Abyssinicanone, an Isoflavone From the Stem Bark of Erythrina abyssinica With Antimicrobial, Antioxidant, and Estrogenic Properties

A previously undescribed isoflavone derivative, abyssinicanone (1), and two known flavonoids, including abyssinoflavanone V (2) and sigmoidin C (3), were isolated from Erythrina abyssinica stem bark. Abyssinicanone's structure was determined by spectroscopic analyses and x-ray crystallography. The isolated compounds were screened against bacterial and fungal strains. Moreover, antioxidant activity was performed using the DPPH free radical test, and a 3-day uterotrophy assay was employed to assay estrogenic activity in rats. Abyssinicanone showed moderate inhibitory activity against a spectrum of bacteria with a MIC of 125 µg/mL. Compound 1 incubation with three fungi inhibited their growth with MIC values of 31.25, 62.50, and 125 µg/mL, respectively. Abyssinicanone exhibited antioxidant activity by scavenging DPPH free radicals with a radical scavenging percentage of 6.41% at 40 µg/mL. The treatment of ovariectomized rats with 2.5 mg/kg of abyssinicanone restored the hormonal decline caused by ovary ablation prior to treatment. The uterine weight loss and the vaginal epithelial height were also restored as compared with the negative control group. Rats treated with compound 1 did not induce an estrogenic response in the endometrium and in mammary glands. Overall, these results demonstrate the antimicrobial, antioxidant, and estrogenic activities of abyssinicanone, a novel compound from Erythrina abyssinica stem bark.