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Phytochemical Composition and Multifunctional Bioactivities of Berchemia discolor Leaf Extract: Antimicrobial, Antioxidant, and Anti-Inflammatory Potential
*Corresponding author: Dr. Abdulaziz Albogami, PhD, Department of Biology, Faculty of Science, Al-Baha University, King Fahd Rd., Alaqiq, Saudi Arabia. aalbogami@bu.edu.sa
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Received: ,
Accepted: ,
How to cite this article: Albogami A. Phytochemical Composition and Multifunctional Bioactivities of Berchemia discolor Leaf Extract: Antimicrobial, Antioxidant, and Anti-In!ammatory Potential. J Qassim Univ Sci. doi: 10.25259/JQUS_43_2025
Abstract
Objectives
This study aimed to evaluate the phytochemical composition and in vitro bioactivities of Berchemia discolor methanolic leaf extract, focusing on antimicrobial, antioxidant, and anti-inflammatory activities.
Material and Methods
The methanolic extract of B. discolor leaves was analyzed for phytochemical content, including phenolics and flavonoids. Antimicrobial activity was assessed using agar well diffusion and broth microdilution methods against bacterial and fungal strains. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, and total antioxidant capacity assays. Anti-inflammatory activity was determined through COX-2 inhibition assay.
Results
The extract showed high levels of phenolics (134.99 mg GAE g-1) and flavonoids (57.47 mg QE g-1). It exhibited broad-spectrum antimicrobial activity with MIC values as low as 312.5 µg mL-1. Strong antioxidant activity was observed 2,2-diphenyl-1-picrylhydrazyl (DPPH IC50 = 29.28 µg mL-1), along with significant COX-2 inhibition (IC50 = 30.09 µg mL-1).
Conclusion
The findings demonstrate that B. discolor is a promising natural source of antimicrobial, antioxidant, and anti-inflammatory agents, supporting its traditional medicinal use.
Keywords
Antimicrobial activity
Antioxidant activity
Berchemia discolor
COX-2 inhibition
Ethnopharmacology
Phytochemical profiling
INTRODUCTION
The accelerating emergence of resistant microbial strains has substantially compromised the clinical efficacy of many first-line antibiotics, placing considerable pressure on global healthcare systems and intensifying the demand for alternative antimicrobial strategies.[1] Natural products have served as major structural sources for antimicrobial drug discovery, providing chemically diverse scaffolds that continue to inform modern therapeutic development, with a significant proportion of current therapeutics originating from or inspired by compounds found in plants.[2] Among natural sources, medicinal plants are particularly valuable due to their rich diversity of bioactive secondary metabolites, including alkaloids, phenolics, and flavonoids, which have shown significant antimicrobial potential.[3]
Berchemia discolor (Klotzsch) Hemsl., commonly known as bird plum or brown ivory, belongs to the family Rhamnaceae. It is a deciduous tree or shrub widely distributed across sub-Saharan Africa and parts of the Arabian Peninsula.[4] In Saudi Arabia, particularly in the southwestern region of Jazan, the plant—locally known as “Nukkr”—is traditionally used to treat infections, gastrointestinal disorders, and skin conditions. This parallels its widespread ethnomedicinal use throughout Africa, where decoctions of the bark, roots, and leaves are employed for wound healing, respiratory infections, and diarrheal diseases.[5-8] In southern Africa, B. discolor remains an important traditional remedy. In Namibia, its bark is used for stomach and skin infections, while in South Africa, it is applied to wounds and infectious ailments. In Botswana and Zimbabwe, various plant parts are prepared for diarrheal and respiratory conditions. These consistent ethnopharmacological practices across regions underscore the species’ broad-spectrum antimicrobial.[5-9]
The phytochemical profile of B. discolor indicated alkaloids, tannins, saponins, flavonoids, and phenolic compounds, representing metabolite groups commonly associated with antimicrobial efficacy.[10-12] Chin et al.[13] identified prenylated flavonoids from the root bark of B. discolor. However, the study was limited to structural elucidation without comprehensive antimicrobial evaluation. Similarly,[6,14] conducted initial antimicrobial screenings, but these were constrained by narrow pathogen panels and relatively crude extraction methods. Furthermore, indigenous African wild food plants, including B. discolor, have been highlighted for their nutritional potential, such as iron content, carotenoids, vitamins, and minerals, which could contribute to alleviating iron deficiency anemia.[9,15]
Despite its long-standing ethnomedicinal use across Africa and southwestern Saudi Arabia, B. discolor remains poorly characterized in terms of its antimicrobial potential. Existing studies lack a comprehensive evaluation of clinically significant pathogens, detailed MIC profiling, and quantification of bioactive compounds linked to activity. This study addresses these gaps by investigating the methanolic extract of B. discolor from the Jazan region through an integrated assessment of its antimicrobial, antioxidant, and anti-inflammatory properties. By integrating phytochemical content with biological activity, and in comparison with previous reports [Table 1], this work provides the most detailed insight to date into the pharmacological relevance of B. discolor, thereby validating traditional knowledge and highlighting its potential as a source of novel plant-based antimicrobial agents.
