Antimicrobial Phenolics and Unusual Glycerides from Helichrysum italicum subsp. microphyllum

Abstract

During a large-scale isolation campaign for the heterodimeric phloroglucinyl pyrone arzanol (1a) from Helichrysum italicum subsp. microphyllum, several new phenolics as well as an unusual class of lipids named santinols (5a-c, 6-8) have been characterized. Santinols are angeloylated glycerides characterized by the presence of branched acyl- or keto-acyl chains and represent a hitherto unreported class of plant lipids. The antibacterial activity of arzanol and of a selection of Helichrysum phenolics that includes coumarates, benzofurans, pyrones, and heterodimeric phloroglucinols was evaluated, showing that only the heterodimers showed potent antibacterial action against multidrug-resistant Staphylococcus aureus isolates. These observations validate the topical use of Helichrysum extracts to prevent wound infections, a practice firmly established in the traditional medicine of the Mediterranean area.

Synthesis, Optical Rotation, and Absolute Configurations of Santinols

“…Some previously unknown (to the best of our knowledge) but rather interesting phenomena were observed for santinols. At sample concentrations ( c = 1.0) significantly higher than that in the literature, the magnitudes of the specific rotations were substantially smaller than those reported7 previously 13. At the same concentration as used in the previous study ( c = 0.2), the specific rotations were indeed consistent (in both sign and the magnitude) with those in the literature, but only within less than ca.…”

“…As part of our studies on glycerolipids,6 we have completed the synthesis of santintols A1 and A2 (Figure 1), two asymmetric 1,3‐diacylglycerols recently isolated from Helichrysum italicum subsp. Microphyllum by Taglialatela‐Scafati, Appendino, et al7 During the synthetic studies, the difficulties associated with the small optical rotations of such asymmetric 1,3‐diacylglycerols, which appear to be rather common, caught our attention. Substantial efforts were therefore also made in developing effective and experimentally feasible means for rapid estimation of the optical purities of such species.…”

Chemical composition and biological activity of the essential oil from Helichrysum microphyllum Cambess. ssp. tyrrhenicum Bacch., Brullo e Giusso growing in La Maddalena Archipelago, Sardinia.

“…The plant is widely used due to different properties as antiinflammatory 20 , antibacterial 8,13,20 and antioxidant 4,6 . In the cosmetic field, products based on extracts and essential oil, have also anti-aging property, because they help to regenerate skin tissue and relieve inflammation through antioxidant properties which protect the skin from damaging free radicals 21 .…”

“…tyrrhenicum is less widespread with respect to the other subspecies, and its chemical composition is peculiar with respect to plants growing in the peninsula. In particular from this subspecies a heterodimeric phloroglucinol pyrone arzanol endowed with interesting biological activities as well as an unusual class of lipids named santinols have been recently characterized 7,8 .…”

Volatiles ofHelichrysum italicum(Roth) G. Don from Croatia

“…It is widely used in traditional medicine (Antunes Viegas et al 2014) due to its antiinflammatory (Sala et al 2002;Appendino et al 2007), antimicrobial (Nostro et al 2001;Mastelić et al 2005;Taglialatela-Scafati et al 2013) and antioxidant properties (Facino et al 1990;Politeo et al 2006), and it finds large application as food supplement (Mari et al 2014) as well as in cosmetic and pharmaceutical field (Perrini et al 2009). …”