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Article

Evaluation of Chemical Composition and Anti-Staphylococcal Activity of Essential Oils from Leaves of Two Indigenous Plant Species, Litsea leytensis and Piper philippinum

by
Genesis Albarico
1,2,
Klara Urbanova
3,
Marketa Houdkova
2,
Marlito Bande
4,
Edgardo Tulin
5,
Tersia Kokoskova
6 and
Ladislav Kokoska
2,*
1
Department of Pure and Applied Chemistry, Visayas State University, Visca, Baybay City 6521-A, Leyte, Philippines
2
Department of Crop Science and Agroforestry, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamycka 129, 165 00 Prague, Czech Republic
3
Department of Sustainable Technologies, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamycka 129, 165 00 Prague, Czech Republic
4
Institute of Tropical Ecology, Visayas State University, Visca, Baybay City 6521-A, Leyte, Philippines
5
Philrootcrops, Visayas State University, Baybay City 6521-A, Leyte, Philippines
6
Department of Animal Science and Food Processing, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamycka 129, 165 00 Prague, Czech Republic
*
Author to whom correspondence should be addressed.
Plants 2024, 13(24), 3555; https://doi.org/10.3390/plants13243555
Submission received: 1 November 2024 / Revised: 4 December 2024 / Accepted: 17 December 2024 / Published: 20 December 2024
(This article belongs to the Special Issue Chemistry of Plant Natural Products)
Review Reports Versions Notes

Abstract

Many indigenous plants of the Philippines, including essential oil-bearing species, remain phytochemically and pharmacologically unexplored. In this study, the chemical composition of leaf essential oils (EOs) hydrodistilled from Litsea leytensis (Lauraceae) and Piper philippinum (Piperaceae) was determined using dual-column (HP-5MS/DB-WAX)/dual-detector gas chromatography and mass spectrometry analysis. Caryophyllene oxide (15.751/16.018%) was identified as the main compound in L. leytensis EO, followed by β-caryophyllene (11.130/11.430%) and α-copaene (9.039/9.221%). Ishwarane (25.937/25.280%), nerolidol (9.372/10.519%) and 3-ishwarone (6.916/2.588%) were the most abundant constituents of P. philippinum EO. Additionally, the in vitro growth-inhibitory activity of the EOs in the liquid and vapour phases against Staphylococcus aureus was evaluated using the broth microdilution volatilisation assay. Although the results showed no anti-staphylococcal effect, the presence of various bioactive compounds in both EOs suggests their potential future use in industrial applications.

1. Introduction

Indigenous plants, especially endemic species, are less explored as sources of new phytochemicals, including those found in essential oils (EOs), with potential industrial uses [1,2]. Most of these plants are found in specific regions known as biodiversity hotspots. The Philippines, a tropical archipelago located in Southeast Asia, is considered one of the world’s best biodiversity hotspots, with more than 5800 species of endemic plants, including EO-bearing flora [3]. Various EOs isolated from the numerous native plants of the Philippines have been recognised worldwide for their commercial and economic importance, and many of them are currently utilised in the cosmeceutical and pharmaceutical industries. For example, EO distilled from the resin of Canarium luzonicum, commonly known as Manila elemi, is used as a fragrance in soap and perfumes and as a base for liniments [4]. Moreover, other economically valuable EOs can also be obtained from plant species commonly belonging to the Annonaceae, Burseraceae, Lauraceae, Piperaceae and Zingiberaceae families, among others. However, the EO chemical composition of some species belonging to these families has not yet been analysed. One typical example is Litsea leytensis Merr. (Lauraceae), a species endemic in the Philippines and commonly known as batikuling or bitokling. It is a medium-sized tree that inhabits low- and medium-altitude forests in Luzon and the Eastern Visayas regions [5]. Light-to-medium-weight wood from the tree is used locally for pattern making, ceilings and carving due to its scent that naturally repels termites, ants and woodworms [6]. Another example of a native Philippine plant is Piper philippinum Miq. (Piperaceae), which is a woody climber distributed throughout southern China, Taiwan and the Philippines in thickets and forests at low and medium altitudes [7]. The older stems are traditionally used for betel quid chewing, together with lime and catechu. With the exception of bioactive lignans isolated from P. philippinum [8], there is currently no information about the chemistry and biological activity of either of these species. Since certain species of the genera Litsea and Piper (e.g., Litsea cubeba and Piper nigrum) are important industrial sources of EOs, we decided to determine the chemical composition of the volatile compounds present in the leaves of two indigenous Philippine plants, namely L. leytensis and P. philippinum, using gas chromatography and mass spectrometry (GC-MS). Additionally, in vitro anti-staphylococcal susceptibility testing of these two EOs was performed in both the liquid and vapour phases.

