Compositional analysis of the essential oil of Boswellia dalzielii frankincense from West Africa reveals two major chemotypes

Unraveling the terpene synthase family and characterization of BsTPS2 contributing to (S)-( +)-linalool biosynthesis in Boswellia

Boswellia tree bark exudes oleo-gum resin in response to wounding, which is rich in terpene volatiles. But, the molecular and biochemical basis of wound-induced formation of resin volatiles remains poorly understood. Here, we combined RNA-sequencing (RNA-seq) and metabolite analysis to unravel the terpene synthase (TPS) family contributing to wound-induced biosynthesis of resin volatiles in B. serrata, an economically-important Boswellia species. The analysis of large-scale RNA-seq data of bark and leaf samples representing more than 600 million sequencing reads led to the identification of 32 TPSs, which were classified based on phylogenetic relationship into various TPSs families found in angiosperm species such as TPS-a, b, c, e/f, and g. Moreover, RNA-seq analysis of bark samples collected at 0-24 h post-wounding shortlisted 14 BsTPSs that showed wound-induced transcriptional upregulation in bark, suggesting their important role in wound-induced biosynthesis of resin volatiles. Biochemical characterization of a bark preferentially-expressed and wound-inducible TPS (BsTPS2) in vitro and in planta assays revealed its involvement in resin terpene biosynthesis. Bacterially-expressed recombinant BsTPS2 catalyzed the conversion of GPP and FPP into (S)-( +)-linalool and (E)-(-)-nerolidol, respectively, in vitro assays. However, BsTPS2 expression in Nicotiana benthamiana found that BsTPS2 is a plastidial linalool synthase. In contrast, cytosolic expression of BsTPS2 did not form any product. Overall, the present work unraveled a suite of TPSs that potentially contributed to the biosynthesis of resin volatiles in Boswellia and biochemically characterized BsTPS2, which is involved in wound-induced biosynthesis of (S)-( +)-linalool, a monoterpene resin volatile with a known role in plant defense.

Phytochemical study of Boswellia dalzielii oleo-gum resin and evaluation of its biological properties

Boswellia dalzielii is a resin-producing tree endemic to West and Central Africa, used by local populations for various medicinal purposes. In this study, B. dalzielii gum resin was analyzed by GC-MS and UHPLC-MS to identify and quantify volatile and non-volatile compounds. Its main volatile constituents were α-pinene (54.9%), followed by α-thujene (4.4%) and α-phellandren-8-ol (4.0%). Pentacyclic triterpenoids such as β-boswellic acids and their derivatives were quantified by UHPLC-MS and their content was shown to reach around 22% of the gum resin. Since some of the volatile and non-volatile compounds identified in this work are known to possess biological effects, the bioactivities of B. dalzielii ethanolic extract, essential oil, as well as fractions of the oil and extract were evaluated. Some of these samples exhibited interesting anti-inflammatory properties, and their antioxidant, anti-ageing and skin-bleaching activities were also tested.

Evaluating the Potential of Boswellia rivae to Provide Sustainable Livelihood Benefits in Eastern Ethiopia

Frankincense is an oleo-gum-resin collected from wild Boswellia spp. trees, and widely used in perfumery, cosmetics, aromatherapy, incense, and other industries. Boswellia rivae, growing in Ethiopia, Somalia, and Kenya, is one source of frankincense, but is little-commercialized compared to species such as B. sacra, B. frereana, and B. papyrifera. In this study, we examine the resin essential oil chemistry and harvesting systems of B. rivae in order to evaluate its potential for increased trade and potential positive livelihood benefits. Boswellia rivae produces an essential oil rich in α-thujene (0.1-12.4%), α-pinene (5.5-56.4%), β-pinene (0.3-13.0%), δ-3-carene (0.1-31.5%), p-cymene (1.4-31.2%), limonene (1.8-37.3%), β-phellandrene (tr-5.6%), trans-pinocarveol (0.1-5.0%), trans-verbenol (0.1-11.2%), and trans-β-elemene (0-5.7%), similar to major commercial species, although it is difficult to detect mixing of B. rivae and Commiphora africana resins from chemistry alone. The B. rivae trees are not actively tapped, so resin collection has a neutral impact on the health of the trees, and resin production is unaffected by drought. Consequently, collecting resins acts as a key income supplementing livestock herding, as well as a safety net protecting pastoral communities from the severe negative effects of climate change-exacerbated drought on livestock. Therefore, Boswellia rivae is well positioned chemically, ecologically, and socially to support expanded trade.

