Phytochemistry and antimicrobial potential of off-grade white pepper (Piper nigrum L.) essential oils extracted using microwave-assisted hydro-distillation (MAHD)

Pepper is one of the agricultural commodities that Indonesia widely exports. Pepper can be processed into various products, including essential oils. Pepper essential oil can be extracted using several methods, including the microwave. This method can speed up the essential oil extraction process. Optimization was carried out using the Box-Behnken design using the three independent parameters: solution ratio, time, and microwave power. The upper and lower limits used for the independent variables are solvent amount of 1,350 mL and 750 mL, time of 90 minutes and 60 minutes, and microwave power of 440 watts and 136 watts. The optimal data generated is treatment with a solvent amount of 1,050 mL, 90 minutes, and 440 watts of power, resulting in validation data of 99.046%. The optimal essential oil treatment gives a specific gravity of 0.8281, a refractive index of 1.4824, solubility in ethanol 1:2, acid number 0.739 mg KOH/g, ester number 19.599 mg KOH/g, and a hue value of 186,38 (green). Oil with optimum treatment also has an IC50 antioxidant activity of 32,919.9 ppm. Keywords: Antioxidant; Extraction; Microwave; Pepper; RSM.

The essential oils of black pepper (Piper nigrum L.) from China were isolated by hydrodistillation (HD) and microwave-assisted hydrodistillation (MHD) in yields of 3.1 % and 3.8%, respectively. The optimum conditions for MHD were: microwave delivered power 800 W, microwave radiation time 5 min. and a 1:10 ratio of spice to water. The obtained oils were analyzed by GC and GC-MS. Twenty-nine components were identified in HD oil and thirty components in MHD oil, representing 97.2 %and 97.7 % of the related oils, respectively. Among the identified volatile compounds from black pepper, the main components from both oils were found to be similar including 3–Δ-carene (31.9 % in HD oil and 33.2 % in MHD), limonene (19.3 %, 20.2 %), caryophyllene (18.4 %, 16.0 %), β-pinene (13.0 %, 14.0 %), α-pinene (5.8 %, 6.7 %), δ-elemene (1.8 %, 1.3 %) and α-copaene (1.9 %, 1.6 %).

The essential oils from Marchantia paleacea obtained by microwave-assisted hydro-distillation (MAHD) and conventional hydrodistillation (HD) methods were compared. For MAHD method, the effects of different parameters, such as extraction time, the moisture of the matrix and the irradiation power, on the yield of essential oils were investigated. Maximum global yields were obtained using the following conditions: extraction time, 40 min; the irradiation power, 450 V and the moisture of the matrix, 80 %. MAHD was superior in terms of saving energy and extraction time (40 min, compared with 3 h for HD). The yield of essential oils by MAHD method was ten-fold higher than that of HD method. The extracts of essential oils were analyzed by GC-MS. The obtained results were compared with references. The result also indicated that the using microwave irradiation did not change the composition of essential oils.

Microwave assisted hydrodistillation (MAHD) and conventional hydrodistillation techniques were compared in the extraction of essential oils from Amomum subulatum seeds. The time required for MAHD method (70 min) is lesser than that for HD method (4 hr). There is a slight increase in the yield of extracted oil in MAHD method (3.35%) compared to HD (3%). GC-MS results show that MAHD extracted essential oil was wealthier in oxygenated compounds. 1, 8-Cineole was found to be a major compound in case of both the essential oil, followed by α-pinene. In MAHD the percentage of the major oxygenated monoterpene (1, 8- cineol) slightly increases from 88% to 89% as compared to hydrodistillation. Contrarily to this, the percentage of monoterpene hydrocarbon were decreased in MAHD than HD extracted oil. MAHD and HD extracted oils show good antibacterial activities against gram-negative and gram-positive bacteria. MAHD extracted oil shows better antibacterial activity than HD extracted against both gram positive and gram-negative bacteria. 2, 2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging antioxidant activities show that MAHD extract has better inhibition percentage than HD extract, and the IC50 value of MAHD was less than HD extracted oil.

