plants Article The Volatile Phytochemistry of Monarda Species Growing in South Alabama Sims K. Lawson 1, Prabodh Satyal 2 and William N. Setzer 2,3,* 1 Kirkland Gardens, P.O. Box 176, Newville, AL 36353, USA; skirkland.lawson@ufl.edu 2 Aromatic Plant Research Center, 230 N 1200 E, Suite 100, Lehi, UT 84043, USA; [email protected] 3 Department of Chemistry, University of Alabama in Huntsville, Huntsville, AL 35899, USA * Correspondence: [email protected]; Tel.: +1-256-824-6519 Abstract: The genus Monarda (family Lamiaceae) contains 22 species of which three are native to southern Alabama, M. citriodora, M. fistulosa, and M. punctata. Several species of Monarda have been used in traditional medicines of Native Americans, and this present study is part of an ongoing project to add to our understanding of Native American pharmacopeia. Plant material from M. citriodora, M. fistulosa, and M. punctata was collected in south Alabama and the essential oils obtained by hydrodistillation. The essential oils were analyzed by gas chromatographic techniques to determine the chemical compositions as well as enantiomeric distributions. The compounds thymol, carvacrol, p-cymene, and their derivatives were the primary terpenoid components found in the essential oils. The known biological activities of these compounds are consistent with the traditional uses of Monarda species to treat wounds, skin infections, colds, and fevers. Keywords: Monarda citriodora; Monarda fistulosa; Monarda punctata; essential oil; thymol; carvacrol; p-cymene Citation: Lawson, S.K.; Satyal, P.; Setzer, W.N. The Volatile Phytochemistry of Monarda Species Growing in South Alabama. Plants 1. Introduction 2021, 10, 482. https://doi.org/ The Plant List [1] shows 22 different Monarda L. (Lamiaceae) species, 18 of which 10.3390/plants10030482 occur in the United States [2]. There are three Monarda species native to south Alabama, namely Monarda citriodora Cerv. ex Lag., Monarda fistulosa L., and Monarda punctata L. Academic Editors: Jésus Palá-Pául, (see Figure1)[2]. Joseph Brophy and Laura Cornara Several Monarda species have been used by Native Americans as medicinal plants [3]. For example, M. fistulosa was used by the Blackfoot, Navajo, Lakota, and Winnebago people Received: 9 February 2021 to treat boils, cuts and wounds; the Cherokee, Chippewa, Flathead, Ojibwa, and Tewa used Accepted: 26 February 2021 Published: 4 March 2021 the plant to treat colds, fever, and influenza; the Crow, Lakota, Menominee, and Ojibwa used the plant for coughs, catarrh, and other respiratory problems. Monarda punctata was Publisher’s Note: MDPI stays neutral used by the Delaware, Mohegan Nanticoke, and Navajo tribes to treat colds, fever coughs, with regard to jurisdictional claims in and catarrh. published maps and institutional affil- Both M. citriodora and M. fistulosa are popular ornamentals and have been introduced iations. to temperate locations around the world [4–6]. Geographical location likely plays an important role in the phytochemistry of Monarda species. To our knowledge, however, there have been no previous examinations of M. citriodora, M. fistulosa, or M. punctata growing in their native range of south Alabama. In this work, we have examined the chemical compositions and enantiomeric distributions of essential oils of the three Monarda Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. species from south Alabama. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Plants 2021, 10, 482. https://doi.org/10.3390/plants10030482 https://www.mdpi.com/journal/plants PlantsPlants2021 2021, 10, 10, 482, x FOR PEER REVIEW 22 of of 14 13 Monarda citriodora Monarda fistulosa Monarda punctata FigureFigure 1. 1.Monarda Monardaspecies speciesdiscussed discussed inin thisthis workwork (photographs(photographs by S. K. L). 2.2. ResultsResults 2.1. Monarda Citriodora 2.1. Monarda Citriodora The M. citriodora essential oils were obtained as clear orange oils. The essential oil yieldsThe M. for citriodoraM. citriodora essentialaerial oils parts were essential obtained oil as were clear 1.59% orange and oils. 1.79% The essential for samples oil #1yields and for #2, M. respectively, citriodora aerial while parts the essential root essential oil were oil 1.59% was obtained and 1.79% in for 0.879% samples yield. #1 and The chemical#2, respectively, compositions while of the the root essential essential oils oil from was the obtained aerial parts in 0.879% and the yield. roots ofTheM. chemical citriodora cultivatedcompositions in south of the Alabama essential are oils summarized from the aerial in Table parts1. and The the essential roots of oils M. were citriodora dominated culti- vated in south Alabama are summarized in Table 1. The essential oils were dominated by by the phenolic monoterpenoids thymol (RIdb = 1289) and carvacrol (RIdb = 1296). The other the phenolic monoterpenoids thymol (RIdb = 1289) and carvacrol (RIdb = 1296). The other major components were p-cymene (RIdb = 1024) and thymol methyl ether (RIdb = 1239). major components were p-cymene (RIdb = 1024) and thymol methyl ether (RIdb = 1239). Table 1. Essential oil compositions of Monarda citriodora cultivated in south Alabama. Table 1. Essential oil compositions of Monarda citriodora cultivated in south Alabama. Aerial Parts Essential Oil Root Essential Oil RIcalc RIdb Compound #1, % ED,Aerial (+):( Parts−) Essential #2, % Oil ED, (+):(−)Root #2, % Essential ED, (+):( Oil− ) RI923calc RIdb 925 Compoundα-Thujene 1.0#1, % 69.0:31.0ED, (+):(−) #2, 0.8 % ED, 66.6:33.4 (+):(−) #2, 0.5% ED, 64.2:35.8 (+):(−) 923930 925 932 α-Thujeneα-Pinene 0.31.0 84.2:15.869.0:31.0 0.30.8 66.6:33.4 62.8:37.2 0.5 0.2 64.2:35.8 74.5:25.5 930947 932 950α Camphene-Pinene tr0.3 84.2:15.8 0.3 tr 62.8:37.2 0.2 tr 74.5:25.5 947970 950 971Camphene Sabinene trtr trtr tr — 975 978 β-Pinene 0.1 64.5:35.5 0.1 0.1 970 971 Sabinene tr tr --- 976 974 1-Octen-3-ol 0.7 0.7 0.5 975983 978 984 3-Octanoneβ-Pinene 0.10.1 64.5:35.5 0.20.1 0.1 0.3 976987 974 9891-Octen-3-ol Myrcene 0.70.7 0.40.7 0.5 0.3 983995 984 9963-Octanone 3-Octanol 0.20.1 0.30.2 0.3 0.3 1002987 989 1004Myrcene Octanal tr0.7 0.4 tr 0.3 — 1003 1004 p-Mentha-1(7),8-diene