Phytochemistry of compounds isolated from the leaf-surface extract of Psiadia punctulata (DC.) Vatke growing in Saudi Arabia

New and Antifungal Diterpenoids of Sunflower against Gray Mold

Sunflower (Helianthus annuus L.) is cultivated around the world as an oil crop, and its receptacle is the byproduct and is usually deemed to be an agro-industrial waste. Then, phytochemical constituents and antifungal bioactivity of the sunflower receptacle against phytopathogenic fungi were investigated. As a result, 17 diterpenoids including 4 new compounds were isolated, and most of them showed potential antifungal activity against Botrytis cinerea, in which compounds 1, 3, 5, and 15 exhibited better inhibitory effect with the minimum inhibitory concentration values of 0.05-0.1 mg/mL. Meanwhile, four antifungal diterpenoids destructed plasma membrane integrity, suspended the biofilm formation ability, and increased the extravasation of cellular contents of B. cinerea. Moreover, the EtOAc extract of sunflower receptacle could keep 42.9% of blueberries from the invasion of B. cinerea at 1.6 mg/mL. The finding suggested that sunflower receptacle might be a biocontrol agent for preventing fruit from postharvest diseases.

Two new triterpenes from Commicarpus grandiflorus (A. Rich.) Standl. aerial parts exudate

The exudate of Commicarpus grandiflorus (A. Rich.) Standl. flowering aerial parts was investigated for its chemical composition. Nine compounds were isolated, five triterpenes and four methylated flavones, of which two were new natural triterpenes, 2α,3β,11α-olean-18-en-2,3,11-triol (1) and 2α,3β-olean-12-en-2,3-diol-11-one (2) that were named commicarpotriol and commicarpodiol, respectively. Structural characterization was carried out using 1D, 2D NMR, and MS techniques and the antimicrobial activity of all isolates was evaluated.

The potential role of plant secondary metabolites on antifungal and immunomodulatory effect

With the widespread use of antibiotic drugs worldwide and the global increase in the number of immunodeficient patients, fungal infections have become a serious threat to global public health security. Moreover, the evolution of fungal resistance to existing antifungal drugs is on the rise. To address these issues, the development of new antifungal drugs or fungal inhibitors needs to be targeted urgently. Plant secondary metabolites are characterized by a wide variety of chemical structures, low price, high availability, high antimicrobial activity, and few side effects. Therefore, plant secondary metabolites may be important resources for the identification and development of novel antifungal drugs. However, there are few studies to summarize those contents. In this review, the antifungal modes of action of plant secondary metabolites toward different types of fungi and fungal infections are covered, as well as highlighting immunomodulatory effects on the human body. This review of the literature should lay the foundation for research into new antifungal drugs and the discovery of new targets. KEY POINTS: • Immunocompromised patients who are infected the drug-resistant fungi are increasing. • Plant secondary metabolites toward various fungal targets are covered. • Plant secondary metabolites with immunomodulatory effect are verified in vivo.

In Vitro Anticancer and Antibacterial Activities of the Essential Oil of Forsskal’s Basil Growing in Extreme Environmental Conditions

Many species belonging to the genus Ocimum are used for aromatic, medicinal, and cosmetic purposes. The essential oil (OFEO) obtained by hydrodistillation of the flowering aerial parts of Forsskal’s Basil “Ocimum forskolei Benth” growing in extreme environmental conditions in Mecca Region, Saudi Arabia was analyzed by GC-MS. The main constituents were phenylpropanoids (methyl eugenol 55.65% and eugenol 11.66%), monoterpene (linalool 9.75%), and sesquiterpenes (germacrene D 3.72% and β-caryophyllene 2.57%). The OFEO was tested against MCF7, HT29, and HCT116 cancer cells and compared with normal fibroblast cells (MRC5). The MTT assay showed that HCT116 was more sensitive to OFEO (IC50 5.34 μg/mL), which reduced the number of HCT116 colonies at 6 μg/mL, while causing complete colony death at 12 and 24 μg/mL. Western Blotting and qRT-PCR were used to evaluate the level change of different proteins with respect to GAPDH. OFEO upregulated the apoptotic protein (caspase 3), and downregulated the cell proliferation proteins (AKT and pAKT), cell cycle arrest (PCNA, Cyclin D1), and the anti-apoptotic Bcl2 proteins. OFEO was also tested against reference strains of Gram-negative and Gram-positive bacteria including Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, and Staphylococcus aureus by using the well-diffusion and assessing their MICs, which ranged from 250 to 500 μg/mL.

