Phytochemical, antioxidant and antibacterial properties of extracts from two spice herbs under different extraction solvents

Costa M, Avelar-Gonzalez FJ, Moreno-Flores AC, Vazquez-Pedroza E, Arreola-Guerra JM, González-Gámez M. Guava Leaf Extract Exhibits Antimicrobial Activity in Extensively Drug-Resistant (XDR) Acinetobacter baumannii

Currently, a global health crisis is being caused by microbial resistance, in which Acinetobacter baumannii plays a crucial role, being considered the highest-priority microorganism by the World Health Organization (WHO) for discovering new antibiotics. As a result, phytochemicals have emerged as a potential alternative to combat resistant strains, since they can exert antimicrobial activity through various mechanisms and, at the same time, represent a more natural and safe option. This study analyzes the antimicrobial effects of guava leaf extract in ten clinical isolates of extensively drug-resistant (XDR) A. baumannii, using the agar diffusion technique and the microdilution method to determine the minimum inhibitory concentrations (MICs). Additionally, possible improvements in antimicrobial activity after the purification of polyphenolic compounds and potential synergy with the antibiotic gentamicin are examined in this research. Moreover, the effect of the plant extract in cell line A549 derived from lung tissue was also evaluated. The extract exhibited antimicrobial activity against all the strains studied, and the purification of polyphenols along with the combination with gentamicin improved the extract activity. The presence of the plant extract induced morphological changes in the lung cells after 24 h of exposure. Therefore, Psidium guajava L. leaf extract is a potential antimicrobial agent.

Antibacterial and Antioxidant Activities, Toxicity, and Physicochemical Properties of Crassocephalum montuosum (S Moore) Milne-Redh and Crassocephalum picridifolium (DC) S Moore

In traditional Congolese medicine, the plants Crassocephalum montuosum (CrasMon) and Crassocephalum picridifolium (CrasPic) are used to treat bacterial gastroenteritis. In the present study, the antibacterial and antioxidant activities as well as the acute and subacute toxicity of organic extracts from the whole plant of the two investigated taxa were evaluated. Physicochemical parameters were also determined, and total phenolics, flavonoids, and tannins were investigated and assayed. The antibacterial and antioxidant activities of the plant extracts were evaluated using disc diffusion, tube macrodilution, and DPPH tests. Conversely, traditional solution reactions, gravimetric tests, and spectrophotometric tests were used to generate physicochemical profiles, identify secondary metabolite groups, and perform microdilution and DPPH tests to evaluate the antibacterial and antioxidant activities, respectively. OECD tests were adapted to assess the acute and subacute toxicity. All the extracts showed antibacterial activity against E. coli and S. typhi strains with the diameter zone of inhibition (DZI) ranging from 12 to 23 mm and the minimum inhibitory concentration (MIC): 15.625-125 μg·mL-1. The methanolic extract of CrasPic showed the most pronounced activity with a DZI of 21-23 mm and MIC of 15.625-62.5 μg·mL-1. All extracts showed high antioxidant activity with IC50 (half maximal inhibitory concentration) ranging from 11.6 to 21.8 μg·mL-1, with the methanolic extract of CrasMon showing the most pronounced activity. Both plants contain a variety of phytochemicals including coumarins, quinones, flavonoids, phenols, saponins, tannins, and terpenoids. The methanolic extract of CrasPic exhibits the highest content of total phenolics (300 mg·GAE·g-1), flavonoids (56 mg·QE·g-1), and tannins (155 mg·GAE·g-1). These extracts have a median lethal dose (LD50) > 5000 mg·kg-1 and no signs of toxicity at 200 mg·kg-1 after 30 days of oral administration to Cavia porcellus. The total ash content was determined to be 14.2% and 15.8% (on a dry weight basis), with the ash insoluble in hydrochloric acid exhibiting a range of 4.04%-5.03%. CrasMon and CrasPic have been demonstrated to exhibit a good antibacterial and antioxidant activities, at least in part, due to the presence of phenolic compounds. These activities may provide a rationale for their use in traditional Congolese medicine against gastroenteritis.

Ultrasound-assisted extraction of scopolamine and hyoscyamine from Hyoscyamus niger roots using central compost design

Hyoscyamus niger is an important medicinal plant used in medicine and contains tropane alkaloid compounds such as hyoscyamine and scopolamine. In this study, after the selection of the solvent for extracting hyoscyamine and scopolamine, the central composite design of the response surface methodology was used to study the effect of solvent concentrations (0, 25, 50, 75, and 100 %), temperatures (25, 30, 35, 40, and 45 °C) and ultrasonication times (10, 20, 30, 40, and 50 min). The hyoscyamine and scopolamine content were obtained by HPLC-DAD. The results indicated that the predicted optimal condition for hyoscyamine and scopolamine extraction from H. niger root was as follows. Hyoscyamine: 100 % methanol, temperature 45 °C and ultrasonication time 10 min, obtained 172.06 μg/g dry weight; and scopolamine: 98.50 % methanol, temperature 25 °C and ultrasonication time 10 min, provided 229.48 μg/g dry weight. To confirm the predicted extraction conditions, a separate experiment was conducted, and the results showed that the hyoscyamine and scopolamine contents were 164.72 and 209.23 μg/g dry weight, respectively.

