plants Article Composition, Antioxidant Potential, and Antimicrobial Activity of Helichrysum plicatum DC. Various Extracts Bojan Vuji´c 1, Vera Vidakovi´c 2 , Milka Jadranin 3, Irena Novakovi´c 3, Snežana Trifunovi´c 1, Vele Teševi´c 1 and Boris Mandi´c 1,* 1 University of Belgrade-Faculty of Chemistry, Studentski trg 12-16, 11000 Belgrade, Serbia; [email protected] (B.V.); [email protected] (S.T.); [email protected] (V.T.) 2 Department of Ecology, Institute for Biological Research “Siniša Stankovi´c”-NationalInstitute of Republic of Serbia, University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia; [email protected] 3 Institute of Chemistry, Technology and Metallurgy, National Institute, University of Belgrade, Studentski trg 12-16, 11000 Belgrade, Serbia; [email protected] (M.J.); [email protected] (I.N.) * Correspondence: [email protected]; Tel.: +381-11-2630477 Received: 11 February 2020; Accepted: 26 February 2020; Published: 6 March 2020 Abstract: Helichrysum plicatum DC. is widely used in folk medicine in treating a variety of health disorders. The aim of this study was to examine the influence of different extraction solvents on the chemical composition, antioxidant potential, and antimicrobial activities of H. plicatum. Aerial parts were separately extracted with ethanol, dichloromethane, and sunflower oil. The oil extract (OE) was re-extracted with acetonitrile. A total of 142 compounds were tentatively identified in ethanolic (EE), dichloromethane (DCME), and acetonitrile (ACNE) extracts using HPLC-DAD/ESI-ToF-MS. The dominant compound class in all extracts were α-pyrones, alongside flavonoids in EE, terpenoids in DCME and ACNE, and phloroglucinols in DCME. The antioxidant potential of the extracts was assessed by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. EE and DCME possessed the most potent radical scavenging capacity. Antimicrobial activity was investigated on eight bacterial, two yeast, and one fungal species. All extracts exhibited high antifungal and notable antibacterial activities compared to control substances, with DCME being the most potent. DCME exhibited stronger antimicrobial activity against P. aeruginosa than the standard chloramphenicol. Keywords: Helichrysum plicatum; antioxidant potential; antimicrobial activity; solvent polarity; phenols; liquid chromatography-mass spectrometry (LC-MS) 1. Introduction The genus Helichrysum Miller (Asteraceae) comprises about 600 species of perennial or annual herbs or shrublets distributed in Europe, Asia, and Africa, the plant parts of which have been traditionally used as infusions or decoctions in the treatment of diverse ailments [1,2]. Interest in phytochemical and pharmacological studies of this genus has increased in recent years. Helichrysum species represent an abundant source of secondary metabolites, such as flavonoids, chalcones, phenolic acids, phthalides, coumarins, pyrones, and terpenes [1]. Plant extracts and their chemical constituents exhibit a range of biological activities, including antioxidant, anti-inflammatory, wound-healing, antimicrobial, photoprotective, anticarcinogenic, etc. [3–12]. Helichrysum plicatum DC. is a herbaceous perennial plant, which is native to the Balkan and Anatolian Peninsulas and Iran [13]. It has been used in folk medicine for wound-healing and the treatment of gastric and hepatic disorders, diabetes, and kidney stones [14–16]. Chemically, this species Plants 2020, 9, 337; doi:10.3390/plants9030337 www.mdpi.com/journal/plants Plants 2020, 9, 337 2 of 20 was mostly studied for its phenolic, mainly flavonoid content, which is thought to be responsible for the therapeutic effects of the plant. H. plicatum polar extracts are reported to possess antimicrobial, antidiabetic,Plants 2020, spasmolytic, 9, x FOR PEER REVIEW nephroprotective, and antimutagenic activities [13,17–21]. 2 of 20 responsibleIt is apparent for the that therapeutic extracts effects from theof the same plant. plant H. plicatum will di polarffer inextracts their are composition reported to ofpossess bioactive compoundsantimicrobial, depending antidiabetic, on the spasmolytic extraction, solvent. nephroprotective Since, with, and the antimutagenic exception of activities the essential [13,17 oil,–21] only. the phenolicIt composition is apparent ofthat polar extracts extractives from the has same been plant investigated will differ inin H.the plicatumir compositionto date, of thebioactive aim of this studycompounds was to perform depending a more on the detailed extraction chemical solvent. analysis Since, with of the the plant exception and toof examinethe essential the oil, influence only of solventsthe phenolic of different composition polarity of on polar the extraction extractives yield, has been composition investigated of in extracts, H. plicatum antioxidant to date, the potential, aim of and antimicrobialthis study activities.was to perform a more detailed chemical analysis of the plant and to examine the influence of solvents of different polarity on the extraction yield, composition of extracts, antioxidant potential, 2. Resultsand antimicrobial activities. 