| Study | Plant part | Extraction method | TPC (mg GAE g-1) | TFC (mg QE g-1) | Antimicrobial activity |
|---|---|---|---|---|---|
| Chin et al.[13], 2006 | Root bark | Organic solvents | NR | NR | Not evaluated |
| Cheikhyoussef et al.[14], 2010 | Leaves | Aqueous | Qualitative only | Qualitative only | Not evaluated |
| Shai et al.[8], 2020 | Fruits/Leaves | Mixed | NR | NR | Not evaluated |
| Molepo et al.[12], 2025 | Leaves | Methanol |
Reported (no MIC) |
Reported (no MIC) |
Not evaluated |
| Present study | Leaves | Methanol | 134.99 | 57.47 | Yes (MIC-based) |
TPC: Total phenolic content; TFC: Total flavonoid content; NR: Not reported; MIC: Minimum inhibitory concentration
MATERIAL AND METHODS
Plant material collection and extraction
Fresh leaves of B. discolor were collected from the Jazan region, southwestern Saudi Arabia, during the summer season. Botanical identification was verified by Dr. Ali Alzahrani, taxonomist at Al-Baha University. Voucher specimen details are as follows: Jazan Province, Harub (17°27′00.2″ N, 42°53′45.2″ E; 507 m), collected on 5 May 2025 by A. Albogami (collector no. 10), and deposited at the Taibah University Herbarium (TAUH) herbarium. The leaves were shade-dried at room temperature (25 ± 2°C), ground into a fine powder, and macerated in 80% methanol (1:5 w v-1) under ambient conditions for 72 h with intermittent shaking. The combined filtrates were concentrated under reduced pressure at 40 °C using a rotary evaporator and stored at 4 °C until use. For antimicrobial assays, the dried extract was reconstituted in dimethyl sulfoxide (DMSO) at a stock concentration of 100 mg mL-1.
Microbial strains and culture conditions
All microbial strains used in this study were obtained either from the Regional Center for Mycology and Biotechnology (RCMB), Al-Azhar University, Cairo, Egypt, or from the Microbiology Laboratory, Faculty of Science, Al-Baha University, Saudi Arabia. Reference strains from RCMB (Egypt) included the yeasts Candida albicans RCMB 005003 (1) [= American Type Culture Collection (ATCC) 10231] and Cryptococcus neoformans RCMB 0049001, as well as the bacteria Staphylococcus aureus ATCC 25923, Bacillus subtilis RCMB 015 (1) NRRL B-543, Enterococcus faecalis ATCC 9790 (formerly Streptococcus faecalis), Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 25922, Proteus vulgaris RCMB 004 (1) ATCC 13315, Enterobacter cloacae RCMB 001 (1) ATCC 23355, and Vibrio parahaemolyticus ATCC 17802 Locally maintained isolates (Al-Baha University) were molecularly identified and deposited in GenBank: Fusarium equiseti (OQ360646.1), Fusarium incarnatum (ON844338), Bipolaris prieskaensis (ON845652), Geotrichum candidum (ON868706), and Aspergillus niger (ON845450).