Conservation Assessment and Chemistry of Boswellia ogadensis, a Critically Endangered Frankincense Tree

Boswellia ogadensis is a critically endangered species of frankincense tree, restricted to a small area of the Shabelle river valley in southern Ethiopia. It has only been recorded from two botanical collecting trips, in 1972 and 2006, with no indication of the abundance, threats, or population status of the trees, and it was listed on the IUCN Red List of Endangered Species as "Critically Endangered" in 2018. More recent expeditions, in 2019 and 2021, were not able to locate the species, raising concerns about its continued survival. We carried out a field survey in June 2022 to re-locate the species, assess the threat level it is facing, and collect samples of resin for analysis. This survey revealed that B. ogadensis is present in more locations than previously recorded, and is more abundant than thought. While it is facing multiple threats, including grazing, cutting for firewood, and insect attacks, these threats vary geographically, and there are populations that appear to be healthy and regenerating well. While more research is needed, the current survey indicates that downlisting to "Endangered" status may be appropriate. Samples of resin were also collected and analyzed using gas chromatographic techniques, revealing that while the essential oil profile is similar to that of other Boswellia species (dominated by α-thujene, α-pinene, p-cymene, and terpenin-4-ol), there are chemical markers that can distinguish it from other sympatric Boswellia species, indicating the potential for this to be used as a tool to monitor whether B. ogadensis is being harvested alongside other more common Boswellia species.

Inter-Tree Variation in the Chemical Composition of Boswellia papyrifera Oleo-Gum-Resin

Frankincense is a fragrant resin produced by Boswellia species, and has been used for centuries as a perfume, medicine, and incense, and is an important cosmetic and therapeutic product today. A number of studies have been conducted on the resin essential oils, but many have used commercial sources outside of the country of origin, leading to potential taxonomic confusion or misidentification. Individual Boswellia papyrifera resin samples were each obtained directly from 11 individual trees in Sudan, hydrodistilled, the volatile phytochemicals determined by gas chromatographic methods, and the chemical compositions subjected to cluster analysis. All samples were very similar, with high levels of octyl acetate (49.5%-81.0%) and octanol (6.5%-13.7%), and varying levels of diterpenoids (6.6%-32.7%). The cluster analysis indicated 3 highly similar groups, defined by (1) relatively higher levels of octyl acetate (58.9%-81.0%), but with low levels of diterpenoids (6.6%-18.6%); (2) relatively lower levels of octyl acetate (49.5%-61.3%), but with a higher proportion of diterpenoids (19.0%-22.8%); and (3) with octyl acetate (51.6%) and diterpenoids (32.7%).

Effects of Frankincense Compounds on Infection, Inflammation, and Oral Health

Boswellia trees, found throughout the Middle East and parts of Africa and Asia, are the source of frankincense oil. Since antiquity, frankincense has been traded as a precious commodity, but it has also been used for the treatment of chronic disease, inflammation, oral health, and microbial infection. More recently, the bioactive components of Boswellia trees have been identified and characterized for their effects on cancer, microbial infection (especially infection by oral pathogens), and inflammation. Most studies have focused on cell lines, but more recent research has also investigated effects in animal models of disease. As natural products are considered to be safer than synthetic drugs, there is growing interest in further developing the use of substances such as frankincense oil for therapeutic treatment.