Saudi Arabian Plants: A Powerful Weapon against a Plethora of Diseases

The kingdom of Saudi Arabia (SA) ranks fifth in Asia in terms of area. It features broad biodiversity, including interesting flora, and was the historical origin of Islam. It is endowed with a large variety of plants, including many herbs, shrubs, and trees. Many of these plants have a long history of use in traditional medicine. The aim of this review is to evaluate the present knowledge on the plants growing in SA regarding their pharmacological and biological activities and the identification of their bioactive compounds to determine which plants could be of interest for further studies. A systematic summary of the plants' history, distribution, various pharmacological activities, bioactive compounds, and clinical trials are presented in this paper to facilitate future exploration of their therapeutic potential. The literature was obtained from several scientific search engines, including Sci-Finder, PubMed, Web of Science, Google Scholar, Scopus, MDPI, Wiley publications, and Springer Link. Plant names and their synonyms were validated by 'The Plant List' on 1 October 2021. SA is home to approximately 2247 plant species, including native and introduced plants that belong to 142 families and 837 genera. It shares the flora of three continents, with many unique features due to its extreme climate and geographical and geological conditions. As plants remain the leading supplier of new therapeutic agents to treat various ailments, Saudi Arabian plants may play a significant role in the fight against cancer, inflammation, and antibiotic-resistant bacteria. To date, 102 active compounds have been identified in plants from different sites in SA. Plants from the western and southwestern regions have been evaluated for various biological activities, including antioxidant, anti-cancer, antimicrobial, antimalarial, anti-inflammatory, anti-glycation, and cytotoxic activities. The aerial parts of the plants, especially the leaves, have yielded most of the bioactive compounds. Most bioactivity tests involve in vitro assessments for the inhibition of the growth of tumour cell lines, and several compounds with in vitro antitumour activity have been reported. More in-depth studies to evaluate the mode of action of the compounds are necessary to pave the way for clinical trials. Ecological and taxonomical studies are needed to evaluate the flora of SA, and a plan for the conservation of wild plants should be implemented, including the management of the protection of endemic plants.

Impairment of Nucleolin Activity and Phosphorylation by a Trachylobane Diterpene from Psiadia punctulata in Cancer Cells

Human nucleolin (hNcl) is a multifunctional protein involved in the progression of various cancers and plays a key role in other pathologies. Therefore, there is still unsatisfied demand for hNcl modulators. Recently, we demonstrated that the plant ent-kaurane diterpene oridonin inhibits hNcl but, unfortunately, this compound is quite toxic for healthy cells. Trachylobane diterpene 6,19-dihydroxy-ent-trachiloban-17-oic acid (compound 12) extracted from Psiadia punctulata (DC.) Vatke (Asteraceae) emerged as a ligand of hNcl from a cellular thermal shift assay (CETSA)-based screening of a small library of diterpenes. Effective interaction between this compound and the protein was demonstrated to occur both in vitro and inside two different types of cancer cells. Based on the experimental and computational data, a model of the hNcl/compound 12 complex was built. Because of this binding, hNcl mRNA chaperone activity was significantly reduced, and the level of phosphorylation of the protein was affected. At the biological level, cancer cell incubation with compound 12 produced a cell cycle block in the subG0/G1 phase and induced early apoptosis, whereas no cytotoxicity towards healthy cells was observed. Overall, these results suggested that 6,19-dihydroxy-ent-trachiloban-17-oic could represent a selective antitumoral agent and a promising lead for designing innovative hNcl inhibitors also usable for therapeutic purposes.

Diterpenoid Constituents of Psiadia punctulata and Evaluation of Their Antimicrobial Activity

Sixteen diterpenes (1-16), along with 10 previously described compounds, including four flavonoids and six diterpenes, were isolated from the aerial parts of Psiadia punctulata growing in Saudi Arabia. The diterpene structures were elucidated using NMR spectroscopy and mass spectrometry data. Furthermore, a DFT/NMR procedure was used to suggest the relative configuration of several compounds. The labdane-derived skeletons, namely, ent-atisane, ent-beyerene, ent-trachylobane, and ent-kaurene, were identified. The extracts, fractions, and pure compounds were then tested against Staphylococcus aureus, Streptococcus mutans, Treponema denticola, and Lactobacillus plantarum. One diterpenoid, namely, psiadin, showed an additive effect with the antiseptic chlorhexidine, with a fractional inhibitory concentration index of less than 1. Additionally, psiadin showed a prospective inhibition activity for bacterial efflux pumps.

