Insights into the antioxidant, anti-inflammatory and anti-microbial potential of Nigella sativa essential oil against oral pathogens

Oral disorders can exert systemic ramifications beyond their localized effects on dental tissues, implicating a wide array of physiological conditions. The utilization of essential oils (EOs) for protection of oral health represents a longstanding practice. Consequently, in this investigation, essential oil derived from Nigella sativa seeds (NSEO) underwent isolation via the hydro-distillation process, followed by a comprehensive evaluation of its antioxidant, anti-inflammatory, anti-fungal, antibacterial activities, and cytocompatibility. The isolated NSEO manifested as a pale-yellow substance and was found to harbor a diverse spectrum of bioactive constituents, including steroids, triterpenoids, flavonoids, phenols, proteins, alkaloids, tannin, sesquiterpenoid hydrocarbons, monoterpenoid alcohol, and monoterpenoid ketone (thymoquinone). Notably, the total phenolic content (TPC) and total flavonoid content (TFC) of NSEO were quantified at 641.23 μg GAE/gm and 442.25 μg QE/g, respectively. Furthermore, NSEO exhibited concentration-dependent inhibition of protein denaturation, HRBC membrane stabilization, and hemolysis inhibition. Comparative analysis revealed that NSEO and chlorhexidine (CHX) 0.2% displayed substantial inhibition of hemolysis compared to aspirin. While NSEO and CHX 0.2% demonstrated analogous antibacterial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, NSEO showcased heightened efficacy against Lactobacillus acidophilus and Candida albicans. Additionally, NSEO exhibited pronounced effects against periodontal pathogens such as Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Prevotella intermedia. Importantly, no cytotoxicity was observed on human gingival fibroblast cell lines. These findings underscore the potential of NSEO as a potent antibacterial and antifungal agent in the management of oral microbial pathogens, thereby offering avenues for the development of innovative therapies targeting diverse oral inflammatory conditions. Nevertheless, further investigations are imperative to unlock its full therapeutic repertoire.

Chemical composition, antimicrobial and antioxidant activities of Algerian Citrus sinensis essential oil extracted by hydrodistillation assisted by electromagnetic induction heating

Hydro-distillation assisted by electromagnetic induction heating (H-EMIH) was employed to extract essential oil (EO) from Algerian fresh orange peels (Citrus sinensis). H-EMIH was compared with conventional hydro-distillation (C-H) in terms of hydro-distillation time, yield, chemical composition and, antibacterial and antioxidant activities. It was found that extraction of EO with H-EMIH gave a maximal yield of 3.77% in 35 min whereas C-H gave 2.72% in 41 min. The extracts obtained by both techniques were analyzed by Gas Chromatography-Mass Spectrometry. Their chemical compositions are relatively similar; limonene and β-myrcene were found as the principal compounds. The antioxidant activity results demonstrated that EO extracted by H-EMIH showed the highest capacity of radical scavenging than EO isolated by C-H process. Otherwise, it was found that EO extracted by H-EMIH exhibited an antimicrobial potential slightly higher than that extracted by C-H.

Effect of variety, location & maturity stage at harvesting, on essential oil chemical composition, and weight yield of Zingiber officinale roscoe grown in Sri Lanka

Our study investigated whether the chemical intensity and weight yield of essential oil fraction of Zingiber officinale roscoe was significantly affected by variety, maturity stage or cultivated location in Sri Lanka. Two varieties, Rangoon and Siddha planted in two geographical locations of Sri Lanka were harvested at three maturity stages. Chinese variety was studied as the control. Study revealed that the ginger essential oil (GEO) weight yield decreased with increasing maturity stage. Maturity stage and location of cultivation was significantly affecting GEO weight yield while chemical intensities were significantly affected by maturity stage only. Variety factor was not significantly affecting any of the dependent variables. Interaction effects between factors suggested that Siddha and Rangoon were the best varieties to cultivate in Sri Lanka. Best time to harvest rhizomes was at 5 months maturity for any tested variety. 13 major compounds were identified in Siddha while 12 major compounds were identified in Rangoon. It was suggested that variety Siddha was better than Rangoon from its antibacterial chemical profile and composition.

Comparison of hydro-distillation, hydro-distillation with enzyme-assisted and supercritical fluid for the extraction of essential oil from pineapple peels

Pineapple peel is a potential feedstock for the extraction of essential oil due to the presence of aromatic compounds. To extract the essential oil from pineapple peels, three different methods were applied, i.e., (1) hydro-distillation (HD); (2) hydro-distillation with enzyme-assisted (HDEA); and (3) supercritical fluid extraction (SFE). SFE had successfully produced an essential oil with the yield of 0.17% (w/w) together with 0.64% (w/w) of concrete, whereby the HD and HDEA had only produced hydrosols with the yield of 70.65% (w/w) and 80.65% (w/w), respectively. Parameters' optimization for HD (substrate to solvent ratio, temperature, and extraction duration) and HDEA (cellulase loading and incubation duration) significantly affected the hydrosol yield, but did not extract out the essential oil. This is because only SFE had successfully ruptured the oil gland after observed under the scanning electron microscope. The essential oil obtained from SFE composed of mainly propanoic acid ethyl ester (40.25%), lactic acid ethyl ester (19.35%), 2-heptanol (15.02%), propanol (8.18%), 3-hexanone (2.60%), and butanoic acid ethyl ester (1.58%). In overall, it can be concluded that the SFE had successfully extracted the essential oil as compared to the HD and HDEA methods.

