Essential Oils from Actinodaphne obovata (Nees) Blume and Caryodaphnopsis bilocellata Van Der Werff & Dao: Chemical Composition and Biological Activity

Abstract

Objective

In this work, the essential oils of two Vietnamese species of the Lauraceae family, Actinodaphne obovata and Caryodaphnopsis bilocellata, were chemically characterized in detail in order to assess their possible cytotoxic and antibacterial properties.

Methods

Essential oils were extracted from fresh leaves and flowers using hydro-distillation, and their chemical components were identified using gas chromatography-mass spectrometry (GC-MS). The antibacterial abilities were tested against several bacterial, fungal, and yeast strains, while the cytotoxicity was assessed on cancer cell lines HeLa, MCF-7, and HepG2.

Results

The major compounds in A. obovata leaf essential oil were (E)-caryophyllene (29.1%), caryophyllene oxide (26.4%), spathulenol (5.6%), hinesol acetate (5.2%), α-copaene (5.1%), and α-humulene (5.0%), whereas the flower essential oil was predominated by β-myrcene (41.7%), α-pinene (11.6%), β-pinene (8.2%), sabinene (7.2%), and (E)-caryophyllene (6.2%). The main constituents identified in the essential oil of Caryodaphnopsis bilocellata leaves were (E)-caryophyllene (26.0%), α-humulene (8.4%), γ-amorphene (8.1%), caryophyllene oxide (5.9%), bicycloelemene, and δ-cadinene (5.4%). A. obovata essential oils showed antimicrobial activities, especially the leaf sample showed strong activity against two fungi Aspergillus niger, and A. brasiliensis with the same MIC value of 32 µg/mL. This essential oil was also cytotoxic against HeLa cancerous cells with the IC₅₀ of 62.12 µg/mL. Caryodaphnopsis bilocellata leaf essential oil was inactive in the antimicrobial assay.

Conclusion

Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and their oxygenated derivatives, are abundant in the essential oils derived from these plants. The oils’ antibacterial properties differed greatly, however the leaf essential oil of A. obovata showed encouraging outcomes. Additionally, this study suggested that A. obovata essential oil may have cytotoxic uses, indicating the need for more investigation into its possible use as a treatment.

Keywords

essential oil antimicrobial activity cytotoxicity

Introduction

Actinodaphne is a genus of flowering plants in the Laurel family (Laureaceae), containing about 70 species. It is widely distributed in tropical and subtropical regions of South Asia, Southeast Asia, southern China, Japan, New Guinea, Queensland, Solomon Islands, and Fiji.¹ Actinodaphne plants have long been used for their medicinal value in many cultures. They are used in traditional Chinese medicine to cure various illnesses, such as fever, rheumatism, and respiratory problems. The bark and leaves are also used as spices in cooking, especially in Southeast Asian cuisine.² The main phytochemical isolates were recorded to be alkaloids, lignans, and phenolic amides.¹ The fresh leaves of Actinodaphne are a good source of essential oils. Germacrene B (16.8%) and globulol (17.8%) were the most abundant compounds in the leaf essential oils of A. macrophylla and A. pruinosa, respectively.¹ Caryophyllene (8.3%) and β-elemene (7.5%) were the main agents of A. lancifolia leaf essential oil, whereas the leaf essential oil of A. cupularis was found to contain isocaryophyllene (8.3%) and germacrene B (7.1%).^3,4 There have been several attempts in biological examinations using Actinodaphne essential oils, especially their role in antioxidant activity. For instance, A. pruinosa leaf essential oil displayed significant activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging (IC₅₀ 85.6 μg/mL), phenolic content (190.2 mg GA (gallic acid equivalent)/g), and in lipoxygenase (IC₅₀ 85.2 μM) assays.¹

Actinodaphne obovata belongs to the genus Actinodaphne, which is a part of the Laurel family. It distribution regions included India, Nepal, Bhutan, Bangladesh, Myanmar, China, and Vietnam.⁵ The plant reaches a height of two to three meters as an evergreen shrub or small tree. It bears little, white flowers in bunches and glossy, and oval leaves. This species has been often used in traditional medicine with antiseptic and anti-inflammatory properties. Chromatographic separation indicated the predominance of alkaloidal compounds in the ethanol extract of this medicinal plant.⁶