Volatile Constituent Analysis of Wintergreen Essential Oil and Comparison with Synthetic Methyl Salicylate for Authentication

A comparative analysis of Gaultheria fragrantissima (Ericaceae) essential oils based on geographical location, distillation time, and varying distillation conditions was carried out, and their compositions were evaluated by gas chromatography-mass spectrometry (GC-MS), chiral GC-MS, and gas chromatography-flame ionization detection (GC-FID). In addition, each of seven commercial wintergreen essential oil samples from Nepal and China were analyzed. The highest extraction yield was 1.48% and the maximum number of compounds identified in natural wintergreen oil was twenty-two. Based on distillation time, the maximum numbers of identified compounds are present in 120 min. Linalool, phenol, vetispirane, and ethyl salicylate were present in commercial wintergreen oils both from Nepal and China. The presence of compounds such as elsholtzia ketone and β-dehydroelsholtzia ketone in the China samples represented a significant difference in wintergreen oil between the two geographical sources. Dimethyl 2-hydroxyterephthalate is a well-known synthetic marker for wintergreen oil when synthesis is carried out using salicylic acid, but the synthetic marker was absent while using acetylsalicylic acid as a precursor during synthesis. Adulteration analysis of wintergreen oil showed an increase in the concentration of dimethyl 2-hydroxyterephthalate, whereas the concentrations of minor components decreased and methyl salicylate remained unchanged. To the best of our knowledge, this is the first report of the enantioselective analysis of wintergreen essential oil. Furthermore, three samples showed notable antibacterial activity against Staphylococcus epidermidis, with an MIC value of 156.3 μg/mL. Similarly, one sample showed effectiveness against Aspergillus niger (MIC = 78.1 μg/mL).

Enantiomeric Distribution of Terpenoids in Juniperus Essential Oils: Composition of Juniperus horizontalis and Juniperus scopulorum Leaf Essential Oils From Southwestern Idaho

The essential oils from the leaves and twigs of Juniperus horizontalis and Juniperus scopulorum, growing in southwestern Idaho, were obtained by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC-MS) and gas chromatography–flame ionization detection (GC(FID)). The major components in the essential oil of J horizontalis were α-pinene, 16.9%, predominantly ( + )-α-pinene; sabinene, 37.1%, exclusively ( + )-sabinene; myrcene, 5.0%; and terpinene-4-ol, predominantly ( + )-terpinen-4-ol. The essential oil of J scopulorum was rich in sabinene, 29.8%, exclusively ( + )-sabinene; terpinene-4-ol, 13.2%, nearly racemic; α-elemol, 9.7%; and 8α-acetoxyelemol, 6.4%. In addition, 12 commercial Juniperus communis fruit essential oils were analyzed by chiral GC-MS. α-Pinene showed considerable variation in enantiomeric distribution, depending on geographical location. The dominant enantiomer of sabinene in J communis essential oils was ( + )-sabinene.

Quality Assessment of Zingiber officinale Roscoe Essential Oil from Nepal

Zingiber officinale Roscoe rhizome plays a vital role in food flavoring as well as utilization in folk medicine. Nepal is categorized among the leading countries of Z. officinale rhizome production and export. Mature Z. officinale rhizome collection is based on the major production sites within Nepal, but we are currently unaware of the chemical composition of essential oil for export. A comparative investigation of Z. officinale rhizome essential oil compositions, collected from 12 different sites of the eastern, mid, and western regions of Nepal, has been carried out. The analysis of essential oils chemical composition by gas chromatographic–mass spectral (GC-MS), enantiomeric composition by chiral gas chromatography–mass spectrometry (CGC-MS), and antimicrobial activity was evaluated. Essential oil yields ranged from 0.28% to 0.34%. The results showed that the essential oils obtained in this study contained α-zingiberene (8.6%-24.1%), camphene (7.2%-12.8%), β-phellandrene (3.8%-10.1%), neral (0.6%-11.8%), geranial (1.0%-17.4%), ar-curcumene (3.0%-10.3%), and β-sesquiphellandrene (3.7%-9.7%). With CGC-MS, the enantiomeric distributions of 21 chiral compounds were determined and showed no contrasting enantiomeric distributions. Two essential oil samples (G3 and G5) possessed good antibacterial activity against Pseudomonas aeruginosa (MIC = 78.1μg/mL) and excellent antifungal activity against Aspergillus niger (MIC = 39.1 μg/mL). Based on the content of α-zingiberene and citral (neral and geranial), samples collected from their respective areas might be used to identify an ideal Z. officinale rhizome production zone in Nepal.