Terpenoids from Glechoma hederacea var. longituba and their biological activities

Glechoma hederacea var. longituba (common name: ground ivy) has been used for the treatment of asthma, bronchitis, cholelithiasis, colds, and inflammation. In the present study, three new sesquiterpene glycosides (1–3), two new diterpene glycosides (4 and 5), and four known compounds (6–9) were isolated from its MeOH extract. A structure elucidation was performed for the five new compounds (1–5) using 1D and 2D NMR, HRESIMS, DP4+ and ECD calculations, and chemical methods. All the isolates (1–9) were assessed for their antineuroinflammatory activities on nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells, nerve growth factor (NGF) secretion stimulation activities in C6 glioma cells, and cytotoxic activities against four human cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 2 and 5–7 exhibited inhibitory effects on the NO production with IC50 values of 52.21, 47.90, 61.61, and 25.35 μM, respectively. Compound 5 also exhibited a significant stimulating effect on NGF secretion (122.77 ± 8.10%). Compound 9 showed potent cytotoxic activity against SK-OV-3 (IC50 = 3.76 μM) and SK-MEL-2 (IC50 = 1.48 μM) cell lines, while 7 displayed a strong cytotoxic activity against the SK-MEL-2 (IC50 = 9.81 μM) cell line.

Recent progress on anti-Candida natural products

Candida is an intractable life-threatening pathogen. Candida infection is extremely difficult to eradicate, and thus is the major cause of morbidity and mortality in immunocompromised individuals. Morevover, the rapid spread of drug-resistant fungi has led to significant decreases in the therapeutic effects of clinical drugs. New anti-Candida agents are urgently needed to solve the complicated medical problem. Natural products with intricate structures have attracted great attention of researchers who make every endeavor to discover leading compounds for antifungal agents. Their novel mechanisms and diverse modes of action expand the variety of fungistatic agents and reduce the emergence of drug resistance. In recent decades, considerable effort has been devoted to finding unique antifungal agents from nature and revealing their unusual mechanisms, which results in important progress on the development of new antifungals, such as the novel cell wall inhibitors YW3548 and SCY-078 which are being tested in clinical trials. This review will present a brief summary on the landscape of anti-Candida natural products within the last decade. We will also discuss in-depth the research progress on diverse natural fungistatic agents along with their novel mechanisms.

Phytomedicine from Middle Eastern Countries: An Alternative Remedy to Modern Medicine against Candida spp Infection

Candida spp are capable of infecting both normal and immunocompromised individuals. More recently, Candida infections have spread considerably in healthcare settings, especially in intensive care units, where it is the most frequently encountered pathogen. Candida albicans is the commonest species encountered, although infections by non-albicans species have also risen in the past few years. The pathogenicity of Candida is credited to its aptitude to change between yeast and hyphal modes of growth. Candida spp produce biofilms on synthetic materials that protect them and facilitate drug resistance and act as a source for chronic and recurrent infections. Primarily, azoles antifungal agents are utilized to treat Candida infection that targets the ergosterol synthesis pathway in the cell wall. The development of antifungal resistance in Candida species is a major reason for treatment failure, and hence, there is a need to develop newer antifungal molecules and/or modifications of existing antifungals to make them more effective and less toxic. This has led researchers to oversee the plants to discover newer antimicrobials. Middle Eastern countries are well known for their landscape ranging from dry and sandy deserts to snow-capped mountains. However, they comprise enormous plant diversity with over 20,000 different species showing various types of bioactivities, such as anticancer, antidiabetic, and antimicrobial activities. Especially, the antifungal potential of these phytoproducts could be exploited in the clinical setting for therapy. The present review examines some of the promising alternative natural compounds that have been tested and found effective in treating Candida infections in vitro in some Middle Eastern countries.

