Antioxidant and antimicrobial activities of Bauhinia racemosa L. stem bark

Abstract

The present study was carried out to evaluate the antioxidant and antimicrobial activities of a methanol extract of Bauhinia racemosa (MEBR) (Caesalpiniaceae) stem bark in various systems. 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical, superoxide anion radical, nitric oxide radical, and hydroxyl radical scavenging assays were carried out to evaluate the antioxidant potential of the extract. The antioxidant activity of the methanol extract increased in a concentration-dependent manner. About 50, 100, 250, and 500 µg MEBR inhibited the peroxidation of a linoleic acid emulsion by 62.43, 67.21, 71.04, and 76.83%, respectively. Similarly, the effect of MEBR on reducing power increased in a concentration-dependent manner. In DPPH radical scavenging assays the IC 50 value of the extract was 152.29 µg/ ml. MEBR inhibited the nitric oxide radicals generated from sodium nitroprusside with an IC 50 of 78.34 µg/ml, as opposed to 20.4 µg/ml for curcumin. Moreover, MEBR scavenged the superoxide generated by the PMS/NADH-NBT system. MEBR also inhibited the hydroxyl radical generated by Fenton's reaction, with an IC 50 value of more than 1000 µg/ml, as compared to 5 µg/ml for catechin. The amounts of total phenolic compounds were also determined and 64.7 µg pyrocatechol phenol equivalents were detected in MEBR (1 mg). The antimicrobial activities of MEBR were determined by disc diffusion with five Grampositive, four Gram-negative and four fungal species. MEBR showed broad-spectrum antimicrobial activity against all tested microorganisms. The results obtained in the present study indicate that MEBR can be a potential source of natural antioxidant and antimicrobial agents.

Development, characterization and antioxidant activity of polysorbate based O/W emulsion containing polyphenols derived from Hippophae rhamnoides and Cassia fistula

“…This is desired for the emulsions preparation, since most of the desired effects are mediated by antioxidants. Our data is in accordance to what is reported by Kumar et al (2005), in which a methanol extract of Bauhinia racemosa preserved its antioxidant and total phenolic content after processing.…”

Chemical composition and antifungal potential of medicinal plants against seedborne mycoflora of eggplant (Solanum melongena L.)

“…M. indica extract was found least effective among all the extracts used. Present results are in harmony with the fi ndings of Kumar et al (2005) and Alberts et al (2006). They reported that pre-and post-harvest bio-deterioration of crop seeds are mainly due to seed infestation by microorganisms and insects, causing up to 100% losses.…”

Active antifungal substances from natural sources

“…54 Preliminary bioassays indicated that the methylene chloride extracts of the seeds of both species had antifungal activity against Colletotrichum fragariae. Examples of other antifungal crude extracts from medicinal species also included Bauhinia racemosa L. (Caesalpiniceae) stem bark, 55 the latex of gazyumaru (Ficus microcarpus L., Moraceae), 56 Larrea divaricata Cav. (Zygophyllaceae) which presented fungitoxic activity against yeasts and fungi, 57 and leaf extracts of Tapinanthus sessilifolius (P. Beauv) Van Tiegh.…”