The Effect of Maturity Stage on Polyphenolic Composition, Antioxidant and Anti-Tyrosinase Activities of Ficus rubiginosa Desf. ex Vent. Extracts

Ficus spp. are often used as food and in traditional medicine, and their biological activities as anti-inflammatory and diuretic, for wound healing, and as antimicrobial agents have been largely reviewed. The aim of this work was to investigate the polyphenol content and the antioxidant and anti-tyrosinase properties of the extracts from F. rubiginosa, a very poorly explored Ficus species. For this purpose, F. rubiginosa leaves were collected at three different maturity stages (H1, H2, and H3), and the environmentally sustainable methanolic extracts were evaluated for the total phenolic content (TPC), total flavonoid content (TFC), and total catechins content (TCC). The polyphenolic profile was studied using HPLC-UV/DAD and UHPLC-MS, and the antioxidant activity was determined in vitro using DPPH, FRAP, and ABTS assays. The study showed that the H2 extract had higher TPC and TFC values (113.50 mg GA/g and 43.27 mg QE/g, respectively) and significant antioxidant activity. Therefore, the H2 extract was selected to study the anti-tyrosinase activity. The results also showed that H2 was able to bind and inhibit tyrosinase, with rutin being the compound responsible for the measured activity on the enzyme.

Aflatoxin B1 Detoxification Potentials of Garlic, Ginger, Cardamom, Black Cumin, and Sautéing in Ground Spice Mix Red Pepper Products

The uses of natural plant origin bioactive compounds are emerging as a promising strategy to detoxify aflatoxin B1 (AFB1). This study aimed to explore the potential of cooking, phytochemicals content, and antioxidant activities derived from garlic, ginger, cardamom, and black cumin to detoxify AFB1 on spice mix red pepper powder (berbere) and sauté. The effectiveness of the samples was analyzed for AFB1 detoxification potential through standard methods for the examination of food and food additives. These major spices showed an AFB1 level below the detection limit. After cooking in hot water for 7 min at 85 ℃, the experimental and commercial spice mix red pepper showed the maximum AFB1 detoxification (62.13% and 65.95%, respectively). Thus, mixing major spices to produce a spice mix red pepper powder had a positive effect on AFB1 detoxification in raw and cooked spice mix red pepper samples. Total phenolic content, total flavonoid content, 2,2-diphenyl-1-picrylhydrazyl, ferric ion reducing antioxidant power, and ferrous ion chelating activity revealed good positive correlation with AFB1 detoxification at p < 0.05. The findings of this study could contribute to mitigation plans of AFB1 in spice-processing enterprises. Further study is required on the mechanism of AFB1 detoxification and safety of the detoxified products.

Comprehensive study on the antioxidant capacity and phenolic profiles of black seed and other spices and herbs: effect of solvent and time of extraction

The effects of solvent and time of extraction on the antioxidant properties and phenolic profiles of 13 herbs and spices used for food seasoning and preservation were investigated. The profiles of phenolics in plant material were analysed by UPLC, and the chemometric approach was used for the deeper evaluation of relationships between phenolic compounds and the antioxidant properties of the samples. The best extraction conditions enabling to obtain the highest total phenolics and the antioxidant activity were: long time extraction (24 h) with 50% aqueous ethanol. The most potent antioxidant was clove with the ABTS—2495.85 µmol/g, DPPH—1443.35 µmol/g and FRAP—1310.91 µmol/g, which resulted from the high total phenolic content (TPC—167.22 mg GAE/g) and total flavonoid content (TFC—26.22 mg QE/g). Wide variations in the antioxidant activity (ABTS: 7.31—2495.85 µmol/g) and TPC (0.87–167.22 mg GAE/g) were observed with black seed extract showing one of the lowest values of the parameters studied. High linear correlation (above 0.95) calculated for the parameters showed significant contribution of phenolics to the antioxidant activity of spices. UPLC analysis together with PCA (principal component analysis) confirmed this relation and ABTS, FRAP, DPPH, TFC, TPC, total phenolic acids, protocatechuic acid, t-cinnamic acid, p-hydroxybenzoic acid determined sample distribution along PC1 (principal component 1), whereas total flavonoids determined by UPLC, kaempferol, catechin and luteolin along PC2. All samples were discriminated with 100% classification’s propriety according to GDA (general discrimination analysis) which proved huge diversity among phenolic profiles and the antioxidant properties of tested samples.