The Pepper (Piper nigrum L.) with spicy flavor, which is considered as one of the special spices in Vietnamese dishes. In the pepper contains a high content of essential oils contained in seeds and leaves, which not only have antioxidant and antibacterial resistance but also anti-Colon toxin, antidepressant, antifungal, analgesic, antidiarrhoeal. In the present study, we optimized the yield of essential oils obtained from Pepper leaves by Microwave-assisted hydrodistillation (MAHD) extraction method by examining the factors that affect the extraction process such as the size of leaves, the ratio of materials with solvent, time and microwave power. The highest essential oil performance achieved 0.94 mL/g by MAHD at grind size, extraction time (40 min), the ratio of water to raw materials (4:1mL/g), and microwave power (450W). A total of 22 volatile constituents were identified from the pepper leaves oil, with the major components being 3-Carene, D-Limonene, Caryophyllene, and β-Pinene.

This study investigated the effectiveness of microwave-assisted hydrodistillation (MAHD) and solvent-less microwave extraction (SLME) for extracting essential oil (EO) from lemon peels in comparison with conventional hydrodistillation (HD) in terms of extraction time, extraction yield, physical properties, chemical composition, operation cost, and antioxidant activity. The results showed that MAHD and SLME methods required an extraction time of 15 minutes while the required extraction time in HD was 120 minutes. There were no significant differences among physical properties (refractive index, specific gravity, and color) of extracted EOs by the three methods. Gas chromatography analysis did not indicate any noticeable change in the composition of EOs extracted by microwave-assisted extraction methods (MAHD and SLME) and HD method. DPPHº analysis of the extracted EOs indicated that microwave irradiation did not adversely influence antioxidant activity of the extracted EOs. The results of this study introduced MAHD and SLME as rapid, economical, and environmentally friendly extraction methods.

Comparative study of chemical composition, antibacterial and antioxidant activity of essential oils isolated from the seeds of Amomum subulatum by using microwave extraction and hydro-distillation methods

The antioxidant and antimicrobial potentials of volatile oil and oleoresins of white pepper (Piper nigrum L.) was investigated in the present study. The white pepper essential oil has shown strong activity for the inhibition of primary and secondary oxidation products in mustard oil added at 0.02 % concentration which was evaluated using peroxide value and thiobarbituric acid value. Moreover it was further supported by complementary antioxidant assays such as ferric thiocyanate method in linoleic acid system, chelating and scavenging effects on 1,1′-diphenyl-2-picrylhydrazyl radical. In antimicrobial investigations, using inverted petriplate and food poison techniques, white pepper essential oil showed strong inhibition for Fusarium graminearum and Penicillium viridicatum. The white pepper ethanol and n-hexane oleoresin showed moderate inhibition for all tested fungal strains. Gas chromatography–Mass spectrometry (GC–MS) technique was used to analyze 40 different components constituting approximately 97.7 % of the volatile oil. Among them β-caryophyllene (16.0 %), sabinene (12.6 %), limonene (11.9 %) and torreyol (9.3 %) were the major components with many minor components. Both ethanol and n-hexane oleoresins comprise of 26 components having piperine, as the major component.