Caryodaphnopsis is also a small genus of the Lauraceae family with a disjunct distribution in tropical Asia and tropical America.⁷ The genus is characterized by its aromatic leaves and twigs, which are used in traditional medicine to treat various ailments, including fever, cough, and respiratory problems.⁸ Caryodaphnopsis extract has also been found to have antimicrobial and antioxidant properties, making it a potential source of new medicinal compounds.⁹ There are several records on Caryodaphnopsis essential oils. As an example, α-pinene (26.8%), β-pinene (23.0%), and bicyclogermacrene (8.5%) were the main constituents of C. tonkinensis leaf essential oil.¹⁰ This essential oil showed good antibacterial activity towards Enterococcus faecalis with a MIC value of 15.99 µg/mL, and anti-candidal action against Candida albicans with a MIC value of 33.68 µg/mL.¹⁰ Caryodaphnopsis bilocellata Van Der Werff & Dao was only found in Cucphuong National Park and other regions of Vietnam.¹¹ Caryodaphnopsis bilocellata is a medium tree with 25 m in height. The twigs and terminal buds are glabrous, the flowers are hermaphrodite, and glabrous. The leaves are opposite, chartaceous, elliptic, or ovate-elliptic, 7–18 × 3–9 cm, glabrous on both surfaces. To date, there have not yet been phytochemical and biological investigations on this species.

The current study aims to provide the chemical profiles of the essential oils from the aerial parts of A. obovata and C. bilocellata, which were collected from Vietnam. The analysis was performed using the GC-MS analysis. The obtained essential oils were subjected to antimicrobial assay against the tested Gram bacteria, fungi, and yeasts, and cytotoxic experiment towards three HeLa, MCF-7, and HepG2 cancer cell lines.

Materials and Methods

Plant Materials

The fresh leaves and flowers of A. obovata were collected from Ké Gõ Nature Reserve (18°8'22'’ N and 105°56'52''E), Hatinh, Vietnam in November 2021. The fresh leaves of C. bilocellata were gathered from Pù Huóng Nature Reserve (19°23'44''N and 104°58'29''E), Nghean, Vietnam in April 2023. Their Latin names were identified by co-author Dr Do Ngoc Dai. Three voucher specimens (AOL-2021: A. obovata leaves, AOF-2021: A. obovata flowers, and CBL-2023: C. bilocellata leaves) have been deposited at the Faculty of Agriculture, Forestry and Fishery, Nghe An College of Economics.

Hydro-Distillation of Essential Oils

The fresh material (1.5 kg, each sample) was hydro-distillated using a Clevenger-type apparatus for 2.5 h. The obtained essential oils were dried over Na₂SO₄ and maintained in small sealed vials at 4 °C for further analysis. The yield (fresh weight/volume-w/v) was calculated by an arithmetic mean value in triplicate.

The GC-MS Analysis

The GC-MS analysis for the studied essential oils was performed using a Shimadzu Technologies GCMS-QP2010 Plus (Shimadzu, Kyoto, Japan) chromatograph equipped with a fused silica Equity-5 capillary column (30 m, 0.25 mm, film thickness 0.25 μm, Supelco, USA).^12,13 The analytical settings were as follows: 1.5 mL/min of carrier helium, the temperature of injector and interface at 280 °C, and the ramp temperature from 60 °C (2 min hold) to 240 °C (10 min hold) at 3 °C/min and to 280 °C at 5 °C/min for the column (10-min hold). A split ratio of 10:1 was used to inject the samples. The inlet pressure was 93.2 kPa and the injection volume was 1.0 µL. The MS settings included an ionization voltage of 70 eV, detector voltage of 0.82 kV, and acquisition scan mass range of 40–500 amu at a sampling rate of 0.5 scan/s. By co-injecting the constituents and comparing the results to a homologous series of n-alkanes (C₇-C₄₀), the retention indices (RI) of chemical constituents were calculated. Chemical identification was carried out by comparing their RI values with those in the literature.^14,15 The MS fragmentations were revised against those of other essential oils of known compositions using the NIST 11 and WILEY 7 Libraries. The quantification of each compound was based on the relative area of volatile compounds’ total ion chromatogram (TIC) peaks.

