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South African Journal of Botany 2002, 68: 386–388 Copyright © NISC Pty Ltd Printed in South Africa — All rights reserved SOUTH AFRICAN JOURNAL OF BOTANY ISSN 0254–6299

Short Communication

Tannins, saponins and calcium oxalate crystals from Nigerian species of Boerhavia L. (Nyctaginaceae)

HO Edeoga* and CI Ikem

Department of Biological Sciences, Federal University of Agriculture, Umudike PMB 7267, Umuahia — Abia State, Nigeria * Corresponding author, e-mail: [email protected]

Received 24 July 2001, accepted in revised form 19 October 2001

Three species of Boerhavia from southern Nigeria have tals were present around the regions of the cortex of the been screened phytochemically. The presence of tan- stem but were localised almost in every tissue of the nins and saponins are being reported for the first time root. Tannins and saponins were isolated from the tis- in B. coccinea and B. erecta whereas the report of these sues (leaves, stems and roots) of these plants hence the substances in B. diffusa corroborates previous reports. significance of these findings remains an area of further The nature of calcium oxalate crystals in the roots and investigations as far as the chemical constituents of stems of B. diffusa and B. erecta could be utilised for these plants are concerned. the characterisation of these plants. The oxalate crys-

Boerhavia L. is a herbaceous dicotyledonous plant distrib- ferent families (Bohm and Koupai–Abyazani 1993, Touyama uted in the tropics and subtropics of the world. The West et al. 1994, Liu et al. 1995, Maxwell et al. 1995, Peng et al. African Flora consists of four genera and about 10 species 1995, Stevens et al. 1995). None of these works were of the family Nyctaginaceae (Hutchinson and Dalziel 1954, specifically on Boerhavia species. Akobundu and Agyakwa 1987). Four species commonly The histochemical characterisation of calcium oxalate found in West Africa are B. erecta, L., B. coccinea Mill., B. crystals in the Boerhavia species is an area that is yet to be diffusa L. and B. repens L. documented in botanical literature. Absence of adequate Boerhavia species are economically important herbs in information relating to the general chemical constituents of Nigeria and they are used as vegetables for man, feeds for these plants also prompted our undertaking of this present animals, and as medicinal plants. They are used for the cure investigation. of convulsion, as mild laxative and in treatment of asthma A phytochemical investigation of three species of (Oliver 1959). The decoction of the whole plant is used in Boerhavia was carried out in the present study. The three treating scabies, skin rashes, small pox and to procure reg- species of Boerhavia that are common in Southern Nigeria ular menstruation. The root extract is used as remedy for are B. erecta, B. coccinea and B. diffusa and they are the yaws, jaundice, diseases of heart and kidneys, gonorrhea Boerhavia species investigated. and dropsy (Gill 1992). The whole parts of the plant comprising of mature and Duhan et al. (1992) assessed the nutritional value of some fresh leaves, stems and roots used for this study were non-conventional plant foods of India, including B. diffusa, obtained from living specimens of these plants, namely B. and showed that this plant contained appreciable amounts of coccinea, B. diffusa and B. erecta. They were collected from phosphorus, iron, manganese and oxalic acid. Nageshwar different parts of southern Nigeria. The voucher specimens and Radhakrishnaiah (1994) studied three species of (EDSUH: 132, 133, 134) were deposited at the Edo State Boerhavia and five of Bougainvillea chemosystematically and University Herbarium Ekpoma, Nigeria. observed that the three species of Boerhavia differed from For the phytochemical screening of the tannins and those of Bougainvillea in the absence of steroids/triter- saponins in these taxa, the whole plants including roots, penoids, ellagic acid, p-methoxy cinnamic acid and salicyclic stems, leaves, seeds, flowers and fruits were washed and acid. The constituents of the roots of B. diffusa were deter- dried under shade. The dried plant specimens were blended mined by Lami et al. (1991). They isolated and determined with 75% aqueous acetone containing 0.10% ascorbic acid. the structure of boeravinones D, E and F in this taxon. Tannins were isolated from the leaves, stems and roots, Attempts have been made by different workers at eluci- purified and analysed following the method described by dating the chemical compositions of plants belonging to dif- Bohm and Koupai-Abyazani (1993). The chromatographic South African Journal of Botany 2002, 68: 386–388 387 analysis of saponin content of these plants was carried out calcium oxalate crystals in B. diffusa clearly separated it using the method described by Brain and Turner (1975). from B. erecta. Several workers have utilised the nature of Histochemical localisation of calcium oxalate crystals in calcium oxalate crystals in systematics of different groups of the leaves, stems and roots of these Boerhavia species was plants (Okoli and McEuen 1986, Okoli and Green 1987, done as described by Edeoga and Ogbebor (1999). The