Pentacyclic Triterpenoids, Phytosteroids and Fatty Acid Isolated from the Stem-bark of Cola lateritia K. Schum. (Sterculiaceae) of Cameroon origin; Evaluation of Their Antibacterial Activity

The phytochemical investigation on the chemical constituents of dichloromethane-methanol (1:1) stem-bark extract ofCola lateritiaK. Schum. (Sterculiaceae) led to the isolationand characterization of five pentacyclic triterpenoids, one fatty acid and two phytosteroids. Thecompounds were identified as heptadecanoic acid (1), maslinic acid (2), betulinic acid (3), lupenone(4), lupeol (5), friedelin (6),b-stigmasterol (7) andß-sitosterol-3-O-ß-D-glucoside (8). Their struc-tures were determined by NMR analysis (1H,13C, DEPT-135, COSY, HMBC and HSQC), high-resolution mass spectrometry (HR-ESI-MS) and comparisons with published data in the literature.This work, to the best of our knowledge, is the first isolation and identification of these compoundsin pure forms fromCola lateritia. Also, compounds1–3are reported for the first time fromColagenus.In vitroantibacterial activity of the isolated compounds (1–8) and the crude extract wereevaluated againstBacillus subtilis,Staphylococcus epidermidis,Enterococcus faecalis,Mycobacterium smegmatis,Staphylococcus aureus,Enterobacter cloacae,Klebsiella oxytoca,Proteusvulgaris,Klebsiella pneumonia,Escherichia coli, Proteus mirabilisandKlebsiella aerogeneswithstreptomycin, nalidixic acid and ampicillin as standard antibacterial drugs. Compound2was activeagainstE. faecalis(MIC = 18.5mg/mL), and it was 6.9 and 28 times lower and active than that ofstreptomycin (MIC 128mg/mL) and nalidixic acid (MIC>512mg/mL) respectively. All the isolatedcompounds and crude extract showed significant activities against the tested bacterial strains.National Research Foundatio

Endoplasmic reticulum stress in pancreatic β-cell dysfunction: The potential therapeutic role of dietary flavonoids

Diabetes mellitus (DM) is a global health burden that is characterized by the loss or dysfunction of pancreatic β-cells. In pancreatic β-cells, endoplasmic reticulum (ER) stress is a fact of life that contributes to β-cell loss or dysfunction. Despite recent advances in research, the existing treatment approaches such as lifestyle modification and use of conventional therapeutics could not prevent the loss or dysfunction of pancreatic β-cells to abrogate the disease progression. Therefore, targeting ER stress and the consequent unfolded protein response (UPR) in pancreatic β-cells may be a potential therapeutic strategy for diabetes treatment. Dietary phytochemicals have therapeutic applications in human health owing to their broad spectrum of biochemical and pharmacological activities. Flavonoids, which are commonly obtained from fruits and vegetables worldwide, have shown promising prospects in alleviating ER stress. Dietary flavonoids including quercetin, kaempferol, myricetin, isorhamnetin, fisetin, icariin, apigenin, apigetrin, vitexin, baicalein, baicalin, nobiletin hesperidin, naringenin, epigallocatechin 3-O-gallate hesperidin (EGCG), tectorigenin, liquiritigenin, and acacetin have shown inhibitory effects on ER stress in pancreatic β-cells. Dietary flavonoids modulate ER stress signaling components, chaperone proteins, transcription factors, oxidative stress, autophagy, apoptosis, and inflammatory responses to exert their pharmacological effects on pancreatic β-cells ER stress. This review focuses on the role of dietary flavonoids as potential therapeutic adjuvants in preserving pancreatic β-cells from ER stress. Highlights of the underlying mechanisms of action are also presented as well as possible strategies for clinical translation in the management of DM