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Pure enzyme samples of ribonuclease from Bacillus intermedius 7P (known commercially as 'binase') were investigated for genotoxicity in four microbial tests: the Ames plate incorporation method, AraR-assay; the prophage induction test; and the DNA-repair test. The weak mutagenic effect of binase at high concentrations (0.1 mg/plate, 1 mg/plate) was established by induction of forward AraR-mutations and histidine-reverse mutations (both frameshift mutations and base pair substitution). Metabolic activation with rat or chicken liver, human placenta or plant (from tulip bulbs) microsomal fractions in vitro was seen to abolish the binase mutagenicity. Bacillus intermedius 7P ribonuclease appears to possess DNA damaging activity in uvrA- and polA- mutants, but not in the recA-deficient Escherichia coli strain, and exhibits an induction of recA-dependent mutagenesis detected by the 8-fold increase of the prophage-induction level in lysogenic Bacillus subtilis culture and by the 5-fold increase of this level in the Streptomyces lavendulae 3 lysogenic strain. The importance of the roles of both of enzyme catalytic activity and native structure is emphasized. A proposed mechanism for exogenous ribonuclease action is discussed. Bacillus intermedius 7P ribonuclease probably does not act as a direct genotoxic agent interacting with DNA, but could provoke nucleotide imbalance through its catalytic action on membrane-associated RNAs, which results in alteration of DNA replication and, as a consequence, in recA-dependent mutagenesis.

Stem bark aqueous extracts of eight woody plants Brachychiton populneus, Ceiba pentandra, Bombax malabaricum, Chorisia speciosa, Albizia lebbeck, Bauhinia variegata, Kigelia africana and Pinus halepensis were tested for their mutagenic and antimutagenic potential in the Ames test with Salmonella typhimurium strains TA98 and TA100. The aqueous extracts were neither toxic nor mutagenic in S. typhimurium tester strains. All of the tested extracts showed detectable antimutagenic effect towards the direct acting mutagens 2-nitrofluorene (2-NF) in TA98 as well as sodium azide in TA100. The extract from Kigelia africana was the most effective in reducing the mutagenicity caused by the direct mutagen 2-NF in the TA98 with 85.42% inhibition rate. A. lebbeck stem bark extract demonstrated the highest antimutagenic activity reducing the base substitution mutations rate for strain TA100 by 94.66% in pre-incubation assay. The results obtained showed that the stem bark aqueous extracts tested can protect cells against induced gene mutations.

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Aqueous extracts were prepared from eight medicinal plants and other plants were prepared as essential oils.The radical-scavenging ability of each plant extract was determined by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay. The total phenolic content of plants was determined by the Folin-Ciocalteu reagent in terms of gallic acid equivalents. The DPPH scavenging potential of the aqueous extracts ranged from 17 to 79%, whereas the essential oils showed inhibition of the DPPH activity in the 12-88% range. The highest inhibition of DPPH radicals was observed for Pinus halepensis extract. Meanwhile, amongst the essential oils, the greatest antioxidant potential was exhibited by Nigella sativa. The Bauhinia variegate extract had the highest phenolic content (149.18 mg/g gallic acid equivalents), followed by Albizzia lebbeck (148.00 mg/g) and Pinus halepensis (145.67 mg/g), whereas, amongst the essential oils, the highest phenolic content (98.57 mg/g) was found for Thymus vulgaris. The lowest contents were observed for Kigelia africana and Rosmarinus officinalis.The antioxidant activity had a positive correlation (R=0.654) with the phenolic content of most aqueous extracts, whereas it had a weak correlation using the essential oils (R=0.335). This confirms that the phenolic content of aqueous extracts may contribute towards their antioxidant properties.