Screening of the antioxidant and antibacterial effects of extracted essential oils from Thunbergia coccinea, Acacia polyacantha, Polygonum micrpcephallum, Abies spectabilis and Clerodendrum colebrookianum

Abstract

During the previous few decades, it has been seen that there is a rapid emergence of pathogens resistant to multiple antibiotics. This has now become a global crisis. Some unexplored or less explored plants also provide some antibacterial, bactericidal and antioxidant properties. The antibacterial, bactericidal effects of extracted essential oils (EEOs) of Thunbergia coccinea, Acacia polyacantha, Polygonum micrpcephallum, Abies spectabilis and Clerodendrum colebrookianum was tested in comparison with standard antibiotics. The methods chosen were disc diffusion and deduction of minimum inhibitory concentration (MIC) by microbroth dilution assays of the EEOs against the bacterial strains.The antioxidant activity was found out utilizing DPPH free radical scavenging assay, MDA, Hydrogen peroxide radical inhibition assay and Superoxide radical inhibition assay (O 2 -). Some commonly used standard antibiotics (metronidazole, amoxicillin, clarithromycin, rifampicin, clindamycin and oxacillin,) were utilized to compare the EEO antibacterial action. Clerodendrum colebrookianum (85.17 ± 3.06 µg MDA/g extract) had a reasonable MDA. Acacia polyacantha in MIC had values of 3.86 ± 0.25 to 6.20 ± 0.16. Polygonum micrpcephallum had excessive H2O2 (48.27 ± 2.4 5%). The antibacterial actions determined by the paper disc‑diffusion technique of the EEO extracted from these plants showed that most had some antibacterial actions. Also, it was seen that the bactericidal action of the EEO extracted from E. alba was most potent against S. pyogenes (4.06 ± 0.15). The extract of the plant at varying concentrations (20, 40, 60, 80 and100 mg/mL) demonstrated noteworthy (P< 0.001) anthelmintic action in an effective change when the dose was adjusted. In conclusion, most of the tested plants contain a medicinal value, which can be utilized in the future to supplement artificial medicines and cure emerging diseases that create havoc for mankind.

Antioxidant Activity of Essential Oils from Pinaceae Species

“…Further differences were found for the endpoint used to report the results of the DPPH test. Whereas in many cases this was based on an IC 50 value (e.g., [ 47 , 54 , 69 ]), despite using a synonym name (such as EC50—half maximal effective concentration [ 41 , 79 ], RC50—50% reduction concentration [ 85 ], or SC50—50% scavenging concentration [ 42 ]), in other cases, different endpoints were used as follows: Percentage of DPPH inhibition measured for a single sample prepared in a wide variety of ways (i.e., very different concentrations, e.g., 5 mg of essential oil diluted to 5 mL with ethanol, treated with 250 µL of DPPH in methanol (5.07 × 10 −4 M) [ 55 ], 100 µL of essential oil mixed with 3.9 mL of DPPH solution [ 86 ], 50 μL/mL [ 87 ], or even without details on the way the sample was processed but referencing a published source without clear statement whether identical amounts were used [ 53 , 82 , 88 ]); Percentage of DPPH inhibition measured on three to five different amounts/concentrations of essential oil with no IC 50 estimation [ 72 , 78 , 89 ]; Equivalents to certain antioxidant substances expressed as mg per gram of essential oil (hydroxytoluene equivalent; ascorbic acid equivalent; Trolox equivalent) [ 90 , 91 ], μM equivalents per gram of essential oil [ 51 ], mM equivalents per ml [ 48 ] or per liter of essential oil [ 56 ], or μg of equivalents per ml of essential oil [ 92 ]. …”

“…Percentage of DPPH inhibition measured for a single sample prepared in a wide variety of ways (i.e., very different concentrations, e.g., 5 mg of essential oil diluted to 5 mL with ethanol, treated with 250 µL of DPPH in methanol (5.07 × 10 −4 M) [ 55 ], 100 µL of essential oil mixed with 3.9 mL of DPPH solution [ 86 ], 50 μL/mL [ 87 ], or even without details on the way the sample was processed but referencing a published source without clear statement whether identical amounts were used [ 53 , 82 , 88 ]);…”

“…Methods gauging the ability to scavenge hydrogen peroxide can be enzymatic or non-enzymatic [ 26 ]. Two such methods applied in assessing EOs from Pinaceae use a spectrophotometric approach based on the direct hydrogen peroxide reaction with the EO in a phosphate buffer (pH 7.4), followed by spectrophotometric measurement at 230 nm [ 61 , 88 ]. Cited several times under the name of “Ruchet et al (1989)” [ 88 , 104 , 105 ], it was actually proposed by R. J. Ruch et al (1989) [ 106 ].…”

“…The following methods were used only once or in a small number of cases: The superoxide radical inhibition based on the autooxidation of pyrogallol [ 88 ]; The superoxide radical scavenging based on nitroblue tetrazolium reduction [ 70 , 111 ]; The method based on 3-morpholino-sydnonimine and 1-keto-4-methylthiobutyric acid (SIN-1—KMB) [ 112 ]; The Fenton system [ 113 ] proposed for use in the antioxidant assessment by Halliwell and Gutteridge (1985) [ 114 ]; The method based on 1-aminocyclopropane-1-carboxylic acid (ACC) fragmentation induced by HOCl (hypochlorous acid) [ 112 ]; The ferric–phenanthroline assay (Phen assay) based on the ability of ferric ions to form a complex with phenanthroline [ 115 ]; The Rancimat method, developed by Hadorn and Zurcher in the 1970s (in a publication in the German language [ 116 ]), established itself as one of the most widely utilized accelerated techniques for assessing the oxidative stability of fats and fat-containing foods [ 117 , 118 ]; A method based on the xanthine/xanthine oxidase system [ 112 ]; A method based on the NADH/diaphorase system [ 112 ]; Two methods based on the impact of the EO on catalase and glutathione reductase [ 119 ]; The phosphomolybdenum method (total antioxidant capacity (TAC) assay) [ 64 ]; The Folin–Ciocâlteu method of quantifying total phenolics [ 43 ]; The 20,70-dichlorofluorescein diacetate probe to estimate the intracellular antioxidant activity in the human keratinocytes HaCaT cell line [ 73 ]. …”

Assessment of antibacterial activity and cytotoxic effects of in vitro and in vivo plant parts of a medicinal plant Gynura procumbens (Lour.) Merr.

“…It is now a worldwide crisis. In addition to antibacterial, bactericidal, and antioxidant properties, some unexplored or underexplored flora may also have antibacterial, bactericidal, and antioxidant properties [ 26 ]. The demand for antibacterial herbal drugs is increasing due to the acquired antibiotic resistance of different bacteria [ 27 ].…”