In Silico Molecular Docking Analysis, Cytotoxicity, and Antibacterial Activities of Constituents of Fruits of Cucumis dipsaceus.

Cucumis dipsaceus (Cucurbitaceae) is a plant traditionally used against diarrhea, teeth-ach, wounds, stomach ache, meningitis, and cancer. The extracts of C. dipsaceus after silica gel column chromatography gave nine compounds identified using spectroscopic methods such as hexacosane (1), octadecane (2), 17-(-5-ethyl-2,6-dihydroxy-6-methylhept-3-en-2-yl)-9-(hydroxymethyl)-13-methylcyclopenta[α]phenanthren-3-ol (3), erythrodiol (4), (9,12)-propyl icosa-9,12-dienoate (5), α-spinasterol (6), 16-dehydroxycucurbitacin (7), cucurbitacin D (8), and 23,24-dihydroisocucurbitacin D (9). Compounds 3 and 4 are new to the genus Cucumis. α-Spinasterol showed better inhibition zone diameter = 13.67 ± 0.57, 15.00 ± 0.10, and 13.33 ± 0.57 mm against Escherichia coli, Pseudomonas aeruginosa, and Streptococcus pyogenes compared with the other tested samples. α-Spinasterol (-8.0 kcal/mol) and 3 (-7.6 kcal/mol) displayed high binding affinity against DNA Gyrase compared to ciprofloxacin (-7.3 kcal/mol). α-Spinasterol and 16-dehydroxycucurbitacin showed better binding affinity against protein kinase. The cytotoxicity results revealed that the EtOAc extract showed the highest potency with IC50 = 16.05 µg/mL. 16-Dehydroxycucurbitacin showed a higher binding affinity (-7.7 kcal/mol) against human topoisomerase IIß than etoposide. The cytotoxicity and antibacterial activities and in silico molecular docking analysis displayed by the constituents corroborate the traditional use of the plant against bacteria and cancer.

Molecular docking analysis and evaluation of the antibacterial and antioxidant activities of the constituents of Ocimum cufodontii.

Ocimum cufodontii ((Lanza) A.J.Paton) has been traditionally used in Ethiopia against bacteria. The extracts of the leaves and roots of O. cufodontii after silica gel column chromatography furnished compounds 1-5, compounds 3 and 4 are new natural products. The oil from the hydro-distillation of the leaves, after analyzed with GC-MS, has led to the identification of ß-caryophyllene as a principal component, suggesting the essential oil as medicine and spices to enhance the taste of food. The constituents of O. cufodontii were assessed for their antibacterial activity against E. coli, K. pneumonia, S. typhymurium and S. aureus. The best activity was displayed against S. aureus by the hexane extract of the roots, compound 4, and the essential oil with an inhibition zone of 17, 15, and 19 mm, respectively. Molecular docking analysis revealed that compound 1 has better docking efficiency and forms hydrophobic interactions with five amino acids (ARG192, PHE196, GLU185, GLU193, and LYS189). This suggests that the compounds may act as potential inhibitors of DNA gyrase. The constituents were also assessed for their antioxidant activities using DPPH, ferric thicyanate and ferric reducing power assay. The hexane extracts of the roots inhibited the DPPH radical and peroxide formation by 90.5 and 83%, respectively, suggesting the potential of the extract as an antioxidant. Furthermore, the hexane extract of the roots of O. cufodontii exhibited the maximum reducing power compared with the EtOAc and methanol extracts. Hence, the activity displayed herein indicated as the plant has great potential as a remedy for diseases caused by bacteria and radicals.

Chemical Constituents of Root Barks of Gnidia involucrata and Evaluation for Antibacterial and Antioxidant Activities.