Culture conditions
Bacteria were grown on Mueller–Hinton agar (MHA) and incubated at 37°C for 24 h, with inocula adjusted to ∼1 × 10⁸ CFU mL-1; V. parahaemolyticus was maintained on MHA supplemented with 2% NaCl due to its halophilic requirement.[16] Yeasts (C. albicans, C. neoformans) were cultured on Sabouraud Dextrose Agar (SDA) and incubated at 37°C for 24–48 h, with inocula standardized to ∼1 × 10⁵ CFU mL-1. Filamentous fungi (Fusarium, Bipolaris, Geotrichum, Aspergillus) were cultured on Potato Dextrose Agar (PDA) and incubated at 28 ± 2°C for 48–72 h to allow sporulation prior to testing.[17]
Extract preparation and screening concentration
The dried 80% methanolic extract of B. discolor was reconstituted in DMSO to prepare a concentrated stock solution, then serially diluted to working levels (e.g., 100, 50, 25, 12.5 mg mL-1) for screening. A 50 mg mL-1 working concentration was selected for primary agar well-diffusion assays because it lies within commonly used ranges for crude plant extracts and yields reproducible, interpretable zones without overloading the agar.[18]
Agar well-diffusion assay
Following lawn inoculation (100 µL standardized suspension) on the appropriate medium (MHA for bacteria, SDA for yeasts, PDA for filamentous fungi), 6 mm wells were aseptically bored, and each was filled with 50 µL of the extract at 50 mg mL-1. Plates were incubated under the organism-specific conditions above, and zones of inhibition were measured in millimetres. Positive controls included: ketoconazole for yeasts (clinical antifungal control); azoxystrobin+difenoconazole (AZ+DFZ) (commercial mixture, Amistar® Top) for filamentous fungi; and metalaxyl-M (mefenoxam) as an oomycete-active agricultural comparator.[19,20] Gentamicin served as the antibacterial positive control. DMSO was the negative control and produced no inhibition. Hereafter, “WT” denotes the untreated inoculated control. The well-diffusion format follows established practice for preliminary screening of crude extract.[18,21]
Determination of minimum inhibitory concentration (MIC)
MICs were determined by broth microdilution in accordance with standard dilution methods for MIC determination (CLSI, 2020), where MIC is the minimum concentration that entirely inhibits visible growth under controlled conditions. Bacteria were tested in cation-adjusted Mueller–Hinton broth (CAMHB); yeasts (Candida albicans, Cryptococcus neoformans) and filamentous fungi in RPMI-1640 buffered with 0.165 M MOPS (pH 7.0) with 2% glucose. Two-fold serial dilutions of the B. discolor extract were prepared in 96-well microplates (final volume 200 µL well-1; final DMSO ≤ 1% v v-1). Final inocula were ∼5×10⁵ CFU mL-1 (bacteria), 0.5–2.5×103 CFU mL-1 (yeasts), and 0.4–5×10⁴ conidia mL-1 (filamentous fungi).
Plates were incubated at 37°C for bacteria and yeasts (18–48 h) and 28 ± 2°C for filamentous fungi (≥ 48 h as needed). Growth was assessed visually and at OD₆₀₀; the MIC was the lowest extract concentration with no visible turbidity and OD₆₀₀ indistinguishable from the sterility control and ≤ 10% of the growth control. Each assay included growth, solvent, and sterility controls and was performed in triplicate.[22]
Phytochemical analysis
All phytochemical contents are reported on a dry-extract basis as mg equivalents per g (mg GAE g-1, mg QE g-1, mg AE g-1, mg TAE g-1, mg LE g-1), while nutritional parameters are reported as mg g-1 dry plant material. Lipid content is expressed as a percentage (%).
Total phenolic content (TPC)
Total phenolic content was measured using the Folin–Ciocalteu colorimetric method.[23] In brief, 0.5 mL of extract was combined with 2.5 mL of 10% Folin–Ciocalteu reagent and 2 mL of 7.5% sodium carbonate. After incubating at room temperature for 30 min, absorbance was read at 760 nm with a UV-Vis spectrophotometer. Gallic acid served as the standard, and results are expressed as mg gallic acid equivalents per gram of dry weight (mg GAE g-1).
