Corrigendum to "Antidiabetic, antioxidant and antimicrobial activities of extracts of Tephrosia bracteolata leaves" [Heliyon 5 (8) (August 2019) e02275].

[This corrects the article DOI: 10.1016/j.heliyon.2019.e02275.].

Antidiabetic, antioxidant and antimicrobial activities of extracts of Tephrosia bracteolata leaves.

AIMS: Plant extracts have long been used for the ethnomedical treatment of diabetes, microbial infections and as a source of antioxidant. This study was aimed at investigating the antidiabetic, antioxidant, and antimicrobial activities of the n-hexane and ethyl acetate extract of Tephrosia bracteolata leaves (TBL) as associated with the ethnobotanical knowledge of the local people of Nigeria. MAIN METHODS: The phytochemical composition of the n-hexane and ethyl acetate extract of the leaves of T. bracteolata were determined following standard procedures in literature, and it's in vitro inhibitory activities against α-glucosidase enzyme. 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS.+) and 1,1-diphenyl-2-picrylhydrazyl (DPPH+) antioxidant activities were also examined. Well diffusion method was employed in evaluating the antimicrobial property of the extracts. KEY FINDINGS: The ethyl acetate extract of T. bracteolata leaves had the greatest inhibitory effect on α-glucosidase, followed by the n-hexane with IC50 43.95 µg/ml and IC50 ˃50 µg/ml respectively. The ethyl acetate also exhibited significant DPPH+ and ABTS.+ antioxidant activity with IC50 of 24.96 µg/ml and 6.48 µg/ml as compared to Ascorbic acid and Trolox (12.24 µg/ml and 5.91 µg/ml) respectively. The zones of inhibition of the ethyl acetate extract of T. bracteolata leaves ranges from 10 - 25 mm at a concentration of 6.25-200 mg/ml, and it showed a greater antibacterial activity than the n-hexane extract, having a zone of inhibition from 10 - 20 mm at concentration of 12.5-200 mg/ml when compared to the standard Gentamycin. Similarly, the ethyl acetate extract of T. bracteolata showed a better anti fungi activity at concentration range 12.5-200 mg/ml than the n-hexane extract at concentration range of 25-200 mg/ml with reference to Tioconazole. These results indicated for the first time that the ethyl acetate extract of T. bracteolata leaves extracts exerted potent inhibitory effects against α-glucosidase, actively scavenge DPPH+ and ABTS.+ free radicals and successfully inhibits the proliferation of Gram positive and Gram negative microorganism. SIGNIFICANCE: TBL is an important source of antidiabetic, antimicrobial and antioxidant agent.

Synthesis of cyclic 1,9-acetal derivatives of forskolin and their bioactivity evaluation.

A new series of 1,9-acetals of forskolin were synthesized by treating with aromatic and aliphatic aldehydes using Ceric ammonium nitrate as catalyst and evaluated for anticancer and α-glucosidase inhibition activities. Among the synthesized compounds 2a, 2b and 3a showed potential cytotoxic activity towards human cancer cell lines MCF-7 (Human Breast Adenocarcinoma), MDA-MB (Human Breast Carcinoma), HeLa (Human Cervix Adenocarcinoma), A498 (Human Kidney Carcinoma), K562 (Human Erythromyeloblastoid leukemia), SH-SY5Y (Human Neuroblastoma), Hek293 (Human Embryonic Kidney) and WRL68 (Human Hepatic) with IC50 values ranging between 0.95 and 47.96 µg/ml. Osmotic fragility test revealed compound 3a as non-toxic to human erythrocytes at the tested concentrations of 50 and 100 µg/ml. Compounds 1g (IC50 value 0.76 µg/ml) and 1p (IC50 value 0.74 µg/ml) significantly inhibited α-glucosidase in in vitro system. In silico based docking, ADME and toxicity risk assessment studies also showed discernible α-glucosidase activity for compounds 1g, 1p compared to standard acarbose.

New antihyperglycemic, alpha-glucosidase inhibitory, and cytotoxic derivatives of benzimidazoles.

Glycosidases play an important role in a wide range of physiological and pathological conditions, and have become potential targets for the discovery and development of agents useful for the treatment of diseases such as diabetes, cancer, influenza, and even AIDS. In this study, several benzimidazole derivatives were prepared from o-phenylenediamine and aromatic and heteroaromatic carboxaldehydes in very good yields, using PdCl2(CH3CN)2 as the most efficient catalyst. Synthesized compounds were assayed for their activity on yeast and rat intestinal alpha-glucosidase inhibition and cytotoxic activity against colon carcinoma cell line HT-29. Compound 3e exhibited 95.6% and 75.3% inhibition of yeast and rat intestinal alpha-glucosidase enzyme, while showing 74.8% cytotoxic activity against the HT-29 cell line at primary screening concentrations of 2.1 mM for yeast and rat intestinal alpha-glucosidase enzyme and 0.2 mM for cytotoxic activity against the HT-29 cell line, respectively. Compound 3c displayed 76% and 34.4% inhibition of yeast and rat intestinal alpha-glucosidase enzyme, and 80.4% cytotoxic activity against the HT-29 cell line at similar primary screening concentrations. The IC50 value for the most potent intestinal alpha-glucosidase inhibitor compound 3e was found to be 99.4 microM. The IC50 values for the most active cytotoxic compounds 3c and 3e were 82 microM and 98.8 microM, respectively. Both compounds displayed significant antihyperglycemic activity in starch-induced postprandial hyperglycemia in rats. This is the first report assigning yeast and rat intestinal alpha-glucosidase enzyme inhibition, cytotoxic activity against the HT-29 cell line, and antihyperglycemic activity to benzimidazole compounds 3c and 3e.