Identification of Antioxidant and Antimicrobial Compounds of Lippia Species by Bioautography

Mendes JW, Dantas AR, de Carvalho NKG, Castro JWG, Salazar GJT, Ferreira MKA, de Meneses JEA, da Silva AW, dos Santos HS, Tavares JF, Silva JPRE, Rodrigues FFG, Cheon C, Kim B, da Costa JGM. Analysis toxicity by different methods and anxiolytic effect of the aqueous extract Lippia sidoides Cham

Lippia sidoides Cham. (Verbenaceae) is a species often mentioned in traditional medicine due to the medicinal properties attributed to its leaves, which include antibacterial, antifungal, acaricidal and antioxidant. Several of these actions have been scientifically proven, according to reports in the literature; however, little is known about toxicological aspects of this plant. This work included studies to determine the chemical composition and toxicity tests, using several methods aiming to evaluate the safety for use of the aqueous extract of L. sidoides leaves, in addition, the anxiolytic effect on adult zebrafish was investigated, thus contributing to the pharmacological knowledge and traditional medicine concerning the specie under study. The chemical profile was determined by liquid chromatography coupled to mass spectrometry-HPLC/MS with electrospray ionization. Toxicity was evaluated by zebrafish, Drosophila melanogaster, blood cells, and Artemia salina models. 12 compounds belonging to the flavonoid class were identified. In the toxicity assays, the observed results showed low toxicity of the aqueous extract in all tests performed. In the analysis with zebrafish, the highest doses of the extract were anxiolytic, neuromodulating the GABAa receptor. The obtained results support the safe use of the aqueous extract of L. sidoides leaves for the development of new drugs and for the use by populations in traditional medicine.

Identification of Anticryptococcal Bornyl Compounds from Verbesina turbacensis and Their Structure-Activity Relationships

Cryptococcus neoformans is an opportunistic fungal pathogen that has limited treatment options. Natural product plant extracts offer a cost-effective option for the discovery of new anticryptococcal lead compounds. The acetone bark extract of Verbesina turbacensis was found to potently inhibit C. neoformans and was subjected to bioautography. Two compounds that inhibited the growth of C. neoformans were isolated and displayed minimum inhibitory concentration values of 10 and 310 µg/mL. The compounds were identified as the bornyl hydroxycinnamic esters bornyl caffeate and bornyl ferulate, respectively. To better understand initial structure-activity relationships, anticryptococcal activity was characterized for similar compounds. All compounds were further evaluated for mammalian cell toxicity using the MTT assay with MCF-7 and HEK-293 cell lines. Overall, bornyl caffeate demonstrated promising anticryptococcal potential given its potent inhibition of C. neoformans and low mammalian cell toxicity.

The Beneficial Impacts of Essential Oils Application against Parasitic Infestation in Fish Farm

Aquaculture is a growing sector due to the high rising demand for fish, shrimp, oysters, and other products, which is partially conflicted by various infectious diseases. The infectious diseases affecting the production and inducing high mortalities cause substantial economic losses in this sector. Also, parasitic infections may induce severe mortality and morbidity in fish farms. Therefore, most farmers apply several kinds of antibiotics to control the problems induced by bacterial diseases and, to some extent, parasitic infections. The extensive usage of antibiotics to control or prevent pathogens may lead to the development of pathogenic resistant strains that might cause hazards to human health. Besides, there is a global trend toward reducing the application of antibiotics in aquaculture farms. Thus, there is a great effort to discover new natural and safe products with pharmaceutical properties, such as natural essential oils (EO). Essential oils are secondary metabolites of many plants (roots, flowers, seeds, leaves, fruits and peels) and their molecular structures provide a high antimicrobial and antiparasitic efficiency against pathogens. Consequently, it is essential to provide sufficient knowledge about the mode of action of EO against fish parasites and its future applications and directions in aquaculture.

TLC Bioautography on Screening of Bioactive Natural Products: An Update Review

Background:

TLC bioautography is a hyphenated technique combining planar chromatographic separation and in situ biological activity detection. This coupled method has been receiving much attention in screening bio-active natural products because of its properties of being simple, rapid, inexpensive, and effective.