2. Results and Discussion

Hydrodistillation of the leaves L. leytensis and P. philippinum produced light, yellow-coloured EOs with yields (v/w) of 0.14% and 0.77% on a dry plant weight basis, respectively. According to the recommendations previously proposed for more effective assessment of the anti-infective potential of natural products, minimum inhibitory concentrations (MICs) below 100 μg/mL for EOs should be considered as an indicator of promising activity. In addition, samples with MICs higher than 1000 μg/mL should strictly be evaluated as not active and excluded from further experiments [9]. Based on these criteria, the EOs did not show any antibacterial activity against S. aureus in the liquid nor vapour phases (MICs > 1024 μg/mL). The complete results of the chemical analysis and the composition of L. leytensis and P. philippinum EOs are provided in Table 1 and Table 2.
Based on the GC-MS analysis using HP-5MS/DB-WAX columns, a total of 68/61 and 54/48 compounds were identified in the samples of L. leytensis and P. philippinum, representing 93.775/90.128% and 88.524/89.045% of the total content, respectively. Analysis revealed that monoterpenes and sesquiterpenes were the predominant chemical classes within the major constituents of the tested EOs. For L. leytensis, 1.825/1.387% monoterpenes and 87.319/81.585% sesquiterpenes were identified, respectively, using HP-5MS/DB-WAX columns, while 7.245/10.807% monoterpenes and 80.384/73.709% sesquiterpenes were identified for P. philippinum. Caryophyllene oxide (15.751/16.018%) was the main component of L. leytensis EO, followed by β-caryophyllene (11.130/11.430%) and α-copaene (9.039/9.221%). All three compounds are known to exhibit various biological activities. For example, analgesic, antibacterial, anticancer, antifungal, anti-inflammatory, antioxidant, cardioprotective, gastroprotective, hepatoprotective, immunomodulatory, nephroprotective and neuroprotective effects were reported for β-caryophyllene [12,13,14]. Likewise, caryophyllene oxide has analgesic and anti-inflammatory properties [15]. Besides its antioxidant and neuroprotective activities [16], α-copaene is a common attractant to insect pests such as the Mediterranean fruit fly [17] and redbay ambrosia beetles [18]. In previous experiments investigating their antimicrobial properties, caryophyllene oxide, β-caryophyllene and α-copaene produced a moderate-to-weak in vitro growth-inhibitory effect against Staphylococcus aureus with MICs of 125, 250 and ~1000 μg/mL, respectively [19,20]. The relatively high MIC values previously detected for all three compounds can explain the absence of anti-staphylococcal activity of EOs assayed in this study. According to the results of our analysis, the chemical composition of L. leytensis EO significantly differs from that of L. cubeba, which is the most important species of the genus economically. Its EO is used in the perfume industry as a commercial source of citral [21]. Although the chemistry of the EO from the leaf of L. cubeba varies significantly depending on the geographical origin of the sample, with 1,8-cineole or linalool being the main constituents [22], its chemical composition differs significantly from that of L. leytensis leaf EO. Previously published analyses of EOs from other species of the Litsea genus suggest that the chemical composition of L. deccanensis left EO is more similar to that of L. leytensis, as it also contains β-caryophyllene and caryophyllene oxide as the main components [22,23]. Reported chemical variability in EOs obtained from leaves of L. cubeba of different geographical origin [24] suggests that environmental factors can also affect the phytochemical variability of other species of the genus, including composition of L. leytensis EO. In addition, the experiment comparing solvent-free microwave extraction and hydrodistillation showed that the chemical composition of L. cubeba EO could be influenced by the extraction method used [25], which should be considered for further scaling-up of the extraction of volatile compounds from species of the Litsea genus.
The chemical analysis showed that ishwarane (25.937/25.280%) is a major component of P. philippinum leaf EO, followed by nerolidol (9.372/10.519%) and 3-ishwarone (6.916/2.588%). The chemical profile of P. nigrum, the most economically and industrially important species of the genus, differs therefore significantly from P. philippinum EO [26,27,28,29]. Nevertheless, leaf EOs of other Piper species, such as P. arboretum, P. aduncum and P. guadianum, also contain a significant amount of δ-cadinene, β-caryophyllene and nerolidol [28]. Nerolidol is an economically important sesquiterpene since it is predominantly utilised as a fragrance component in the perfume industry [30] with known anticancer, anti-inflammatory, antimicrobial, antinociceptive, antioxidant and antiparasitic (anti-leishmanial, -malarial, -schistosomal and -trypanosomal) activities [31,32,33,34]. On the other hand, ishwarane is a rare sesquiterpene among the species of the Piper genus [35], which is only found in the leaf EO of P. fulvescens [36] and P. alatipetiolatum [37], as well as in the fruit EO of P. guineense [38]. Ishwarane was reported to have antifungal activity against Cladosporium cladosporioides [35]. 3-Ishwarone, another rare sesquiterpene detected in P. philippinum, was also found in the leaf EO of Peperomia oreophila [39] and Peperomia scandens [40]. Since considerable variations in chemical composition of EOs have previously been demonstrated for different populations of P. nigrum grown in China [41], the potential influence of environmental conditions on the chemistry of plants belonging to the Piper genus should be considered prior to the industrial utilisation of their EOs. It has also recently been reported that the chemical composition of P. nigrum hydrodistilled EO varies from its supercritical carbon dioxide extract [42]. This result suggests that the analysis of composition of volatile compounds present in the Piper genus can be influenced by the extraction method used.
The separation of EOs using GC on stationary phases of different polarity provides an analytical tool useful for various applications, the most notable being the confirmation of specific isomers [43]. Effective separation of several isomers from the two plant EOs in the current study was conducted using non-polar HP-5MS and polar DB-WAX columns. Using this approach, isomeric cadinenes detected in L. leytensis EO were identified, whereas α- and γ-cadinene were found on HP-5MS, and δ-cadinene was found on DB-WAX only. In the case of P. philippinum EO, effective separation was achieved for α- and β-copaene on both columns, and their corresponding isomer, ylangene, was found only when using DB-WAX. Moreover, the polar DB-WAX column offered additional information regarding the components of each EO sample, such as the detection of hexadecenoic acid in P. philippinum EO.

3. Materials and Methods

3.1. Chemicals and Reagents

Camphene (CAS 79-92-5), β-caryophyllene (CAS 87-44-5), geraniol (CAS 106-24-1), α-caryophyllene (CAS 6753-98-6), linalool (CAS 126-91-0), methyl octanoate (CAS 111-11-5), myrcene (CAS 123-35-3), α-pinene (CAS 7785-70-8) and β-pinene (CAS 18172-67-3) were used as analytical standards. Furthermore, n-alkanes (ranging from C8 to C40) were used as calibration standards. With the exception of n-hexane (CAS 110-54-3; Merck, Darmstadt, Germany), which was used as a solvent for the preparation of analytical EO samples, all other chemicals were obtained from Sigma-Aldrich (Prague, Czech Republic).

3.2. Plant Material

The leaves of L. leytensis and the aerial parts of P. philippinum were collected during January 2019 at the base of Mount Pangasugan, Leyte Island, the Philippines. The plants were authenticated at the Jose Vera Santos Memorial Herbarium of the College of Science of the University of the Philippines by plant taxonomist Edwino S. Fernando. Voucher specimens were deposited at CZU, in the herbarium of the Department of Botany and Plant Physiology, Faculty of Agrobiology, Food and Natural Resources: 02576KBFRB (L. leytensis) and 02576KBFRB (P. philippinum). For EO extraction, separate air-dried plant samples were homogenised (Grindomix GM 100, Retsch, Haan, Germany). Residual moisture content was analysed in triplicate using a Scaltec SMO 01 (Scaltec Instruments, Gottingen, Germany) at 130 °C.

3.3. Hydrodistillation

The EOs from L. leytensis and P. philippinum were extracted via hydrodistillation from air-dried plant material. A Clevenger-type apparatus (Merci, Brno, Czech Republic) was used to extract the EO from the material placed in 1 L of distilled water for 3 h, according to the European Pharmacopoeia [44]. After distillation, the EOs were stored in sealed glass vials at 4 °C until analysed.