Antimicrobial Assay

The pathogenic ATCC (American Type Culture Collection) strains, consisting of three Gram positve bacteria Bacillus subtilis ATCC 5230, Staphylococcus aureus ATCC 33591 and Clostridium sporogenes ATCC 7955, two Gram negative bacteria Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 27853, three fungi Aspergillus niger ATCC 9587, A. brasiliensis ATCC 9642, and Fusarium oxysporum ATCC 11739, and two yeasts Candida albicans ATCC 12354 and Saccharomyces cerevisiae ATCC 4078, have been used in this study. All pathogenic strains were cultured on Muller Hilton Agar (MHA, Merck) plates for 24 h at 37 °C.¹⁶ The essential oil samples were dissolved in DMSO (5%) to reach concentrations of 4–256 µg/mL. A total of 180 µL of bacterial suspension with 10⁶ CFU mL⁻¹ in Muller Hilton Broth and 20 µL of essential oil were placed in each well (MHB, Merck). The mixture was incubated at 37 °C, and the OD (optical density) was determined at 600 nm using an Elisa reader (RNE-9002, USA). The lowest concentration that showed no growth was identified as the MIC. The assays were performed 3 times. The same procedures were used for the negative control, which contained MHB and Tween, and the positive controls, which contained MHB and bacterial suspension without the tested sample. Streptomycin and tetracycline were used as reference compounds for the Gram-positive and Gram-negative bacteria, respectively, whereas nystatin was used for fungi and yeasts.

Cytotoxic assay The protocol was identical to our previous publication.¹²

Statistical Analysis

Data are processed using Microsoft Excel and represented as Mean ± SD (Standard Deviation). The difference was statistically meaningful with p < 0.05.

Results

Phytochemical Analysis

Hydro-distillation of fresh A. obovata leaves produced a yellowish essential oil, with a yield of 0.56% v/w based on fresh weight. GC-MS analysis identified 15 compounds, accounting for 98.6% of the oil composition (Table 1 and Fig. S1). The identified chemical classes comprised sesquiterpene hydrocarbons (53.4%), oxygenated sesquiterpenes (42.9%), and monoterpene hydrocarbons (2.3%). The principal components were (E)-caryophyllene (29.1%), caryophyllene oxide (26.4%), spathulenol (5.6%), hinesol acetate (5.2%), α-copaene (5.1%), and α-humulene (5.0%). Additional compounds were present in notable amounts, with concentrations ranging from 1.0% to 5.0%.

Table 1.

Chemical Compounds in Essential Oils of Two Studied Plants.

