Essential Oils from Bolivia. XV. Herzogole, an Original Monoterpene Benzodioxole from an Essential Oil from Pentacalia herzogii (Cabrera) Cuatrec

Over 15 years, with the support of a Canadian funding agency, the Universidad Mayor de San Simón, in Bolivia, undertook a large survey of aromatic plants of the South American country. More than a hundred species were studied under various aspects, including the production and characterization of essential oils. As part of this survey, the chemical composition of an essential oil sample obtained from Pentacalia herzogii (Asteraceae) growing wild in the High Valley region of the department of Cochabamba was determined by a combination of GC and GC-MS measurements. α-Pinene was the main constituent of this essential oil (34%), accompanied by limonene (22%) and germacrene D (7.5%) as well as an important fraction of methoxylated monoterpenoids. They were mainly isomers of thymol methyl ether, accounting for 13% of the chromatogram. A new quantitatively important compound (9%) was identified through NMR and chemical synthesis as 4-isopropyl-6-methylbenzo[d][1,3]dioxole, and designated herzogole, alongside the minor related compound 1-isopropyl-2,3-dimethoxy-5-methylbenzene. The monoterpene benzodioxole featured a distinctive green-phenolic aroma which could raise interest for fragrance use. Since these compounds were not known naturally, a biosynthetic mechanism of their formation was proposed and put in perspective to illustrate the metabolic originality of P. herzogii.

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery

The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.

Chemical Composition of the Essential oil of Syzygium kanarense: An Endemic and Rediscovered Species from the Western Ghats, India

The hydro-distilled essential oil obtained from the aerial parts of Syzygium kanarense(Talbot) Raizada (Myrtaceae) was investigated for the first time by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Fifty-two constituents were identified, which represented 91.9% of the total oil. The major compounds were seychellene (7.3%), α-muurolol (5.4%), cis-cadinene ether (5.3%), β-vetivenene (5.1%), 10 epi-γ-eudesmol (4.8%), guaiol (4.5%), longiborneol (4.1%), δ-elemene (4.1%) and α-muurolene (4.1%). The oil was found to be rich in sesquiterpene hydrocarbon (49.5%) type constituents.

GC/MS Analysis of the Essential Oil of Vernonia cinerea

The hydro-distilled essential oil obtained from the roots of V. cinerea Less. (Asteraceae) was investigated by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Twenty-five constituents were identified, which represented 97.4% of the total oil. The major compounds were α-muurolene (30.7%), β-caryophyllene (9.6%), α-selinene (8.7%), cyperene (6.7%) and α-gurjunene (6.5%). The essential oil was dominated by sesquiterpene hydrocarbons (87.8%).

GC/MS Analysis of the Essential Oil of Leucas indica from India

The aim of the present study was to investigate and identify the essential oil constituents of Leucas indica (L.) R.Br. (Lamiaceae). The chemical composition of the hydro-distilled essential oil was obtained from the flowering aerial parts of L. indica for the first time. The oil was analyzed by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Fifty-six compounds were identified, representing 99.1% of the total oil. The main constituents were β-caryophyllene (51.1%) and α-caryophyllene (10.2%). The oil was found to be rich in sesquiterpene hydrocarbons (71.8%).

Chemical Composition of Vernonia albicans Essential Oil from India

The chemical composition of the hydro-distilled essential oil obtained from the flowering aerial parts of Vernonia albicans DC. (Asteraceae) was analyzed by gas chromatography equipped with a flame ionization detector (GC-FID) and gas chromatography coupled with a mass spectrometry (GC/MS). Thirty-nine compounds have been identified, representing 97.5% of the total oil. The major constituents were β-caryophyllene (34.3%), γ-amorphene (19.5%), 9-epi-β-caryophyllene (6.9%), and α-pinene (6.9%). The oil was found to be rich in sesquiterpene hydrocarbons (73.9%).

Chemical Composition of the Essential Oil of Croton bonplandianus from India

The essential oil obtained from the aerial parts of Croton bonplandianus Baill. was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). A total of 37 compounds have been identified, representing 96.2% of the total oil. The main constituents were identified as β-caryophyllene (16.7%), germacrene D (14.7%), borneol (8.3%), Z-β-damascenone (6.(%), isobornyl acetate (6.2%), α-humulene (6.1%), germacrene A (5.2%) and caryophyllene oxide (4.5%). The oil was rich in sesquiterpene hydrocarbons (60.1%).

Chemical Composition of the Essential Oil of the Flowering Aerial Parts of Pimpinella monoica

The essential oil composition of the flowering aerial parts of Pimpinella monoica Dalzell was analyzed by gas chromatography equipped with flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Fifty four compounds were identified, representing 94.7% of the total oil. The main constituents were bornyl acetate (26.2%), β-caryophyllene (24.0%), limonene (6.7%) and amorpha-4, 11-dien (4.9%). The oil was dominated by sesquiterpene hydrocarbons (40.7%), followed by oxygenated monoterpenes (27.2%), monoterpene hydrocarbons (15.6%), oxygenated sesquiterpenes (7.6%) and others (3.6%).

Chemical Composition of the Essential Oil of Baccharoides lilacina from India

The essential oil composition from the aerial parts of Baccharoides lilacina (Dalzell & A. Gibson) M. R. Almeida was analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). A total of 41 compounds have been identified, representing 97.4% of the total oil. The main constituents were identified as β-caryophyllene (27.7%), epi-α-cadinol (25.1%), caryophyllene oxide (9.9%), α-muurolol (7.6%), α-cadinene (6.1%) and α-cadinol 4.5%). The oil was found to be rich in oxygenated sesquiterpenes (47.1%) and sesquiterpene hydrocarbons (46.2%).

Essential Oil Composition and Antibacterial Activity of Monticalia greenmaniana (Asteraceae)

The essential oils from fresh aerial parts of Monticalia greenmaniana (Hieron) C. Jeffrey (Asteraceae) collected in March, were analyzed by GC/MS. Oil yields (w/v) of 0.1% (flowers), 0.07%, (stems) and 0.1% (leaves) were obtained by hydrodistillation. Thirteen, sixteen and eighteen components, respectively, were identified by comparison of their mass spectra with those in the Wiley GC-MS Library data base. The major components of the flower and stem oils were 1-nonane (38.8% flowers; 33.5% stems), α-pinene (29.0% flowers; 14.8% stems) and germacrene D (15.6% flowers; 18.6% stems). However, in the leaf oil, germacrene D was observed at 50.7%, followed by β-cedrene at 8.4 %. The leaf essential oil showed a broad spectrum of antibacterial activity against the important human pathogenic Gram-positive and Gram-negative bacteria Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 19433), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Klebsiella pneumoniae (ATCC 25955) with MIC values ranging from 75 to 6000 ppm.