The GC-MS analysis revealed a diverse range of 210 compounds in the stem extract and 346 compounds in the leaf extract of B. polystachya. The chemicals come from several chemical classes, showing the intricate composition of the plant extracts analyzed. The B. polystachya stem extract included high levels of carbohydrates, phenolic compounds, fatty acids, and steroidal components as shown in Table 1; Figs. 1 and 3.

The chemical classes include carbohydrates (1‒3), phenolic derivatives (4), fatty acids and their derivatives (4‒11), and steroidal components 12 and 13. The prevalence of water-loving carbohydrates 1‒3 are the main elements in this extraction, and when their peak area (%) is greater than 20%, it indicates a potential for water-soluble applications. The stem extract of B. polystachya also included fatty acids and their derivatives 4‒11 as the second most abundant components.

Two highly lipophilic steroidal substances, stigmasterol 12 and stigmast-5-en-3-ol 13, were detected in 3.9% of the samples with retention durations exceeding 20 min. The existence of phenolic derivatives and fatty acids suggests a wide range of biological effects, such as antioxidant and anti-inflammatory characteristics. Identifying steroidal components such as stigmasterol and stigmast-5-en-3-ol highlights the possibility for developing drugs based on steroidal scaffolds. The phenolic component 3-hydroxy-4-methoxycinnamic acid was found in this extract. The sugar compound Ethyl.alpha.-d-glucopyranoside (2) was the predominant component in this extract, with a peak area above 15%. Thus, it may be inferred that the stem extract of B. polystachya primarily consists of hydrophilic components.

Chemical structures of constituents identified through GC-MS of Buddleja polystachya (stem) extracts

GC-MS profiling of B. polystachya leaves extract revealed the presence of 10 main phytochemicals, shown in Table 1; Figs. 2 and 3. The analysis of this extract revealed a combination of hydrophilic carbohydrates and lipophilic fatty acids and their derivatives. The significant amount of octadecanoic acid, 2,3-dihydroxypropyl ester, suggests its possible use in lipid-based formulations or as a bioactive chemical with specific therapeutic capabilities. Carbohydrates (1‒4) make up 7.99% of the total constituents and exhibit peaks with limited retention periods (< 10 min) because of their hydrophilic properties. Fatty acids and their derivatives were the predominant components in the B. polystachya (leaves) extract, with a total peak area % above 13%. Due to their elongated hydrocarbon chains, these components exhibited retention durations greater than 11 min. The phenolic component, 9, 2-methoxy-4-(1-propenyl)-phenol, was present in less than 2% abundance. The main phytoconstituent in this extract was identified as octadecanoic acid, 2,3-dihydroxypropyl ester (10), a fatty acid ester with a peak area greater than 5%. This molecule was the most lipophilic among the primary components due to its lengthy hydrophobic chain.

Chemical structures of constituents identified through GC-MS of Buddleja polystachya (leaves) extract

The peak areas% of the major components in Buddleja polystachya stem (A) and leaves (B) extracts

Bacterial eye infections attributable to a variety of bacteria, with Gram-positive species being most involved. Symptoms of these infections vary, including blepharitis and conjunctivitis, as well as more serious illnesses such as keratitis, endophthalmitis, and orbital cellulitis. Bacterial isolates’ distribution is regulated by clinical diagnosis and is not limited to certain ocular areas. To effectively manage these infections, a diagnostic approach focused on identifying the cause and a collaborative effort to reduce risks are essential [16, 17].

In this research study, we have also assessed the antibacterial capabilities of B. polystachya extracts from the stem and leaves against six microbial strains using the agar diffusion method. The results are detailed in Table 2. The antibacterial effectiveness was measured using inhibition zones (in millimetres ± standard deviation, n = 2). Results showed that B. polystachya (stem) extracts had a wide range of activity, with inhibition zones ranging from 14 ± 1.0 mm to 18 ± 1.0 mm against Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae. However, there was no activity observed against Haemophilus influenzae and Neisseria gonorrhoeae. On the other hand, extracts from B. polystachya (stem and leaves) showed a similar range of action but were not effective against S. aureus and Candida albicans, suggesting a limited antibacterial spectrum.

Amikacin was employed as a positive control for comparison. It exhibited expected inhibitory efficacy against P. aeruginosa with a zone of 21 ± 0.0 mm, but its effect on the other strains was not evaluated. Vancomycin showed inhibition zones of 160.0 mm and 150.0 mm against S. aureus and S. pneumoniae, respectively, in line with its known effectiveness against Gram-positive bacteria. The negative control, DMSO, showed no action against any tested organisms, confirming that the antimicrobial activities reported were due to the active components of the plant extracts and not the solvent.