Methods:

The recent progress in the development of method of TLC bioautography for detecting antimicrobial and enzyme inhibitory activities dating between 2012 and early 2018 has been reviewed. The applications of this method in biological screening of natural products were also presented.

Results:

Some anaerobic and microaerophilic bacteria and a causative bacterium of tuberculosis have been adopted to TLC direct bioautography. Seven types of enzymes including acetylcholinesterase, glucosidase, lipase, xanthine oxidase, tyrosinase, monoamine oxidase, and dipeptidyl peptidase IV have so far been adopted on TLC bioautography. Its new application in screening antiurolithiatic agents was included.

Conclusion:

The standard experimental procedures are required for TLC antioxidant and antimicrobial assays. Some new enzymes should be attempted and adopted on TLC bioautography. The existing TLC methods for enzyme inhibition need more application studies to assess their screening capacity in the discovery of active compounds. The GC-MS or LC-MS approaches have gradually been coupled to TLC bioautography for fast structural characterization of active compounds.

Factors Affecting the Retention Efficiency and Physicochemical Properties of Spray Dried Lipid Nanoparticles Loaded with Lippia sidoides Essential Oil

Essential oils (EOs) are widely used in various industrial sectors but can present several instability problems when exposed to environmental factors. Encapsulation technologies are effective solutions to improve EOs properties and stability. Currently, the encapsulation in lipid nanoparticles has received significant attention, due to the several recognized advantages over conventional systems. The study aimed to investigate the influence of the lipid matrix composition and spray-drying process on the physicochemical properties of the lipid-based nanoparticles loaded with Lippia sidoides EO and their retention efficiency for the oil. The obtained spray-dried products were characterized by determination of flow properties (Carr Index: from 25.0% to 47.93%, and Hausner ratio: from 1.25 to 1.38), moisture (from 3.78% to 5.20%), water activity (<0.5), and powder morphology. Zeta potential, mean particle size and polydispersity index, of the redispersed dried product, fell between −25.9 mV and −30.9 mV, 525.3 nm and 1143 nm, and 0.425 and 0.652, respectively; showing slight differences with the results obtained prior to spray-drying (from −16.4 mV to −31.6 mV; 147 nm to 1531 nm; and 0.459 to 0.729). Thymol retention in the dried products was significantly lower than the values determined for the liquid formulations and was affected by the drying of nanoparticles.

Antifungal Phenylpropanoid Glycosides from Lippia rubella

Lippia species share various pharmacological activities and are used in traditional cooking and medicine worldwide. Combined chromatographic techniques such as column chromatography, high-performance liquid chromatography, and countercurrent chromatography led to the purification of two new antifungal phenylpropanoid glycosides, lippiarubelloside A (1) and lippiarubelloside B (2), by bioactivity-directed fractionation of an ethanol-soluble extract from Lippia rubella, in addition to the known active related compounds forsythoside A (3), verbascoside (4), isoverbascoside (5), and poliumoside (6). The structures of compounds 1 and 2 were determined by comparison of their NMR spectroscopic data with the prototype active compound 4. Cryptococcus neoformans, which causes opportunistic lung infections, was sensitive to compounds 1-6 in the concentration range of 15-125 μg/mL. A synergistic effect (FIC_index = 0.5) between 3 and amphotericin B was demonstrated. The glycosylated flavonoids pectolinarin (7), linarin (8), and siparunoside (9) were also isolated.