3.4. Bacterial Strain and Culture Media

S. aureus standard strain ATCC 29213 was cultivated in Mueller–Hinton broth and agar, both purchased from Oxoid (Basingstoke, UK). The pH of the broth was equilibrated to 7.6 with Trizma base (Sigma-Aldrich).
A stock culture of S. aureus was cultivated at 37 °C for 24 h prior to susceptibility testing. The turbidity of the bacterial suspension was then adjusted to 0.5 McFarland standard, using a Densi-La-Meter II (Lachema, Brno, Czech Republic), to obtain a final concentration of 107 CFU/mL. Susceptibility of the bacterium to oxacillin (86.3%, CAS 7240-38-2; Sigma-Aldrich) was utilised as a positive antibiotic control [45].

3.5. Antimicrobial Assay

The antibacterial potential of the plant EOs was assessed, in both the liquid and vapour phase, using the broth microdilution volatilisation method [46]. Standard 96-well immune plates with flanged lids designed to reduce evaporation (SPL Life Sciences, Naechon-Myeon, Pocheon-si, Republic of Korea) were utilised. First, 30 μL of agar was pipetted into each flange, except the outermost flanges, and inoculated with 5 μL of the bacterial suspension. Secondly, samples of the EOs were dissolved in dimethylsulfoxide (DMSO) (Sigma-Aldrich) at a maximum concentration of 1% and diluted in broth medium. Serial dilutions were prepared from the samples of both EOs (seven two-fold dilutions), starting at 1024.00 μg/mL. A 96-pin multi-blot replicator (National Institute of Public Health, Prague, Czech Republic) was used to inoculate the plates with the bacterial suspension. Wells containing inoculated and non-inoculated broth were used as growth and purity controls simultaneously. Lastly, the plates and lids were fastened together to ensure an air-tight fit using clamps (Lux Tool, Prague, Czech Republic) and handmade wooden pads and incubated at 37 °C for 24 h. The MICs were evaluated by visual assessment. A metabolically active bacterial colony was coloured with thiazolyl blue tetrazolium bromide dye (Sigma-Aldrich) at a concentration of 600.00 μg/mL. When the colour changed from yellow to purple (relative to the colours in the control wells and flanges), the endpoint (MIC value) was recorded in the broth and agar. The MIC values (μg/mL) were the lowest concentrations capable of inhibiting bacterial growth, compared with the compound-free control. The negative control containing 1% of DMSO did not inhibit the growth of the strain tested, neither in the broth or agar media. All experiments were performed in triplicate, in three independent experiments. According to the widely accepted norm in MIC testing, the mode and median were used for the final value calculation when the triplicate endpoints were within the two- and three-dilution range, respectively [47].

3.6. GC-MS Analysis

GC-MS analysis was used to determine the main components of the EOs. An Agilent GC-7890B dual-column/dual-detector gas chromatograph (Agilent Technologies, Santa Clara, CA, USA) was utilised, equipped with an Agilent 7693 autosampler, two columns, a fused-silica HP-5MS column (30 m × 0.25 mm, film thickness 0.25 µm, Agilent 19091s-433) and a DB-WAX column (30 m × 0.25 mm, film thickness 0.25 µm, Agilent 122–7132), and a flame ionisation detector (FID) coupled with a single quadrupole mass selective detector Agilent MSD-5977B (Agilent Technologies, Santa Clara, CA, USA). Helium was used as a carrier gas (1 mL/min) and the injector temperature for both columns was set at 250 °C. The oven temperature was increased after 3 min from 50 to 280 °C for both columns. After an isothermic period of 3 min, a heating rate of 3 °C/min was used until 120 °C, after which 5 °C/min was utilised until 250 °C. This was followed by a 5 min holding time at 250 °C, after which the heating rate increased to 15 °C/min until 280 °C. An isothermic period of 20 min followed. EOs were diluted to a concentration of 20 µL/mL in n-hexane, and, subsequently, 1 µL of each sample was injected into the GC-MS in a split mode (split ratio 1:50). The mass detector conditions were as follows: ionisation energy 70 eV, ion source temperature 230 °C, scan time 1 s and mass range 40–600 m/z. Identification of the constituents was performed by comparing their retention indices (RIs), retention times (RTs) and spectra with those in the National Institute of Standards and Technology Library ver. 2.0.f (NIST, Gaithersburg, MD, USA) [10,11], as well as against authentic standards (Sigma-Aldrich) and with the literature. The RIs were calculated using the RTs of the n-alkane series (ranging from C8 to C40) for compounds separated on the HP5-MS column. The relative percentages of the EO components were determined on both columns using FID. The analysis of each EO was performed in three independent measurements and the relative peak area percentage was expressed as an average plus/minus standard deviation.

4. Conclusions

This is the first report of the chemical composition of EOs hydrodistilled from the leaves of L. leytensis (Lauraceae) and P. philippinum (Piperaceae), which provides new insights into the phytochemistry of these indigenous plant species found in the Philippines. Sesquiterpenoids, namely caryophyllene oxide, α-copaene and β-caryophyllene (L. leytensis), and 3-ishwarone, ishwarane and nerolidol (P. philippinum), were the predominant class of compounds identified in both EOs. Using GC-MS equipped with two columns of differing polarity, isomeric cadinenes were detected in L. leytensis EO and copaenes and ylangene were identified in P. philippinum EO. Although the assessment of the antibacterial activity of the EOs showed no growth-inhibitory effect on S. aureus, the presence of bioactive compounds such as caryophyllene oxide, β-caryophyllene, α-copaene, ishwarane and nerolidol in the EOs suggests their potential future use in cosmetic and pharmaceutical applications. However, the evaluation of safety and knowledge of a broader spectrum of biological properties, such as anticancer, antifungal and antioxidant effects, will be necessary before their possible industrial usage.

Author Contributions

Conceptualisation, L.K.; methodology, G.A. and L.K.; software, G.A. and K.U.; validation, L.K., M.H. and K.U.; formal analysis, G.A.; investigation, G.A.; resources, E.T., M.B. and M.H.; data curation, G.A.; writing—original draft preparation, G.A.; writing—review and editing, G.A., L.K., M.H., K.U. and T.K.; visualisation, G.A.; supervision, L.K.; project administration, L.K.; funding acquisition, L.K. All authors have read and agreed to the published version of the manuscript.

Funding

This study was financially supported by the Internal Grant Agency of the Faculty of Tropical AgriSciences of the Czech University of Life Sciences Prague [grant number IGA.20243109].

Data Availability Statement

The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.

