Antibacterial and Antifungal Activities of Ethiopian Medicinal Plants: A Systematic Review

Diplopterys pubipetala (Malpighiaceae): Insights into Antioxidant, Antibacterial, and Antifungal Activities with Chemical Composition Analysis via UHPLC-MS/MS and GC/MS

Diplopterys pubipetala (Malpighiaceae) is a liana native to the Brazilian Cerrado biome, traditionally used in Ayahuasca preparations. Despite its cultural importance, research on its chemical composition and biological activities, which may have therapeutic potential, is limited. This study investigated the volatile and non-volatile secondary metabolites of D. pubipetala leaves, their antioxidant capacity, and their antibacterial and antifungal activities. Volatile compounds were identified using gas chromatography-mass spectrometry (GC-MS) coupled to solid-phase microextraction (SPME), while non-volatile compounds were annotated using UHPLC-MS/MS-ESI-Q-TOF. Antioxidant capacity was evaluated by DPPH assay, and antimicrobial activity was assessed in vitro against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida species (C. albicans, C. tropicalis, C. glabrata). GC-MS analysis revealed 25 predominant volatile compounds, including ethyl dodecanoate, ethyl tetradecanoate, nonanoic acid, and 5-methylhexan-2-one, with documented antifungal, antioxidant, and antimicrobial activities. The crude extract and ethyl acetate fraction showed strong antioxidant capacity (EC50 9.83 µg/mL and 6.42 µg/mL, respectively), and antifungal effects were observed against Candida species. This study provides the first comprehensive investigation of the antioxidant capacity and antibacterial and antifungal activities of D. pubipetala, together with a detailed chemical profile of its volatile compounds.

Mechanism of antibacterial phytoconstituents: an updated review

The increase of multiple drug resistance bacteria significantly diminishes the effectiveness of antibiotic armory and subsequently exaggerates the level of therapeutic failure. Phytoconstituents are exceptional substitutes for resistance-modifying vehicles. The plants appear to be a deep well for the discovery of novel antibacterial compounds. This is owing to the numerous enticing characteristics of plants, they are easily accessible and inexpensive, extracts or chemicals derived from plants typically have significant levels of action against infections, and they rarely cause serious adverse effects. The enormous selection of phytochemicals offers very distinct chemical structures that may provide both novel mechanisms of antimicrobial activity and deliver us with different targets in the interior of the bacterial cell. They can directly affect bacteria or act together with the crucial events of pathogenicity, in this manner decreasing the aptitude of bacteria to create resistance. Abundant phytoconstituents demonstrate various mechanisms of action toward multi drug resistance bacteria. Overall, this comprehensive review will provide insights into the potential of phytoconstituents as alternative treatments for bacterial infections, particularly those caused by multi drug resistance strains. By examining the current state of research in this area, the review will shed light on potential future directions for the development of new antimicrobial therapies.

In vitro antibacterial activity of fruit pulp extracts of Tamarindus indica against Staphylococcus aureus and Klebsiella pneumoniae

BACKGROUND

Infectious diseases are increasingly recognized as public health concern worldwide as the rising incidence in multidrug resistance bacteria. This consequently enforces the need to find a new antimicrobial agent where plants have a potential source. This study investigated the antibacterial activity of fruit pulp extract of the Tamarindus indica against Staphylococcus aureus (S. aureus) and Klebsiella pneumoniae (K. pneumoniae).

METHODS AND MATERIALS

Maceration technique was employed for subsequent extraction of the sample using acetone and ethanol. Antibacterial activity of the plant extract was investigated based on minimum inhibitory concentration (MIC) against Gram-negative strain (K. pneumoniae (ATCC 700603)) and Gram-positive strain (S. aureus (ATCC 25923)) using agar disc-diffusion technique.

RESULTS

It was found that both acetone and ethanol extracts showed significant antibacterial activities, against both S. aureus and K. pneumoniae as compared to the negative control (P = 0.00), but no significantly different from the drug (P > 0.05). However, K. pneumoniae showed more sensitivity to the extracts than S. aureus with MIC value of 18.75 mg/mL and 9.38 mg/mL for both acetone and ethanol extracts against S. aureus and K. pneumoniae respectively.