tr — — 995 996 3-Octanol 0.2 0.3 0.3 1005 1006 α-Phellandrene 0.1 95.1:4.9 0.1 100:0 tr 100:0 10021007 1004 1008 δOctanal-3-Carene 0.1tr 100:0 0.1tr 100:0 --- 0.1 100:0 10031015 1004 1017 p-Mentha-1(7),8-dieneα-Terpinene 1.8tr 100:0 1.1--- 100:0 --- 0.7 100:0 10051016 1006 1022 α-Phellandrenem-Cymene tr0.1 95.1:4.9 0.1 tr 100:0 tr — 100:0 10071023 1008 1024 δ-3-Carenep-Cymene 7.80.1 100:0 6.40.1 100:0 0.1 7.2 100:0 1027 1030 Limonene 0.5 26.7:73.3 0.4 63.3:36.7 0.3 57.3:42.7 10151028 1017 1029 βα-Phellandrene-Terpinene 0.21.8 0:100100:0 0.11.1 100:0 0:100 0.7 0.1 100:0 0:100 10161030 1022 1033 Benzylm-Cymene alcohol —tr —tr --- 0.4 10231030 1024 1030 p 1,8-Cineole-Cymene 0.27.8 0.36.4 7.2 0.2 10271055 1030 1057 Limoneneγ-Terpinene 1.70.5 26.7:73.3 0.50.4 63.3:36.7 0.3 0.2 57.3:42.7 1067 1069 cis-Sabinene hydrate 0.8 95.3:4.7 1.0 89.5:10.5 0.9 90.7:9.3 Plants 2021, 10, 482 3 of 13 Table 1. Cont. Aerial Parts Essential Oil Root Essential Oil RIcalc RIdb Compound #1, % ED, (+):(−) #2, % ED, (+):(−) #2, % ED, (+):(−) 1083 1086 Terpinolene tr tr tr trans-Linalool oxide 1084 1086 — tr 0.1 (furanoid) 1087 1093 p-Cymenene — — tr 1098 1099 Linalool 0.1 71.9:28.1 0.1 49.7:50.3 0.3 50.1:49.9 1099 1099 trans-Sabinene hydrate tr 76.5:23.5 0.3 71.1:28.9 0.3 66.8:33.2 1165 1167 exo-Acetoxycamphene — — 0.1 1169 1170 Borneol 0.1 0:100 0.1 0:100 0.3 0:100 1178 1180 Terpinen-4-ol 0.4 60.2:39.8 0.4 58.5:41.5 1.9 20.9:79.1 1183 1186 p-Cymen-8-ol — — 0.1 1187 1190 Methyl salicylate tr — — 1195 1195 α-Terpineol 0.1 100:0 0.1 100:0 0.2 100:0 1196 1197 Methyl chavicol (= Estragole) — 1.5 — 1236 1239 Thymol methyl ether 4.4 5.6 11.3 1252 1252 Thymoquinone 0.2 0.7 1.3 1253 1246 Carvone tr 39.9:60.1 — — 1290 1289 Thymol 38.2 37.0 29.0 1297 1296 Carvacrol 38.3 39.9 38.3 1305 1309 4-Vinylguaiacol — — 0.1 1306 1306 iso-Ascaridole tr tr — 1342 1345 Thymyl acetate 0.3 0.2 0.3 1347 1356 Eugenol tr — 0.3 1361 1365 Carvacryl acetate 0.8 0.5 1.0 1372 1375 α-Copaene tr 100:0 tr 0.1 100:0 1380 1382 β-Bourbonene tr tr 0.1 1389 1392 (Z)-Jasmone tr tr tr 1398 1398 Cyperene — — 0.2 1404 1408 Decyl acetate tr — — 1415 1417 (E)-β-Caryophyllene 0.3 100:0 0.4 100:0 0.5 100:0 1426 1430 β-Copaene tr tr tr 1451 1453 α-Humulene tr tr tr 1457 1457 Rotundene — — 0.1 1471 1475 γ-Muurolene tr 0.1 0.1 1473 1481 (E)-β-Ionone — — tr 1477 1480 Germacrene D 0.1 100:0 0.1 100:0 0.1 1481 1485 γ-Thujaplicin tr — 0.1 1483 1489 β-Selinene tr — — 1487 1490 γ-Amorphene tr — — 1491 1497 α-Selinene tr tr 0.1 1494 1497 α-Muurolene tr tr tr 1509 1512 γ-Cadinene tr tr 0.1 1514 1518 δ-Cadinene 0.1 0.1 0.1 0:100 1548 1549 Thymohydroquinone 0.3 0.1 0.1 1577 1577 Caryophyllene oxide tr 0.1 0.1 1649 1655 α-Cadinol — — 0.1 1689 1691 Cyperotundone — — 0.2 1835 1841 Phytone — — 0.1 Monoterpene hydrocarbons 14.3 10.2 9.6 Oxygenated monoterpenoids 84.0 86.3 86.0 Sesquiterpene hydrocarbons 0.5 0.7 1.4 Oxygenated sesquiterpenoids tr 0.1 0.4 Benzenoid aromatics tr 1.5 0.8 Others 1.0 1.2 1.2 Total identified 99.8 99.8 99.3 RIcalc = Retention indices determined with respect to a homologous series of n-alkanes on a ZB-5ms column.