Total flavonoid content (TFC)
Flavonoid content was determined using the aluminum chloride colorimetric method outlined by Chang et al.[24] A sample of 0.5 mL of extract was mixed with 0.1 mL of 10% AlCl₃, 0.1 mL of 1 M potassium acetate, and 2.8 mL of distilled water. After a 30-min reaction period, absorbance was measured at 415 nm. Quercetin served as the reference standard, and the results are expressed as mg quercetin equivalents per gram of dry weight (mg QE g-1).
Total alkaloid content
Alkaloid content was measured using Dragendorff’s reagent method, following the procedure outlined by Shamsa et al.[25] A known volume of extract was reacted with phosphate buffer (pH 4.7) and bromocresol green (BCG), followed by extraction with chloroform. The complex was measured at 470 nm using atropine as a standard. Results are presented as mg atropine equivalents per gram of dry weight (mg AE g-1).
Total terpene content
Total terpenes were measured using a vanillin–sulfuric acid colorimetric assay.[26] The extract was reacted with vanillin–sulfuric acid reagent and incubated in the dark for 2 h. After dissolving the resulting precipitate in methanol, absorbance was measured at 546 nm. Limonene was used as a standard, and results were expressed as mg limonene equivalents per gram dry weight (mg LE g-1).
Total tannin content
Tannin content was estimated by the vanillin-HCl method.[27] 400 μL of extract was mixed with 3 mL of 4% vanillin in methanol and 1.5 mL of concentrated HCl. After 15 min at 30 °C, absorbance was read at 500 nm. Tannic acid was used as a reference, and results were expressed as mg tannic acid equivalents per gram dry weight (mg TAE g-1).
Crude lipid content
Crude lipid content was determined using the conventional Soxhlet extraction method as described by Khilari and Sharma.[28] Briefly, 2 g of dried plant powder were placed in a porous thimble plugged with cotton and inserted into the Soxhlet extraction chamber. The thimble was positioned above a previously weighed flask containing methanol–chloroform solvent mixture. The assembly was heated using a heating mantle for 8–10 h to allow continuous extraction. After extraction, the solvent was removed under reduced pressure to obtain the crude lipid fraction. The flask containing the lipid residue was then dried in an oven at 100°C for 30 min, cooled in a desiccator, and weighed. Crude lipid content was calculated gravimetrically and expressed as a percentage (%) of dry plant material.
Protein content
Protein extraction was carried out using the salt/alkaline extraction method described by Mæhre et al.[29] with modifications. In brief, 0.5 g of dried plant material was homogenized in 30 mL of 0.1 M sodium hydroxide (NaOH) containing 3.5% sodium chloride (NaCl). The homogenate was incubated at 60°C for 90 min and then centrifuged at 4000 × g for 30 min at 4°C. The supernatant was collected and stored at −20°C until analysis.
Total protein concentration was determined using the Bradford assay according to Bradford.[30] For measurement, 100 µL of extract was mixed with 5 mL of Bradford reagent and incubated for 5 min. Absorbance was measured at 570 nm using a UV–Vis spectrophotometer. A bovine serum albumin (BSA) standard curve (0–1 mg mL-1) was used for quantification, and protein content was expressed as mg g-1 dry plant material.
Total carbohydrate content
Total carbohydrate content was measured with the phenol–sulfuric acid method as outlined in study by Roberts and Elias.[31] In brief, 100 mg of the sample was heated in a water bath for 3 h, then cooled to room temperature. The sample was neutralized with solid sodium carbonate until bubbling stopped, and the volume was adjusted to 100 mL with distilled water. Following centrifugation, the supernatant was taken for analysis.
For quantification, aliquots of glucose working standards (0.1 mg mL-1) were prepared and adjusted to 1 mL with distilled water. Subsequently, 1 mL of 5% phenol and 5 mL of 96% sulfuric acid were added sequentially, mixed thoroughly, and incubated for 10 min, followed by incubation at 25–30°C for 15 min. Absorbance was measured at 490 nm using a spectrophotometer. Carbohydrate content was calculated from the glucose standard curve and expressed as mg g-1 dry plant material.