Antiparasitic activity, histopathology and physiology of Colossoma macropomum (tambaqui) exposed to the essential oil of Lippia sidoides (Verbenaceae)

In vivo and in vitro antiparasitic activity of the essential oil of Lippia sidoides and blood and histological alterations were assessed in Colossoma macropomum (tambaqui). Essential oil concentrations of 10, 20, 40, 80, 160 and 320mg/L were assayed in vitro against monogenoideans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri from fish gills. Lippia sidoides essential oil concentrations of 320 and 160mg/L were 100% effective against monogenoideans in 10min and 1h of exposure, respectively. However, the effectiveness of 100% concentrations of 80mg/L and 40mg/L occurred in 3 and 6h, respectively. In the in vivo tests, juvenile fish were submitted to 60min of baths with 10mg/L and 15min of baths with 20mg/L of the essential oil of L. sidoides. These therapeutic baths were not efficient against Ichthyophthirius multifiliis, and monogenoideans present in the gills of C. macropomum. In addition, 10 and 20mg/L of the essential oil of L. sidoides caused an anesthetic effect on the fish and did not influence total glucose and protein plasma levels; however, it decreased the number of total erythrocytes in fish exposed to the higher concentration of this essential oil. Severe alterations and irreversible damage were observed in the fish gills just after L. sidoides essential oil baths and after 24h of recovery. The most recurrent lesions found were hyperplasia and fusion of the lamellar epithelium, vasodilation, detachment of the gill epithelium and lamellar aneurism, epithelial breakdown with hemorrhage, congestion, edema and necrosis, proliferation of the mucous cells and chloride cells and lamellar hypertrophy. Therefore, since the essential oil of L. sidoides has in vitro antiparasitic activity and low concentrations of it have shown toxic effects, the bioactive potential of its main chemical components should be investigated, as well as more efficient forms of its administration in therapeutic baths in order to eliminate fish parasites.

Phytochemical Constituents and Antioxidant and Antimicrobial Activity of Selected Plants Used Traditionally as a Source of Food

Many indigenous plants have also been used as a source of food and medicine in many African rural communities in the past. The study investigated the antimicrobial activity, phytochemical constituent, and antioxidant activity of selected traditional plants used traditionally as a source of food and medicine. The methanol and water extracts of different plant parts were analyzed for phytochemicals using standard phytochemical screening reagents while the broth microdilution assays were used to analyze antimicrobial activities. Alkaloids, phenols, flavonoids, saponins, tannins, and terpenes were found in one or more of the plant extracts, and all the plant extracts demonstrated scavenging activities. The back extracts of Sclerocarya birrea and the leaf extracts of Garcinia livingstonei exhibit the best antioxidant activities, while the water and methanol back extracts of S. birrea and G. livingstonei were the most active against all the tested foodborne bacteria.

Antibacterial action against food-borne microorganisms and antioxidant activity of carvacrol-rich oil from Lippia origanoides Kunth

Background

Lippia origanoides Kunth from Northeast Brazil is a plant of pleasant odor used by local people as a food seasoning in substitution the oregano where its carvacrol-rich oil has showed significant antimicrobial activity against human pathogens.

Methods

GC and GC-MS analyzed the plant oil composition and its antibacterial activity was evaluated by disk diffusion and microdilution broth methods. The determination of oil antioxidant activity was made by DPPH radical scavenging assay. Oil toxicity was performed on mice.

Results

The main constituents of the oil were carvacrol (47.2 %), thymol (12.8 %), p-cymene (9.7 %), and p-methoxythymol (7.4 %). The oil was active against the bacteria of Bacillus cereus, B. subtilis, and Salmonella typhimurium, except for Pseudomonas aeruginosa. The antioxidant activity has displayed a high dose–response (r² = 0.92), with the inhibition of DPPH radical from 15 to 82 %, at concentrations from 5 to 50 μg/mL, and also by the β-carotene bleaching assay, which showed a high inhibition of 85.2 ± 6.8 %, corresponding to about 80 % of the inhibition of Trolox (93.4 ± 0.7 %), used as a standard. The lethal dose (LD₅₀) of the oil was determined in 1673.84 mg mL⁻¹.

Conclusion

The results confirmed that the oil of L. origanoides could be utilized for the prevention of food bacterial growth, and as an antioxidative agent for retardation of food oxidation process. The oil has low toxicity, allowing its application in the food industry.