Herbal Extracts with Antifungal Activity against Candida albicans: A Systematic Review

In the era of antimicrobial resistance, fungal pathogens are not an exception. Several strategies, including antimicrobial stewardship programs and high throughput screening of new drugs, are being implemented. Several recent studies have demonstrated the effectiveness of plant compounds with antifungal activity. In this systematic review, we examine the use of natural compounds as a possible avenue to fight fungal infections produced by Candida albicans, the most common human fungal pathogen. Electronic literature searches were conducted through PubMed/MEDLINE, Cochrane, and Science Direct limited to the 5 years. A total of 131 articles were included, with 186 plants extracts evaluated. Although the majority of the natural extracts exhibited antifungal activities against C. albicans (both in vivo and in vitro), the strongest antifungal activity was obtained from Lawsonia inermis, Pelargonium graveolens, Camellia sinensis, Mentha piperita, and Citrus latifolia. The main components with proven antifungal activities were phenolic compounds such as gallic acid, thymol, and flavonoids (especially catechin), polyphenols such as tannins, terpenoids and saponins. The incorporation of nanotechnology greatly enhances the antifungal properties of these natural compounds. Further research is needed to fully characterize the composition of all herbal extracts with antifungal activity as well as the mechanisms of action of the active compounds.

How to face COVID-19: proposed treatments based on remdesivir and hydroxychloroquine in the presence of zinc sulfate. Docking/DFT/POM structural analysis

Remdesivir and hydroxychloroquine derivatives form two important classes of heterocyclic compounds. They are known for their anti-malarial biological activity. This research aims to analyze the physicochemical properties of remdesivir and hydroxychloroquine compounds by the computational approach. DFT, docking, and POM analyses also identify antiviral pharmacophore sites of both compounds. The antiviral activity of hydroxychloroquine compound's in the presence of zinc sulfate and azithromycin is evaluated through its capacity to coordinate transition metals (M = Cu, Ni, Zn, Co, Ru, Pt). The obtained bioinformatic results showed the potent antiviral/antibacterial activity of the prepared mixture (Hydroxychloroquine/Azithromycin/Zinc sulfate) for all the opportunistic Gram-positive, Gram-negative in the presence of coronavirus compared with the complexes Polypyridine-Ruthenium-di-aquo. The postulated zinc(II) complex of hydroxychloroquine derivatives are indeed an effective antibacterial and antiviral agent against coronavirus and should be extended to other pathogens. The combination of a pharmacophore site with a redox [Metal(OH₂)₂] moiety is of crucial role to fight against viruses and bacteria strains. [Formula: see text]Communicated by Ramaswamy H. Sarma.

Isolation and In Silico Anti-COVID-19 Main Protease (Mpro) Activities of Flavonoids and a Sesquiterpene Lactone from Artemisia sublessingiana

The emergence of the COVID-19 pandemic declared the huge need of humanity for new and effective antiviral drugs. The reported antimicrobial activities of Artemisia sublessingiana encouraged us to investigate the ethanol extract of its aerial parts which led to the isolation of six flavonoids and a sesquiterpenoid. The structures of the isolated compounds were elucidated by EI-MS, 1D, and 2D NMR spectroscopic methods to be (1) eupatilin, (2) 3′,4′-dimethoxyluteolin, (3) 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone, (4) hispidulin, (5) apigenin, (6) velutin, and (7) sesquiterpene lactone 8α,14-dihydroxy-11,13-dihydromelampolide. The isolated compounds were in silico examined against the COVID-19 main protease (Mpro) enzyme. Compounds 1–6 exhibited promising binding modes showing free energies ranging from −6.39 to −6.81 (kcal/mol). The best binding energy was for compound 2. The obtained results give hope of finding a treatment for the COVID-19 pandemic.

Plant Preparations and Compounds with Activities against Biofilms Formed by Candida spp

Fungi from the genus Candida are very important human and animal pathogens. Many strains can produce biofilms, which inhibit the activity of antifungal drugs and increase the tolerance or resistance to them as well. Clinically, this process leads to persistent infections and increased mortality. Today, many Candida species are resistant to drugs, including C. auris, which is a multiresistant pathogen. Natural compounds may potentially be used to combat multiresistant and biofilm-forming strains. The aim of this review was to present plant-derived preparations and compounds that inhibit Candida biofilm formation by at least 50%. A total of 29 essential oils and 16 plant extracts demonstrate activity against Candida biofilms, with the following families predominating: Lamiaceae, Myrtaceae, Asteraceae, Fabaceae, and Apiacae. Lavandula dentata (0.045–0.07 mg/L), Satureja macrosiphon (0.06–8 mg/L), and Ziziphora tenuior (2.5 mg/L) have the best antifungal activity. High efficacy has also been observed with Artemisia judaica, Lawsonia inermis, and Thymus vulgaris. Moreover, 69 plant compounds demonstrate activity against Candida biofilms. Activity in concentrations below 16 mg/L was observed with phenolic compounds (thymol, pterostilbene, and eugenol), sesquiterpene derivatives (warburganal, polygodial, and ivalin), chalconoid (lichochalcone A), steroidal saponin (dioscin), flavonoid (baicalein), alkaloids (waltheriones), macrocyclic bisbibenzyl (riccardin D), and cannabinoid (cannabidiol). The above compounds act on biofilm formation and/or mature biofilms. In summary, plant preparations and compounds exhibit anti-biofilm activity against Candida. Given this, they may be a promising alternative to antifungal drugs.