Antioxidant and anti-inflammatory activities
Reducing power (Oyaizu) assay
The ferric reducing power of the extract was assessed using the method of Oyaizu,[32] and Ferreira et al.[33] In this assay, 1 mL of the methanolic extract was combined with 2.5 mL of 0.2 M sodium phosphate buffer (pH 6.6) and 2.5 mL of 1% potassium ferricyanide [K3Fe(CN)6]. After incubation at 50°C for 20 min, the mixture was acidified with 2.5 mL of 10% trichloroacetic acid and centrifuged at 1000 × g for 10 min. The supernatant (2.5 mL) was mixed with 2.5 mL of distilled water and 0.5 mL of 0.1% ferric chloride. The absorbance was then measured at 700 nm against a blank. Ascorbic acid served as the reference standard.
DPPH radical scavenging assay
The extract’s free radical scavenging activity was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) following the method in study by Yen and Duh.[34] A 0.004% DPPH methanolic solution was freshly prepared and stored in the dark at 10°C. An aliquot of 40 µL of the test extract was added to 3 mL of the DPPH solution. The decrease in absorbance at 515 nm was recorded every min for 16 min via a UV-visible spectrophotometer. Ascorbic acid served as the control. The percentage inhibition (PI) was calculated using the formula: PI (%) = [(AC – AT)/AC] × 100. The IC50 value was obtained from the dose-response curve.
Cyclooxygenase (COX-2) inhibition assay
The anti-inflammatory activity of the extract was evaluated using the COX-2 inhibition assay as described by Canabady-Rochelle et al.[35] Leuco-DCF was prepared by hydrolyzing 5 mg of leuco-2,7-dichlorofluorescein diacetate in 50 µL of 1 M NaOH for 10 min, followed by neutralization with 30 µL of 1 M HCl. The resulting product was diluted in 0.1 M Tris buffer (pH 8.0). COX-2 enzyme was pre-incubated with 20 µL of the test extract in the presence of hematin for 5 min. The reaction was initiated by adding premixed phenol, 1-DCF, and arachidonic acid. The final mixture (1 mL) was monitored at 502 nm for 1 min. A blank without an enzyme was included. Celecoxib was used as the standard.
Statistical analysis
All experiments were performed in triplicate and are presented as mean ± standard deviation (SD). Statistical analyses were conducted in R (v4.5.0). For comparisons involving more than two treatments (e.g., WT, extract, and fungicides), we used one-way analysis of variance (ANOVA) followed by Tukey’s honestly significant difference (HSD) for pairwise contrasts, which inherently accounts for multiple pairwise comparisons. For two-group comparisons (e.g., extract vs. gentamicin/ketoconazole), we used two-sided independent t-tests. Significance thresholds were p < 0.001.
RESULTS AND DISCUSSION
Phytochemical and nutritional composition
The methanolic extract of B. discolor revealed a rich phytochemical composition with high concentrations of total phenolics (134.99 ± 1.55 mg GAE g-1) and flavonoids (57.47 ± 1.44 mg QE g-1) [Table 2]. Nutritional profiling further demonstrated substantial protein content (228.19 ± 4.59 mg g-1), moderate carbohydrates (20.80 ± 0.34 mg g-1), and low lipid concentration (2.72 ± 0.13 mg g-1). In addition, measurable levels of alkaloids (7.22 ± 0.11 mg AE g-1), tannins (10.87 ± 0.16 mg TAE g-1), and terpenes (2.97 ± 0.06 mg LE g-1) were detected [Table 2].