Antibacterial, Immunomodulatory, and Lung Protective Effects of Boswelliadalzielii Oleoresin Ethanol Extract in Pulmonary Diseases: In Vitro and In Vivo Studies

Lung diseases such as asthma, chronic obstructive pulmonary diseases, and pneumonia are causing many global health problems. The COVID-19 pandemic has directed the scientific community's attention toward performing more research to explore novel therapeutic drugs for pulmonary diseases. Herein, gas chromatography coupled with mass spectrometry tentatively identified 44 compounds in frankincense ethanol extract (FEE). We investigated the antibacterial and antibiofilm effects of FEE against Pseudomonas aeruginosa bacteria, isolated from patients with respiratory infections. In addition, its in vitro immunomodulatory activity was explored by the detection of the gene expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide synthase (iNOS), cycloxygenase-2 (COX-2), and nuclear factor kappa-B (NF-κB) in lipopolysaccharide (LPS)-induced peripheral blood mononuclear cells (PBMC). In addition, its anticancer activity against the A549 lung cancer cell line and human skin fibroblast (HSF) normal cell line was studied. Moreover, the in vivo lung protective potential of FEE was explored histologically and immunohistochemically in mice using a benzo(a)pyrene induced lung damage model. FEE exhibited antibacterial and antibiofilm activities besides the significant inhibition of gene expression of TNFα, IL-6, and NF-κB. FEE also exerted a cytotoxic effect against A549 cell line. Histological and immunohistochemical investigations with morphometric analysis of the mean area percentage and color intensity of positive TNF-α, COX-2, and NF-κB and Bcl-2 reactions revealed the lung protective activity of FEE. This study outlined the promising therapeutic activity of oleoresin obtained from B. dalzielii in the treatment of different pulmonary diseases.

Cembranoids from Boswellia species

Frankincense of Boswellia species has long been used in traditional medicines, mainly for its interesting anti-inflammatory and anti-depressant properties of its di- and triterpenes. Boswellic acids (triterpenes) and cembranoids (diterpenes) are the major constituents of frankincense from all reported species which are responsible for the overall biological activity of frankincense. Boswellic acids have been thoroughly investigated for decades but cembranoids have attracted considerable attention only recently, and a good number of publications have highlighted the important role of these 14-membered rings in contributing to the superior anti-inflammatory activity of the sacred resin. Partial and total syntheses of some cembranoids from frankincense have been reported. Their therapeutic potential is not limited to the well proven anti-inflammatory activity but also to their recently reported anti-depressant properties. There is a considerable number of publications in the field of cembranoids of Boswellia species where we feel a review in this topic will be of interest to the readership of Phytochemistry. In this article we have discussed the chemistry (isolation and chemical structures as well as synthetic studies), biogenesis and bioactivity of the reported cembranoids of Boswellia species. The structural discrepancies due to wrongly assigned structures of some cembranoids have been highlighted and corrected. We have covered the related literature up to the end of 2020.

The Chemical Composition of Single-Tree Boswellia frereana Resin Samples

Frankincense is an aromatic terpenoid oleo-gum resin produced by trees in the genus Boswellia. It has been used for medicinal and religious purposes for millennia, and is today an important component in perfume and aromatherapy. The resin of Boswellia frereana is especially prized, and has been found to contain a high proportion of monoterpenes. However, previous studies have relied on commercial samples; in this study, we characterize the compositions of essential oil and DCM extract samples from 12 individual B frereana trees. The triterpenoid fraction was largely consistent between samples, with lupeol (14.7%-32.5%), α-amyrin (13.0%-25.2%), 3- epi-lupeol (6.4%-14.2%), and β-amyrin (5.3%-8.0%) as the primary constituents. The essential oil showed more intersample diversity, but still represented a single, variable chemotype characterized by a moderate to high level of α-thujene (14.5%-43.9%) and a varying, often significant, level of α-pinene (3.0%-63.0%).