Since ancient times, the three Salvia L. species: Salvia aegyptiaca L., Salvia lanigera Poir., and Salvia multicaulis Vahl, have been utilised in traditional medicine all across the world. These species are now subjected to in-depth chemical and pharmacological investigations in order to find physiologically active chemicals. In the present study, the essential oil composition and biological activity of these Salvia L. species were studied. Using various extraction methods: hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) to compare extraction efficiency, volatile metabolites were analysed and characterised by Gas chromatography/mass spectroscopy (GC/MS), while the antimicrobial efficiency for both the HD and MAHD essential oils was examined against four pathogens: Staphylococcus aureus, Escherichia coli, Aspergillus niger, and Candida albicans using microdilution assay. S. aegyptiaca, 12 and 14 compounds, were characterised by HD and MAHD extraction, respectively. Sesquiterpene hydrocarbons (85.87% HD & 72.74% MAHD) repidentified by HD and MAHD extraction, respectively. Monoterpenes (36.58% HD and 49.63% MAHD) and their oxygenated derivatives (31.4% HD and 28.63% MAHD) were the predominant compound classes. From S. lanigera, 12 and 8 compounds were identified by HD and MAHD extraction, respectively. Sesquiterpene hydrocarbons were present in S. lanigera essential oils with 8.3% HD and 2.4% MAHD. Moreover, the most potent antimicrobial activity was observed with the S. multicaulis essential oil collection employing either HD or MAHD extraction, while S. lanigera essential oils extracted by MAHD exhibited almost as high antimicrobial activity. The approach of MAHD saves time with all the improvements in product yield. Essential oils extracted using MAHD might be used to treat bacterial infections instead of standard antibacterial medications.

This study was conducted to compare between chemical composition, antimicrobial and cytotoxic activities of black pepper (Piper nigrum L.) essential oil and oleoresin. The essential oil and oleoresin were obtained by hydrodistillation and maceration techniques, respectively. The main constituents were analyzed using gas chromatography and mass spectrometry. The ratio of monoterpene hydrocarbons to sesquiterpene hydrocarbons indicated the higher quality of the essential oil and the oleoresin. The essential oil and oleoresin were screened for their antimicrobial activity against four pathogenic bacteria and two fungi strains. The black pepper essential oil exhibited higher antimicrobial activity than the oleoresin. In vitro, cytotoxicity evaluation against five cell lines of human hepatocellular, cervical, breast, prostate and larynx carcinoma, showed a potent anti-proliferative activity of the oleoresin with the lowest IC50 value belonging to the larynx carcinoma cells. The present results suggested promising cytotoxic, antimicrobial properties of the black pepper essential oil and oleoresin.

The essential oils from peels and leaves of Citrus clementine Hort. ex Tan. were extracted via two methods: conventional hydrodistillation (CHD) and microwave-assisted hydrodistillation (MAHD). Their physicochemical properties were investigated. Their chemical compositions of the oils were determined by GC/FID and GC/MS. A total of forty-one and seventy-seven compounds of the total essential oil composition of the peels and leaves respectively were identified. The peel oils were dominated by monoterpene hydrocarbons in which limonene was the main component (95.48% [CHD], and 95.03% [MAHD]). The leaf oils were also dominated by sesquiterpene hydrocarbons with sabinene (26.02% [CHD], and 19.52% [MAHD]), β-elemene (10.50% [CHD], and 18.04% [MAHD]), linalool (9.88% [CHD], and 7.51% [MAHD]), (E)-β-ocimene (5.87% [CHD], and 5.00% [MAHD]), β-caryophyllene (4.04% [CHD], and 7.49% [MAHD]), and δ-selinene (4.76% [CHD], and 8.02% [MAHD]) as major components. The oil contents of peels were obtained with 5.31% and 5.67% by CHD method and MAHD method, respectively. The oil contents of the leaves were obtained with 0.33% and 0.20% by CHD method and MAHD method, respectively. The antimicrobial activity (disc diffusion antibiotic sensitivity assay) of the oils was investigated against six reference test organisms including two Gram (+) bacteria (Bacillus subtilis, Staphylococcus aureus), three Gram (-) bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella flexneri), and one fungus (Candida albicans).