| Constituent | Content (Mean ± Standard deviation) | Unit |
|---|---|---|
| Total Phenolics | 134.99 ± 1.55 | mg GAE g-1 |
| Total Flavonoids | 57.47 ± 1.44 | mg QE g-1 |
| Proteins | 228.19 ± 4.59 | m g-1 |
| Carbohydrates | 20.80 ± 0.34 | mg g-1 |
| Lipids | 2.72 ± 0.13 | % |
| Alkaloids | 7.22 ± 0.11 | mg AE g-1 |
| Tannins | 10.87 ± 0.16 | mg TAE g-1 |
| Terpenes | 2.97 ± 0.06 | mg LE g-1 |
Antimicrobial activity
Antibacterial activity
The methanolic extract of B. discolor showed significant antibacterial activity against both Gram-positive and Gram-negative bacteria compared to gentamicin [Figure 1, Supplementary Table S1]. Among Gram-positive species, inhibition zones ranged from 7 mm (Enterococcus faecalis) to 18 mm (Staphylococcus epidermidis), while gentamicin produced larger zones (20.3–34.6 mm). Similarly, for Gram-negative bacteria, the extract produced zones of 12–16 mm, compared with 23.3–39.6 mm for gentamicin. No inhibition was observed for the DMSO negative control. Although the extract’s activity was generally lower than that of gentamicin, it demonstrated consistent broad-spectrum effects, confirming its potential as a natural antimicrobial agent.
Antifungal activity (filamentous fungi)
The antifungal potential of the extract was evaluated against five pathogenic molds and compared with two commercial fungicides—azoxystrobin + difenoconazole (AZ+DFZ) and metalaxyl-M [Figure 2, Supplementary Table S2]. The extract inhibited Aspergillus niger, Bipolaris prieskaensis, Fusarium equiseti, Fusarium incarnatum, and Geotrichum candidum, with growth inhibition zones ranging from 9.0 to 19.2 mm under treatment. Notably, activity against B. prieskaensis (19.2 mm) and F. equiseti (15.2 mm) was comparable to that of AZ+DFZ (18.4–10.8 mm), indicating a pronounced antifungal effect. Metalaxyl-M showed moderate to weak activity across the tested isolates, while DMSO exhibited no inhibition.
Antifungal activity (yeasts)
To better characterize the extract’s effects on unicellular fungi, the yeast pathogens were examined separately [Figure 3; Supplementary Table S3]. The methanolic extract of B. discolor produced growth zones of 20.6 mm against Candida albicans and 27.3 mm against Cryptococcus neoformans. In contrast, the reference antifungal ketoconazole yielded markedly smaller growth zones (10.3 mm and 14.3 mm, respectively), reflecting its stronger growth-inhibitory potency. These results indicate that, although the B. discolor extract exhibited moderate anti-yeast activity, it remained less effective than ketoconazole, yet significantly inhibited growth compared with the untreated WT. The DMSO control showed no inhibitory effect, with growth comparable to the WT, confirming that the observed inhibition was attributable solely to the extract or antifungal agent.
MIC determination
The minimum inhibitory concentrations (MICs) of the methanolic extract of B. discolor were determined against all tested bacterial and fungal strains using the broth microdilution method [Table 3]. MIC values ranged from 312.5 µg mL-1 for B. prieskaensis and S. epidermidis to 2500 µg mL-1 for E. faecalis, E. coli, and E. cloacae. Notably, the extract displayed strong inhibitory effects (MIC ≤ 625 µg mL-1) against several clinically relevant pathogens, including S. aureus, B. subtilis, P. vulgaris, C. albicans, and A. niger. These results support the broad-spectrum antimicrobial potential of B. discolor, complementing the inhibition-zone data observed in the diffusion assays.