CONCLUSION

This study suggested that the fruit pulp have antibacterial properties, which might validate their traditional uses.

Ethnoveterinary medicinal plants and their utilization by indigenous and local communities of Dugda District, Central Rift Valley, Ethiopia

BACKGROUND

Ethnoveterinary medicinal plants have been used by the people of Dugda District in the primary health care system to treat various livestock ailments for generations, particularly, in underserved rural areas. However, these ethnoveterinary practices and medicinal plants are dwindling without proper documentation, due to undergoing socio-cultural and environmental changes. Hence, this study aimed at inventory and analysis of ethnoveterinary medicinal plants and the associated indigenous and local knowledge used in the treatment of livestock health problems in Dugda District.

METHODS

Data were collected from 378 local inhabitants through semi-structured interviews, 18 focus group discussions with 6 to 8 participants in each couple with participant field observations. Informant consensus factor (ICF), fidelity-level (FL) and relative importance value (RI) were used to evaluate the agreement of informants on ethnoveterinary practices, healing potential of medicinal plants and the most multipurpose species. Using standard taxonomic procedures, voucher specimens were collected, identified and deposited at the National Herbarium of Addis Ababa University.

RESULTS

In total, 64 medicinal plants of ethnoveterinary uses, belonging to 33 families were reported to treat 37 livestock health problems. Anthrax, inappetence and diarrhoea were said to be the most prevalent veterinary health problems treated by traditional medicinal plants. Family Fabaceae was the most widely reported (7 spp.), followed by Apocynaceae, Cucurbitaceae and Solanaceae (5 spp. each). Herbs were the dominant life forms (21spp.), followed by shrubs (20 spp.). The most commonly sought plant parts were leaves (55.25%), followed by roots (23.44%). The principal method of preparation was pounding remedial parts (46.85%) and mixing with cold water. The main route of administration was via oral application (72.67%), drenching diseased livestock. Withania somnifera and Kedrostis foetidissima were the most cited medicinal plants with 53 and 43 use reports (URs), respectively. ICF showed that respiratory diseases scored the highest value (0.94), while most of the reported medicinal plants were gastrointestinal agents. RI value analysis revealed that Croton macrostachyus had highest diversity of uses, followed by K. foetidissima and W. somnifera. Ethnoveterinary uses of some medicinal plants such as Phytolacca dodecandra, Calpurnia aurea, Cyphostemma cyphopetalum and Verbascum sinaiticum as prophylaxis against rabies were a new input for ethnoveterinary database.

CONCLUSION

The study revealed that the people of the Dugda District are endowed with rich ethnoveterinary knowledge and medicinal plants. However, ethnoveterinary knowledge associated with medicinal plant species significantly differ (P < 0.05) between general and key informants, young and matured age groups and informants' educational level. This infers the impact of mode of ethnoveterinary knowledge transfer, literacy, modern education and globalization on ethnoveterinary uses of medicinal plant species. And also most of the medicinal plants are found in wild habitats with nearly no conservation attention. Therefore, it is imperative to implement participatory conservation actions for medicinal plants in collaboration with traditional institutions (Gada system). The disparity of ethnoveterinary knowledge could be also minimized through awareness creation among local communities about the knowledge and its revitalization. Furthermore, medicinal plants, which are widely utilized and multipurpose, should be screened for their phytochemicals, pharmacological and toxicological activities to confirm ethnoveterinary uses and for future development of veterinary pharmaceuticals.

Ethnobotanical study on medicinal plant knowledge among three ethnic groups in peri-urban areas of south-central Ethiopia

BACKGROUND

Documenting traditional knowledge on plant use among ethnic groups has enabled researchers to obtain a better understanding of how indigenous flora is seen and used in daily life. Their therapeutic applications will also encourage future conservation and phytochemical research, potentially leading to the development of novel drugs. However, past ethnobotanical studies conducted in Ethiopia mainly focused on rural areas, and limited coverage to document the ethnobotanical knowledge at the rural‒urban interface. Therefore, this study was conducted to document and analyze traditional ethnobotanical knowledge on medicinal plants among three selected ethnic groups in peri-urban areas of south-central Ethiopia. In addition, we attempted to investigate the range of cultural similarity and disparity between the studied ethnic groups in relation to traditional medicinal plants and diseases treated.