Kinetics of mace (Myristicae arillus) essential oil extraction using microwave assisted hydrodistillation: Effect of microwave power

White pepper is one of the staple spices of East Kalimantan. In order to boost the competitiveness of white pepper commodities, it is necessary to raise the added value of the commodity by transforming it into high-value goods, such as white pepper oil. This research intends to evaluate the production of local (LPL) white pepper oil (MLP) with commercial white pepper oil (LPK) using different extraction techniques (microwave-assisted hydro distillation, MAHD; and ultrasonic following hydro distillation, US-HD). This experiment also evaluated the effect of extraction factors on oil yield, including microwave power on MAHD, ultrasonic wave power on US-HD, sonication duration on US-HD, and solvent volume. A comparison of the energy usage of both approaches was also conducted in order to identify the most effective approach. The MAHD and US-HD techniques were used to extract 80 grams of dry white pepper powder mixed with aquadest for 90 and 180 minutes, respectively. Specifically for US-HD, the combination of raw materials was sonicated for 3-5 minutes prior to extraction utilizing the HD method. In both MAHD and US-HD, LPK includes more MLP than LPL, according to experimental findings. MLP yield may be increased by the addition of solvent, wave power (micro and ultrasonic), and sonication time. Based on its efficiency and energy consumption, the US-HD approach is superior to the MAHD.

A microwave-assisted hydrodistillation (MAHD) method was investigated for extraction of essential oils from lavender. The essential oil extracts at optimized MAHD conditions was compared with hydrodistillation (HD). Response surface methodology coupled with Box-Behnken design was applied to optimize the parameters for MAHD. The optimized MAHD conditions were 500 W microwave power, 17 mL/g liquid-to-solid ratio and 40 min microwave time. The ANOVA results revealed that microwave time had the greatest impact on the essential oil yield followed by liquid-to-solid ratio and microwave power. Under the MAHD optimized conditions, the essential oil yield was 3.19%, approximating the predicted yield (3.20%). MAHD was superior in terms of saving energy and extraction time (40 min, compared to 120 min in HD). The essential oil analyzed by GC-MS, presented 39 compounds constituting 98.37% and 97.51% of the essential oils obtained through MAHD and HD, respectively. No obvious differences were found in composition between MAHD oil and HD oil. Antimicrobial study showed that the lavender essential oil exhibited broad-spectrum antibacterial activity and the MAHD oil showed a higher antimicrobial activity than the HD oil. This study revealed that MAHD could be a good method for extracting essential oil in lavender and other aromatic plants.

The present study aimed to evaluate the chemical analysis and antimicrobial effects of the Thamnobryum alopecurum (Hedw.) Gangulee essential oils were obtained by different distillation methods (Clevenger apparatus hydrodistillation (HD) and microwave-assisted hydrodistillation (MD)). In this study obtained volatile oils were analyzed by gas chromatography-mass spectrometry which revealed the presence of forty-five compounds present in the essential oil obtained by HD method representing 99.48 % of the total identified compounds and thirty-four compounds were identified in the essential oil extracted by MD method representing 95.39 % of the total identified compounds. 3-octanone was the major constituent of the essential oils extracted by both HD (14.28 %) and MD (20.07 %). Terpenes were the major constituents in the essential oil extra-cted by both methods (54.41 % in HD and 52.21 % in MD) followed by oxygenated terpenoids (17.16 % in HD and 14.94 % in MD). The other major compounds of the essential oil in HD was limonene (9.65 %) followed by β-pinene (9.13 %), cuparene (6.04 %), gymnomitrone (5.72 %) and 4-epi-abietal (5.59 %). While in MD essential oil the other major compounds were β-pinene (12.20 %) followed by limonene (8.56 %), α-pinene (9.01 %), cupa-rene (6.44 %), abietadiene (5.97 %). The antimicrobial effects of the essential oils were determined tested quantitatively in respective broth media by using double microdilution and the minimal inhibition concentration (MIC) values (μg/mL). The isolated essential oils of T. alopecurum showed effective antimicrobial activities against Escherichia coli, Yersinia pseudotuberculosis, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Mycobacterium smegmatis and Candida albicans. However, no activity was not observed against Pseudomonas aeruginosa. The hydrodistillation method was found to be more effective than the microwave method in iden-tifying the chemical composition of the structure of T. alopecurum essential oil. While for antimicrobial study MD method was found to be more effective in terms of antimicrobial effect. The T. alopecurum thus is a potential source of an antimicrobial agent with a wide range of chemical compounds that could be responsible for their activity.