Acknowledgments

We would like to express our utmost gratitude to Edwino S. Fernando for his invaluable help in the identification of the plant species used in this study. His expertise was instrumental in the definite realisation of this paper.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Aumeeruddy-Elalfi, Z.; Gurib-Fakim, A.; Mahomoodally, F. Antimicrobial, antibiotic potentiating activity and phytochemical profile of essential oils from exotic and endemic medicinal plants of Mauritius. Ind. Crops Prod. 2015, 7, 197–204. [Google Scholar] [CrossRef]
  2. Afshari, M.; Rahimmalek, M. Variation in essential oil composition, bioactive compounds, anatomical and antioxidant activity of Achillea aucheri, an endemic species of Iran, at different phenological stages. Chem. Biodivers. 2018, 15, e1800319. [Google Scholar] [CrossRef]
  3. Myers, N.; Mittermeier, R.A.; Mittermeier, C.G.; da Fonseca, G.A.B.; Kent, J. Biodiversity hotspots for conservation priorities. Nature 2000, 403, 853–858. [Google Scholar] [CrossRef] [PubMed]
  4. Boer, E.; Ella, A.B. Plant Resources of Southeast Asia, No. 18: Plants Producing Exudates; Backhuys Publishers: Leiden, The Netherlands, 2000; pp. 55–60. [Google Scholar]
  5. Engay-Gutierrez, K.G.; Espaldon, M.V.O.; Tiburan, C.L., Jr.; Villanueva-Peyraube, J.D.; Macandog, D.M.; Sobremisana, M.J. Predicting species occurrence of Litsea leytensis Merr. in the provinces of Laguna and Quezon, Philippines. J. Environ. Sci. Manag. 2023, 26, 27–44. [Google Scholar] [CrossRef]
  6. Langenberger, G. Forest Vegetation Studies on the Foothills of Mt. Pangasugan, Leyte/The Philippines; Deutsche Gesellschaft für, Technische Zusammenarbeit: Eschborn, Germany, 2000; p. 54. [Google Scholar]
  7. Gardner, R. Piper (Piperaceae) in the Philippine islands: The climbing species. Blumea 2006, 51, 569–586. [Google Scholar] [CrossRef]
  8. Chen, Y.; Liao, C.; Chen, I. Lignans, an amide and anti-platelet activities from Piper philippinum. Phytochem. 2007, 68, 2101–2111. [Google Scholar] [CrossRef] [PubMed]
  9. Kokoska, L.; Kloucek, P.; Leuner, O.; Novy, P. Plant-derived products as antibacterial and antifungal agents in human health care. Curr. Med. Chem. 2019, 26, 5501–5541. [Google Scholar] [CrossRef]
  10. William, E.W. Retention Indices by NIST Mass Spectrometry Data Center, WebBook Chemie. NIST Standard Reference Database Number 69. Available online: https://webbook.nist.gov/chemistry/ (accessed on 5 January 2021).
  11. Adams, R.P. Identification of Essential Oil Components by Gas Chromatography/Mass Spectrometry, 4th ed.; Allured Publishing Corporation: Carol Stream, IL, USA, 2007. [Google Scholar]
  12. Danham, S.S.; Tabana, Y.M.; Iqbai, M.A.; Ahamed, M.B.K.; Ezzat, M.O.; Majid, A.S.A.; Majid, A.M.S.A. The anticancer, antioxidant and antimicrobial properties of the sesquiterpene β-caryophyllene from the essential oil of Aquilaria crassna. Molecules 2015, 20, 11808–11829. [Google Scholar] [CrossRef]
  13. Fidyt, K.; Fiedorowicz, A.; Strzadala, L.; Szumny, A. β-Caryophyllene and β-caryophyllene oxide—Natural compounds of anticancer and analgesic properties. Cancer Med. 2016, 5, 3007–3017. [Google Scholar] [CrossRef]
  14. Machado, K.D.; Islam, M.T.; Ali, E.S.; Rouf, R.; Uddin, S.J.; Dev, S.; Shilpi, J.A.; Shill, M.C.; Reza, H.M.; Das, A.K.; et al. A systematic review on the neuroprotective perspectives of beta-caryophyllene. Phytother. Res. 2018, 32, 2376–2388. [Google Scholar] [CrossRef] [PubMed]
  15. Chavan, M.J.; Wakte, P.S.; Shinde, D.B. Analgesic and anti-inflammatory activity of caryophyllene oxide from Annona squamosa L. bark. Phytomedicine 2009, 17, 149–151. [Google Scholar] [CrossRef]
  16. Turkez, H.; Togar, B.; Tatar, A. Tricyclic sesquiterpene alpha-copaene prevents H2O2-induced neurotoxicity. J. Intercult. Ethnopharmacol. 2014, 3, 21–28. [Google Scholar] [CrossRef]
  17. Shelly, T.E. Exposure to α-copaene and α-copaene-containing oils enhances mating success of male Mediterranean fruit flies (Diptera: Tephritidae) (Diptera: Tephritidae). Ann. Entomol. Soc. Am. 2001, 9, 497–502. [Google Scholar] [CrossRef]
  18. Kendra, P.E.; Montgomery, W.S.; Deyrup, M.A.; Wakarchuk, D. Improved lure for redbay ambrosia beetle developed by enrichment of alpha-copaene content. J. Pest Sci. 2016, 89, 427–438. [Google Scholar] [CrossRef]
  19. Ben Hsouna, A.; Ben Halima, N.; Abdelkafi, S.; Hamdi, N. Essential oil from Artemisia phaeolepis: Chemical composition and antimicrobial activities. J. Oleo Sci. 2013, 62, 973–980. [Google Scholar] [CrossRef] [PubMed]
  20. Chen, S.Y.; Zheng, H.; Yang, S.P.; Qi, Y.G.; Li, W.; Kang, S.N.; Hu, H.; Hua, Q.; Wu, Y.K.; Liu, Z.J. Antimicrobial activity and mechanism of α-copaene against foodborne pathogenic bacteria and its application in beef soup. LWT—Food Sci. Technol. 2024, 195, 115848. [Google Scholar] [CrossRef]
  21. Nor Azah, M.A.; Susiarti, S. Litsea cubeba (Lour.) Persoon. In Plant Resources of Southeast Asia, No. 19: Essential-Oil Plants; Oyen, L.P.A., Dung, N.X., Eds.; Backhuys Publishers: Leiden, The Netherlands, 1999; pp. 123–126. [Google Scholar]
  22. Azhar, M.A.M.; Salleh, W.M.N.H.W. Chemical composition and biological activities of essential oils of the genus Litsea (Lauraceae)—A review. Agric. Conspec. Sci. 2020, 85, 97–103. [Google Scholar]
  23. Chang, H.S.; Chen, I.S. Chemical constituents and bioactivity of Formosan lauraceous plants. J. Food Drug Anal. 2016, 24, 247–263. [Google Scholar] [CrossRef] [PubMed]
