 and 2.

Multiple readout assay for hormonal (androgenic and antiandrogenic) and cytotoxic activity of plant and fungal extracts based on differential prostate cancer cell line behavior.

ETHNOPHARMACOLOGICAL RELEVANCE: Prostate cancer is one of the most diagnosed forms of cancer among men in western regions. Many traditional applications or phytotherapeutic concepts propose to inhibit the proliferation of prostate cancer cells. In order to detect influences of plant or fungal extracts and derived fractions on androgen receptor signaling pathways, a differentiating cell proliferation assay was established, which enables the simultaneous detection of hormonal and cytotoxic effects. MATERIAL AND METHODS: The well characterized prostate cancer cell lines LNCaP and PC-3 were used in a multiple readout assay. In all, 186 fractions of 23 traditionally used organisms were screened regarding their effects on proliferation of the two prostate cancer cell lines. The fractions were prepared by accelerated solvent extraction followed by gradient extrography. Extracts of the potential hormonally active plants Cibotium barometz, Heteropterys chrysophylla, and Sideroxylon obtusifolium (= Bumelia sartorum) were phytochemically investigated. RESULTS: Fractions from Cibotium barometz, Cortinarius rubellus, Cyrtomium falcatum, Heteropterys chrysophylla, Nephrolepis exaltata, Salvia miltiorrhiza, Sideroxylon obtusifolium, Trichilia emetica, and Trimeria grandifolia exhibited hormonal influences on prostate cancer cells. Cytotoxic activity towards human cell lines was detected for the first time for fractions from Aglaia spectabilis (A. gigantea), Nephrolepis exaltata and Cortinarius brunneus. CONCLUSIONS: The differential behavior of the two prostate cancer cell lines allows the discrimination between potential androgenic or antiandrogenic activities and effects on the estrogen or glucocorticoid receptor as well as cytotoxic activities. The combined cell lines assay can help to assess the biological activities of material used in traditional medicine.

Dichapetalins from Dichapetalum species and their cytotoxic properties.

Six dichapetalins named dichapetalins N-S were isolated from Dichapetalum mombuttense, Dichapetalum zenkeri and Dichapetalum leucosia. They were accompanied in the same plants by the known dichapetalins A, B, C, I, L and M. The structures of the compounds were elucidated by 1D and 2D NMR experiments and mass spectrometry. They all possessed the dammarane skeleton substituted at position C-3 by a C6-C2 unit forming a 2-phenylpyran moiety. All contained a lactone ring in the side chain except dichapetalins O, Q and R, in which this ring was replaced by a lactol. Dichapetalin Q and R were also the first dichapetalins bearing a tertiary methyl and a double bond instead of the cyclopropane of the dammaranes. All these compounds were assayed against cancer cell lines HCT116 and WM 266-4 and displayed cytotoxic and anti-proliferative activities in the 10(-6) to 10(-8)M range.

Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) extracts inhibit the growth of the breast cancer cell lines MDA-MB-231 and MCF-7, but not the brain tumour cell line U251 in vitro.

Zanthoxylum usambarense (Engl.) Kokwaro has traditionally been used for the treatment of malaria, upper respiratory tract infections, cough, rheumatism, tooth decay and sore gums in Kenya and other African countries. Dried ground parts of Z. usambarense were extracted by maceration using methanol (MeOH) at room temperature, extract was dried and reconstituted in 70% aq. MeOH and partitioned against n-hexane and chloroform (CHCl3 ) to obtain MeOH, n-hexane and CHCl3 extracts. All extracts were assessed for cytotoxicity against two breast cancer cell lines, MDA-MB-231 and MCF-7, and the brain tumour cell line U251 by the MTT assay. The free-radical scavenging activity of the extracts was also determined by the 2,2-diphenyl-1-picryhydrazyl (DPPH) assay. In the DPPH assay, the MeOH extract was found to be the most active free-radical scavenger with a RC50 value of 41.1 × 10(-3) mg/mL. It also displayed significant cytotoxicity against the MCF-7 cell line (IC50 42.9 µg/mL) and appeared to have induced cell death through apoptosis. None of the test extracts showed any activity against the U251 cell line at test concentrations. The present findings demonstrated that Z. usambarense could be a potential source for new cytotoxic compounds for possible anticancer drug development.

Ethnobotanical studies of medicinal plants used by Traditional Health Practitioners in the management of diabetes in Lower Eastern Province, Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetes mellitus is a growing problem in many developing countries and the financial burden associated with it is enormous. In traditional African communities, majority of people relies on traditional medicines and Traditional Health Practitioners as the primary source of health care. Hence, this study was undertaken in the Lower Eastern province of Kenya to document the medicinal plants used by the traditional practitioners to treat diabetes and to assess the existing knowledge in management of this condition. MATERIALS AND METHODS: Data was collected using structured open- and close-ended questionnaires. RESULTS: Thirty-nine species belonging to 33 genera and 26 families were encountered and the most frequently cited species were from Caesalpiniaceae, Ebenaceae, Solanaceae and Labiatae families. Twenty-eight percent of the plant species are reported to have hypoglycaemic activity. CONCLUSIONS: Currently there is no data on medicinal plants used to treat diabetes in Kenya. Therefore, these findings are important in the management of diabetes and future research on traditional medicine in drug development.

