The chemical composition of the essential oils of Melaleuca armillaris Sm., Melaleuca styphelioides Sm. and Melaleuca acuminata F. Muell., collected in Tunisia, was studied by means of GC and GC-MS analysis. In all, 46 compounds were identified, 38 for M. armillaris, 20 for M. acuminata and eight for M. styphelioides, respectively. The presence of a sesquiterpenic fraction (52.2%) characterized the oil from M. armillaris; M. sthypheliodes oil was rich in methyl eugenol, a phenolic compound (91.1%), while M. acuminata oil is mainly constituted by oxygenated monoterpenoids (95.6%). The essential oils were evaluated for their in vitro potentially phytotoxic activity against germination and initial radicle growth of Raphanus sativus L., Lepidium sativum L., Sinapis arvensis L., Triticum durum L. and Phalaris canariensis L. seeds. The radicle elongation of five seeds was inhibited at the highest doses tested, while germination of all seeds was not affected. Moreover, the essential oils showed low antimicrobial activity against eight selected microorganisms.

The chemical composition of the essential oil of Helichrysum italicum (Roth) Don ssp. italicum, collected in the National Park of Cilento and Diano Valley, Southern Italy, was studied by means of GC and GC/MS. Forty four compounds of 45 constituents were identified in the oil, mainly oxygenated sesquiterpenes. The essential oil was evaluated for its potential in vitro phytotoxic activity against germination and early radicle elongation of radish and garden cress. The radicle elongation of radish was significantly inhibited at the highest doses tested, while germination of both seeds was not affected.

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We studied the polyphenol composition and antioxidant activity of the ethanolic and ethyl acetate extracts of Hypericum connatum (Guttiferae), in addition to their antimicrobial and antiquorum-sensing (AQS) properties. The extracts exhibited a similar polyphenol content and a notable antioxidant activity, which was stronger in the ethanolic extract (EC50=3.2 μg/mL). Ultrahigh-performance liquid chromatography analyses revealed different polyphenol profiles, with rutin and apigen being the main components of the ethanolic extract and caffeic acid, (-)-epicatechin and p-coumaric acid being abundant in the ethyl acetate extract. The ethyl acetate extract exhibited a more effective antimicrobial activity than the ethanolic extract against the pathogens Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa. For the first time, AQS activity was detected in H. connatum: the ethanolic extract inhibited the production of violacein, a quorum-sensing-regulated pigment, in a Chromobacterium violaceum tester strain, without interfering with its growth.

De Feo (2016) The protective effect of Hypericumconnatum on stress-induced escape deficit in rat is related to its flavonoid content, Pharmaceutical Biology, 54:9, 1782-1792, DOI: 10.3109/13880209.2015 Objective This study evaluates the antidepressant-like effect of H. connatum in rats and identifies the components involved in this activity. Materials and methods First, the effects of acute and 14-d oral administrations of an extract derived from H. connatum aerial parts were studied using the Escape Deficit (ED) test. Next, methanol-extracted flavonoid-enriched fractions B and C and fraction-purified flavonoids (quercetin, rutin and isoquercitrin) were evaluated in the ED test after acute administration. To rule out possible confounding effects of the flavonoids, we examined nociceptive threshold using the tailflick test and anxious behaviour using the elevated plus maze (EPM) test. Results Hypericum connatum increased reactivity of unavoidable stress-exposed rats after acute