  24. Bighelli, A.; Muselli, A.; Casanova, J.; Tam, N.T.; Van Anh, V.; Bessière, J.M. Chemical variability of Litsea cubeba leaf oil from Vietnam. J. Essent. Oil Res. 2005, 17, 86–88. [Google Scholar] [CrossRef]
  25. Qiu, Y.F.; Wang, Y.; Li, Y. Solvent-free microwave extraction of essential oils from Litsea cubeba (Lour.) Pers. at different harvesting times and their skin-whitening cosmetic potential. Antioxidants 2022, 11, 2389. [Google Scholar] [CrossRef] [PubMed]
  26. Dosoky, N.S.; Satyal, P.; Barata, L.M.; da Silva, J.K.R.; Setzer, W.N. Volatiles of black pepper fruits (Piper nigrum L.). Molecules 2019, 24, 4244. [Google Scholar] [CrossRef] [PubMed]
  27. Pino, O.; Sánchez, Y.; Rodríguez, H.; Correa, T.M.; Demedio, J.; Sanabria, J.L. Chemical characterization and acaricidal activity of the essential oil from Piper aduncum subsp. ossanum against Varroa destructor. Rev. Prot. Veg. 2011, 26, 52–61. [Google Scholar]
  28. da Silva, A.; Matias, E.; Rocha, J.; Araújo, A.; de Freitas, T.; Campina, F.; Costa, M.; Silva, L.; Amaral, W.; Maia, B.; et al. Gas chromatography coupled to mass spectrometry (GC-MS) characterization and evaluation of antibacterial bioactivities of the essential oils from Piper arboreum Aubl., Piper aduncum L. e Piper gaudichaudianum Kunth. Z. Naturforsch. C. 2021, 76, 35–42. [Google Scholar] [CrossRef]
  29. Parthasarathy, V.A.; Chempakam, B.; Zachariah, J.T. Chemistry of Spices; CAB International: London, UK, 2008. [Google Scholar] [CrossRef]
  30. Lapczynski, A.; Bhatia, S.P.; Letizia, C.S.; Api, A.M. Fragrance material review on nerolidol (isomer unspecified). Food Chem. Toxicol. 2008, 46, 247–250. [Google Scholar] [CrossRef] [PubMed]
  31. Bezerra, C.F.; Júnior, J.G.d.A.; Honorato, R.d.L.; dos Santos, A.T.L.; da Silva, J.C.P.; Silva, D.V.D.; Leal, A.L.A.B.; de Freitas, T.S.; Vieira, T.A.T.; Rocha, J.E.; et al. Antifungal properties of nerolidol-containing liposomes in association with fluconazole. Membranes 2020, 10, 194. [Google Scholar] [CrossRef] [PubMed]
  32. Saito, A.Y.; Marin, R.A.A.; Menchaca, V.D.S.; Sussmann, R.A.C.; Kimura, E.A.; Katzin, A.M. Antimalarial activity of the terpene nerolidol. Int. J. Antimicrob. Agents 2016, 48, 641–646. [Google Scholar] [CrossRef]
  33. Silva, M.P.; de Oliveira, R.N.; Mengarda, A.C.; Roquini, D.B.; Allegretti, M.S.; Salvadori, M.C.; Teixeira, F.S.; de Sousa, D.P.; Pinto, P.L.S.; da Silva Filho, A.A.; et al. Antiparasitic activity of nerolidol in a mouse model of schistosomiasis. Int. J. Antimicrob. Agents 2017, 50, 467–472. [Google Scholar] [CrossRef]
  34. Chan, W.K.; Tan, L.T.H.; Chan, K.G.; Lee, L.H.; Goh, B.H. Nerolidol: A sesquiterpene alcohol with multi-faceted pharmacological and biological activities. Molecules 2016, 21, 529. [Google Scholar] [CrossRef] [PubMed]
  35. Ratnayake, R.; Jayasinghe, S.; Ratnayake, B.M.; Andersen, R.J.; Karunaratne, V. Complete 2D NMR assignment and antifungal activity of ishwarane isolated from Hortonia, a genus endemic to Sri Lanka. J. Natl. Sci. Found. Sri Lanka 2008, 36, 109–112. [Google Scholar] [CrossRef]
  36. Vila, R.; Milo, B.; Tomi, F.; Casanova, J.; Ferro, E.A.; Canigueral, S. Chemical composition of the essential oil from the leaves of Piper fulvescens, a plant traditionally used in Paraguay. J. Ethnopharmacol. 2001, 76, 105–107. [Google Scholar] [CrossRef] [PubMed]
  37. de Oliveira, A.C.; Sá, I.S.C.; Mesquita, R.S.; Brenner, L.; Pereira, B.L.; Leandro, A.; Pocrifka, L.A.; de Souza, T.P.; Amado, J.R.R.; Azevedo, S.G.; et al. Nanoemulsion loaded with volatile oil from Piper alatipetiolatum as an alternative agent in the control of Aedes aegypti. Rev. Bras. Farmacogn. 2020, 30, 667–677. [Google Scholar] [CrossRef]
  38. Oyedeji, O.A.; Adeniyi, B.A.; Ajayi, O.; Konig, W.A. Essential oil composition of Piper guineense and its antimicrobial activity. Another chemotype from Nigeria. Phytother. Res. 2005, 19, 362–364. [Google Scholar] [CrossRef] [PubMed]
  39. Lago, J.H.G.; Oliveira, A.; Guimarães, E.F.; Kato, M. 3-Ishwarone and 3-ishwarol, rare sesquiterpenes oil from leaves of Peperomia oreophila Hensch. J. Braz. Chem. Soc. 2007, 18, 638–642. [Google Scholar] [CrossRef]
  40. Dos, S.; Junior, F.M.; Velozo, L.S.M.; De Carvalho, E.M.; Marques, A.M.; Borges, R.M.; Trindade, A.P.F.; Dos Santos, M.I.S.; De Albuquerque, A.C.F.; Costa, F.L.P.; et al. 3-Ishwarone, a rare ishwarane sesquiterpene from Peperomia scandens Ruiz & Pavon: Structural elucidation through a joint experimental and theoretical study. Molecules 2013, 18, 13520–13529. [Google Scholar] [CrossRef] [PubMed]
  41. Li, Y.X.; Zhang, C.; Pan, S.Y.; Chen, L.; Liu, M.; Yang, K.L.; Zeng, X.B.; Tian, J. Analysis of chemical components and biological activities of essential oils from black and white pepper (Piper nigrum L.) in five provinces of southern China. LWT—Food Sci. Technol. 2020, 117, 108644. [Google Scholar] [CrossRef]
  42. Vihanova, K.; Urbanova, K.; Nguon, S.; Kokoska, L. Chemical composition of essential oils and supercritical carbon dioxide extracts from Amomum kravanh, Citrus hystrix and Piper nigrum ‘Kampot’. Molecules 2023, 28, 7748. [Google Scholar] [CrossRef]
  43. Vernin, G.A.; Parkanyi, C.; Cozzolino, F.; Fellous, R. GC/MS analysis of the volatile constituents of Corymbia citriodora Hook. from Reunion Island. J. Essent. Oil Res. 2004, 16, 560–565. [Google Scholar] [CrossRef]
  44. Council of Europe (EDQM). European Pharmacopoeia, 7th ed.; EDQM: Strasbourg, France, 2013. [Google Scholar]
