Antioxidant and anti-inflammatory effects of Boswellia dalzielii and Hibiscus sabdariffa extracts in alloxan-induced diabetic rats

Diabetes mellitus (DM) is one of the leading worldwide public health problems. It is characterized by hyperglycemia which induces oxidative stress and inflammation, both involved in the pathogenesis of diabetes. We previously showed that Boswellia dalzielii (BD) and Hibiscus sabdariffa (HS) extracts reduced hyperglycemia and hyperlipidemia in alloxan-induced diabetic rats. In the present study, we evaluated the antioxidant and anti-inflammatory activities of both plants in alloxan-induced diabetic rats. Two sets of experiments were conducted in male Wistar rats subjected to a single intraperitoneal injection of alloxan monohydrate (150 mg/kg, b. w.). Then, diabetic rats were daily administered with either BD (1st set of experiments) or HS (2nd set of experiments) at 100, 200, and 400 mg/kg orally for 21 consecutive days. Glibenclamide (10 mg/kg) was also administered as a reference drug. At the end of the study, the animals were anesthetized, and blood samples were collected from each animal. Then, oxidative stress and inflammatory biomarkers in the serum were determined. We found that treatment with BD and HS significantly reduced malondialdehyde (MDA) and enhanced the levels of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT). These extracts also significantly decreased the inflammatory markers tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β). From the results obtained, it can therefore be concluded that BD and HS have the potential to being developed as natural sources of antioxidant and anti-inflammatory agents that can be used for the prevention or treatment of DM.

(Burseraceae) for antibacterial agents and a new glucopyranoxylmethoxybenzyle

Stem barks of Boswellia dalzielii are used traditionally for the treatment of various bacterial infections. A bioassay guided fractionation of the MeOH-CH₂Cl₂ (1/1, v/v) stem barks extract led to the isolation of fourteen compounds 1-14, identified based on spectroscopic data. Dalzienoside (1) is reported here for the first time. The broth microdilution method was used to evaluate the antibacterial activity of the crude extract, fractions and compounds against six bacterial strains. The crude extract exhibited moderate antibacterial activity with MIC of 250 μL/ml; two fractions showed significant activities with MICs ranging from 7.8 to 125 μg/ml, while α-boswellic acid (2), β-boswellic acid (3), acetyl-11-keto-β-boswellic acid (4) from these fractions exhibited strong activities with MIC value of 3.125 µg/mL against Staphylococcus aureus, Salmonella typhi, Enterobacter cloacae, Streptococcus pneumonia and Pseudomonia aeruginosa. This study gives insight into the antibacterial constituents of the stem bark of B. dalzielii and justifies its use in ethnomedicine.

Toxicological studies and bioactivity-guided identification of antimicrobially active compounds from crude aqueous stem bark extract of Boswellia dalzielii

OBJECTIVE

The main objective of this study is to isolate, identify, and quantify the active antimicrobial compounds present in the crude aqueous stem bark extract of B. dalzielii using some common pathogenic microorganisms as well as toxicological profile.

MATERIAL AND METHODS

Crude aqueous stem bark extract of Boswellia dalzielii (CASEB) was partitioned by preparative thin layer chromatography (PTLC) using chloroform-methanol-water, 8:2:1 (v/v). The resulting bands were extracted using chloroform-methanol (50:50). The extract of each band was evaluated for antimicrobial activity on Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Klebsiella pneumonia, Pseudomonas aeruginosa, Proteus mirabilis, Salmonella typhi, and Candida albicans by disc diffusion. Compounds in the most antimicrobially bioactive fraction (MAAF) were identified by high performance liquid chromatography (HPLC), Fourier transform infrared spectrophotometry (FT-IR), and gas chromatography-mass spectrometry (GC-MS). Toxicological profile of the CASEB was evaluated by studying its effect in albino Wister rats.

RESULTS

PTLC produced five bands/fractions of which the MAAF was identified as RF2-fraction being active against all the isolates except E. coli and K. pneumoniae. HPLC of the MAAF revealed seven components; FT-IR revealed 17 functional groups; GC-MS revealed five compounds of which 93.18% are Oleic acid (44.88%), Squalene (34.16%), and n-Hexadecanoic acid (14.14%). The acute toxicity showed LD50 > 3,000 mg/kg. Sub-chronic toxicity showed that higher doses of the CASEB caused significant changes in liver function indices and a fatty change with lymphocytic infiltration (sign of acute hepatitis) in the liver tissues, but none of these changes were observed in the kidneys.

CONCLUSION

The antimicrobially active compounds in CASEB were Oleic acid, Squalene, and n-Hexadecanoic acid. These can be further purified and used as precursors of new antimicrobial agents for treating infections especially those due to fungi and Pseudomonas spp. that are known to resist wide array of antimicrobial agents. The LD50 of CASEB is >3,000 mg/kg in rats. However, long-term consumption of CASEB is associated with significant liver damage.

Toxicity of Boswellia dalzielii (Burseraceae) Leaf Fractions Against Immature Stages of Anopheles gambiae (Giles) and Culex quinquefasciatus (Say) (Diptera: Culicidae)

Mosquitoes are vectors of several human pathogens, and great attention has recently been placed on insecticides from plant-derived products, in search for mosquito control agents. This study, thus, investigated the potency of Boswellia dalzielii methanol leaf extract and its four fractions as mosquito ovicide, larvicide, and pupicide against Anopheles gambiae and Culex quinquefasciatus. The plant products were tested at the following concentrations: 125, 250, 500, 1000, and 2000 ppm on eggs and 312.5, 625, 1250, and 2500 ppm on the larvae and pupae of the mosquitoes. For results, hatchability of A. gambiae eggs was reduced to 5% with n-hexane fraction at 2000 ppm. Among the plant products tested, n-hexane fraction was most toxic against A. gambiae (LC50 = 385.9 ppm) and C. quinquefasciatus (LC50 = 3394.9 ppm). The n-hexane fraction of B. dalzielii might be used as a mosquitocidal agent in the breeding sites of A. gambiae and C. quinquefasciatus.