Antimicrobial studies of the leaf extract of Argemone mexicana and its ointment formulation

Background: Skin infections are rampant in children and there is a widespread resistance to common antibacterial and antifungal therapies for these infections.

Objective: This study aims to screen the extract of Argemone mexicana leaf for antibacterial and antifungal activity; and formulate the extract into ointment dosage forms using simple ointment B.P.C.

Methods: Preliminary phytochemical studies were performed and the methanol, ethanol and n-hexane leaf extracts of Argemone mexicana Linn. were evaluated for antimicrobial activity against some pathogenic bacteria- Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia(Gram negative) and Streptococcus spp, Staphylococcus aureus (Gram positive) and dermatophytes such as Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum audouinii (fungi) using well diffusion method. The most active extract was formulated into ointment and evaluated for physicochemical and antimicrobial activity.

Results: Flavonoids and alkaloids were present in all the extracts while anthraquinones and saponin were present in methanol and n hexane extract. The ranking for extract activity was methanol>n- hexane> ethanol. The methanol extract showed comparable activity with gentamicin against Staphylococcus aureus and higher activity against Escherichia coli at 250mg/ml and 500mg/ml. The order of activity of the methanol extract against the test organisms is Staphylococcus aureus> Escherichia coli> Streptococcus spp> Klebsiella pneumonia> Trichophyton mentagrophyte> Trichophyton rubrums> Microsporum audouinii. There was no significant variation (P> 0.05) in the zones of inhibition of bacteria with the methanol extract. The formulated ointment had a characteristic odour, smooth texture, was easy to apply on rubbing, easy to remove with soap and water and non-irritant on skin.

Conclusion: The result of this study supports the traditional uses of these plants and shows that the plant extract possesses antibacterial and antifungal activities

背景：儿童皮肤感染高发，且此类感染对常用抗菌及抗真菌治疗普遍存在耐药性。

目的：本研究旨在筛选墨西哥蓟罂粟（Argemone mexicana）叶提取物的抗菌与抗真菌活性，并采用英国药典处方（B.P.C.）基质将该提取物制备为软膏剂型。

方法：开展前期植物化学研究，采用打孔扩散法（well diffusion method），对墨西哥蓟罂粟（Argemone mexicana Linn.）叶的甲醇、乙醇及正己烷提取物进行抗菌活性评价，测试菌株包括革兰氏阴性（Gram negative）致病菌：铜绿假单胞菌（Pseudomonas aeruginosa）、大肠埃希菌（Escherichia coli）、肺炎克雷伯菌（Klebsiella pneumonia），以及革兰氏阳性（Gram positive）致病菌：链球菌属（Streptococcus spp.）、金黄色葡萄球菌（Staphylococcus aureus），还包括须毛癣菌（Trichophyton mentagrophytes）、红色毛癣菌（Trichophyton rubrum）、奥杜盎小孢子菌（Microsporum audouinii）等皮肤癣菌。选取活性最优的提取物制备为软膏，并对其理化性质与抗菌活性进行评价。

结果：所有提取物中均检出黄酮类（flavonoids）与生物碱类（alkaloids）成分，甲醇及正己烷提取物中额外含有蒽醌类（anthraquinones）与皂苷类（saponin）成分。提取物的活性排序为甲醇提取物＞正己烷提取物＞乙醇提取物。在250mg/ml与500mg/ml浓度下，甲醇提取物对金黄色葡萄球菌的抑菌活性与庆大霉素（gentamicin）相当，对大肠埃希菌的抑菌活性则更优。甲醇提取物对各受试菌株的活性强弱顺序为：金黄色葡萄球菌＞大肠埃希菌＞链球菌属＞肺炎克雷伯菌＞须毛癣菌＞红色毛癣菌＞奥杜盎小孢子菌。甲醇提取物对各细菌的抑菌圈直径无显著差异（P＞0.05）。制备得到的软膏具有特征性气味、质地细腻，涂抹时顺滑易推，可通过肥皂水轻松清洗，且对皮肤无刺激性。

结论：本研究结果印证了该植物的传统使用价值，并证实其提取物具备抗菌与抗真菌活性。