^aRT	^bRI_E	^cRI_L	Compound	A. obovata leaves	A. obovata flowers	C. bilocellata leaves
6.48	925	924	α-Thujene	-	0.6	-
6.71	932	932	α-Pinene	2.3	11.6	-
7.18	946	946	Camphene	-	0.1	0.3
8.01	972	969	Sabinene	-	7.2	-
8.13	976	974	β-Pinene	-	8.2	-
8.73	994	988	β-Myrcene	-	41.7	0.4
9.10	1005	1002	α-Phellandrene	-	-	2.3
9.57	1016	1014	α-Terpinene	-	0.4	-
9.86	1024	1022	ο-Cymene	-	1.3	-
10.04	1028	1024	Limonene	-	4.0	0.5
10.38	1036	1032	(Z)-β-Ocimene	-	-	0.2
10.80	1047	1044	(E)-β-Ocimene	-	0.9	4.0
11.24	1057	1054	γ-Terpinene	-	1.2	-
12.47	1088	1086	Terpinolene	-	0.4	-
13.01	1101	1102	Perillene	-	0.7	-
13.68	1116	1114	endo-Fenchol	-	-	0.8
16.36	1177	1174	Terpinen-4-ol	-	2.5	-
22.33	1312	1312	Citronellic acid	-	0.2	-
23.01	1328	1328	neoiso-Verbanol acetate	-	-	0.7
23.41	1337	1338	Bicycloelemene	-	0.3	5.4
23.95	1350	1348	α-Cubebene	-	0.5	-
24.9	1372	1373	α-Ylangene	-	-	0.5
25.09	1377	1374	α-Copaene	5.1	0.4	3.4
25.48	1386	1387	β-Bourbonene	-	-	2.1
25.70	1391	1387	β-Cubebene	5.0	0.2	-
25.78	1393	1389	β-Elemene	3.8	0.3	-
26.43	1408	1408	(Z)-Caryophyllene	-	-	2.8
26.94	1421	1417	(E)-Caryophyllene	29.1	6.2	26.0
27.32	1430	1430	β-Copaene	-	0.6	0.9
27.50	1434	1434	γ-Elemene	-	0.2	-
27.77	1441	1439	Aromadendrene	-	-	3.8
27.95	1445	1442	6,9-Guaiadiene	-	0.2	0.6
28.33	1454	1452	α-Humulene	5.0	1.3	8.4
28.58	1460	1458	allo-Aromadendrene	-	-	0.5
28.65	1462	1460	dehydro-Aromadendrane	-	-	0.3
29.28	1478	1475	trans-Cadina-1(6),4-diene	2.0	0.2	0.5
29.30	1478	1475	γ-Gurjunene	-	-	3.0
29.45	1482	1480	Germacrene D	1.5	2.1	0.8
29.68	1487	1489	β-Selinene	-	-	0.6
29.90	1493	1492	δ-Selinene	-	-	0.2
30.10	1497	1495	γ-Amorphene	-	0.4	8.1
30.26	1501	1500	α-Muurolene	-	-	0.7
30.55	1509	1505	(E,E)-α-Farnesene	-	0.3	2.2
30.79	1515	1511	δ-Amorphene	-	0.2	1.3
31.17	1524	1522	δ-Cadinene	1.9	0.5	5.4
31.53	1534	1532	γ-Cuprenene	-	-	0.2
31.74	1539	1537	α-Cadinene	-	-	0.3
31.90	1543	1545	Selina-3,7(11)-diene	-	-	0.8
32.49	1558	1555	Elemicin	-	-	0.2
32.72	1564	1561	(E)-Nerolidol	-	0.2	0.4
33.31	1579	1577	Spathulenol	5.6	0.9	1.4
33.52	1585	1582	Caryophyllene oxide	26.4	1.7	5.9
34.52	1611	1608	Humulene epoxide II	2.7	0.2	1.0
35.26	1630	1627	1-epi-Cubenol	-	0.3	0.3
35.36	1634	1631	(E)-Sesquilavandulol	-	0.1	-
35.53	1638	1634	Camphoric acid	-	-	0.3
35.74	1643	1638	epi-α-Cadinol	-	0.2	-
36.03	1651	1649	β-Eudesmol	-	0.4	0.2
36.21	1656	1652	α-Cadinol	1.8	0.2	0.5
36.33	1659	1658	Gymnomitrol	1.2	-	-
40.97	1788	1783	Hinesol acetate	5.2	-	-
Total				98.6	99.1	97.9
Monoterpene hydrocarbons				2.3	78.3	7.4
Oxygenated monoterpenes				-	2.7	1.5
Sesquiterpene hydrocarbons				53.4	13.9	78.8
Oxygenated sesquiterpenes				42.9	4.2	9.7
Non-terpenic compounds				-	-	0.5

RT: Retention time, ^bRI_E: Experimental retention index, ^cRI_L: Literature retention index, bold: Major compounds.

