Aloe genus plants, distributed in Old World, are widely known and have been used for centuries as topical and oral therapeutic agents due to their health, beauty, medicinal, and skin care properties. Among the well-investigated Aloe species are A. arborescens, A. barbadensis, A. ferox, and A. vera. Today, they account among the most economically important medicinal plants and are commonly used in primary health treatment, where they play a pivotal role in the treatment of various types of diseases via the modulation of biochemical and molecular pathways, besides being a rich source of valuable phytochemicals. In the present review, we summarized the recent advances in botany, phytochemical composition, ethnobotanical uses, food preservation, and the preclinical and clinical efficacy of Aloe plants. These data will be helpful to provide future directions for the industrial and medicinal use of Aloe plants.

The present study aimed to compare the polyphenol content, total phenolic, total flavonoid, antioxidant and antimicrobial activity of the extracts obtained from Centaurea amaena Boiss. & Balansa and Centaurea aksoyi Hamzaoğlu & Budak. Both species were subjected to maceration, Soxhlet and ultrasonication extractions with methanol in order to macerated (ME), Soxhlet (SE) and ultrasonicated (UE) extracts. Their phenolic profiles were qualitatively examined by LC-MS. Their antioxidant activities were determined by phosphomolybdenum, β-carotene bleaching and DPPH assays. Agar diffusion and broth dilution methods were carried out to find the antimicrobial activity of these extracts against fifteen microorganisms. Quercetin, quercetin-3-β-D-glucoside and protocatechuic acid were the main components of the both extracts obtained by Soxhlet extraction. The highest phenolic and flavonoid contents were found in the UE for both species. All the extracts exhibited good total antioxidant and DPPH radical scavenging activity. UE obtained from C. amaena showed the highest antioxidant activity with the highest phenolic and flavonoid contents. The antibacterial activity of UE obtained from C. amaena was better than other extracts and antibacterial activity of C. amaena was also better than C. aksoyi. This study confirms that ultrasonic extraction may be an ideal, simple and rapid method to obtain polyphenol-rich extracts have antioxidant as well as antibacterial activity from both Centaurea species especially from C. amaena.

The antioxidant activity of the methanolic extracts of 4 plants from genus Helichrysum Mill. (Asteraceae) [H. arenarium (L.) Moench subsp. erzincanicum Davis & Kupicha, H. arenarium (L.) Moench subsp. rubicundum (C.Koch.) Davis & Kupicha, H. armenium DC. subsp. araxinum (Kirp.) Takht., and H. plicatum DC. subsp. pseudoplicatum (Nab.) Davis & Kupicha] was investigated with 2 complementary test systems, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and phosphomolybdenum assay. H. plicatum subsp. pseudoplicatum showed the highest level of total antioxidant activity (161.79 ± 0.3 mg ascorbic acid equivalent/g extract) in the phosphomolybdenum assay. H. arenarium subsp. erzincanicum showed the highest level of free radical scavenging activity, with an IC_{50} value of 23.03 µg/mL. The total phenolic contents of the extracts ranged from 71.81 to 144.50 mg gallic acid/g dry extract. Chlorogenic acid, apigenin-7-glucoside, and apigenin were found by HPLC analysis to be the main components in the extracts. Antimicrobial activity was investigated with the agar diffusion method. The methanolic extracts had antibacterial activity against Aeromonas hydrophila, Bacillus brevis, B. cereus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus ATCC 29213. However, no activity was found against Escherichia coli, Morganella morganii, Mycobacterium smegmatis, Proteus mirabilis, Yersinia enterocolitica, or Saccharomyces cerevisiae.

A series of new benzimidazolium salts (1a–g) were synthesized from the reaction of 1-(4-vinylbenzyl)benzimidazole with various alkyl halides. These salts were used to synthesize silver N-heterocyclic carbene (Ag-NHC) complexes (2a–f). The thirteen compounds were characterized by FT-IR, NMR (¹H and ¹³C) spectroscopic methods and an elemental analysis technique. These selected candidates were tested for their in vitro antimicrobial activities. Antibacterial and antifungal results indicated that the new salts, and particularly their silver complexes, were found to be strongly effective against seven Gram (−) bacterial strains, three Gram (+) bacterial strains and one yeast (Candida albicans).

In this study, the methanolic extracts and lichens acids obtained from six Umbilicaria species were tested for their antimicrobial activity (against three Gram-positive bacteria, five Gram-negative bacteria and two yeasts species) and their antioxidant activity. Total phenolic content in the extracts was determined by the Folin–Ciocalteu assay. It ranged from 0.91 to 48.25 mg gallic acid/g. The antioxidant ability was measured using a free radical-scavenging activity assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH). The methanolic extracts showed moderate DPPH radical-scavenging activity. Among the lichen acids, umbilicaric acid showed the highest antioxidant activity with 68.14% inhibition. Antimicrobial activity was determined by the agar diffusion method. Extracts were found to possess antimicrobial activity against some of the bacteria and yeasts tested. Gyrophoric acid was effective against six out of eight bacteria tested, but no activity was observed against the yeasts. Practical Applications This article evaluates antimicrobial, antioxidant activities and their active compounds have been shown in some Umbilicaria lichens species. This is the first study reporting in vitro biological activities of U. aprina var. halei, U. cylindrica, U. decussata, U. leiocarpa, U. nylanderiana, U. virginis, gyrophoric acid, leconaric acid and umbilicaric acid isolated from them. Results of this study will contribute significantly to efforts to used antimicrobial and antioxidant agents in the country and elsewhere in Turkey.

In this study, the effect of gamma irradiation on the total phenolic content and antioxidant activity of Satureja hortensis, Thymus vulgaris, and Thymbra spicata was evaluated. Plants irradiated in a ⁶⁰Co irradiator to 0, 1.2, 3.0, and 5.1 kGy at 25°C. Control and irradiated samples were extracted with methanol. The antioxidant activity of methanol extracts was determined using phosphomolybdenum assay and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. The total phenolic content in three spices was found to decrease with irradiation except at 5.1 kGy for S. hortensis. The DPPH radical scavenging activity of the extracts decreased after irradiation.