Phytochemical Analysis of the Essential Oils From Aerial Parts of Four Scutellaria “Skullcap” Species Cultivated in South Alabama: Scutellaria baicalensis Georgi, S. Barbata D. Don, S. Incana Biehler, and S. Lateriflora L

Scutellaria (skullcap) are important medicinal plants. Scutellaria baicalensis and S.barbata have been used in Chinese traditional medicine, while S. incana and S. lateriflora were used as herbal medicines by Native Americans. In this work, the essential oils of Scutellaria baicalensis Georgi, Scutellaria barbata D. Don , Scutellaria incana Biehler, and Scutellaria lateriflora L. were obtained from plants cultivated in south Alabama and analyzed by gas chromatographic techniques, including chiral gas chromatography. The most abundant components in the Scutellaria essential oils were 1-octen-3-ol (31.2% in S. incana), linalool (6.8% in S. incana), thymol (7.7% in S. barbata), carvacrol (9.3% in S. baicalensis), ( E)-β caryophyllene (11.6% in S. baicalensis), germacrene D (39.3% in S. baicalensis), ( E)-nerolidol (10.5% in S. incana), palmitic acid (15.6% in S. barbata), phytol (19.7% in S. incana), and linolenic acid (8.0% in S. barbata). These analyses of the essential oil compositions and enantiomeric ratios of predominant aromatic molecules add to our understanding of the medicinal phytochemistry of the genus Scutellaria.

The Chemical Profiling of Essential Oils from Different Tissues of Cinnamomum camphora L. and Their Antimicrobial Activities

Cinnamomum camphora L. is grown as an ornamental plant, used as raw material for furniture, as a source of camphor, and its essential oil can be used as an important source for perfume as well as alternative medicine. A comparative investigation of essential oil compositions and antimicrobial activities of different tissues of C. camphora was carried out. The essential oils were extracted by hydrodistillation with a Clevenger apparatus and their compositions were evaluated through gas chromatography-mass spectrometry (GC-MS), enantiomeric composition by chiral GC-MS, and antimicrobial properties were assayed by measuring minimum inhibitory concentrations (MICs). Different plant tissues had different extraction yields, with the leaf having the highest yield. GC-MS analysis revealed the presence of 18, 75, 87, 67, 67, and 74 compounds in leaf, branch, wood, root, leaf/branch, and leaf/branch/wood, respectively. The significance of combining tissues is to enable extraction of commercial quality essential oils without the need to separate them. The oxygenated monoterpene camphor was the major component in all tissues of C. camphora except for safrole in the root. With chiral GC-MS, the enantiomeric distributions of 12, 12, 13, 14, and 14 chiral compounds in branch, wood, root, leaf/branch, and leaf/branch/wood, respectively, were determined. The variation in composition and enantiomeric distribution in the different tissues of C. camphora may be attributed to the different defense requirements of these tissues. The wood essential oil showed effective antibacterial activity against Serratia marcescens with an MIC of 39.1 μg/mL. Similarly, the mixture of leaf/branch/wood essential oils displayed good antifungal activity against Aspergillus niger and Aspergillus fumigatus while the leaf essential oil was notably active against Trichophyton rubrum. C. camphora essential oils showed variable antimicrobial activities against dermal and pulmonary-borne microbes.

Essential Oils of Four Virginia Mountain Mint (Pycnanthemum virginianum) Varieties Grown in North Alabama