2.1. Phytochemical2. Results Profile 2.1.Aerial Phytochemical parts of wild ProfileH. plicatum at the full blooming stage were extracted with solvents of different polarity. The yields were 7.14%, 2.88%, and 0.62% for ethanol (EE), dichloromethane (DCME), and Aerial parts of wild H. plicatum at the full blooming stage were extracted with solvents of acetonitrile oil (ACNE) extracts, respectively. The phytochemical content of the extracts was assessed different polarity. The yields were 7.14%, 2.88%, and 0.62% for ethanol (EE), dichloromethane by HPLC-DAD(DCME), and/ESI-ToF-MS. acetonitrile oil The (ACN peaksE) extracts in chromatograms, respectively. The were phytochemical tentatively content identified of the on extracts the basis of the exactwas assessed molecular by massesHPLC-DAD and formulas,/ESI-ToF-MS. UV The spectra, peaks and in chromatograms literature data were (Tables tentatively S1–S3, Supplementary identified Material).on the Thebasis total of the ion exact chromatograms molecular masses (TIC) and in formulas the positive, UV (forspectra EE, and literature DCME) anddatanegative (Tables S1 (for– EE, DCMES3, andSupplementary ACNE) modes material). and HPLC-DADThe total ion chromatograms chromatograms (TIC) of the in the investigated positive (for extracts EE and areDCM shownE) in the Supplementaryand negative (for Material EE, DCM (FiguresE and ACN S1–S3).E) modes and HPLC-DAD chromatograms of the investigated extractsA total are of 142shown compounds in the Supplementary were identified material in (H.Figures plicatum S1–S3)aerial. parts. Their distribution in the different extractsA total of is 14 presented2 compounds in Table were1 .identified The indicated in H. plicatum structures aerial are parts in agreement. Their distribution with the in literature the different extracts is presented in Table 1. The indicated structures are in agreement with the literature on Helichrysum species and/or the Asteraceae family [4,22–106] (Figure1). All the extracts were on Helichrysum species and/or the Asteraceae family [4,22–106] (Figure 1). All the extracts were α α characterizedcharacterized by by-pyrones. α-pyrones. Simple Simple α-pyrones-pyrones ( (suchsuch as as micropyrone micropyrone and and compound compound 1), homodimers1), homodimers (helipyrone,(helipyrone, bisnorhelipyrone), bisnorhelipyrone) as, as well well asas heterodimersheterodimers of of αα-pyrones-pyrones and and phloroglucinols phloroglucinols (arenol, (arenol, arzanol,arzanol, heliarzanol, heliarzanol, auricepyrone, auricepyrone, etc.) etc.) were were found. found. The prevailingThe prevailing compounds compounds in EE in were EE flavonoids.were Fourflavonoids. classes of flavonoidsFour classes wereof flavonoids identified: were flavones, identified: flavanones, flavones, flavanones flavonols,, flavonols and chalcones., and chalcones Compared. to DCMECompared and ACNE,to DCM onlyE and EE ACN containedE, only E glycosylatedE contained glycosylated flavonoids flavonoids (compounds (compounds43, 44, 58 43–60, 44, ,63 58––65, 67, 68, 7060–72, 63).– Being65, 67, more68, 70 hydrophilic–72). Being more than hydrophilic their aglycone than counterpartstheir aglycone because counterparts of the because presence of the of sugar moieties,presence glycosides of sugar aremoieties, easily glycosides extracted are with easily polar extracted protic with solvents. polar proticα-Pyrones solvents. and α-P terpenoidsyrones and were predominantterpenoids in were both ACNEpredominant and DCME, in both while ACN DCMEE and also DCM possessedE, while phloroglucinols DCME also possessed as dominant phloroglucinols as dominant compounds (Table 1). An interesting feature of nonpolar DCM and compounds (Table1). An interesting feature of nonpolar DCM and ACN extracts is the presence of ACN extracts is the presence of (poly)methoxylated flavones, i.e. dimethoxy- (49, 53) and (poly)methoxylatedpentamethoxyflavones flavones, in DCM i.e.E dimethoxy- (46, 47) and ( 49methoxy, 53) and- (51 pentamethoxyflavones, 52), dimethoxy- (50), and in DCMEtriethoxy (46- , 47) and methoxy-dimethoxy (flavones51, 52), dimethoxy-in ACNE (54, ( 5055,), 57 and). triethoxy-dimethoxy flavones in ACNE (54, 55, 57). FigureFigure 1. Phenolic 1. Phenolic representatives representatives ofofH. H. plicatumplicatum::( (aa) )naringenin naringenin (flavanone (flavanone),), (b) (isosalipurposideb) isosalipurposide (chalcone),(chalcone),