  45. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing, 25th Informational Supplement M100-S25; CLSI: Wayne, PA, USA, 2015; pp. 158–163. [Google Scholar]
  46. Houdkova, M.; Rondevaldova, J.; Doskocil, I.; Kokoska, L. Evaluation of antibacterial potential and toxicity of plant volatile compounds using new broth microdilution volatilization method and modified MTT assay. Fitoterapia 2017, 118, 56–62. [Google Scholar] [CrossRef] [PubMed]
  47. Frankova, A.; Vištejnova, L.; Merinas-Amo, T.; Leheckova, Z.; Doskocil, I.; Wong Soon, J.; Kudera, T.; Laupua, F.; Alonso-Moraga, A.; Kokoska, L. In vitro antibacterial activity of extracts from Samoan medicinal plants and their effect on proliferation and migration of human fibroblasts. J. Ethnopharmacol. 2021, 264, 113220. [Google Scholar] [CrossRef]
Table 1. Litsea leytensis leaf essential oil chemical composition.
Table 1. Litsea leytensis leaf essential oil chemical composition.
a RICompoundsb Cl.c Content [%]d,e Identification
Obs.Lit.HP-5MSDB-WAXHP-5MS
929939α-PineneMH0.234 ± 0.0020.183 ± 0.035RI, MS, Std.
944943CampheneMH0.022 ± 0.002-RI, MS, Std
972980β-PineneMH0.090 ± 0.0010.074 ± 0.011RI, MS, Std
9909892-AmylfuranO0.037 ± 0.0000.022 ± 0.002RI, MS
10221026β-CymeneMH0.090 ± 0.0030.077 ± 0.024RI, MS
10261031D-LimoneneMH0.057 ± 0.0010.043 ± 0.006RI, MS
10281033EucalyptolOM0.247 ± 0.0010.195 ± 0.014RI, MS
10991098LinaloolOM0.120 ± 0.0060.059 ± 0.036RI, MS, Std
11031102NonanalA0.042 ± 0.003-RI, MS
11661166δ-TerpineolOM0.024 ± 0.002-RI, MS
11761177Terpinen-4-olOM0.099 ± 0.002-RI, MS
11901189α-TerpineolOM0.824 ± 0.0270.738 ± 0.162RI, MS
12281215Linalool formateOM0.017 ± 0.0010.017 ± 0.003RI, MS
13081305UndecanalA0.073 ± 0.007-RI, MS
13401341δ-EIemeneSH0.028 ± 0.001-RI, MS
13521351α-CubebeneSH0.478 ± 0.0000.349 ± 0.191RI, MS
13681368CyclosativeneSH0.220 ± 0.035-RI, MS
13811376α-CopaeneSH9.039 ± 0.1379.221 ± 0.258RI, MS
13861388CedreneSH0.039 ± 0.008-RI, MS
13941391β-ElemeneSH0.459 ± 0.001-RI, MS
14091398β-LongipineneSH0.576 ± 0.0120.283 ± 0.084RI, MS
14121409α-GurjuneneSH0.630 ± 0.0200.102 ± 0.006RI, MS
14261418β-CaryophylleneSH11.130 ± 0.06511.430 ± 0.334RI, MS, Std.
14301429α-IononeOS0.179 ± 0.0060.108 ± 0.012RI, MS
14321432β-GurjuneneSH0.218 ± 0.0030.104 ± 0.004RI, MS
14391442α-MaalieneSH0.064 ± 0.001-RI, MS
14431439AromandendreneSH1.058 ± 0.0350.686 ± 0.096RI, MS
14471447Selina-5,11-dieneSH0.059 ± 0.023-RI, MS
14551455Geranyl acetoneOS2.144 ± 0.0182.393 ± 0.101RI, MS
14601455α-CaryophylleneSH4.906 ± 0.0844.299 ± 0.217RI, MS, Std.
14661465AlloaromadendreneSH1.453 ± 0.0631.056 ± 0.038RI, MS
14761477γ-HimachaleneSH0.143 ± 0.031-RI, MS
14801477γ-MuuroleneSH1.219 ± 0.0331.028 ± 0.025RI, MS
14881485β-IononeOS0.146 ± 0.032-RI, MS
14911485β-EudesmeneSH0.935 ± 0.0770.904 ± 0.031RI, MS
14991489LedeneSH1.361 ± 0.107-RI, MS
15031499α-MuuroleneSH0.743 ± 0.0630.709 ± 0.046RI, MS
15191513γ-CadineneSH0.871 ± 0.014-RI, MS
15221527Selina-3,7(11)-dieneSH0.121 ± 0.010-RI, MS
15291521(Z)-CalameneneSH4.194 ± 0.0723.298 ± 0.136RI, MS
15441541α-Cadinene SH0.345 ± 0.092-RI, MS
15561562Cadala-1(10),3,8-trieneSH0.441 ± 0.054-RI, MS
15681564EpiglobulolOS0.963 ± 0.0531.143 ± 0.639RI, MS
15741574PalustrolOS0.304 ± 0.076-RI, MS
15771574YlangenolOS0.770 ± 0.293-RI, MS
15901576SpathulenolOS4.244 ± 0.1513.267 ± 0.112RI, MS
15951581Caryophyllene oxideOS15.751 ± 0.06416.018 ± 0.913RI, MS
159716042a,3,4a,7a-Tetramethyl-2,2a,4a,5,6,7,7a,7b-octahydro-1H-cyclopenta[cd]inden-7-olOS1.753 ± 0.037-RI, MS
16011590ViridiflorolOS1.314 ± 0.081-RI, MS
16131611TetradecanalA1.784 ± 0.0531.610 ± 0.249RI, MS
16201606Humulene epoxide 2OS4.240 ± 0.0105.144 ± 0.347RI, MS
1628161610-epi-β-EudesmolOS0.139 ± 0.0060.113 ± 0.061RI, MS
16361627EpicubenolOS0.826 ± 0.0050.916 ± 0.350RI, MS
1639NALongifolenaldehydeOS2.432 ± 0.2230.924 ± 0.143RI, MS
16421631Caryophylla-4(12),8(13)-dien-5α-olOS2.458 ± 0.071-RI, MS
16501640α-epi-CadinolOS1.191 ± 0.0520.329 ± 0.124RI, MS
16531645δ-CadinolOS0.279 ± 0.0180.173 ± 0.050RI, MS
1676165310-HydroxycalameneneOS0.376 ± 0.0450.160 ± 0.047RI, MS
16831674CadaleneSH0.456 ± 0.0440.212 ± 0.003RI, MS
16871676MustakoneOS0.441 ± 0.076-RI, MS
17271729Murolan-3,9(11)-diene-10-peroxySH1.305 ± 0.1092.079 ± 0.448RI, MS
17771772Pentadecan-1-olO0.617 ± 0.014-RI, MS
18171817HexadecanalA1.763 ± 0.0332.249 ± 0.121RI, MS
18441845Hexahydrofarnesyl acetoneOS0.373 ± 0.003-RI, MS
18921903HomosalateE0.088 ± 0.012-RI, MS
19011906Heptadecan-2-oneK0.227 ± 0.016-RI, MS
19231922Farnesyl acetoneOS4.316 ± 0.0724.879 ± 0.097RI, MS
21122111PhytolOS0.189 ± 0.0060.337 ± 0.002RI, MS
-13906-Ethyl-2-methyldecaneO-0.022 ± 0.001-
1532CypereneSH-0.305 ± 0.022-
-1589IsocaryophylleneSH-0.136 ± 0.004-
-1629RotundeneSH-0.091 ± 0.021-
-1698ViridifloreneSH-0.514 ± 0.029-
-1725α-SelineneSH-0.487 ± 0.029-
-1718Heptadec-8-eneSH-0.095 ± 0.007-
-1742δ-CadineneSH-2.154 ± 0.089-
-1814Tridecan-2-oneK-0.017 ± 0.002-
-1915γ-Dehydro-ar-himachaleneSH-0.140 ± 0.003-
-1921α-CalacoreneSH-0.168 ± 0.051-
-NA5,5-Dimethyl-4-[(1E)-3-methyl-1,3-butadienyl]-1-oxaspiro[2.5]octaneO-0.197 ± 0.052-
-2043LedolOS-0.142 ± 0.013-
-2063CubenolOS-0.917 ± 0.201-
-2175τ-CadinolOS-0.219 ± 0.010-
-NA3β,9β-Dihydroxy-3,5α,8-trimethyl tricyclo[6.3.1.0(1,5)] dodecaneO-2.080 ± 0.102-
-NADiepicedrene-1-oxideOS-1.164 ± 0.029-
-NAUndec-10-ynoic acid, tetradecyl esterE-0.841 ± 0.008-
-NA11,11-Dimethyl-4,8-dimethylenebicyclo[7.2.0]undecan-3-olOS-1.499 ± 0.054-
-NAGermacra-4(15),5,10(14)-trien-1β-olOS-1.890 ± 0.061-
-NARetinalD-0.119 ± 0.021-
Total identified [%] 93.77590.128
