Browsing by Author "Komlaga, Gustav"

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    Antiplasmodial compounds from Ghanaian medicinal plants
    (December 2015) Komlaga, Gustav
    Malaria is a major public health challenge in Ghana, and many indigenes employ medicinal plants, beside orthodox medicines, to treat the disease. An ethnobotanical survey was performed in the Bosomtwi and Sekyere East Districts of Ghana to identify plants used locally to manage malaria. This was done in comparison with the plant ingredients in marketed herbal antimalarial remedies in the Kumasi metropolis. The survey inventoried ninety-eight (98) plant species; twelve (12; 12.2%) reported for the first time globally, and twenty (20; 20.4%) others for the first time in Ghana for the treatment of malaria. Twenty-three (23) locally available finished, often multi/polyherbal antimalarial products examined contained aerial or underground parts of twenty-nine (29) of the plants cited in the survey as ingredients. Twenty-two (22) of these products were registered by the Ghana Food and Drugs Authority; four (4) were included in the Ghana Health Service recommended herbal medicine list for treating malaria in Ghana. The aqueous as well as serially extracted organic solvents (petroleum ether, ethyl acetate, and methanol) extracts of five plants parts, selected based on their importance in the traditional treatment of malaria and lack of the appropriate data in the literature, were studied against the chloroquine-sensitive 3D7 and chloroquine-resistant W2 P. falciparum parasite in vitro. The plant materials included the whole of Phyllanthus fraternus, leaves of Tectona grandis, Terminalia ivorensis and Bambusa vulgaris, and root of Senna siamea. All the aqueous extracts showed notable antiplasmodial activity (IC50 < 10 µg/mL), except that of S. siamea, against 3D7 P. falciparum. Only T. ivorensis and S. siamea extracts showed activity against W2 P. falciparum (IC50 < 50 µg/mL). The extracts demonstrated high selectivity index (SI) for 3D7 P. falciparum (SI > 3.5) but very low SI for W2 P. falciparum. Resistance index (RI) was largely under 20. The organic fractions were equally active (IC50 < 50 µg/mL; 3D7 P. falciparum). The methanol extracts of the two most potent plant materials, the whole of P. fraternus and leaf of B. vulgaris, were subjected to phytochemical study to isolate and elucidate the chemical constituents, which were then assayed for antiplasmodial activity. The phytochemical study of the v methanol extract of P. fraternus yielded six compounds; Pf 1 to Pf 6 identified as the lignan, phyllanthin, and five securinega alkaloids namely nirurine, ent-norsecurinine, allo-norsecurinine, bubbialine and epibubbialine. This is the first isolation of allo - norsecurinine from a natural source and bubbialine from the Phyllanthus genus. The compounds displayed significant antiplasmodial activity against both 3D7 and W2 P. falciparum (1.14 ± 0.32 µM ≤ IC50 ≤ 59.00 ± 5.43 µM); ent-norsecurinine being the most active (IC50=1.14± 0.32 µM) and against the W2 P. falciparum. Only Pf2 (nirurine) and Pf1 (phyllanthin) displayed cytotoxicity (CC50 < 100 μM; HUVECs). This is the first report of the antiplasmodial activity of these compounds. Similar study of the methanol extract of B. vulgaris yielded 6 compounds, Bv1 to Bv6, identified as p-coumaric acid [(E)-3-(4-hydroxyphenyl) acrylic acid], cinnamic acid, dehydrovomifoliol [(E)-4-hydroxy-3,5,5-trimethyl-4-(3-oxobut-1-en-1-yl)cyclohex- 2-en-1-one], 3-oxo-α-ionol [9-hydroxy megastigma-4, 7-dien-3-one], loliolide [6- hydroxy-4, 4, 7a-trimethyl-5, 6, 7, 7a-tetrahydrobenzofuran-2(4H)-one] and tricin [5,7,4’-trihydroxy-3’,5’-dimethoxyflavone]. The six compounds are the first everreported isolations from B. vulgaris. All the compounds from B. vulgaris displayed significant activity against 3D7 (IC50 < 5 μΜ and W2 strains of P. falciparum (IC50 < 7 μM). Bv1 (p-coumaric acid) was the most active against 3D7 P. falciparum (IC50: 0.84 ± 0.90 μM) and Bv2 (cinnamic acid) the most active against W2 P. falciparum (IC50: 1.41 ± 0.38 μM). The compounds displayed no cytotoxicity (CC50 > 100 μM; HUVECs). This is the first report of the antiplasmodial activity of the six compounds. These twelve (12) compounds with remarkable antiplasmodial activity add to the library of natural compounds with antiplasmodial activity. This study has illustrated the potentials of Ghanaian medicinal plants as source of natural antiplasmodial compounds, and has justified the use of the plants in traditional treatment of malaria.
