Nigerian propolis: chemical composition, antioxidant activity and α-amylase and α-glucosidase inhibition.

Propolis is an attractive natural ingredient to design health products due to its pharmacological effects. Our chemical investigation of a polar extract of Nigerian propolis (NP) led the isolation and identification of five isoflavonoids (1-4, 6), one diarylpropane (5) and one prenylated flavanone (7) by the combination of chromatographic and spectroscopic techniques. Compounds 1, 4 and 7 were found to be the main markers in NP (8.0, 5.0 and 4.0 mg/g of dry extract, respectively). Moreover, NP and its phenolic constituents exhibited in vitro free radical scavenging activity together with a promising antidiabetic effect against α-amylase and α-glucosidase enzymes. Finally, NP showed also a moderate inhibition of Helicobacter pylori growth. These results suggested that NP could be a good candidate in nutraceuticals and food products.

Analgesic and Antioxidant Activities of Stem Bark Extract and Fractions of Petersianthus macrocarpus.

BACKGROUND: Petersianthus macrocarpus (Lecythidaceae) is widely used in the folk medicine in Nigeria to relieve pain and fever associated with malaria. This study evaluated the analgesic and antioxidant activities of the methanol extract and fractions of the stem bark of the plant. MATERIALS AND METHODS: The analgesic activity was determined in mice using hotplate and acetic acid-induced writhing models. Morphine sulphate (5 mg/kg, i.p.) and aspirin (100 mg/ml, p.o.) were used as reference analgesic agents. The antioxidant potential was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical; reducing power, iron chelating properties and determination of total phenolic content. RESULTS: The extract at 200 and 500 mg/kg, produced an insignificant (P > 0.05) increase in pain threshold in hotplate but a significant (P < 0.05) increase at 1000 mg/kg. The extract significantly (P < 0.05) reduced the writhing induced by acetic acid in mice in a dose dependent manner. Fractionation increased the analgesic activities significantly (P < 0.05) in ethyl acetate and aqueous fractions (200 mg/kg). The extract demonstrated strong DPPH radical scavenging activity with IC50 0.05 mg/ml, good reducing power and weak iron chelating activities. The total phenol content was 142.32 mg/gin term of gallic acid. The antioxidant effects were more pronounced in ethyl acetate and aqueous fractions. CONCLUSION: The findings of the study suggested that the extract has strong analgesic and antioxidant activities which reside mainly in the polar fractions thus confirming the traditional use of the plant to alleviate pains. SUMMARY: Analgesic and antioxidant activities of extract and solvent fractions of Petersianthus macrocarpus investigated indicated that extract has analgesic and antioxidant properties that reside mainly in the polar fractions. Abbreviations Used: DMSO: Dimethyl sulphoxide, ANOVA: analysis of variance, EDTA: ethylene diamne tetraacetic acid, SDM: standard deviation of mean, PGE: prostaglandins E, PDF: prostaglandins F.

Evaluation of Antioxidant Potential of Melanthera scandens.

A methanol extract of dried leaves of Melanthera scandens was examined for antioxidant activities using a variety of assays, including 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, ferrous chelating, and ferric thiocyanate methods with ascorbic acid and EDTA as positive controls. The extract showed noticeable activities in most of these in vitro tests. The amount of phenolic compounds in the extract expressed in gallic acid equivalent was found to be 52.8 mg/g. The extract demonstrated inhibition of linoleic acid lipid peroxidation, active reducing power, and DPPH radical scavenging activities which were less than that of the positive controls. The extract also showed weaker iron chelating effect when compared with the EDTA positive control. The present results showed that M. scandens leaf extract possessed antioxidant properties and this plant is a potential useful source of natural antioxidants.