a RI = retention index. Obs. = retention index determined relative to a homologous series of n-alkanes (C8–C40) using a HP-5MS column. Lit. = literature RI value [10,11]. b Cl. = chemical classification; A—aldehyde, DH—diterpene hydrocarbon, E—ester, K—ketone, MH—monoterpene hydrocarbon, O—other, OD—oxygenated diterpene, OM—oxygenated monoterpene, OS—oxygenated sesquiterpene, SH—sesquiterpene hydrocarbon, c relative peak area percentage as the mean of three measurements. d Identification method: MS = mass spectrum was identical to that of National Institute of Standards and Technology Library (ver. 2.0.f), RI = the retention index matching literature database; Std = constituent identity confirmed by co-injection of authentic standards. e Identification on DB-WAX was confirmed based on the MS spectrum. NA = RI values not available in the literature.
Table 2. Piper philippinum aerial part essential oil chemical composition.
Table 2. Piper philippinum aerial part essential oil chemical composition.
a RI Compoundsb Cl.c Content [%]d,e Identification
Obs.Lit.HP-5MSDB-WAXHP-5MS
929939α-PineneMH0.068 ± 0.0030.044 ± 0.002RI, MS, Std
944953CampheneMH0.352 ± 0.0130.256 ± 0.029RI, MS, Std
10261031LimoneneMH0.048 ± 0.0030.047 ± 0.005RI, MS
10281033EucalyptolOM0.085 ± 0.0140.057 ± 0.003RI, MS
10991098LinaloolOM0.467 ± 0.0260.518 ± 0.018RI, MS, Std
11971195EstragoleOM1.232 ± 0.0750.973 ± 0.009RI, MS
13401339δ-EIemeneSH0.053 ± 0.005-RI, MS
13521351α-CubebeneSH0.214 ± 0.0090.131 ± 0.006RI, MS
13741373EugenolOM4.662 ± 0.0618.462 ± 0.117RI, MS
13781376α-CopaeneSH1.979 ± 0.2980.945 ± 0.028RI, MS
13871384β-BourboneneSH0.273 ± 0.0410.189 ± 0.024RI, MS
13931391β-ElemeneSH1.079 ± 0.049-RI, MS
14051401MethyleugenolOM0.331 ± 0.0270.449 ± 0.032RI, MS
14171415(Z)-α-BergamoteneSH0.039 ± 0.007-RI, MS
14231418β-CaryophylleneSH3.486 ± 0.1854.367 ± 0.300RI, MS, Std
14321432β-CopaeneSH0.364 ± 0.0040.196 ± 0.018RI, MS
14411440AromadendreneSH0.280 ± 0.008-RI, MS
14471447Selina-5,11-dieneSH0.609 ± 0.0010.490 ± 0.047RI, MS
14591454HumuleneSH1.649 ± 0.0931.527 ± 0.034RI, MS
14711467IshwaraneSH25.937 ± 0.80125.280 ± 0.450RI, MS
14811477γ-MuuroleneSH4.591 ± 0.1984.807 ± 0.079RI, MS
14851480Germacrene DSH0.564 ± 0.1880.249 ± 0.224RI, MS
14891487AristolocheneSH1.604 ± 0.1931.137 ± 0.011RI, MS
14911485β-EudesmeneSH1.400 ± 0.1901.965 ± 0.033RI, MS
14981491ValenceneSH3.363 ± 0.748-RI, MS
14991494α-SelineneSH1.964 ± 0.0843.414 ± 0.076RI, MS
15031499α-MuuroleneSH0.452 ± 0.0650.071 ± 0.015RI, MS
15101503β-BisaboleneSH0.094 ± 0.010-RI, MS
15181513γ-CadineneSH0.732 ± 0.018-RI, MS
15231522α-MaalieneSH0.479 ± 0.017-RI, MS
15271524δ-CadineneSH2.614 ± 0.1172.659 ± 0.171RI, MS
15371535CubeneneSH0.136 ± 0.0140.107 ± 0.003RI, MS
15421538α-CadineneSH0.134 ± 0.006-RI, MS
15481546α-CalacoreneSH0.226 ± 0.0140.142 ± 0.022RI, MS
15681565NerolidolOS9.372 ± 0.68010.519 ± 0.195RI, MS
15841576SpathulenolOS0.461 ± 0.0300.473 ± 0.008RI, MS
15901581Caryophyllene oxideOS0.956 ± 0.0440.722 ± 0.074RI, MS
16171606Humulene epoxide 2OS0.365 ± 0.0140.296 ± 0.026RI, MS
16211630α-AcorenolOS0.146 ± 0.006-RI, MS
16351642CubenolOS0.462 ± 0.0090.238 ± 0.081RI, MS
1644164410,10-Dimethyl-2,6-dimethylenebicyclo[7.2.0]undecan-5-olOS0.114 ± 0.012-RI, MS
16491640α-epi-MuurololOS0.325 ± 0.055-RI, MS
16531645δ-CadinolOS0.259 ± 0.0500.110 ± 0.021RI, MS
16631662NeointermedeolOS0.815 ± 0.084-RI, MS
16681669IntermedeolOS0.565 ± 0.0580.646 ± 0.019RI, MS
16821685Eudesma-4(15),7-dien-1β -olOS1.141 ± 0.0921.516 ± 0.082RI, MS
16901680Germacra-4(15),5,10(14)-trien-1α-olOS0.518 ± 0.0090.318 ± 0.054RI, MS
169116803-IshwaroneOS6.916 ± 0.1422.588 ± 0.141RI, MS
17691763AristoloneOS0.127 ± 0.009-RI, MS
17761778β-CosolOS2.677 ± 0.0602.945 ± 0.104RI, MS
18041805τ-Cadinol acetateE/OS0.128 ± 0.0110.119 ± 0.003RI, MS
18141831Valerenyl acetateE/OS0.720 ± 0.0430.433 ± 0.004RI, MS
21122111PhytolOD0.731 ± 0.0691.067 ± 0.015RI, MS
22172218Phytol, acetateE/OD0.164 ± 0.010-RI, MS
-1488YlangeneSH-0.197 ± 0.001-
-1603α-GuaieneSH-0.163 ± 0.034-
-1832Cadina-1,3,5-trieneSH-0.549 ± 0.037-
-1895EpicubebolOS-0.106 ± 0.004-
-1924TetradecanalA-0.072 ± 0.005-
-NAβ-CyperoneOS-3.352 ± 0.057-
-2104GlobulolOS-0.635 ± 0.057-
-2299AromadendrenepoxideOS-0.112 ± 0.015-
-2910Hexadecanoic acidFA-3.391 ± 0.063-
Total identified [%] 88.52489.045
a RI = retention index. Obs. = retention index determined relative to a homologous series of n-alkanes (C8–C40) using a HP-5MS column. Lit. = literature RI value [10,11]. b Cl. = chemical classification; A—aldehyde, DH—diterpene hydrocarbon, E—ester, K—ketone, MH—monoterpene hydrocarbon, O—other, OD—oxygenated diterpene, OM—oxygenated monoterpene, OS—oxygenated sesquiterpene, SH—sesquiterpene hydrocarbon, c relative peak area percentage as the mean of three measurements. d Identification method: MS = mass spectrum was identical to that of National Institute of Standards and Technology Library (ver. 2.0.f), RI = the retention index matching literature database; Std = constituent identity confirmed by co-injection of authentic standards. e Identification on DB-WAX was confirmed based on the MS spectrum. NA = RI values not available in the literature.
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Albarico, G.; Urbanova, K.; Houdkova, M.; Bande, M.; Tulin, E.; Kokoskova, T.; Kokoska, L. Evaluation of Chemical Composition and Anti-Staphylococcal Activity of Essential Oils from Leaves of Two Indigenous Plant Species, Litsea leytensis and Piper philippinum. Plants 2024, 13, 3555. https://doi.org/10.3390/plants13243555