Essential Oil Analysis and Antimicrobial Evaluation of Three Aromatic Plant Species Growing in Saudi Arabia

Arabian flora is a rich source of bioactive compounds. In this study, we investigated three aromatic plant species with the aim of finding valuable sources of antimicrobial agents against common pathogenic microorganisms. We focused especially on microorganisms, which cause outbreaks of infectious disease during mass gatherings and pilgrimages season in Saudi Arabia. The essential oils of three aromatic plant species were hydrodistilled from flowering aerial parts of Lavandula pubescens Decne. and Pulicaria incisa subsp. candolleana E.Gamal-Eldin, and from leaves, stems, ripe and unripe fruits of Juniperus procera Hochst. Ex Endl. They were subsequently analyzed by gas chromatography-mass spectrometry (GC-MS). The main constituents of L. pubescens were found to be carvacrol (55.7%), methyl carvacrol (13.4%), and β-bisabolene (9.1%). P. incisa subsp. Candolleana essential oil was rich in linalool (33.0%), chrysanthenone (10.3%), eugenol (8.9%), and cis-chrysanthenol (8.0%); the major components of J. procera essential oil were α-pinene (31.3-62.5%) and δ-3-carene (7.3-30.3%). These essential oils were tested against thirteen American Type Culture Collection (ATCC) strains of Gram-positive and Gram-negative bacteria using the agar diffusion assay. The only effective essential oil was that of L. pubescens and the most sensitive strains were Acinetobacter baumannii, Salmonella typhimurium, Shigella sonnei, Enterococcus faecalis and Staphylococcus epidermidis. Carvacrol, the major constituent of L. pubescens, was tested on these strains and was compared with vancomycin, amikacin, and ciprofloxacin. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays of L. pubescens essential oil and carvacrol revealed that Gram-negative strains were more susceptible than the Gram-positive ones.

Evaluation of Antimicrobial Activity of Triphala Constituents and Nanoformulation

The prevalence of nosocomial infections due to multidrug resistant (MDR) bacterial strains is associated with high morbidity and mortality. Folk medicine and ethnopharmacological data can provide a broad range of plants with promising antimicrobial activity. Triphala, an Ayurvedic formula composed of three different plants: Terminalia chebula Retz., Terminalia bellirica (Gaertn.) Roxb. (Combretaceae), and Phyllanthus emblica L. (Phyllanthaceae), is used widely for various microbial infections. Various extraction techniques were applied in the extraction of the biologically active constituents of Triphala in order to compare their efficiency. Microwave-assisted extraction (MAE) was shown to be the most efficient method based on yield, extraction time, and selectivity. The Triphala hydroalcoholic extract (TAE) has been chemically characterized with spectroscopic and chromatographic techniques. Triphala hydroalcoholic extract was evaluated alone or with carvacrol. Different drug formulations including cream and nanoemulsion hydrogel were prepared to assess the antimicrobial activity against selected microorganism strains including Gram-positive and Gram-negative bacteria and fungi. We used a lipophilic oil of carvacrol (5 mg/mL) and a hydrophilic TAE (5 mg/mL) ingredient in a dosage form. Two solutions were created: hydrogel containing nanoemulsion as a lipophilic vector dispersed in the gel as a hydrophilic vehicle and a cream formulation, an oil-in-water emulsion. In both cases, the concentration was 250 mg of active ingredient in 50 mL of final formulation. The formulas developed were stable from a physical and chemical perspective. In the nanoemulsion hydrogel, the oil droplet size ranged from 124 to 129 nm, with low polydispersity index (PdI) 0.132 ± 0.013 and negative zeta potential -46.4 ± 4.3 mV. For the cream, the consistency factor (cetyl alcohol and white wax) induced immobilization of the matrix structure and the stability. Triphala hydroalcoholic extract in drug nanoformulation illustrated might be an adjuvant antimicrobial agent for treating various microbial infections.