The antimicrobial assays conducted in this study highlighted t the potential of the extracts under study in combating ocular infections. The variation in the zone of inhibition among different extracts and microbial strains emphasises the specificity and broad-spectrum nature of the antimicrobial compounds present in the extracts.

The determination of MIC and MBC values for the stem and leaves extracts quantifies their efficiency and provides a basis for dose optimization in potential therapeutic applications. Therefore, the antimicrobial properties of B. polystachya were further investigated by determination of MICs and MBCs against Staphylococcus aureus and Pseudomonas aeruginosa (Table 3). The MIC assessments showed similar values for both extracts. The stem extracts showed MICs of 6.2 ± 0.03 mg/mL for S. aureus and 6.1 ± 0.05 mg/mL for P. aeruginosa. The leaf extracts had MICs of 6.3 ± 0.02 mg/mL and 6.3 ± 0.01 mg/mL against the same bacteria, respectively. The results suggest that the extracts have a strong ability to prevent the growth of bacteria.

B. polystachya stem extracts had MBCs of 12.1 ± 0.09 mg/mL for S. aureus and 12.9 ± 0.02 mg/mL for P. aeruginosa. B. polystachya leaf extracts exhibited MBCs of 12.5 ± 0.02 mg/mL and 12.5 ± 0.06 mg/mL against the same bacteria, respectively. The close proximity of MIC to MBC values for both extracts indicate strong bactericidal effectiveness, capable of not only inhibiting but also completely eliminating bacterial cells at concentrations somewhat higher than the MICs. The low standard deviations highlight the accuracy of these data.

The preliminary findings indicate that the plant extracts, particularly B. polystachya (stem) extracts, have significant antibacterial properties that justify further investigation. It is essential to isolate and structurally elucidate the phytochemical components of these extracts to comprehend the factors behind their antibacterial effects. This study confirms the strong antibacterial properties of the plant extracts, suggesting the existence of bioactive chemicals that could be used as templates for developing novel antimicrobial medicines.

This research evaluated the cytotoxic effects of the extracts of stems and leaves of B. polystachya plant compared to doxorubicin and camptothecin on various cancer cell lines including breast carcinoma (MCF7), colorectal adenocarcinoma (HT29), and hepatocellular carcinoma (HepG2), and normal fibroblast (MRC5). Cytotoxic activities of B. polystachya extracts are summarized in Table 4.

B. polystachya stem extracts showed high to moderate cytotoxicity with IC50 values of 8.18 ± 0.72 µg/ml, 18.20 ± 0.93 µg/ml, and 25.55 ± 1.42 µg/ml against MCF7, HT29, and HepG2 cell lines, respectively. B. polystachya leaves extract showed moderate to low cytotoxicity in various cancer cell lines, with IC50 values of 34.37 ± 3.43 µg/ml for MCF7, 40.97 ± 0.39 µg/ml for HT29, and 18.38 ± 0.41 µg/ml for HepG2. The average IC50 values for B. polystachya extracts from the stem and leaves against the cancer cell lines were determined to be 17.31 µg/ml and 31.24 µg/ml, respectively. As expected, the used reference compound (doxorubicin) showed stronger cytotoxicity with IC50 values of 0.07 ± 0.01 µg/ml, 1.98 ± 0.10 µg/ml, and 2.15 ± 0.15 µg/ml against MCF7, HT29, and HepG2 cell lines, respectively. Camptothecin also exhibited notable cytotoxicity with IC50 values of 0.08 ± 0.01 µg/ml, 2.50 ± 0.26 µg/ml, and 0.76 ± 0.07 µg/ml against the cancer cell lines.

Extracts of the stems and leaves of Buddleja polystachya have significant antimicrobial and cytotoxic potential, according to the study’s results. The phytochemical composition of the sample was determined through GC-MS analysis to be diverse, comprising steroidal components, phenolic derivatives, carbohydrates, and fatty acids. These constituents are responsible for the observed biological activities. The comprehensive results of this investigation regarding the antimicrobial and cytotoxic properties of B. polystachya extracts are presented. It emphasizes the notable antibacterial characteristics of the plant, particularly in stem extracts, which are effective against common bacteria that cause ophthalmic infections. Further, the cytotoxic analysis demonstrates the stem extract’s specific effectiveness against various cancer cell lines, thereby emphasizing its potential as a therapeutic agent for cancer. Further research is required to isolate and purify the bioactive constituents of B. polystachya, and to test the pure compounds against normal and human microbial flora, other normal cells, and resistant cells and microorganisms, in addition to investigating their mechanism of action including combination studies. Regarding clinical investigations, successful hits would be employed in multiple eye models, including cornea and eye lens. All this could provide a potentially fruitful avenue for the development of innovative antimicrobial and anticancer therapies, specifically for the benefit of ocular health and cancer therapy.