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    Hepatoprotective Potential of Hura crepitans L.: A Review of Ethnomedical, Phytochemical and Pharmacological Studies
    (Journal of Complementary and Alternative Medical Research, 2020-03) Owojuyigbe, Oluwole S.; Firempong, Caleb K.; Larbie, Christopher; Komlaga, Gustav; Emikpe, Benjamin O.
    Herbal medicines are the main source of treatment of diseases in non-urban centres of the developing world. Secondary metabolites obtained from herbal sources contain bioactive phytochemicals, many of which have been the origin for the development of novel pharmaceutical drugs. Hura crepitans L. (Euphorbiaceae) or sandbox tree has been beneficial in many ethnomedicinal applications as a purgative, emetic, hepatoprotective, anti-inflammatory, antimicrobial and the treatment of leprosy. Toxicological, phytochemical and bactericidal studies have also been documented. This paper reviews the potential of the Hura crepitans plant in protecting the liver against drug-induced toxicity. The paper dwells extensively on the ethnomedical, phytochemical and pharmacological properties of the plant. In achieving the above, intensive analyses of books and published peer-reviewed journal articles were carried out using credible scientific databases. Four main phytochemicals were revealed to be contained in Hura crepitans stem-bark. Their protective effects were enunciated using animal models. However much more biochemical studies need to be done to establish the hepatoprotective potentials of the various parts and various phytochemicals of Hura crepitans with the need for more preclinical and clinical studies. We, therefore, present in this paper efforts to elucidate and bring to the fore the therapeutic potentials of Hura crepitans plant.
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    Isolation and characterisation of the chemical constituents and the hypoglycaemic potentials of the fruit of Tetrapleura Tetraptera T. (Mimosaceae)
    (2004-11-24) Komlaga, Gustav
    The fruit of T. tetraptera is a popular spice and component of many traditional medicinal products in West Africa. It is used for the treatment of various disease conditions including hypertension, malaria, inflammation, leprosy, rheumatoid pains, convulsion and epilepsy. In some communities of Ghana, the fruit is used in the treatment of diabetes mellitus (Amoako-Atta B., Director-CBUD, KNUST, 2001, personal communication). However, there is no scientific data to ascertain this claim. Besides, there is no documentation on the antidiabetic/hypoglycaemic property of the fruit. In the light of these facts, this project was undertaken to investigate the antidiabetic activity of the alcoholic extract of the fruit in normoglycaemic rats and also to isolate and elucidate the structures of the chemical constituents present in the alcoholic extract of the fruit. Basic phytochemical screening of the extract confirmed the presence of saponins, reducing sugars and phenolic compounds. However, cyanogenetic glycosides though previously reported were not detected in this study. Series of column and preparative thin layer chromatography of the alcoholic extract led to the isolation of five compounds. On the basis of spectral data the identities of these compounds were established as sucrose; two known chalcones, 2’, 4, 4’- trihydroxychalcone and 2’, 3, 4, 4’—tetrahydroxychalcone; a known flavanone, 4’, 5, 7- trihydroxyflavanone along with a new monodesmosidic saponin, 3-0- {2’-aceto- ,8-D- glucopyranosyl} olean-12 (13)-ene-28-oic acid. All these isolates except sucrose are being reported in T tetraptera for the first time. The hypoglycaemic effect of the alcoholic extract of the fruit of T. tetraptera was studied in normoglycaemic rats. The extract administered per os at doses of 1000, 2000 and 4000 mg/kg body weight exhibited a biphasic effect in the rats. It caused an initial increase in blood glucose level followed by a falling blood glucose level. The hypoglycaemic effect of the extract at the dose of 2000 mg/kg was comparable to that of glibenclamide (standard drug) between the 2 and 8th hour after administration. In the 10th hour however, the extract at 2000 mg/kg and 4000 mg/kg showed a significantly better (P<0.001) blood glucose lowering effect than the glibenclamide. This thus validates the traditional use of the fruit in the treatment of diabetes mellitus and present an opportunity to develop a molecular antidiabetic drug.