Antihypernociceptive and Neuroprotective Effects of the Aqueous and Methanol Stem-Bark Extracts of Nauclea pobeguinii (Rubiaceae) on STZ-Induced Diabetic Neuropathic Pain

The greatest common and devastating complication of diabetes is painful neuropathy that can cause hyperalgesia and allodynia. It can disturb psychosocial functioning by increasing levels of anxiety and depression. This work was designed to evaluate the antihyperalgesic, antidepressant, and anxiolytic-like effects of the aqueous and methanol extracts of Nauclea pobeguinii stem-bark in diabetic neuropathy induced by streptozotocin in mice. Diabetic neuropathy was induced in mice by the intraperitoneal administration of 200 mg/kg streptozotocin (STZ) to provoke hyperglycemia. Nauclea pobeguinii aqueous and methanol extracts at the doses of 150 and 300 mg/kg were administered by oral route, and their effects were evaluated on antihyperalgesic activity (Von Frey filaments, hot plate, acetone, and formalin tests), blood glucose levels, body weight, serum, sciatic nerve proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and sciatic nerve growth factor (IGF and NGF) rates, depression (open field test, forced swimming test, tail suspension test), and anxiety (elevated plus maze, light-dark box test, social interaction). Oral administration of Nauclea pobeguinii stem-bark aqueous and methanol extracts (150 and 300 mg/kg) produced antihyperalgesic, antidepressant, and anxiolytic-like effects in STZ-induced diabetic neuropathic mice. Extracts also triggered a decrease in glycaemia and increased body weight in treated animals. They also significantly ( p <0.001) reduced tumour necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-6 and significantly ( p <0.001) increased nerve growth factor (NGF) and insulin-like growth factor (IGF) in sciatic nerves. The results of this study confirmed that Nauclea pobeguinii aqueous and methanol extracts possess antihyperalgesic, antidepressant, and anxiolytic activities and could be beneficial therapeutic agents.

Pobeguinine: a monoterpene indole alkaloid and other bioactive constituents from the stem bark of Nauclea pobeguinii

Phytochemical investigation of dichloromethane neutral phase of stem bark ofNauclea pobeguiniiled to the isolation of a new monoterpene indole alkaloid, pobeguinine1along with 14 known compounds including (−)-naucleofficine D (2a), (+)-naucleofficine D (2b), naucleidinal (3), quafrinoic acid (4), betulinic acid (5), ursolic acid (6), quinovic acid (7), quinovic acid 3-O-α-L-rhamnopyranoside (8a), quinovic acid 3-O-β-D-fucopyranoside (8b), β-sitosterol (9), β-sitosterol 3-O-β-D-glucopyranoside (10), benzoic acid (11), lacceroic acid (12) andn-heptacosane (13). The structure of compound1was unambiguously assigned on the basis of single-crystal X-ray diffraction technique. The Hirshfeld surface analysis was further carried out to quantitatively analyze the role of various types of hydrogen bonding in crystal stability. These structures were elucidated using spectroscopic methods. The isolates were evaluated for their radical scavenging properties as well as inhibitory activities against urease and tyrosinase enzymes with IC50values ranging from 13.4 to 58.9, 46.0 to 86.7 and 39.4 to 87.1 μg/mL, respectively. Compound6exhibited maximum radical scavenging activity with IC5013.4 μg/mL, while compound4exhibited maximum tyrosinase with IC5039.4 μg/mL. All the isolates showed moderate urease inhibition.

Analgesic, anti-inflammatory and anti-arthritic properties of aqueous and methanolic stem bark extracts from Nauclea pobeguinii (Rubiacee) in rats

Background Nauclea pobeguinii is a plant species found in the centre region of Cameroon. The stem bark of this plant is traditionally used to ease pain and cure inflammation. Method This study was undertaken to evaluate the effects of doses 150 and 300 mg/kg of the aqueous and methanolic stem bark extracts from Nauclea pobeguinii on acute pain, acute and chronic inflammation induced by formalin and arthritis induced by zymosan A in rats. Oxidative stress parameters such as catalase, malondialdehyde and nitric oxide were measured in rats subjected to chronic inflammation. The standard used was diclofenac at 5 mg/kg. Results Aqueous extract as well as methanolic extract of Nauclea pobeguinii led to a significant reduction in the second phase of formalin induced pain with 54.22 and 48.02% of inhibition percentage, respectively. The formalin-induced inflammatory oedema was reduced by both extracts, and this effect remains significant until the tenth day of treatment. Equally, extracts significantly increased the catalase activity and inhibited the production of malondialdehyde (MDA) in serum, brain and spinal cord and NO reduction only in serum. Both extracts significantly reduced the articular oedema induced by zymosan A for 6 h and for 5 days. Furthermore, the histological study of the articulations shows a non-altered synovial membrane and a small cartilage in all treated animals versus negative control group. Conclusions From these results, it can be concluded that pain, inflammation and arthritic healing activities of both stem bark extracts were expressed in rats and could conciliate the use of this vegetable by traditional African healers.

Antimicrobial Activities of a Plethora of Medicinal Plant Extracts and Hydrolates against Human Pathogens and Their Potential to Reverse Antibiotic Resistance

Microbial infections till date remain a scourge of humanity due to lack of vaccine against some infections, emergence of drug resistant phenotypes, and the resurgence of infections amongst others. Continuous quest for novel therapeutic approaches remains imperative. Here we (i) assessed the effects of extracts/hydrolates of some medicinal plants on pathogenic microorganisms and (ii) evaluated the inhibitory potential of the most active ones in combination with antibiotics. Extract E03 had the highest DZI (25 mm). Extracts E05 and E06 were active against all microorganisms tested. The MICs and MBCs of the methanol extracts ranged from 16.667 × 103 μg/mL to 2 μg/mL and hydrolates from 0.028 to 333333 ppm. Extract E30 had the highest activity especially againstS. saprophyticus(MIC of 6 ppm) andE. coli(MIC of 17 ppm). Combination with conventional antibiotics was shown to overcome resistance especially with E30. Analyses of the extracts revealed the presence of alkaloids, flavonoids, triterpenes, steroids, phenols, and saponins. These results justify the use of these plants in traditional medicine and the practice of supplementing decoctions/concoctions with conventional antibiotics.Nauclea pobeguinii (E30), the most active and synergistic of all these extracts, and some hydrolates with antimicrobial activity need further exploration for the development of novel antimicrobials.