In vitro antioxidant and free radical scavenging activity of four Alkanna species growing in Iran.

BACKGROUND: Medicinal plants are recognized as sources of natural antioxidants that can protect biological system from oxidative stress. OBJECTIVE: In this study, the antioxidant activities of four species of the Alkanna genus (Alkanna bracteosa, Alkanna frigida, Alkanna orientalis and Alkanna tricophila) were evaluated. MATERIALS AND METHODS: The dried roots of plant samples (100 g) were extracted separately by percolation method with MeOH/H2O (80/20) and four fractions were provided respectively with hexane, chloroform, ethyl acetate, butanol and water. Antioxidant activities were investigated by using 1,1-diphenyl-2-picrylhydrazyl, ferric thiocyanate and thiobarbituric acid methods and compared with quercetin (as positive control). RESULTS: The results indicated that the butanol fractions of four species had the highest antioxidant activity and radical scavenging activity compared with the other fractions studied (P < 0.05). The 50% effective concentration (half - effective doses) values of butanol fractions are less than quercetin and other fractions, so, these fractions showed potent antioxidant activity. This indicated that the active compounds in the root parts of Alkanna species dissolved in the butanol. All the fractions of four species of Alkanna had antioxidant activity, while, there were no significant differences (P > 0.05) between the total antioxidant activities of same fractions. The total antioxidant activity values of Alkanna fractions in a descending order are as follows: Butanol fraction > ethyl acetate fraction > total extract > hexane fraction > chloroform fraction > aqueous fraction. CONCLUSION: The antioxidant activities of butanol fractions of samples were higher than quercetin. This may be because most of the active compounds of Alkanna species dissolved in the butanol.

Antimicrobial effect of the Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (higher Basidiomycetes) and its main compounds.

Mushrooms are considered one of the richest sources of natural antibiotics, and various species of them inhibit the growth of a wide diversity of microorganisms. Ganoderma lucidum, a well-known medicinal mushroom. has many pharmacological and biological activities including an antimicrobial effect, although few studies have investigated the antibacterial and antifungal effects of its purified compounds. The chemical structure of the purified compounds from the hexane fraction was elucidated as ergosta-7,22-dien-3ß-yl acetate, ergosta-5,7,22-trien-3ß-yl acetate (isopyrocalciferol acetate), ergosta-7,22-dien-3-one, ergosta-7,22-dien-3ß-ol, and ergosta-5,7,22-trien-3ß-ol (ergostrol). In addition, the structure of ganodermadiol was demonstrated after purification from the chloroform fraction. The fractions inhibited Gram-positive bacteria and yeast, with minimum inhibitory concentration values of 6.25 mg/mL, but were ineffective against Gram-negative bacteria in the tested concentrations. The results were comparable for isolated compounds, whereas the mixture of ergosta-7,22-dien-3ß-yl acetate and isopyrocalciferol acetate was weakly effective against Escherichia coli (minimum inhibitory concentration, 10 mg/mL). It could be assumed that the antimicrobial effect of crude fractions is the consequence of mixing triterpenoid and steroid compounds.

Anti-inflammatory and analgesic activity of Alkanna bracteosa and Alkanna tricophila.

Alkanna bracteosa and Alkanna tricophila, Boraginaceae, have been reported to be useful for their anti-inflammatory and wound-healing effects in traditional medicine. Methanol extracts of A. bracteosa and A. tricophila were evaluated for their potential analgesic and anti-inflammatory properties. Alkanna bracteosa was observed to produce a maximum of 42% reduction of hind paw licking in acute as well as 68% alleviation in inflammatory phase of formalin test in mice and about 30% declination of carrageenan-induced rats paw swelling at doses 100-400 mg kg⁻¹ in comparison to negative control; on the other hand, A. tricophila required at least 200 mg kg⁻¹ to exhibit a significant reduction in paw licking or oedemas at the early phase of formalin test and the late phase of carrageenan test, respectively. Our results suggest that the extracts may be of use for their analgesic and anti-inflammatory effects.