The yellow essential oil derived from A. obovata flowers yielded 0.13% v/w. The GC-MS analysis revealed 40 compounds, representing 99.1% of the oil's composition (Table 1 and Fig. S2). Unlike the leaf oil, the flower oil was predominantly composed of monoterpene hydrocarbons (78.3%), followed by sesquiterpene hydrocarbons (13.9%), oxygenated sesquiterpenes (4.2%), and oxygenated monoterpenes (2.7%). Key constituents of the flower oil included β-myrcene (41.7%), α-pinene (11.6%), β-pinene (8.2%), sabinene (7.2%), and (E)-caryophyllene (6.2%). Other notable components included limonene (4.0%), terpinen-4-ol (2.5%), germacrene D (2.1%), caryophyllene oxide (1.7%), ο-cymene and α-humulene (1.3%), and γ-terpinene (1.2%). The chemical profile of the flower oil contrasts sharply with that of the leaf oil, as certain compounds, like β-myrcene, β-pinene, and sabinene, were unique to the flower oil. Furthermore, α-pinene, a major component in the flower oil, was minimal in the leaf oil, while dominant leaf compounds were either drastically reduced or absent in the flower oil.

Hydro-distillation of fresh C. bilocellata leaves produced a yellow essential oil with a yield of 0.15% v/w. A comprehensive GC-MS analysis identified 42 compounds, accounting for 97.9% of the oil's composition (Table 1 and Fig. S3). Sesquiterpene hydrocarbons were predominant, constituting 78.8% of the total, followed by oxygenated sesquiterpenes (9.7%), monoterpene hydrocarbons (7.4%), oxygenated monoterpenes (1.5%), and non-terpenic compounds (0.5%). The primary constituents were (E)-caryophyllene (26.0%), α-humulene (8.4%), γ-amorphene (8.1%), caryophyllene oxide (5.9%), and bicycloelemene and δ-cadinene (5.4%). Additional compounds exceeding 1.0% included (E)-β-ocimene (4.0%), aromadendrene (3.8%), α-copaene (3.4%), γ-gurjunene (3.0%), and (Z)-caryophyllene (2.8%).

Antimicrobial Activity

The antimicrobial activities of all studied essential oils were assessed, with varying levels of efficacy observed for A. obovata leaf and flower essential oils (Table 2), while C. bilocellata leaf essential oil showed no activity (MIC > 256 µg/mL). This can be attributed to the great role of some major compounds, such as α-pinene, sabinene, β-pinene, and β-myrcene. Notably, A. obovata leaf essential oil demonstrated superior antimicrobial potency compared to the flower essential oil. The leaf oil effectively inhibited two Gram-positive bacteria, Bacillus subtilis, and Clostridium sporogenes, both with an MIC of 64 µg/mL, and Staphylococcus aureus at a MIC of 128 µg/mL, when streptomycin was used as a positive control (MIC 4-8 µg/mL). In comparison, the flower essential oil showed lower activity, with MIC values of 128 µg/mL for B. subtilis, 64 µg/mL for C. sporogenes, and 256 µg/mL for S. aureus.

Table 2.

Antimicrobial Activity of the Tested Essential Oils.

Microbial strains		Minimum inhibitory concentration (MIC: μg/mL)
Microbial strains		A. obovata leaves	A. obovata flowers	C. bilocellata leaves	Streptomycin	Tetracycline	Nystatin
Gram (+)	B. subtilis	64	128	> 256	4
	C. sporogenes	64	64	> 256	8
	S. aureus	128	256	> 256	8
Gram (–)	E. coli	128	128	> 256		4
Gram (–)	P. aeruginosa	> 256	256	> 256		4
Fungi	A. niger	32	> 256	> 256			8
	A. brasiliensis	32	> 256	> 256			8
	F. oxysporum	128	128	> 256			8
Yeasts	C. albicans	128	> 256	> 256			4
Yeasts	S. cerevisiae	64	64	> 256			8