| Microorganism | Type | MIC (µg mL-1) |
|---|---|---|
| Fusarium equiseti | Fungus | 625 |
| Fusarium incarnatum | Fungus | 1250 |
| Bipolaris prieskaensis | Fungus | 312.5 |
| Geotrichum candidum | Fungus | 1250 |
| Aspergillus niger | Fungus | 625 |
| Cryptococcus neoformans | Yeast | 625 |
| Candida albicans | Yeast | 625 |
| Staphylococcus aureus | Gram + Bacteria | 625 |
| Enterococcus faecalis | Gram + Bacteria | 2500 |
| Staphylococcus epidermidis | Gram + Bacteria | 312.5 |
| Bacillus subtilis | Gram + Bacteria | 312.5 |
| Escherichia coli | Gram - Bacteria | 2500 |
| Proteus vulgaris | Gram - Bacteria | 625 |
| Enterobacter cloacae | Gram - Bacteria | 2500 |
| Vibrio parahaemolyticus | Gram - Bacteria | 1250 |
MIC: Minimum inhibitory concentrations
Antioxidant and Anti-inflammatory activities
The methanolic extract of B. discolor demonstrated strong antioxidant activity across multiple assays [Table 4]. In the DPPH radical-scavenging assay, the extract showed an IC₅₀ of 29.28 ± 1.22 µg mL-1, while the reducing power assay yielded an IC₅₀ of 81.55 ± 7.04 µg mL-1. The total antioxidant capacity (TAC) was 33.93 ± 1.22 mg GAE g-1. Ascorbic acid (positive control) showed IC₅₀ values of 6.85 ± 0.31 µg mL-1(DPPH) and 14.17 ± 0.57 µg mL-1 reducing power, and a TAC of 78.04 ± 1.49 mg GAE g-1 [Table 4]. The extract also exhibited dose-dependent anti-inflammatory activity in the COX-2 inhibition assay (IC₅₀ 30.09 ± 1.14 µg mL-1), compared with 5.95 ± 0.63 µg mL-1 for celecoxib [Table 4].
| Assay | Measure | Sample | Mean ± SD |
|---|---|---|---|
| DPPH | IC₅₀ (µg mL-1) | B. discolor (MeOH extract) | 29.28 ± 1.22 |
| Ascorbic acid (control) | 6.85 ± 0.31 | ||
| Reducing Power | IC₅₀ (µg mL-1) | B. discolor (MeOH extract) | 81.55 ± 7.04 |
| Ascorbic acid (control) | 14.17 ± 0.57 | ||
| TAC | (mg GAE g-1) | B. discolor (MeOH extract) | 33.93 ± 1.22 |
| Ascorbic acid (control) | 78.04 ± 1.49 | ||
| COX-2 | IC₅₀ (µg mL-1) | B. discolor (MeOH extract) | 30.09 ± 1.14 |
| Celecoxib (control) | 5.95 ± 0.63 |
DPPH: 2,2-diphenyl-1-picrylhydrazyl; TAC: Total antioxidant capacity; SD: Standard deviation
This study provides the first integrated evaluation of B. discolor methanolic leaf extract, linking its phytochemical composition with antimicrobial, antioxidant, and anti-inflammatory activities. The results validate its traditional medicinal use and demonstrate its pharmacological relevance.
The extract exhibited high levels of total phenolics (134.99 mg GAE g-1) and flavonoids (57.47 mg QE g-1), which may contribute to the biological activities observed. Previous studies on B. discolor and other Rhamnaceae members have reported similar qualitative profiles, including phenolics, tannins, flavonoids, alkaloids, and saponins.[9,12-14] However, previous investigations were largely qualitative, whereas the present study extends this understanding by providing quantitative characterization of these constituents and linking them to measurable biological activities.
Although total-content colorimetric assays provide useful quantitative estimates, they are inherently non-specific and do not allow identification of individual compounds. Therefore, while the present findings offer valuable insight into the phytochemical richness of B. discolor, future studies will incorporate chromatographic profiling techniques such as HPLC-DAD or LC-MS to characterize the dominant bioactive constituents underlying the observed biological activities.
The extract demonstrated wide-ranging antimicrobial effects against Gram-positive and Gram-negative bacteria, along with pathogenic fungi. Notably, the MIC results confirmed potent inhibition of S. epidermidis, B. subtilis, and B. prieskaensis (312.5 µg mL-1). The inhibition of B. prieskaensis (19.2 mm) is of special interest because filamentous fungi typically exhibit lower susceptibility to crude botanical extracts.[36] Earlier reports had noted inhibition of S. aureus and C. albicans by aqueous extracts of B. discolor, but without MIC determination.[14] By presenting both inhibition-zone data and MIC values, the current study strengthens the pharmacological evidence for B. discolor and provides reproducible quantitative confirmation of its antimicrobial efficacy.
