The lack of treatment options for COVID-19 has raised many concerns among populations worldwide, which has led to many attempts to find alternative options to prevent the transmission of the disease or to alleviate the progression of the infection, including focusing more on preventive measures (to prevent transmission to other individuals) and the use of natural products and herbal extracts to increase immunity and decrease the probability of getting infected. This study explored the knowledge of the population of the Kingdom of Saudi Arabia (KSA) about COVID-19 preventive measures and their belief about the consumption of herbal products for the prevention of COVID-19 infection. A total of 5,258 individuals participated in this study. Participants’ knowledge about the appropriate COVID-19 preventive measures in terms of handwashing procedures, self-quarantine and social distancing was moderate, with a mean score of 5.5 (SD: 1.7) out of 10 (representing around 55.0% of the total score). About 22.1% (n= 1,161) of the participants reported that they have used herbal products or nutritional supplements during the pandemic period, to protect themselves from the disease. Social media and the Internet (39.4%, n= 372) were the main motivators for the participants to try herbal products. Vitamin C was the most commonly used food supplement to increase immunity and reduces the chance of contracting COVID-19. Our study demonstrated that the general population in Saudi Arabia has a moderate level of knowledge about COVID-19 transmission and preventive measures. A considerable proportion of the population reported the use of herbal products or food supplements in order to protect themselves from the disease. Policymakers are suggested to provide further educational campaigns that increase population knowledge about the disease transmission routes and preventive measures. In addition, the use of herbal products should be evidence-based to ensure patient safety.

Objectives: Considering the transmissible nature of COVID-19 it is important to explore the trend of the epidemiology of the disease in each country and act accordingly. This study aimed to examine the trend of COVID-19 epidemiology in the Kingdom of Saudi Arabia in term of its incidence rate, recovery rate, and mortality rate. Material and Methods: We conducted an observational study using publicly available national data taken from the Saudi Ministry of Health for the period between 3 March and 7 June 2020. The number of newly confirmed cases, active cases, critical cases, percentage of cases stratified by age group [adults, children, and elderly] and gender were extracted from the reports of the Saudi Ministry of Health. Results: During the study period, the total number of confirmed cases with COVID-19 rose from one on 2 March 2020 to 101,914 on 7 June, representing an average of 1,039 new cases per day, [trend test, p < 0.000]. Despite the increase in the number of newly confirmed daily cases of COVID-19, the number of reported daily active cases started to stabilize after 2 months from the start of the pandemic in the country and the overall recovery rate was 71.4%. The mortality rate decreased by 6.4% during the study period. COVID-19 was more common among adults and males compared to other demographic groups. Conclusion: The epidemiological status of COVID-19 in the Kingdom of Saudi Arabia showing promising improvement. Males and adults accounted for the majority of COVID-19 cases in the KSA. Further studies are recommended to be conducted at the patient level to identify other patient groups who are at higher risk of getting infected with COVID-19, and for whom the best pharmacological intervention could be provided.

Three new hellinoyl-type ellagitannins, nilotinins M4 (7), D7 (8), and D8 (9), and a new macrocyclic-type, nilotinin D9 (10), together with eight known tannins, hirtellins B (2), C (11), and F (12), isohirtellin C (13), tamarixinin A (3), tellimagrandins I and II, and 1,2,6-tri-O-galloyl-beta-d-glucose (14), were isolated from an aqueous acetone extract of Tamarix nilotica dried leaves. Nilotinin M4 (7) is a monomeric tannin possessing a hellinoyl moiety. The structure of 8 demonstrated replacement of one of the HHDP groups at the glucose core O-4/O-6 in ordinary dimeric tannins with a galloyl moiety at O-6. This is a new structural feature among the tamaricaceous ellagitannins. On the basis of the results, reported spectroscopic assignments for 2, 3, and the macrocyclic tannins 11-13 were revised. Unusual shifts in the NMR spectra of these macrocyclic tannins are also discussed in relation to their conformations. Several tannins isolated from T. nilotica were assessed for possible cytotoxic activity against four human tumor cell lines, and nilotinin D8 (9) and hirtellin A (1) showed high cytotoxic effects.

No abstract

Three new ellagitannin monomers, nilotinins M5-M7 (1-3), a dimer, nilotinin D10 (4), and a trimer, nilotinin T1 (5), together with three known dimers, hirtellin D (7) and tamarixinins B (8) and C (9), and a trimer, hirtellin T2 (6), were isolated from Tamarix nilotica dried leaves. The structures of the tannins were elucidated by intensive spectroscopic methods and chemical conversions into known tannins. The new trimer (5) is a unique macrocyclic type whose monomeric units are linked together by an isodehydrodigalloyl and two dehydrodigalloyl moieties. Additionally, dimeric and trimeric macrocyclic-type tannins isolated from T. nilotica in this study were assessed for possible cytotoxic activity against four human tumor cell lines. Tumor-selective cytotoxicities of the tested compounds were higher than those of synthetic and natural potent cytotoxic compounds, including polyphenols, and comparable with those of 5-fluorouracil and melphalan.

No abstract

Partially unacylated new oligomeric hydrolyzable tannins, nilotinin T2 (1, trimer) and nilotinin Q1 (2, tetramer), together with four known trimers, nilotinin T1 (3) and hirtellins T1-T3 (4-6), and a dimer, tamarixinin B (7), were isolated from the aqueous acetone extracts of leaves of Tamarix nilotica. Among them, the new trimer 1 and the known trimers 4 and 6, in addition to the partially unacylated new trimer nilotinin T3 (8), the known dimers nilotinin D3 (9) and tamarixinin C (10), and the monomer tellimagrandin I (11), were isolated from the cultured shoots of Tamarix tetrandra. The structures of the new hydrolyzable tannins were established by chromatographic analyses and extensive 1D and 2D NMR, HRESI-TOFMS, and ECD spectroscopic experiments. Among the new oligomeric tannins, the particular unacylated position of a glucose core is attributed to a possible biosynthetic route. Isolation of the same oligomeric tannins from cultured shoots of T. tetrandra emphasizes the unique biogenetic ability of the obtained cultures on production of the structurally and biologically characteristic tamaricaceous tannins commonly produced by the intact Tamarix plants. Additionally, tannins obtained in the present study together with gemin D (12) and 1,3-di-O-galloyl-4,6-O-(aS)-hexahydroxydiphenoyl-β-d-glucose (13), from our previous investigation of the leaves of T. nilotica, exhibited variable tumor-specific cytotoxic effects. The ellagitannin trimers 4, 6, and 8 and the dimer 9 exerted predominant tumor-selective cytotoxic effects with high specificity toward human promyelocytic leukemia cells.

Since our previous study revealed that several licorice phenolics have antibacterial effects on methicillin-resistant Staphylococcus aureus (MRSA), and suppressive effects on the oxacillin resistance of MRSA, we further investigated effectiveness of licorice constituents on vancomycin-resistant Enterococcus (VRE) bacteria, and purified 32 phenolic compounds. Two flavonoids among them were characterized structurally, and identified their structures as demethylglycyrol (31) and 5,7-di-O-methylluteone (32), respectively. Examination of antibacterial effects of licorice phenolics showed that 3-arylcoumarins such as licoarylcoumarin (9) and glycycoumarin (26), and 2-arylcoumarones such as gancaonin I (17), have moderate to potent antibacterial effects on the VRE strains used in this study.