Virginia mountain mint (Pycnanthemum virginianum) is a peppermint-flavored aromatic herb of the Lamiaceae and is mainly used for culinary, medicinal, aromatic, and ornamental purposes. North Alabama's climate is conducive to growing mint for essential oils used in culinary, confectionery, and medicinal purposes. There is, however, a need for varieties of P. virginianum that can be adapted and easily grown for production in North Alabama. Towards this end, four field-grown varieties with three harvesting times (M1H1, M1H2, M1H3; M2H1, M2H2, M2H3; M3H1, M3H2, M3H3, M4H1, M4H2, M4H3) were evaluated for relative differences in essential oil yield and composition. Thirty-day-old greenhouse-grown plants of the four varieties were transplanted on raised beds in the field at the Alabama A & M University Research Station in North Alabama. The plots were arranged in a randomized complete block with three replications. The study's objective was to compare the four varieties for essential oil yield and their composition at three harvest times, 135, 155, and 170 days after planting (DAP). Essential oils were obtained by hydrodistillation with continuous extraction with dichloromethane using a Likens-Nickerson apparatus and analyzed by gas chromatographic techniques. At the first harvest, the essential oil yield of the four varieties showed that M1H1 had a yield of 1.15%, higher than M2H1, M3H1, and M4H1 with 0.91, 0.76, and 1.03%, respectively. The isomenthone concentrations increased dramatically through the season in M1 (M1H1, M1H2, M1H3) by 19.93, 54.7, and 69.31%, and M3 (M3H1, M3H2, M3H3) by 1.81, 48.02, and 65.83%, respectively. However, it increased only slightly in M2 and M4. The thymol concentration decreased slightly but not significantly in all four varieties; the thymol in M2 and M4 was very high compared with M1 and M3. The study showed that mountain mint offers potential for production in North Alabama. Two varieties, M1 and M3, merit further studies to determine yield stability, essential oil yield, composition, and cultivation development practices.

The Volatile Phytochemistry of Monarda Species Growing in South Alabama

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.

Review of aromatherapy essential oils and their mechanism of action against migraines

ETHNOPHARMACOLOGICAL RELEVANCE

Migraines have become a major threat to human health, as they significantly affect human health and quality of life due to a high prevalence rate, attack rate and pain intensity. Aromatherapy, with its comfortable and pleasant natural characteristics and rapid and efficient characteristics, is widely favored by patients in the folk. Chinese folk also have the application history and related records of aromatic plants in the treatment of migraine.

AIM OF THE STUDY

This study was conducted to review the pathogenesis of migraine, the application of plant essential oils in the treatment of migraine, and further explore the material basis and mechanism of action of plant essential oils against migraine.

MATERIALS AND METHODS

Search the electronic literature of essential oils with anti-migraine effect in Google Scholar, PubMed and China National Knowledge Infrastructure, and further search the research situation of the monomer components of essential oils in migraine, inflammation, pain and other aspects.

RESULTS

studies show that there are 10 types of plant essential oils that could relieve migraine symptoms, and that 16 monomers may play a role in migraine treatment by effectively inhibiting neurogenic inflammation, hyperalgesia and balancing vasorelaxation.

CONCLUSION

Aromatic plant essential oils can relieve migraine effectively, these findings can be used as an important part of the development of anti-migraine drugs.

11-Keto-α-Boswellic Acid, a Novel Triterpenoid from Boswellia spp. with Chemotaxonomic Potential and Antitumor Activity against Triple-Negative Breast Cancer Cells

Boswellic acids, and particularly 11-keto-boswellic acids, triterpenoids derived from the genus Boswellia (Burseraceae), are known for their anti-inflammatory and potential antitumor efficacy. Although boswellic acids generally occur as α-isomers (oleanane type) and β-isomers (ursane type), 11-keto-boswellic acid (KBA) was found only as the β-isomer, β-KBA. Here, the existence and natural occurrence of the respective α-isomer, 11-keto-α-boswellic acid (α-KBA), is demonstrated for the first time. Initially, α-KBA was synthesized and characterized by high-resolution mass spectrometry (HR-MS) and nuclear magnetic resonance (NMR) spectroscopy, and a highly selective, sensitive, and accurate high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method was developed by Design of Experiments (DoE) using a pentafluorophenyl stationary phase. This method allowed the selective quantification of individual 11-keto-boswellic acids and provided evidence for α-KBA in Boswellia spp. oleogum resins. The contents of α-KBA as well as further boswellic acids and the composition of essential oils were used to chemotaxonomically classify 41 Boswellia oleogum resins from 9 different species. Moreover, α-KBA exhibited cytotoxicity against three treatment-resistant triple-negative breast cancer (TNBC) cell lines in vitro and also induced apoptosis in MDA-MB-231 xenografts in vivo. The respective β-isomer and the acetylated form demonstrate higher cytotoxic efficacies against TNBC cells. This provides further insights into the structure-activity relationship of boswellic acids and could support future developments of potential anti-inflammatory and antitumor drugs.