METHODS

Data were collected using semistructured questionnaires and in-depth interviews of 189 key informants, floristic species inventories, and field observations. Several cultural importance indices and Rahman's similarity indices were applied to analyze the relevance of medicinal plants and cultural similarity among the ethnic groups.

RESULTS

A total of 189 therapeutic plants representing 159 genera and 69 families were identified and documented across the three studied ethnic groups. Of these, the Sidama, Gedeo, and Oromo ethnic groups reported 28, 34, and 38%, respectively. Most medicinal plants were represented by herbs (36%), followed by shrubs (31%), trees (27%), and herbaceous climbers (7%). Rahman's similarity index (RSI) revealed considerable ethnobotanical knowledge variation among ethnic groups. Oromo and Sidama showed the highest disparity (63.8%), followed by Gedeo and Oromo (63.2%). Of the total collected therapeutic plants, 78 most important medicinal plants were selected for the cultural importance analysis, which revealed that Croton macrostachyus Hochst. ex Delile scored the highest point in the Gedeo and Oromo ethnic groups and Zingiber officinale Roscoe in the Sidama ethnic group. Whereas Cinnamomum verum J.Presl, Psidium guajava L., and Melia azedarach L. are the least.

CONCLUSION

The present study revealed the presence of cultural differences in medicinal plant knowledge practices and therapeutic plant use among the studied ethnic groups in rural-urban interface areas of south-central Ethiopia. The diverse healing potential of plants would support future pharmacological investigations, emphasizing the need for adequate documentation of indigenous knowledge and versatile flora to prevent their further loss.

Antidiarrheal Activities of the Methanol Leaf Extracts of Olinia rochetiana (Oliniaceae) Against Castor Oil-Induced Diarrhea in Mice

Background

Olinia rochetiana has been used traditionally to cure diarrheal disease. Therefore, this study aimed to investigate the acute toxicity and antidiarrheal effect of O. rochetiana leaf extracts.

Methods

Cold maceration was used to extract plant leaf powder with 80% methanol. The extract's antidiarrheal action was tested against a castor oil-induced diarrheal model, a charcoal meal test, and enteropooling tests at doses of 100, 200, and 400 mg/kg. Negative controls received the vehicle at 10 mL/kg, while positive controls received loperamide at 3 mg/kg.

Results

From the study, no apparent toxicity was observed when a single dose of 2000 mg/kg was administered. In the castor oil-induced model, the extract delayed the onset of diarrhea, reduced stool frequency, and decreased wet feces weight and number in a dose-dependent manner at 200 mg/kg (p < 0.05) and 400 mg/kg (p < 0.01). The percent reduction in moist feces at 100, 200, and 400 mg/kg was 54.2, 23.97, and 18.26%, respectively, indicating a significant dose-dependent decrease. In a charcoal meal test, the extracts at 200 and 400 mg/kg revealed a peristaltic index of 65 and 46%, respectively, with considerable inhibition of charcoal transport at 23 and 39%. The weight and volume of intestinal contents dropped significantly at a dose of 400 mg/kg (p < 0.01), which is 0.43 mg/kg, in the enteropooling test when compared with the tested dose. The computed in vivo antidiarrheal index revealed diarrheal inhibition values of 46.06 and 71.06% at 200 and 400 mg/kg, respectively.

Conclusion

In the current investigation, O. rochetiana showed significant antidiarrheal activity with no symptoms of toxicity in mice.

Thymoquinone ameliorates acrylamide-induced reproductive toxicity in female rats: An experimental study

Background

Acrylamide (AA) is a carcinogenic compound that causes severe reproductive impairments and represents a high environmental risk factor. Thymoquinone (TQ) has a unique antioxidant activity and has been widely used as a protective agent against various types of toxicity.

Objective

To evaluate the protective effects of TQ against AA-induced reproductive toxicity in female rats.

