Antimycobacterial activities, cytotoxicity and phytochemical screening of extracts for three medicinal plants growing in Kenya

Abstract

Tuberculosis (TB), an airborne disease, is among the ten leading deadly diseases worldwide. Despite the efforts of WHO and its partners to eradicate it, it is still a public health issue especially with the rise of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). Commiphora species (Burseraceae family) are known in the Kenyan traditional medicine to treat respiratory diseases including TB. In the search of new anti-TB alternative drugs, plant materials from Commiphora mildbraedii Engl. (root bark and stem bark), Commiphora edulis (Klotzsch) Engl. (stem bark and leaves) and C. ellenbeckii Engl. (Stem bark and leaves) were tested for antimycobacterial activity, cytotoxicity and phytochemistry. 100 g of the powdered plant materials were macerated using the serial method with solvents of increasing polarity. Aqueous extraction was carried out by decoction. The microbroth dilution method was used to determine the antimycobacterial activity (MIC) against a model Mycobacterium smegmatis ATCC607 while the cytotoxicity evaluation (CC 50 ) was carried out using the MTT assay. The most active extract was fractionated using preparative TLC and fractions were analysed by GC-MS. Thirty extracts were obtained from the 6 different plant materials and eleven of them exhibited the antimycobacterial activity with the methanolic extracts of the stem and root bark of C. mildbraedii, and the aqueous extract of the C. ellenbeckii leaves exhibiting high activities (MIC= 0.39, 0.78 and 0.78 mg/L respectively). The MTT assay showed no or low cytotoxicity. The GC-MS analysis of the preparative TLC fractions from the methanolic extract of C. mildbraedii revealed the presence of 42 compounds belonging to 10 different classes of phytochemicals. Lup-20(29)-en-3-one and o-xylene were the most abundant. Except o-xylene and α-terpineol, all the compounds were detected for the first time in the Commiphora genus. These findings justify the ethnomedicinal uses of Commiphora species in TB treatment.

Phytochemical characterization and antimicrobial activity of Nigella sativa seeds

“…sativa seeds volatile oil and it mirrored its isomer (decane) which is detected in the named extract under study [ 39 ]. In another study done by François et al [ 32 ] based on other medicinal plants (commiphora species), decane and o-xylene have been detected in extracts using the GC-MS and these results agreed with the findings of the current study. Previous pharmacological studies done on N .…”

“…It has also been reported that ndecane is among the main components of N. sativa seeds volatile oil and it mirrored its isomer (decane) which is detected in the named extract under study [39]. In another study done by Franc ¸ois et al [32] based on other medicinal plants (commiphora species), decane and oxylene have been detected in extracts using the GC-MS and these results agreed with the findings of the current study. Previous pharmacological studies done on N. sativa seeds and their extracts well attributed them as food flavoring agents and appetite stimulants or suppressants.…”

“…The results of the present study showed that N. sativa seeds are great reservoirs of medicinally active ingredients (phytochemicals) and they are consistent with earlier phytochemical screening studies done on different solvent extracts and oil of N. sativa seeds which also reported that N. sativa seeds or extracts and oil are rich in the above-mentioned phytoconstituents [1,31]. Bioactive constituents such as alkaloids, flavonoids, phenols, tannins and terpenoids are known to elicit broad antimicrobial responses against bacteria, fungi, viruses and parasites [3,17,32,33]. A number of studies documented that these phytochemicals also…”

“…sativa seeds or extracts and oil are rich in the above-mentioned phytoconstituents [ 1 , 31 ]. Bioactive constituents such as alkaloids, flavonoids, phenols, tannins and terpenoids are known to elicit broad antimicrobial responses against bacteria, fungi, viruses and parasites [ 3 , 17 , 32 , 33 ]. A number of studies documented that these phytochemicals also possess many pharmacological properties, including but not limited to anticancer, antioxidant, anti-inflammatory, cytotoxicity, anti-diarrheal, anti-hemostatic, anti-hemorrhoidal, anti-apoptosis, anti-aging, and growth regulation [ 31 , 34 ].…”

Chemical Profiles of Herbal Compress and Their Persistence Affected by Steaming and Storage Time

“…α-Terpinyl acetate in plai has exhibited anticholinesterase activity, and it has proved to be a neuroprotective agent in in vitro studies [28]. Tetradecane is identified in extracts of plai, lemongrass, and soap pod, and it is reported to have antifungal and antibacterial activities [29,30]. Caryophyllene and β-bisabolene are sesquiterpenes that are identified in essential oils extracted from kaffir lime, turmeric, lemongrass, and plai.…”