Melanin Synthesis Inhibition Activity of Compounds Isolated from Bamboo Shoot Skin (Phyllostachys pubescens).

This study targets the evaluation of melanin synthesis inhibition activity of the bamboo shoot skin as agro-waste. The total methanolic extract of bamboo peel extract was evaluated for its skin protective effects via measuring its melanin inhibitory activity and its suppression activity on the expression of tyrosinase mRNA levels. Results showed that bamboo peel extract has a good ability for the inhibition of melanin synthesis so further studies were performed for the isolation of its constituents. Twelve compounds have been isolated from the shoot skin of Phyllostachys pubescens. Their structures were elucidated based on extensive spectroscopic methods. The melanin inhibition potential of the isolates was tested with their collagen-production-promoting activity for the determination of active principles. Results showed that Betulinic acid, tachioside, and 1,2-dilinolenin significantly suppressed melanin production per cell compared to control. Triacontanol, tricin, and (+)-lyoniresinol 9'-O-glucoside also tended to decrease melanin production per cell. These findings indicated that the skin of bamboo shoots, a significant agricultural waste, is a useful natural source for further research on its potential for aging problems such hyperpigmentation and cognitive function impairment.

New quinolizidine alkaloid and insecticidal activity of Sophora secundiflora and Sophora tomentosa against Culex pipiens (Diptera: Culicidae).

Phytochemical investigation of Sophora secundiflora alkaloid fraction led to isolation of one new quinolizidine alkaloid (1) 13-methoxyanagyrine together with six known ones (2-7). The insecticidal activity of 70% methanol extract of leaves of S. secundiflora, S. tomentosa and the isolated alkaloids were assessed against 3rd instar larvae of Culex pipiens (Diptera: Culicidae) using different concentrations and mortality rate was recorded. Sophora tomentosa extract showed highest mortality rate with median lethal concentration LC50 3.11 ppm after 24 h and 0.66 ppm after 48 h and anagyrine (6) exhibited remarkably insecticidal activity with LC50 value of 3.42 ppm after 24 h of exposure. Additionally, cytotoxic activity of alkaloid fraction of S. secundiflora, S. tomentosa and isolated alkaloids was also studied using crystal violet assay against MCF-7 and HEPG-2 cell lines. Anagyrine (6) exhibited IC50 values of 27.3 ± 0.7 and 30.2 ± 0.9 µg/mL against MCF-7 and HEPG-2 cancer cells, respectively.

Suppression of cytokine production by newly isolated flavonoids from pepper.

New flavonoid glycoside, kaempferol 3-O-α-[(6-P-coumaroyl galactopyranosyl-O-ß-(→4)-O-α-rhamnopyranosyl-(1→4)]-O-α-rhamnopyranoside 1, in addition to five known flavonoid glycosides (2-6) kaempferol 3-O-[α-rhamnopyranosyl-(1→4)-O-α-rhamnopyranosyl-(1→6)-O]-ß-galactopyranoside (kaempferol 3-O-ß-isorhamninoside) 2, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1 â†’ 6)-ß-galactopyranoside 3, quercetin 3-O-[(2,4-diacetyl-α-rhamnopyranosyl)-(1 â†’ 6)]-3,4-diacetyl-ß-galactopyranoside 4, quercetin 3-O-[(2,4-diacetyl-α-rhamnopyranosyl)-(1→6)]-2,4-diacetyl-ß-galactopyranoside 5, quercetin 3-O-[(2,3,4-triacetyl-α-rhamnopyranosyl)-(1 â†’ 6)-3-acetyl-ß-galactopyranoside 6 were isolated from bell pepper (Capsicum annum L.) fruits and tested for both anti-inflammatory activity through cytokine production (TNF-α and IL-1ß) and antioxidant activity through scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Compounds 1-3 significantly suppressed production of TNF-α / IL-1ß in cultured THP-1 cells previously co-stimulated by LPS in a dose-dependent manner (10.2/49.1, 28.1/55.7, and 35.2/57.5 µM respectively) whereas compounds 4-6 have relatively weaker inhibitory activity. (45.3/73.5, 48.2/65.6, and 42.2/67.4 µM respectively). All compounds 1-6 showed no cytotoxic activity against the growth of THP-1where the percentage of cell viability was (127.4, 108.5, 105.4, 103.9, 103.4, and 104.2 µM respectively). All isolated compounds exhibited higher radical scavenging activity than ascorbic acid in (DPPH) assay. These results indicated that bell pepper fruits could be an effective candidate for ameliorating inflammatory-associated complications.

In silico study of natural compounds from sesame against COVID-19 by targeting Mpro, PLpro and RdRp.