Materials and Methods

In this experimental study, 40 female albino rats (120-150 gr, 8-10 wk) were sorted into 4 groups, (n = 10/each), vehicle group (received a daily oral administration of 0.5 ml saline [9%]); AA group (received a daily oral administration with freshly prepared AA, 20 mg/kg body weight) for 21 days which is less than the lethal dose LD50 of AA in rats (20 mg/kg body weight); AA+TQ group (received a daily oral administration of TQ, 10 mg/kg body weight) after AA intoxication for 21 days, and TQ group (received a daily oral administration of TQ only, 10 mg/kg body weight) for 21 consecutive days. Reproductive hormones, carcinogenic biomarkers, and oxidative stress markers were measured. The histological assessment showed the protective effect of TQ against AA-induced ovarian injury. Network pharmacology analysis and molecular docking approach were carried out to determine the binding affinity of TQ with cyclooxygenase 2.

Results

TQ administration significantly enhanced the functional capacity of the ovary at hormones, oxidative biomarkers, and tumor markers at a significant level of p < 0.001. Besides, TQ protects the ovary of AA-treated rats from the severe degeneration effect.

Conclusion

TQ showed a promising protective effect against AA-induced reproductive toxicity in female rats.

Plant Spices as a Source of Antimicrobial Synergic Molecules to Treat Bacterial and Viral Co-Infections

The COVID-19 pandemic exposed the lack of antiviral agents available for human use, while the complexity of the physiological changes caused by coronavirus (SARS-CoV-2) imposed the prescription of multidrug pharmacotherapy to treat infected patients. In a significant number of cases, it was necessary to add antibiotics to the prescription to decrease the risk of co-infections, preventing the worsening of the patient's condition. However, the precautionary use of antibiotics corroborated to increase bacterial resistance. Since the development of vaccines for COVID-19, the pandemic scenario has changed, but the development of new antiviral drugs is still a major challenge. Research for new drugs with synergistic activity against virus and resistant bacteria can produce drug leads to be used in the treatment of mild cases of COVID-19 and to fight other viruses and new viral diseases. Following the repurposing approach, plant spices have been searched for antiviral lead compounds, since the toxic effects of plants that are traditionally consumed are already known, speeding up the drug discovery process. The need for effective drugs in the context of viral diseases is discussed in this review, with special focus on plant-based spices with antiviral and antibiotic activity. The activity of plants against resistant bacteria, the diversity of the components present in plant extracts and the synergistic interaction of these metabolites and industrialized antibiotics are discussed, with the aim of contributing to the development of antiviral and antibiotic drugs. A literature search was performed in electronic databases such as Science Direct; SciELO (Scientific Electronic Library Online); LILACS (Latin American and Caribbean Literature on Health Sciences); Elsevier, SpringerLink; and Google Scholar, using the descriptors: antiviral plants, antibacterial plants, coronavirus treatment, morbidities and COVID-19, bacterial resistance, resistant antibiotics, hospital-acquired infections, spices of plant origin, coronaviruses and foods, spices with antiviral effect, drug prescriptions and COVID-19, and plant synergism. Articles published in English in the period from 2020 to 2022 and relevant to the topic were used as the main inclusion criteria.

Evaluation of Insecticidal Potentials of Five Plant Extracts against the Stored Grain Pest, Callosobruchus maculatus (Coleoptera: Bruchidae)

Plant based insecticides are considered among the most economic and ecofriendly chemicals for the protection of plants and stored grains. The cowpea weevil (Callosbruchus maculatus) causes more than 90% damage to sored grains in three to six months. The current study investigates insecticidal potentials of five selected botanicals: Melia azedarach, Nicotiana rustica, Azadirachta indica, Nicotiana tabacum and Thuja orientalis. They are explored at six different concentrations (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0%) against C. maculatus and compared to effects of distilled water which is used as a control. Toxicities of 3%(V/V) extracts of N. tabacum, N. rustica, A. indica and T. orientalis against C. maculatus were 100%, 86.11%, 80.56% and 72.22%, respectively. Maximum mortality was caused by N. tabacum and N. rustica (100%), followed by A. indica (82%), whereas minimum mortality was observed in T. orientalis (64%) at 2.5%. Several phytochemicals, alkaloids, saponins, diterphenes, phytosterol, flavonoids and phenols were identified in N. tabacum and N. rustica, while few were present in A. indica. Phytosterol was present in greatest abundance. Saponins were only detected in aqueous extracts of N. rustica and N. tabacum. Taken together, these results indicate the utility of N. tabacum, N. rustica and A. indica as potential botanicals to control pest beetle and cowpea weevil.