AMA Style

Albarico G, Urbanova K, Houdkova M, Bande M, Tulin E, Kokoskova T, Kokoska L. Evaluation of Chemical Composition and Anti-Staphylococcal Activity of Essential Oils from Leaves of Two Indigenous Plant Species, Litsea leytensis and Piper philippinum. Plants. 2024; 13(24):3555. https://doi.org/10.3390/plants13243555

Chicago/Turabian Style

Albarico, Genesis, Klara Urbanova, Marketa Houdkova, Marlito Bande, Edgardo Tulin, Tersia Kokoskova, and Ladislav Kokoska. 2024. "Evaluation of Chemical Composition and Anti-Staphylococcal Activity of Essential Oils from Leaves of Two Indigenous Plant Species, Litsea leytensis and Piper philippinum" Plants 13, no. 24: 3555. https://doi.org/10.3390/plants13243555

APA Style

Albarico, G., Urbanova, K., Houdkova, M., Bande, M., Tulin, E., Kokoskova, T., & Kokoska, L. (2024). Evaluation of Chemical Composition and Anti-Staphylococcal Activity of Essential Oils from Leaves of Two Indigenous Plant Species, Litsea leytensis and Piper philippinum. Plants, 13(24), 3555. https://doi.org/10.3390/plants13243555

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