Both the studied samples showed the same MIC value of 128 µg/mL to suppress the Gram-negative bacterium E. coli. Compared to the positive control tetracycline (MIC 4 µg/mL), the flower oil sample had weak antimicrobial activity against the Gram-negative bacterium P. aeruginosa with the MIC value of 256 µg/mL, whereas the leaf oil sample was inactive (MIC > 256 µg/mL). Regarding the fungi, the leaf essential oil strongly controlled A. niger and A. brasiliensis with the same MIC value of 32 µg/mL, when the MIC value of 8 µg/mL was assigned to the standard compound nystatin. However, the flower essential oil failed to do so (MIC > 256 µg/mL). Both samples also exhibited moderate antifungal activity against the fungus F. oxysporum with the same MIC value of 128 µg/mL. Considering the yeast inhibition, the leaf essential oil exerted the MIC value of 128 µg/mL against the yeast C. albicans, whereas the flower essential oil was inactive. In the final case, both samples possessed the same MIC value of 64 µg/mL in an antimicrobial assay against the yeast S. cerevisiae.

Cytotoxicity

The best sample, A. obovata leaf essential oil, was then subjected to a cytotoxic assay against three cancer cell lines HeLa, MCF-7, and HepG2. At the highest tested concentration of 256 µg/mL. This sample inhibited 77.98% growth of HeLa cancerous cells, and less than 50% growth of MCF-7 and HepG2 (Table 3). Actinodaphne obovata leaf essential oil showed cytotoxicity toward HeLa cells with the IC₅₀ value of 66.12 µg/mL, when ellipticine was used as a positive control with the IC₅₀ value of 0.78 µg/mL. However, this essential oil did not exhibit activity against two remaining cancerous cell lines (IC₅₀> 100 µg/mL).

Table 3.

Cytotoxicity of A. obovata Leaf Essential Oil.

Samples	Concentration (µg/mL)	Inhibitory percentage
Samples	Concentration (µg/mL)	HeLa	MCF-7	HepG2
A. obovata leaves	256	77.98 ± 0.3	38.02 ± 0.7	44.34 ± 0.2
	128	60.14 ± 0.6	21.15 ± 0.2	36.13 ± 0.2
	64	46.03 ± 0.2	17.05 ± 0.6	28.41 ± 0.5
	32	25.23 ± 0.2	9.56 ± 0.3	19.34 ± 0.6
	IC₅₀ (µg/mL)	66.12	> 100	> 100
Ellipticine	IC₅₀	0.78	0.81	0.69

Discussion

Previously, much attention has been paid to Asian Actinodaphne essential oils. The main chemical compounds of Malaysian A. perakensis leaf essential oil were bicyclogermacrene (15.8%), δ-cadinene (11.7%), γ-cadinene (6.3%), and aromadendrene (5.6%).¹⁷ Actinodaphne macrophylla leaf essential oil from East Kalimantan, Indonesia, was accompanied by the presence of 2-monopalmitin (11.23%), spathulenol (10.54%), (+)-sabinene (8.49%), and copaene (7.01%).¹⁸ The major compounds in Vietnamese A. pilosa leaf essential oils were α-pinene (6.0-7.2%), (Z)-β-ocimene (10.1-14.3%), (E)-β-ocimene (6.5-10.4%), β-caryophyllene (9.0-14.9%), germacrene D (12.0-16.2%), bicyclo germacrene (11.0-15.9%), and spathulenol (1.0-6.2%).¹⁹

It should be noted that Actinodaphne essential oils are suitable for bacterial treatments. A. pilosa leaf essential oils exerted broad antimicrobial activity with MIC values of 16–64 μg/mL against E. faecalis, S. aureus, B. cereus, P. aeruginosa, and C. albicans.¹⁹ Actinodaphne macrophylla leaf essential oil could inhibit the growth of S. aureus, C. albicans, S. sobrinus, and S. mutans with inhibition zones of 17.22, 20.89, 22.34 and 22.89 mm, respectively.¹⁸ It is also recognized that essential oils extracted from the Laurel plants are well-known for antimicrobial treatments. Laurus nobilis essential oil from Serbia showed a MIC value of 6.30 µg/mL against E. coli and P. aeruginosa and a MIC value of 25.0 µg/mL against B. cereus and S. aureus.²⁰ Essential oil from Vietnamese Beilschmiedia tonkinensis leaves also strongly suppressed the Gram-negative bacterium P. aeruginosa and the fungus A. niger with the MIC values of 16 and 32 µg/mL, respectively.²¹ The Chilean Laureliopsis philippiana is often used in traditional medicine by the Mapuche and their ancestors. Besides cytotoxicity, its leaf essential oil exhibited antimicrobial activity against C. albicans (MIC 64 μg/mL), S. aureus (MIC 32 μg/mL), and E. coli (MIC 8 μg/mL).²²