Promising Antifungal Activity of Encephalartos laurentianus de Wild against Candida albicans Clinical Isolates: In Vitro and In Vivo Effects on Renal Cortex of Adult Albino Rats

Candida albicans can cause various infections, especially in immunocompromised patients. Its ability to develop resistance to the current antifungal drugs as well as its multiple virulence factors have rendered the problem even more complicated. Thus, in the present investigation, we elucidated an in vitro and in vivo antifungal activity of Encephalartos laurentianus methanol extract (ELME) against C. albicans clinical isolates for the first time. A phytochemical identification of 64 compounds was conducted in ELME using LC-MS/MS. Interestingly, ELME exhibited antifungal activity with MIC values that ranged from 32–256 µg/mL. Furthermore, we investigated the antibiofilm activity of ELME against the biofilms formed by C. albicans isolates. ELME displayed antibiofilm activity using a crystal violet assay as it decreased the percentages of cells, moderately and strongly forming biofilms from 62.5% to 25%. Moreover, the antibiofilm impact of ELME was elucidated using SEM and fluorescent microscope. A significant reduction in the biofilm formation by C. albicans isolates was observed. In addition, we observed that ELME resulted in the downregulation of the biofilm-related tested genes (ALS1, BCR1, PLB2, and SAP5) in 37.5% of the isolates using qRT-PCR. Besides, the in vivo antifungal activity of ELME on the kidney tissues of rats infected with C. albicans was investigated using histological and immunohistochemical studies. ELME was found to protect against C. albicans induced renal damage, decrease desmin and inducible nitric oxide synthase, increase alkaline phosphatase, and increase infected rats’ survival rate. Additionally, the cytotoxicity of ELME was elucidated on Human Skin Fibroblast normal cells using MTT assay. ELME had an IC50 of 31.26 µg/mL. Thus, we can conclude that ELME might be a promising future source for antifungal compounds.

Secondary plant metabolites as potent drug candidates against antimicrobial-resistant pathogens

Antibiotic resistance is a major public health threat of the twenty-first century and represents an important risk to the global economy. Healthcare-associated infections mainly caused by drug-resistant bacteria are wreaking havoc in patient care worldwide. The spread of such pathogens limits the utility of available drugs and complicates the treatment of bacterial diseases. As a result, there is an urgent need for new drugs with mechanisms of action capable of curbing resistance. Plants synthesize and utilize various metabolic compounds to deter pathogens and predators. Utilizing these plant-based metabolites is a promising option in identifying novel bioactive compounds that could be harnessed to develop new potent antimicrobial drugs to treat multidrug-resistant pathogens. The purpose of this review is to highlight medicinal plants as important sources of novel antimicrobial agents that could be developed to help combat antimicrobial resistance.

In vitro antifungal and antibacterial potentials of organic extracts of Avicennia marina collected from Rabigh Lagoon, Red Sea Coasts in Saudi Arabia

Abstract Mangrove shrub Avicennia marina (Forsk.) Vierh was used to test the antifungal and antibacterial activities of aerial fractions in vitro. Aspergillus sp, Candida sp and Gram positive bacteria have all been found to be sensitive to mangrove extracts, whereas Gram negative bacteria have been found to be resistant to them. Agar disc diffusion and well-cut diffusion were employed to conduct antifungal and antibacterial activities. The MICs (minimum inhibitory concentrations) for each assay have been established. Several extracts from Mangrove reduced fungus growth (diameters fluctuated between 11 and 41 mm). The Ethyl acetate fraction showed particularly strong inhibition of C. tropicalis, C. albicanis, and A. fumigatus. They had 41, 40, and 25 mm-diameter inhibition zones, respectively. Nesoral, a synthetic antifungal medication, showed no significant changes in its MICs compared to different extracts. Enterococcus faecalis and Bacillus subtilis were inhibited by Petroleum Ether extracts at MICs of 0.78 and 0.35 mg/mL, respectively. It is possible that A. marina extracts may be exploited as a viable natural alternative that may be employed in the management of various infections, notably nosocomial bacterial infections, as anti-candidiasis and as anti-aspergillosis agents.