Four new carvotanacetone derivatives from Sphaeranthus ukambensis, inhibitors of the ubiquitin-proteasome pathway.

Six carvotanacetone derivatives (1- 6), amongst which four new compounds (1- 4), were isolated from the aerial parts of Sphaeranthus ukambensis Vatke & O. Hoffm. The structures of the molecules were elucidated by complementary spectroscopic methods, and their biological properties were investigated using human DLD-1 colon cancer cells engineered to stably express a 4 ubiquitin-luciferase (4 Ub-Luc) reporter protein. Five of the isolated carvotanacetone derivatives (2- 6) were found to inhibit the proliferation of the colon cancer cells and interfere with the ubiquitin-proteasome pathway, with potencies in a micromolar range.

Chemical studies on the roots of Uvaria welwitschii.

A chemical investigation of the chloroform extract of the roots of Uvaria welwitschii (Annonaceae), an African traditional medicine taken for stomach ache, led to the isolation of eight new compounds, named welwitschins A-H (1-8), together with five known compounds (9-13). The structural elucidation by spectroscopic studies of the compounds isolated is described. All new compounds were flavonoids having a 2-hydroxy-3,4,6-trimethoxyphenyl moiety in the A-ring, and unsubstituted phenyl in the B-ring. Four of them (1-4) were monomeric flavonoids while the others (5-8) were dimeric flavonoids. The cytotoxicity of the isolated compounds against human promyelocytic leukemia HL-60 cells was investigated.

Prenylated pterocarpanes from Erythrina melanacantha.

The stem bark of Erythrina melanacantha ssp. melanacantha Taub. ex Harms. afforded one new and five known prenylated pterocarpanes (phaseollin, isoneorautenol, erybraedin A, phaseollidin, and homoedudiol). The new compound was identified as 2',3'-epoxy-homoedudiol [3-hydroxy-8-(3,3-dimethyl-oxiranyl-methyl)pterocarpane]. All structures were elucidated by interpretation of their 1D and 2D NMR spectra.

Antinociceptive effects of the extracts of Xylopia parviflora bark and its alkaloidal components in experimental animals.

In the present study, we attempted to elucidate the antinociceptive activity of Xylopia parviflora bark using the acetic acid-induced writhing test, hot plate test, and formalin test in mice. The MeOH extract (100 and 200 mg/kg, administered intraperitoneally (i.p.)) had an antinociceptive effect demonstrated by its inhibitory effects on writhing number induced by acetic acid. Three alkaloidal fractions exhibited significant antinociceptive effects in three animal models; the chloroform-soluble fraction, including secondary and tertiary alkaloids, exhibited the strongest effect. This result supported its use in folk medicine as an analgesic agent. We tested the main alkaloids of these fractions for their antinociceptive effects to clarify the active components. (+)-Corytuberine (6.3 and 12.5 mg/kg, i.p.) showed very strong activity, had a significant antinociceptive effect in the acetic acid-induced writhing test (with 49.4 and 98.9% reduction of writhes), in the hot plate test, and in the formalin test (with 55.4 and 90.6% inhibition during the first phase, and 73.9 and 99.9% during the second phase, respectively). (+)-Glaucine (12.5 and 25 mg/kg, i.p.) showed strong activity in three animal models, too. The activity of these compounds was also observed following oral administration in the acetic acid-induced writhing test.

Secondary and tertiary isoquinoline alkaloids from Xylopia parviflora.

From the secondary and tertiary alkaloidal fractions of the root and the bark of Xylopia parviflora (Annonaceae), the isoquinoline alkaloids, 10,11-dihydroxy-1,2-dimethoxynoraporphine and parvinine were isolated, along with 39 known alkaloids. Their structures were determined on the basis of analysis of spectroscopic data.

Quaternary isoquinoline alkaloids from Xylopia parviflora.

From the quaternary alkaloidal fraction of the bark and the root of Xylopia parviflora (Annonaceae), four isoquinoline alkaloids, xylopinidine, dehydrocoreximine, N, N-dimethylanomurine and N-methylphoebine were isolated along with the known compounds, pycnarrhine, lotusine, 6,7-dimethoxy-2-methyl-isoquinolinium salt, 1,2-dehydroreticuline, (-)-phellodendrine, (+)-tembetarine, (-)-litcubine, (+)-magnoflorine, tetradehydroreticuline, (-)-oblongine, (+)-menisperine, (+)-N-methylcorydine, stepharanine, (+)-xanthoplanine, dehydrodiscretine, jatrorrhizine and palmatine. 3,4-Dihydro-6,7-dimethoxy-2-methyl-isoquinolinium and N-methylpurpuerine were isolated as natural products for the first time. Their structures were determined on the basis of spectroscopic evidence.