Graphical Abstract

General Characteristics, Phytochemistry and Pharmacognosy of Lippia sidoides

Lippia sidoides Cham. is a plant that belongs to the family Verbenaceae and is commonly known as “alecrim-pimenta”. It was first found in northeastern Brazil, where it is extensively used in traditional medicine. Many studies have been made with the essential oil of L. sidoides, which has a high content of the isomeric compounds thymol and carvacrol. L. sidoides extracts, and particularly the essential oil extracted from its aerial parts, have shown many biological activities such as antifungal, antibacterial, and insecticidal. Given the great biological potentialities of L. sidoides and the amount of recent studies about this plant, the present study aimed to make a survey of its general attributes, cultivation methods, chemical characterization of its extracts and essential oil, as well as its different biological activities.

Antifungal activity against Cryptococcus neoformans strains and genotoxicity assessment in human leukocyte cells of Euphorbia tirucalli L

In the last times, focus on plant research has increased all over the world. Euphorbia tirucalli L., a plant known popularly as Aveloz, and originally used in Africa, has been drawing attention for its use in the United States and Latin America, both for use as an ornamental plant and as a medicinal plant. E. tirucalli L. is a member of the family Euphorbiaceae and contains many diterpenoids and triterpenoids, in particular phorbol esters, apparently the main constituent of this plant, which are assumed to be responsible for their activities in vivo and in vitro. The in vitro antifungal activities of Euphorbia tirucalli (L.) against opportunistic yeasts were studied using microbroth dilution assay. The results showed that aqueous extract and latex preparation were effective against ten clinical strains of Cryptococcus neoformans in vitro (Latex and extract MIC range of 3.2 – > 411 μg/mL). Aiming the safe use in humans, the genotoxic effects of E. tirucalli were evaluated in human leukocytes cells. Our data show that both aqueous extract and latex preparation have no genotoxic effect in human leukocytes cells in vitro. Although the results cannot be extrapolated by itself for use in vivo, they suggest a good perspective for a therapeutic application in future. In conclusion, our results show that the aqueous extract and latex preparation from E. tirucalli L. are antifungal agents effectives against several strains of C. neoformans and do not provoke DNA damage in human leukocyte cells, considering the concentrations tested.

Antifungal activity of Andrographis paniculata extracts and active principles against skin pathogenic fungal strains in vitro

CONTEXT

Andrographis paniculata Nees. (Acanthaceae) is an annual herbaceous plant widely cultivated in southern Asia, China, and Europe. It is used in the treatment of skin infections in India, China, and Malaysia by folk medicine practitioners.

OBJECTIVE

Antifungal activity of the whole plant extracts and isolation of active principles from A. paniculata were investigated.

MATERIALS AND METHODS

Dichloromethane (DCM) and methanol (MEOH) extracts of A. paniculata whole plant were screened for their antifungal potential using broth microdilution method in vitro against seven pathogenic fungal species responsible for skin infections. Active principles were detected through bioguided assays and isolated using chromatography techniques. Structures of compounds were elucidated through spectroscopy techniques and comparisons were made with previously reported data for similar compounds.

RESULTS

DCM extract revealed lowest minimum inhibitory concentration (MIC) value (100 μg/mL) against Microsporum canis, Candida albicans, and Candida tropicalis, whereas MEOH extract revealed lowest MIC (150 µg/mL) against C. tropicalis and Aspergillus niger. DCM extract showed lowest minimum fungicidal concentration (MFC) value (250 µg/mL) against M. canis, C. albicans, C. tropicalis and A. niger, whereas MEOH extract showed lowest MFC (250 µg/mL) against Trichophyton mentagrophytes, Trichophyton rubrum, M. canis, C. albicans, C. tropicalis and A. niger. Bioassay guided isolation from DCM and MEOH extract afforded 3-O-β-d-glucosyl-14-deoxyandrographiside, 14-deoxyandrographolide, and 14-deoxy-11,12-didehydroandrographolide as antifungal compounds. The lowest MIC (50 µg/mL) and MFC (50 µg/mL) was exerted by 14-deoxyandrographolide on M. canis.

DISCUSSION AND CONCLUSION

This is first report on the isolation of antifungal substances through bioassay-guided assay from A. paniculata. Our finding justifies the use of A. paniculata in folk medicines for the treatment of fungal skin infections.