Essential Oil Compositions, Antibacterial and Antifungal Activities of Nigerian Members of the Burseraceae: Boswellia dalzielii and Canarium schweinfurthii

The Burseraceae is an important family of resin-producing trees and shrubs, which have yielded biologically active essential oils. Boswellia dalzielii and Canarium schweinfurthii are members of the family that are used in West African traditional medicine for a variety of ailments. The leaf essential oils of B. dalzielii have been obtained from 2 different locations in north-central Nigeria, while the leaf and stem bark essential oils of C. schweinfurthii have been obtained from 3 locations. The chemical compositions of the essential oils have been determined by gas chromatography-mass spectrometry and show wide variation, especially for the leaf essential oils. The leaf essential oils of B. dalzielii and C. schweinfurthii have been screened for antibacterial and antifungal activity; C. schweinfurthii leaf essential oil showed remarkable activity against Aspergillus niger with a minimum inhibitory concentration of 78.1 μg/mL.

The Essential Oil Composition and Antimicrobial Activity of Liquidambar formosana Oleoresin

The oleoresin essential oils of Liquidambar formosana have potential therapeutic benefits. However, current research on L. formosana oleoresin essential oil is still in its early stages, and its chemotypic characterization is undefined. For better leveraging of plant resources and application of the essential oil, we collected 25 L. formosana oleoresin essential oil samples of individual trees from different geographical areas of Southern China. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The major components of the essential oils were (E)-caryophyllene (3.3%-64.4%), α-pinene (0.6%-34.5%), β-pinene (0.6%-26.0%), camphene (0.3%-17.3%), and limonene (0.2%-7.9%). A chiral GC-MS analysis was carried out on the essential oil samples and (-)-α-Pinene, (-)-β-pinene, (-)-camphene, and (-)-limonene were the dominant enantiomers in L. formosana essential oil. The chemical categories of L. formosana oleoresin essential oils were clarified by agglomerative hierarchical cluster analysis (AHC) and principal component analysis (PCA). The multivariate analyses demonstrated that a total of four chemical groups can be delineated for L. formosana. The L. formosana essential oils were screened for antimicrobial activity against a panel of potentially pathogenic bacteria and fungi and showed promising antimicrobial activities with minimum inhibitory concentration (MIC) ≤ 625 μg/mL. These results highlight the economic value of L. formosana oleoresin essential oil, the importance of L. formosana sustainability, and the potential therapeutic benefits of its oleoresin essential oils.

Experimental Data Based Machine Learning Classification Models with Predictive Ability to Select in Vitro Active Antiviral and Non-Toxic Essential Oils

In the last decade essential oils have attracted scientists with a constant increase rate of more than 7% as witnessed by almost 5000 articles. Among the prominent studies essential oils are investigated as antibacterial agents alone or in combination with known drugs. Minor studies involved essential oil inspection as potential anticancer and antiviral natural remedies. In line with the authors previous reports the investigation of an in-house library of extracted essential oils as a potential blocker of HSV-1 infection is reported herein. A subset of essential oils was experimentally tested in an in vitro model of HSV-1 infection and the determined IC₅₀s and CC₅₀s values were used in conjunction with the results obtained by gas-chromatography/mass spectrometry chemical analysis to derive machine learning based classification models trained with the partial least square discriminant analysis algorithm. The internally validated models were thus applied on untested essential oils to assess their effective predictive ability in selecting both active and low toxic samples. Five essential oils were selected among a list of 52 and readily assayed for IC₅₀ and CC₅₀ determination. Interestingly, four out of the five selected samples, compared with the potencies of the training set, returned to be highly active and endowed with low toxicity. In particular, sample CJM1 from Calaminta nepeta was the most potent tested essential oil with the highest selectivity index (IC₅₀ = 0.063 mg/mL, SI > 47.5). In conclusion, it was herein demonstrated how multidisciplinary applications involving machine learning could represent a valuable tool in predicting the bioactivity of complex mixtures and in the near future to enable the design of blended essential oil possibly endowed with higher potency and lower toxicity.