The genus Gnidia, with species close to 152, is traditionally used to treat wide ranges of ailments in humans and animals. Gnidia involucrata is one of the species found in Ethiopia and traditionally used as a laxative, antirheumatic agent, insecticide, antibacterial agent, and antimalarial agent. In view of its traditional use, the root bark was sequentially extracted with n-hexane, EtOAc, and MeOH to afford 0.78%, 4%, and 6% crude extracts, respectively. The chromatographic separation of the EtOAc extract using silica gel column chromatography yielded three pure compounds: tetratriacontanyl caffeate (1), 12-O-dodeca-2,4-dienoylphorbol-13-acetate (2), and naringenin (3). This is the first report of the isolation of 1 and its kind from the genus and most probably from the Thymelaeaceae family. The structures of these compounds were characterized and identified by NMR and mass spectrometric analyses and comparison with literature data. The EtOAc extract and isolated compounds were assessed for their in vitro antibacterial and antioxidant activities. The EtOAc extract (1.5 mg/mL) showed significant inhibitory activity against S. aureus, E. coli, P. mirabilis, and K. pneumonia bacterial strains with the highest inhibition zone observed against S. aureus (23 mm), which is even greater than that of the reference drug ciprofloxacin (22 mm). However, the inhibition displayed on these bacterial strains for the three pure compounds was marginal with variable degrees of potency between the compounds. The better activity of the crude extract could be due to the synergistic interactions of several phytochemicals present in the extract, which cannot be the case when pure compounds are evaluated alone. The antioxidant activities of the extracts and isolated compounds were evaluated using DPPH and ferric thiocyanate methods. The EtOAc and MeOH extracts and compounds 1 and 2 were found to inhibit the DPPH radical by 70.7, 66.9, 85.8, and 52.8%, respectively. The EtOAc extract and compound 1 inhibited peroxidation of lipids by 84 and 86%, respectively. The radical scavenging displayed by compound 1 was significant compared with that displayed by ascorbic acid, indicating the strong antilipid peroxidation potential of the extract of root barks of G. involucrata. Therefore, the extracts of the root bark of G. involucrata can be used as a remedy in combating diseases caused by bacteria and free radicals provided that further comprehensive evaluation could be recommended for the conclusive decision on potential candidacy of this plant.

Composition of the essential oil of the liverwort Radula perrottetii of Japanese origin.

Analysis of the essential oil of the liverwort Radula perrottetii afforded two novel viscidane diterpenes, viscida-3,9,14-triene (1), viscida-3,11(18),14-triene (2), four bisabolane sesquiterpenes, bisabola-2,6,11-triene (3), bisabola-1,3,5,7(14),11-pentaene (4), bisabola-1,3,5,7,11-pentaene (5), 6,7-epoxybisabola-2,11-diene (6), and 1-methoxy-4-(2-methylpropenyl)benzene (7) as new natural products. In addition, the known compounds bisabola-1,3,5,7(14),10-pentaene (8), ar-tenuifolene (9), alpha-helmiscapene (10), and beta-helmiscapene (11) were also isolated. Isolation was carried out by preparative gas chromatography, and the structures were established by extensive NMR analysis. This is the first finding of viscidane diterpenes in liverworts. Compounds 8, 9 and the rarely encountered eudesmane sesquiterpene hydrocarbons 10 and 11 are reported for the first time from R. perrottetii.

Secondary metabolites of Peucedanum tauricum fruits.

From the essential oil of fruits of Peucedanum tauricum Bieb., two guaiane type sesquiterpene hydrocarbons guaia-1(10),11-diene (1) and guaia-9,11-diene (2) were identified. The structures of 1 and 2 were assigned by 1D and 2D NMR analysis. The relative configurations of the compounds were established by 2D-NOESY experiments while the absolute configurations were deduced through chemical correlations with (+)-gamma-gurjunene (9) and capillary GC analysis using modified cyclodextrins as the stationary phases. From the dichloromethane extract of the less volatile fraction of the fruits, coumarins, viz. peucedanin (3), oxypeucedanin hydrate (4) and officinalin isobutyrate (5) were isolated. Compound 5 was confirmed to be 6-carbomethoxy-7-isobutyroxycoumarin by its 1D and 2D NMR data as well as by conversion into officinalin (7) by alkaline hydrolysis. Peuruthenicin, a positional isomer of officinalin, is assigned structure 8 on spectral basis. Bergapten (6) was identified by its mass spectrum. This is the first report on the isolation of compounds 4 and 5 from P. tauricum.

Terpenes from Otostegia integrifolia.

The essential oil and chloroform extract of air-dried leaves of Otostegia integrifolia Benth. were investigated for the first time using analytical and preparative gas chromatography (GC), GC-mass spectrometry (MS) and NMR techniques. A total of 40 constituents including monoterpenes, sesquiterpenes, diterpenes and their derivatives were identified. A prenylbisabolane type diterpene, 1-methyl-4-(5,9-dimethyl-1-methylene-deca-4,8-dienyl)cyclohexene was identified as a major component. The chloroform extract of the leaves yielded two labdane type diterpenoids, 15,16-epoxy-3alpha,9alpha-dihydroxy-labda-13(16),14-diene and 9(13),15(16)-diepoxy-3alpha-hydroxy-16-dihydrolabda-14-ene, a saturated hydrocarbon, pentatriacontane, and stigmasterol. The structures of the isolated compounds were established by spectroscopic methods.