In-vitro anti-cholinesterase activity of essential oil from four tropical medicinal plants

The chemical inhibition of acetyl-cholinesterase (AChE) is a potent strategy for addressing signal related neuropathology and natural products are potential sources of compounds with such properties. Essential oil extracts from leaf, seed, stem and rhizome of four medicinal plants [Aframomum melegueta K. Schum, Crassocephalum crepidioides (Benth S. More), Monodora myristica (Gaertn.), and Ocimum gratissimum (Linn)] were tested for acetyl-cholinesterase inhibitory activity (AChEI) using Ellman's colorimentric method and compared to a reference acetyl-cholinesterase inhibitor (galantamine). The seed (IC₅₀ = 6.71 mg/l) and leaf (IC₅₀ = 6.54 mg/l) extracts from O. gratissimum showed values that matched the capacity of the reference inhibitor (IC₅₀ = 6.62 mg/l). The least potent extract was rhizome extracts of A. melegueta (IC₅₀ = 28.97 mg/l) about four times that of the reference inhibitor. Principal component analysis (PCA) showed that the intrinsic properties (bioactive ingredient factor) of each extract (PC1 = 29.50%) was the most important factor defining the difference or similarity in potency to the reference acetyl-cholinesterase inhibitor while 'dose response' (PC2 = 11.38%) was the second most important factor. The outstanding AChEI property of O. gratissimum extracts could largely be attributed to the high monoterpene content while the weak potency of rhizome extracts of A. melegueta may be attributed to its predominant concentrations of sesquiterpenes. Since potency could be related to interaction between bioactive components, understanding the interaction between ratios of monoterpene and sesquiterpene in extracts could be important in determining their potency for AChEI.

Essential oil composition of Eucalyptus microtheca and Eucalyptus viminalis

OBJECTIVE

Eucalyptus (Fam. Myrtaceae) is a medicinal plant and various Eucalyptus species possess potent pharmacological actions against diabetes, hepatotoxicity, and inflammation. This study aims to investigate essential oil composition from leaves and flowers of E. microtheca and E. viminalis leaves growing in the Southeast of Iran.

MATERIALS AND METHODS

The aerial parts of these plants were collected from Zahedan, Sistan and Baluchestan province, Iran in 2013. After drying the plant materials in the shade, the chemical composition of the essential oils was obtained by hydro-distillation method using a Clevenger-type apparatus and analyzed by GC/MS.

RESULTS

In the essential oil of E. microtheca leaves, 101 compounds representing 100%, were identified. Among them, α-phellandrene (16.487%), aromadendrene (12.773%), α-pinene (6.752%), globulol (5.997%), ledene (5.665%), P-cymen (5.251%), and β-pinene (5.006%) were the major constituents. In the oil of E. microtheca flowers, 88 compounds representing 100%, were identified in which α-pinene (16.246%), O-cymen (13.522%), β-pinene (11.082%), aromadendrene (7.444%), α-phellandrene (7.006%), globulol (5.419%), and 9-octadecenamide (5.414%) were the major components. Sixty six compounds representing 100% were identified in the oil of E. viminalis leaves. The major compounds were 1, 8-cineole (57.757%), α-pinene (13.379%), limonene (5.443%), and globulol (3.054%).

CONCLUSION

The results showed the essential oils from the aerial parts of Eucalyptus species are a cheap source for the commercial isolation of α-phellandrene, α-pinene, and 1, 8-cineole compounds to be used in medicinal and food products. Furthermore, these plants could be an alternative source of insecticide agents.

Antioxidant activity of Piper nigrum L. essential oil extracted by supercritical CO₂ extraction and hydro-distillation

The aim of this study was to optimize the antioxidant activity of Piper nigrum L. essential oil extracted using the supercritical carbon dioxide (SC-CO₂) technique. Response surface methodology was applied using a three-factor central composite design to evaluate the effects of three independent extraction variables: pressure of 15-30 MPa, temperature of 40-50 °C and dynamic extraction time of 40-80 min. The DPPH radical scavenging method was used to evaluate the antioxidant activity of the extracts. The results showed that the best antioxidant activity was achieved at 30 MPa, 40 °C and 40 min. The extracts were analyzed by GC-FID and GC-MS. The main components extracted using SC-CO₂ extraction in optimum conditions were β-caryophyllene (25.38 ± 0.62%), limonene (15.64 ± 0.15%), sabinene (13.63 ± 0.21%), 3-carene (9.34 ± 0.04%), β-pinene (7.27 ± 0.05%), and α-pinene (4.25 ± 0.06%). The essential oil obtained through this technique was compared with the essential oil obtained using hydro-distillation. For the essential oil obtained by hydro-distillation, the most abundant compounds were β-caryophyllene (18.64 ± 0.84%), limonene (14.95 ± 0.13%), sabinene (13.19 ± 0.17%), 3-carene (8.56 ± 0.11%), β-pinene (9.71 ± 0.12%), and α-pinene (7.96 ± 0.14%). Radical scavenging activity of the extracts obtained by SC-CO₂ and hydro-distillation showed an EC₅₀ of 103.28 and 316.27 µg mL(-1) respectively.