Okoli 1988, Edeoga and Okoli 1992, 1995, Edeoga and type of crystals of calcium oxalate localised in the different Ugbo 1997, Edeoga and Ogbebor 1999). Flower, fruit and tissues were microscopically examined and their morpholo- seed morphology were compared and utilised by Noba and gy was noted. The localisation of these calcuium oxalate Ba (1992) in re-examining the systematic positions of B. dif- crystals in the tissues of some of the Boerhavia species was fusa, B. repens and B. erecta. Thus the inclusion of the his- investigated. tochemical characters of these plants in their systematics is The results of the qualitative assesment of both the pow- suggested and recommended based on the findings of this dered (all blended) and unpowdered (anatomical sections) study. tissues are summarised in Table 1. Hydrolyzable tannins So the present investigation has shown that different were isolated from the extracts obtained from all the species of Nigerian species of Boerhavia are characterised Boerhavia species investigated. The analysis of the isolate by the presence of tannins, saponins and calcium oxalate (tannins) by NMR spectra and chromatographic comparison crystals. The importance of these chemical constituents in with authentic materials showed that the tannins are related these plants cannot be over-emphasised; hence the possi- to the glucopyranose group. Saponins were also extracted bility of utilising these characters in the biological recognition from the powdered dried tissues of all the Boerhavia species of these plants has been suggested. Further screening of studied. The leaves, stems and roots were rich in saponins. these plants phytochemically is recommended in view of the The histochemical studies on the vegetative tissues of the utilisation of the plants in traditional medicine (Sofowora three taxa showed that calcium oxalate crystals are present 1982, Gill 1992, Akah and Nwambie 1993). in the roots and stems of B. diffusa and B. erecta but were not detected in any of the vegetative tissues of B. coccinea. Acknowledgements — The authors are grateful to Prof. BE Okoli of The site of localisation varied; being mostly found around the University of Port-Harcourt, Nigeria, for his useful advice and the corticular regions of the stem and almost in every tissue inspirational suggestions. of the root. The shape also varied markedly, being ‘missile’- shaped in B. diffusa but both irregular and ‘missile’-shaped References in B. erecta (Table 1). The three Boerhavia species are used in traditional medi- Akah PA, Nwambie AI (1993) Nigerian plants with anti-convulsant property. Fitoterapia 64: 42–44 cines in different parts of Nigeria (Oliver 1959, Sofowora Akobundu IO, Agyakwa CW (1987) A Hand-book of West African 1982, Gill 1992, Akah and Nwambie 1993). Akah and Weeds. International Institute of Tropical Agriculture, Ibadan, Nwambie (1993) included B. diffusa among the eleven 521pp species of Nigeria plants used medicinally by the Ibo tribe in Bohm BA, Koupia-Abyazani MR (1993) Flavonoids and condensed Nigeria which they screened for anticonvulsant properties. tannins from leaves of Hawaiian Vaccinium reticulatum and V. They reported that tannins and saponins were among the calycinum (Ericaceae). Pacific Science 48: 458–463 chemical substances they detected in their medicinal plants Brain KR, Turner TD (1975) The Practical Evaluation of including B. diffusa but they lamented the fact that there Phytopharmaceuticals. Wright Scientechnica, Bristol, UK, pp were differences in the presence/absence of these chemical 152–158 constituents. The present report on the presence of tannins Duhan A, Chuhan BM, Punia D (1992) Nutritional value of some non conventional plant foods of India. Plant Foods and Human and saponins in B. diffusa therefore reconfirms the previous Nutrition 42: 193–200 findings by Akah and Nwambie (1993) and at the same time Edeoga HO, Okoli BE (1992) Ergastic substances: Distribution in is the first report of these compounds in B. erecta and B. certain species of Dioscorea L. (Dioscoreaceae) and the taxo- coccinea from southern Nigeria. nomic importance. Journal of Experimental and Applied The results on the histochemical localisation of calcium Biology 4: 65–75 oxalate crystals among the three Boerhavia species investi- Edeoga HO, Okoli BE (1995) Histochemical studies in the leaves of gated is significant especially in their grouping. Thus the some Dioscorea L. (Dioscoreaceae) and the taxonomic impor- absence of calcium oxalate crstals in the vegetative tissues tance. Feddes Repertorium 105: 113–120 of B. coccinea (Table 1) separates this taxon from the other Edeoga HO, Ugbo HN (1997) Histochemical localisation of calcium two taxa studied. The occurrence of mostly missile-shaped oxalate crystals in the leaf epidermis of some Commelina L.

Table 1: Distribution of tannins, saponins and calcium oxalate crystals in the Boerhavia species

Character/component B. coccinea B. diffusa B. erecta Tannins + + + Saponins + + + Calcium oxalate crystals – + + Shape of calcium oxalate crystals – Missile-like Both missile-like and irregular shaped

+ = Present; – = absent 388 Edeoga and Ikem

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Edited by AK Jäger