Optimization and characterization of oil extracted from Croton macrostachyus seed for antimicrobial activity using experimental analysis of variance

The aim of this study was to optimizing the process variables, assessing the phytochemical constituents and antimicrobial activity of the extracted oil from Croton macrostachyus seed by Soxhlet extraction using n-hexane as a solvent. The maximum oil yield of 45.89 % extracted from Croton macrostachyus seed was obtained at a reaction temperature of 70 °C, particle size of 0.5 mm, reaction time of 5 h, and solute to solvent ratio of 0.06 g/ml. The physicochemical properties of the extracted Croton macrostachyus seed oil investigated were; specific gravity of 0.9, the density of 900 kg/m³ at 15 °C, refractive index of 1.461, acid value of 3.5 mg KOH/g, and free fatty acids of 1.75 mg KOH/g, match the relevant international standards of oil quality. The qualitative test analysis of the extracted Croton macrostachyus seed oil showed that the presence of different phytochemical constituents of an antimicrobial activity were flavonoids, alkaloids, tannins, saponins, terpenoids, and phenols. The functional groups and composition of the extracted oil from Croton macrostachyus seeds were determined using FT–IR and GC-MS respectively. The results exhibited that the oil obtained from Croton macrostachyus seeds can be used for modern medicine instead of traditional purposes.

Zanthoxylum Species: A Review of Traditional Uses, Phytochemistry and Pharmacology in Relation to Cancer, Infectious Diseases and Sickle Cell Anemia

The health benefits and toxicity of plant products are largely dependent on their secondary metabolite contents. These compounds are biosynthesized by plants as protection mechanisms against environmental factors and infectious agents. This review discusses the traditional uses, phytochemical constituents and health benefits of plant species in genus Zanthoxylum with a focus on cancer, microbial and parasitic infections, and sickle cell disease as reported in articles published from 1970 to 2021 in peer-reviewed journals and indexed in major scientific databases. Generally, Z. species are widely distributed in Asia, America and Africa, where they are used as food and for disease treatment. Several compounds belonging to alkaloids, flavonoids, terpenoids, and lignans, among others have been isolated from Z. species. This review discusses the biological activities reported for the plant species and their phytochemicals, including anticancer, antibacterial, antifungal, antiviral, anti-trypanosomal, antimalarial and anti-sickling properties. The safety profiles and suggestions for conservation of the Z. species were also discussed. Taken together, this review demonstrates that Z. species are rich in a wide range of bioactive phytochemicals with multiple health benefits, but more research is needed towards their practical application in the development of functional foods, nutraceuticals and lead compounds for new drugs.

Occurrence and Health Risk Assessment of Aflatoxins through Intake of Eastern Herbal Medicines Collected from Four Districts of Southern Punjab-Pakistan

Eastern herbal medicines (HMs) are plant-derived naturally occurring substances with minimum or no industrial processing that have long been used in traditional medicine. Aflatoxins are frequent contaminants of plants. Therefore, these mycotoxins are likely to contaminate HMs and pose a health risk to individuals using them on a regular basis as preventive or curative treatments of various diseases. The present study aimed to determine aflatoxin levels in the most popular Pakistani HM formulations and to assess the health risk associated with the intake of aflatoxins. A total of 400 samples of HM formulations collected from four districts of Punjab were analyzed for the quantification of aflatoxins, out of which 52.5% were found to be contaminated. The average daily dose (ADD) of AFB1 and AFs through the intake of HM formulations ranged between 0.00483 and 0.118 ng/kg bw/day and between 0.00579 and 1.714 ng/kg bw/day, respectively. The margin of exposure (MOE) and population cancer risk ranged from 99.49 to 29378.8 and from 0.00011 to 0.0325 liver cancer cases/105 individuals/year (0.0075-2.455 liver cancer cases/105 individuals/75 years), respectively. Despite the low exposure to aflatoxins from HM formulations in the four studied Punjab (Pakistan) districts, the frequent contamination of the analyzed samples suggests that official measures should be considered to manage the associated risk.