Volatile Compositions and Antifungal Activities of Native American Medicinal Plants: Focus on the Asteraceae

In the past, Native Americans of North America had an abundant traditional herbal legacy for treating illnesses, disorders, and wounds. Unfortunately, much of the ethnopharmacological knowledge of North American Indians has been lost due to population destruction and displacement from their native lands by European-based settlers. However, there are some sources of Native American ethnobotany remaining. In this work, we have consulted the ethnobotanical literature for members of the Asteraceae used in Cherokee and other Native American traditional medicines that are native to the southeastern United States. The aerial parts of Eupatorium serotinum, Eurybia macrophylla, Eutrochium purpureum, Polymnia canadensis, Rudbeckia laciniata, Silphium integrifolium, Smallanthus uvedalia, Solidago altissima, and Xanthium strumarium were collected from wild-growing plants in north Alabama. The plants were hydrodistilled to obtain the essential oils and the chemical compositions of the essential oils were determined by gas chromatography-mass spectrometry. The essential oils were tested for in-vitro antifungal activity against Aspergillus niger, Candida albicans, and Cryptococcus neoformans. The essential oil of E. serotinum showed noteworthy activity against C. neoformans with a minimum inhibitory concentration (MIC) value of 78 μg/mL, which can be attributed to the high concentration of cyclocolorenone in the essential oil.

Chemical Composition of the Oleogum Resin Essential Oils of Boswellia dalzielii from Burkina Faso

Frankincense, the oleogum resin from members of Boswellia, has been used as medicine and incense for thousands of years, and essential oils derived from frankincense are important articles of commerce today. A new source of frankincense resin, Boswellia dalzielii from West Africa has been presented as a new, alternative source of frankincense. In this work, the oleogum resins from 20 different Boswellia dalzielii trees growing in Burkina Faso, West Africa were collected. Hydrodistillation of the resins gave essential oils that were analyzed by GC-MS and GC-FID. The essential oils were dominated by α-pinene (21.0%–56.0%), followed by carvone (2.1%–5.4%) and α-copaene (1.8%–5.0%). Interestingly, there was one individual tree that, although rich in α-pinene (21.0%), also had a substantial concentration of myrcene (19.2%) and α-thujene (9.8%). In conclusion, the oleogum resin essential oil compositions of B. dalzielii, rich in α-pinene, are comparable in composition to other frankincense essential oils, including B. sacra, B. carteri, and B. frereana. Additionally, the differences in composition between samples from Burkina Faso and those from Nigeria are very slight. There is, however, a rare chemotype of B. dalzielii that is dominated by myrcene, found both in Burkina Faso as well as Nigeria.

The Chemical Composition of Boswellia occulta Oleogum Resin Essential Oils

Frankincense is an aromatic oleogum resin that has been traded for thousands of years for medicine and incense and is today frequently distilled into essential oils for aromatherapy and perfume. A new species of frankincense, Boswellia occulta Thulin, DeCarlo, & S.P. Johnson, was recently described from Somaliland (northern Somalia), but pure essential oils from this species have not yet been described. Samples of resin were collected directly from 12 individual B. occulta trees, hydrodistilled, and analyzed via GC-MS, GC-FID, and agglomerative hierarchical clustering. This revealed a significant level of methyl ethers in all samples (34.5%-62.6%), especially 1-methoxydecane (26.6%-47.9%) and 1-methoxyoctane (3.6%-8.6%). All samples were similar, but 3 groups were defined: (1) a methoxydecane/serratol/methoxyoctane group with 26.6% to 47.4% 1-methoxydecane, 14.5% to 31.8% serratol, and 3.6% to 8.6% 1-methoxyoctane; (2) a methoxydecane/di- epi-guaiol/serratol group with 26.6% to 29.1% 1-methoxydecane, 11.1% to 15.1% 4,10-di- epi-guaiol, and 10.3% to 16.8% serratol; and (3) a methoxydecane/methoxyoctane/di- epi-guaiol group with 38.9% to 47.9% 1-methoxydecane, 7.0% to 9.2% 1-methoxyoctane, and 2.2% to 12.3% 4,10-di- epi-guaiol.