For the first time, the cytotoxic activity of Actinodaphne essential oils was first evaluated. Previous results evidenced the potential of Actinodaphne plant extracts and their isolated compounds in anticancer developments. (+)-N-(2-Hydroxypropyl)lindcarpine, a new alkaloidal aporphine was isolated from A. pruinosa alcoholic extract, and showed cytotoxicity against P-388 murine leukemia cells with the IC₅₀ value of 3.9 μg/mL.²³ Besides antioxidant, thrombolytic, and antidiarrheal properties, the 80% EtOH extract of A. angustifolia leaves exhibited cytotoxicity.²⁴ Collectively, the current study first describes chemical profiles of essential oils from two Vietnamese laurel plants, and their in vivo antimicrobial and cytotoxic examinations. However, the underlying mechanisms of action remain unknown. The effects of the major compounds have not yet been considered.

Conclusions

For the first time, the current study provides a detailed chemical profile of the essential oils from A. obovata and C. bilocellata. Similar to various reports, monoterpenes, sesquiterpenes, and their oxygenated derivatives were elucidated as the main chemical classes of the Laurel plants. (E)-Caryophyllene, caryophyllene oxide, spathulenol, hinesol acetate, α-copaene, and α-humulene were the main compounds of A. obovata leaf essential oil, while A. obovata flower essential oil was characterized by β-myrcene, α-pinene, β-pinene, sabinene, and (E)-caryophyllene. In the meantime, (E)-caryophyllene, α-humulene, γ-amorphene, caryophyllene oxide, and bicycloelemene and δ-cadinene were present in C. bilocellata leaf essential oil as the principal compounds. The essential oils from A. obovata leaves and flowers exhibited antimicrobial at various levels. Especially, the leaf essential oil strongly monitored the growth of the fungi A. niger and A. brasiliensis. It was also found that A. obovata leaf moderately exhibited cytotoxic activity against HeLa cancerous cells. Chromatographic isolations of the major compounds in A. obovata essential oils as purified compounds are necessary. In vivo antimicrobial research and molecular mechanisms of action are encouraged.

Supplemental Material

sj-docx-1-npx-10.1177_1934578X251333702 - Supplemental material for Essential Oils from Actinodaphne obovata (Nees) Blume and Caryodaphnopsis bilocellata Van Der Werff & Dao: Chemical Composition and Biological Activity

Supplemental material, sj-docx-1-npx-10.1177_1934578X251333702 for Essential Oils from Actinodaphne obovata (Nees) Blume and Caryodaphnopsis bilocellata Van Der Werff & Dao: Chemical Composition and Biological Activity by Do Ngoc Dai, Le Thi Huong, Ty Viet Pham, Nguyen Dinh Luyen, Nguyen Thi Mai Huong and Ninh The Son in Natural Product Communications

Footnotes

Acknowledgments

The authors are grateful to the boards of directors of Kẻ Gỗ Nature Reserve Natural Reserve, and Pù Huống Nature Reserve, for allowing sample collection.

Statement of Human and Animal Rights

This article does not contain any studies with human or animal subjects.

Statement of Informed Consent

There are no human subjects in this article and informed consent is not applicable.

ORCID iDs

Do Ngoc Dai

Ty Viet Pham

Ninh The Son

Ethical Considerations

Ethical approach is not applicable for this article.

Author Contributions/CRediT

Do Ngoc Dai: Conceptualization, Le Thi Huong: Plant collection, Ty Viet Pham: Data curation, Nguyen Dinh Luyen: Formal analysis, Nguyen Thi Mai Huong: Validation, Ninh The Son: Writing draft manuscript. All authors have read and approved the final manuscript.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Supplemental Material

Supplemental material for this article is available online.

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