Natural products and traditional medicine products with known safety profiles are a promising source for the discovery of new drug leads. Natural products as sesame were reported to exhibit potential to protect from COVID-19 disease. In our study, the total methanolic extract of Sesamum indicum L. seeds (sesame) were led to isolation of seven known compounds, five lignan; sesamin 1, sesamolin 2, pinoresinol 3, hydroxymatairesinol 6, spicatolignan 7, together with two simple phenolic compounds; ferulic acid 4 and vanillic acid 5. All isolated compounds were evaluated in silico against three important SARS-CoV-2 protein targets; main protease (Mpro), papain-like protease (PLpro) and RNA-dependent RNA polymerase (RdRp) which possessed crucial role in replication and proliferation of the virus inside the human cell. The results revealed that compound 6 has the high affinity against the three main proteins, specially towards the SARS-CoV-2 Mpro that exceeded the currently used SARS-CoV-2 Mpro inhibitor darunavir as well as, exhibiting a similar binding energy at SARS CoV-2 PLpro when compared with the co-crystallized ligand. This activity continued to include the RdRp as it displayed a comparable docking score with remdesivir. Inferiorly, compounds 1 and 2 showed also similar triple inhibitory effect against the three main proteins while compound 7 exhibited a dual inhibitory effect against SARS CoV-2 PLPro and RdRp. Further molecular dynamic simulation experiments were performed to validate these docking experiments and to calculate their binding free energies (ΔGs). Compounds 1, 2, 3, 6, and 7 showed comparable binding stability inside the active site of each enzyme with ΔG values ranged from -4.9 to -8.8 kcal mol-1. All the compounds were investigated for their ADME and drug likeness properties, which showed acceptable ADME properties and obeying Lipinski's rule of five parameters. It can be concluded that the isolated compounds from sesame lignans could be an alternative source for the development of new natural leads against COVID-19.

Forsskamide, a new ceramide from aerial parts of Forsskaolea tenacissima Linn.

Although the various folk medicine uses and the biological activity of Forsskaolea tenacissima L., few chemical constituents of this plant have been reported, this provoked us to make our study. Forsskamide, a new ceramide was isolated from aerial parts of F. tenacissima L. (Urticaceae). The chemical structure was established by different spectroscopic methods (1H, 13C-NMR, HMBC, HSQC, ROESY, FAB-MS and HR-FAB-MS). Forsskamide showed a moderate cytotoxic activity by (MTT) method against human colorectal carcinoma cell line (HCT-116) with IC50 33.25 µM in comparison with 5-fluorouracil IC50 26.42 µM. While, it did not show any activity against human hepatocarcinaoma cell line (HepG-2).

Suppression of melanin synthesis by the phenolic constituents of sappanwood (Caesalpinia sappan).

Sappanwood (Caesalpinia sappan Linn.) is used as an herbal medicine. It is sometimes used to treat skin damage or as a facial cleanser. In the present study, the methanol (MeOH) extract of sappanwood was found to inhibit melanin synthesis in cultured human melanoma HMV-II cells stimulated with forskolin, and six active compounds (1-5 and 7) were isolated from the extract along with a non-active compound (6). Compounds 2-7 were identified as sappanchalcone (2), 3'-deoxy-4-O-methylsappanol (3), brazilein, (4), brazilin (5), sappanol (6), and 4-O-methylsappanol (7). Compound 1 was a new compound, and its structure was determined to be (6aS,11bR)-7,11b-dihydro-6H-indeno[2,1-c]chromene-3,6a,10,11-tetrol by spectroscopic analyses. Among the six active compounds, brazilin (5) (EC50: 3.0 ± 0.5 µM) and 4-O-methylsappanol (7) (EC50: 4.6 ± 0.7 µM) strongly suppressed melanin synthesis in HMV-II cells. Bioactive compounds showed moderate cytotoxicities against HMV-II cells with IC50 values of 83.1 ± 4.0 µM (for 2), 72.0 µM ± 2.4 (for 3), 33.8 ± 1.1 µM (for 4), 18.4 ± 0.8 µM (for 5), and 20.2 ± 0.8 (for 7), respectively. Brazilin (5) selectively suppressed the expression of mRNAs for tyrosinase-related protein (TYRP) 2 and tyrosinase but did not influence the expression of TYRP1. These results suggest that brazilin (5) is a new class of melanin inhibitor and that sappanwood could be used as a cosmetic material.

Two new acetylated flavonoid glycosides from Centaurium spicatum L.

Two new acetylated flavonol glycosides, quercetin 3-O-[(2,4-diacetyl-α-L-rhamnopyranosyl)-(1→6)]-2,4-diacetyl-ß-D-galactopyranoside (1) and quercetin 3-O-[(2,4-diacetyl-α-L-rhamnopyranosyl)-(1→6)]-3,4-diacetyl-ß-D-galactopyranoside (2), in addition to two known acetylated quercetin glycosides quercetin 3-O-[(2,3,4-triacetyl-α-L-rhamnopyranosyl)-(1→6)-ß-D-galactopyranoside (3) and quercetin 3-O-[(2,3,4-triacetyl-α-L-rhamnopyranosyl)-(1→6)-3-acetyl-ß-D-galactopyranoside (4), were isolated from the aerial part of Centaurium spicatum (L.) Fritsch (Gentianaceae). Structure elucidation, especially the localization of the acetyl groups, and complete (1)H and (13)C NMR assignments of these biologically active compounds were carried out using one- and two-dimensional NMR measurements, including (1)H- and (13)C-NMR, DEPT-135, H-H COSY, HMQC and HMBC, in addition to HR-FAB/MS experiments.