Antibacterial and ATP Synthesis Modulating Compounds from Salvia tingitana

A surface extract of the aerial parts of Salvia tingitana afforded a nor-sesterterpenoid (1) and eight new sesterterpenoids (2-̵9), along with five known sesterterpenoids, five labdane and one abietane diterpenoid, one sesquiterpenoid, and four flavonoids. The structures of the new compounds were established by 1D and 2D NMR spectroscopy, HRESIMS, and VCD data and Mosher's esters analysis. The antimicrobial activity of compounds was evaluated against 30 human pathogens including 27 clinical strains and three isolates of marine origin for their possible implications on human health. The methyl ester of salvileucolide (10), salvileucolide-6,23-lactone (11), sclareol (15), and manool (17) were the most active against Gram-positive bacteria. The compounds were also tested for the inhibition of ATP production in purified mammalian rod outer segments. Terpenoids 10, 11, 15, and 17 inhibited ATP production, while only 17 inhibited also ATP hydrolysis. Molecular modeling studies confirmed the capacity of 17 to interact with mammalian ATP synthase. A significant reduction of ATP production in the presence of 17 was observed in Enterococcus faecalis and E. faecium isolates.

Synthesis of (-)-Mitrephorone A via a Bioinspired Late Stage C-H Oxidation of (-)-Mitrephorone B

We present a bioinspired late-stage C-H oxidation of the ent-trachylobane natural product mitrephorone B to mitrephorone A. The realization of this unprecedented transformation was accomplished by either an iron-catalyzed or electrochemical oxidation and enabled access to the densely substituted oxetane in one step. Formation of mitrephorone C, which is lacking the central oxetane unit but features a keto-function at C2, was not formed under these conditions.

Ethnobotanical survey of medicinal plants in central Abyan governorate, Yemen

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicinal plant knowledge in Yemen is still only passed on orally from one generation to another. A few studies, mostly very limited in scope, have been dedicated to this indigenous knowledge so far. This paper presents the results of the first extensive field study in southern mainland Yemen, undertaken in three communities in the central region of Abyan governorate. The study is aimed to preserve the heritage of this indigenous knowledge and to explore and select local medicinal plants that promise high pharmacological efficacy for further pharmacological and phytochemical investigations.

METHODS

356 indigenous informants (273 males, 83 females) were interviewed about the modes of application and uses of the medicinal plants in the region. The ethnobotanical data were recorded by semi-structured face-to-face interviews, substantiated by specimen collections and taxonomic identifications and quantitative data analysis including informant consensus factor (ICF) and number of use-reports.

RESULTS

In total, 195 medicinal plant species (170 wild and 25 cultivated) belonging to 138 genera and 55 flowering plant families, were recorded for the treatment of 155 different ailments classified into 16 categories. Apocynaceae (25 species), Fabaceae (18 species), Euphorbiaceae (16 species) and Asteraceae (14 species) were the most frequently used plant families. Paste (86) followed by unprepared plant exudates (77) and decoction (55) were the most common herbal preparation modes. Dermal application (51.8%) was the most common administration route. The highest number of use reports and the maximum number of used medicinal plants were recorded for treatment of skin and gastrointestinal ailments. Forty-five species have never been reported in the ethnomedicinal literature before. Plant species with the most citations were Aloe vacillans Forssk. (malaria), Solanum incanum L. (tooth decay), Caralluma awdeliana (Deflers) A. Berger (diabetes), Tribulus terrestris L. (kidney stones), Aristolochia bracteolata Lam. (snake poison), Hydnora abyssinica A.Br. (stomach ulcer), Indigofera oblongifolia Forssk. (urine retention) and Chrozophora oblongifolia (Delile) A. Juss ex Spreng (haemorrhoids).

CONCLUSIONS

Significant traditional knowledge of the uses of local medicinal plant species was recorded for the first time for central Abyan in particular and southern Yemen in general. The study shows that the medicinal plants still play an important role in the primary health care in the study area. The ethnobotanical results provide a basis for further pharmacological, biological, pharmacognostical, and phytochemical investigations.