For crude plant extracts, antimicrobial activity is commonly interpreted using established quantitative benchmarks. MIC values ≤500 µg mL-1 indicate strong activity, while values between 500–1500 µg mL-1 reflect moderate activity.[37] Extracts with MIC values below 1 mg mL-1 are also considered biologically active.[38] Accordingly, the MIC values obtained for B. discolor (312.5–625 µg mL-1) indicate moderate to strong antimicrobial activity that is pharmacologically relevant for a crude botanical extract.
Comparisons with commercial fungicides provided additional context. Azoxystrobin + difenoconazole (AZ+DFZ) and metalaxyl-M effectively suppressed filamentous phytopathogens, consistent with their established mechanisms of action.[19,20,39] The use of agricultural fungicides as reference compounds reflects the plant-associated nature of most tested filamentous fungi, which are primarily phytopathogens rather than clinical isolates. Accordingly, a clinical antifungal (ketoconazole) was used for yeast pathogens to ensure appropriate medical relevance. However, these fungicides were inactive against yeasts such as C. albicans and C. neoformans. In contrast, B. discolor inhibited both filamentous and unicellular fungi, suggesting a wider antifungal spectrum that may have value for topical or agricultural applications.
The extract also demonstrated strong antioxidant capacity across DPPH, reducing power, and TAC assays, reflecting its phenolic and flavonoid enrichment. These compounds are well recognized for neutralizing reactive oxygen species and maintaining redox balance.[40] The anti-inflammatory potential observed in the COX-2 inhibition assay (IC₅₀ = 30.09 µg mL-1) further supports the multifunctional nature of the extract. Only COX-2 inhibition was evaluated as an initial in vitro screening. Therefore, the absence of COX-1 data limits conclusions regarding enzyme selectivity and gastrointestinal safety. Future studies should include parallel COX-1 assays to better assess selectivity and safety profiles. The presence of proteins at substantial levels supports literature showing that amino-acid-rich plant fractions contribute to tissue repair and wound healing.[41] Meanwhile, plant constituents such as tannins, alkaloids, and terpenes, which are present at moderate to low concentrations, may still contribute synergistically to antimicrobial and anti-inflammatory responses.[42,43]
Taken together, these findings expand the pharmacological understanding of B. discolor, bridging traditional use and modern experimental validation. The methanolic leaf extract demonstrated broad-spectrum antimicrobial activity (MIC range 312.5–2500 µg mL-1), alongside significant antioxidant effects and measurable COX-2 inhibition, supporting its multifunctional bioactivity. The high phenolic and flavonoid content likely underpin these biological activities and provides a biochemical basis for its observed pharmacological potential.
Although only a single crude extract was evaluated, limiting correlation analysis between specific phytochemicals and bioactivity, the integrated phytochemical and biological assessment highlights B. discolor as a promising candidate for further pharmacological investigation. This study remains limited to in vitro evaluation; therefore, future research should include in vivo validation, safety assessment, and isolation of active constituents to substantiate its therapeutic applicability.
CONCLUSION
The present study demonstrates that the methanolic leaf extract of Berchemia discolor possesses significant antimicrobial, antioxidant, and anti-inflammatory activities. The extract exhibited broad-spectrum antimicrobial effects with MIC values ranging from 312.5-2500 µg mL-1, along with strong antioxidant capacity and measurable COX-2 inhibitory activity. These bioactivities are likely associated with its high phenolic and flavonoid content.
Although the findings support the ethnomedicinal relevance of B. discolor, the study is limited to in vitro evaluation using a single crude extract. Therefore, further investigations, including in vivo studies, toxicity assessment, and isolation of active compounds, are required to fully establish its therapeutic potential.
Ethical approval
Institutional Review Board approval is not required.
Declaration of patient consent
Patient consent is not required as no patients are involved in the study.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation
The authors confirm that they have used artificial intelligence (AI)-assisted technology at a minimal level to support idea organization and to facilitate efficient identification of relevant literature. The tools were also used for minor language refinement. All scientific content, data analysis, and interpretations were developed and verified entirely by the author.
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