Total Phenolic, Flavonoid Contents, and Antioxidant Activities of Fruit, Seed, and Bark Extracts of Zanthoxylum armatum DC.

Natural antioxidants present in several medicinal plants are responsible for inhibiting the harmful effects of oxidative stress. These plants contain polyphenols and flavonoids that act as free radical scavengers and reduce oxidative stress and may be an alternative remedy to cure various harmful human diseases. This study aims to quantify the total phenolic and flavonoid contents (TPC and TFC) and antioxidant properties of methanol extracts of fruits, seeds, and bark of an important medicinal and aromatic plant, Zanthoxylum armatum collected from wild and cultivated populations in Nepal. TPC was determined by Folin-Ciocalteu colorimetric method using gallic acid as standard, and various concentrations of the extract solutions were measured at 760 nm. TFC was calculated by aluminum chloride colorimetric assay. Quercetin was used as standard, and the absorbance was measured at 510 nm. The antioxidant potential of the different extracts was estimated by DPPH free radical scavenging assay, and the absorbance was measured at 517 nm. The highest TPC value was 226.3 ± 1.14 mg GAE/g in wild fruits, and the lowest was 137.72 ± 4.21 mg GAE/g in cultivated seeds. Similarly, the highest TFC value was 135.17 ± 2.02 mg QE/g in cultivated fruits, and the lowest was 76.58 ± 4.18 mg QE/g in cultivated seeds. The extracts showed variable antioxidant properties. The fruits exhibited excellent antioxidant properties with IC50 values of 40.62 µg/mL and 45.62 µg/mL for cultivated and wild fruits, respectively. Similarly, the IC50 values of the bark were 63.39 µg/mL and 67.82 µg/mL, respectively, for cultivated and wild samples. And the least antioxidant capacity was shown by the seeds extract with IC50 values of 86.75 µg/mL and 94.49 µg/mL for wild and cultivated seeds, respectively. The IC50 value of the standard ascorbic acid was 36.22 µg/mL. Different extracts of Z. armatum contain considerable amount of phenols and flavonoids, including antioxidant properties, suggesting the potential use of this species in pharmacy and phytotherapy as a source of natural antioxidants.

Phenolic-linked biochemical rationale for the anti-diabetic properties of Swertia chirayita (Roxb. ex Flem.) Karst.

The crude extract of Swertia chirayita, an important medicinal plant of Nepal, is locally used for many diseases including type 2 diabetes. In this study, crude aqueous and 12% ethanol solution extracts of S. chirayita collected from nine districts of Nepal were analyzed for anti-diabetic-linked anti-hyperglycemia potential using in vitro biochemical assays. There was moderate-to-high positive correlation between antioxidant activity and total phenolic content of both extracts and moderate-to-high α-glucosidase inhibitory activity. Although the anti-diabetic property of S. chirayita is mainly attributed to the phytochemical swerchirin present in its hexane fraction, we propose that the crude extract of this plant used in local healing also has anti-hyperglycemia potential. The crude extracts indicated the presence of three main phytochemicals mainly mangiferin, swertiamarin, and amarogentin and their derivatives. Among the standard compounds (mangiferin, swertiamarin, and amarogentin), mangiferin showed α-glucosidase and 2,2-diphenyl-1-picrylhydrazyl radical inhibitory activity indicating anti-hyperglycemia potential.

Phytochemical and antioxidant-related investigations on bark of Abies spectabilis (D. Don) Spach. from Nepal.

The bark of several coniferous species, a waste product of the timber industry, contains significant amounts of natural antioxidants. In our ongoing studies of Nepalese medicinal plants, we examined the bark from Abies spectabilis as the starting material for extracting antioxidant compounds. In vitro antioxidant activity evaluated by means of three antioxidant methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH), Briggs-Rauscher oscillating reaction (BR) and Trolox Equivalent Antioxidant Capacity (TEAC) and total phenol contents with the Folin-Ciocalteau reagent; the ferrous iron chelating capacity was also assessed. The methanol extract of A. spectabilis showed significant antioxidant activity and polyphenol contents (IC(50) 4.13 µg/mL, 0.20 µg/mL eq. resorcinol, 4.22 mM eq. Trolox, 3.9 µg/g eq. gallic Acid in the DPPH, BR, TEAC and Folin-Ciocalteau tests, respectively) and weak Fe(2+) chelating capacity. Phytochemical studies were also carried out with 1D- and 2D NMR experiments and DI-ESI-MS, HPLC-DAD and LC-MSn measurements. Oligomeric C-type proanthocyanidins, mainly trimeric gallocatechin derivatives, were the most abundant compounds (16% of extract expressed as procyanindin B1). Gallocatechin oligomers (up to six units) and prodelphynidin-gallocatechin polymers were also identified in the extract. Prodelphynidin B4, cyclograndisolide and trans-docosanil ferulate were also isolated and characterized by NMR and MS spectroscopy.

In Vitro Antibacterial Activities of Methanolic Extracts of Fruits, Seeds, and Bark of Zanthoxylum armatum DC.

Crude methanol extracts of fruits, seeds, and bark of Zanthoxylum armatum were investigated in vitro for antimicrobial activities against 9 different bacterial strains: Bacillus subtilis, Enterococcus faecalis, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus epidermidis using agar well diffusion method, and the MBC values were determined. Only 5 bacteria, i.e., Bacillus subtilis, Enterococcus faecalis, MRSA, Staphylococcus aureus, and Staphylococcus epidermidis exhibited antibacterial properties against the different extracts. The fruit and seed extracts showed activities against 5 bacteria, while the bark extract was active against 2 bacteria only (MRSA and Staphylococcus aureus). Staphylococcus aureus was found to be more susceptible for all the extracts compared to other strains. The maximum ZOI of 20.72 mm was produced by fruits (wild) and 18.10 mm (cultivated) against Staphylococcus aureus. Likewise, the least ZOI of 11.73 mm was produced by seeds (wild) and 11.29 mm (cultivated) against Escherichia faecalis. Similarly, the lowest MBC value of 0.78 mg/mL was obtained for fruit extracts against MRSA, 1.56 mg/mL for fruits, seeds, and bark extracts against Bacillus subtilis, MRSA, and Staphylococcus aureus, and highest value of 50 mg/mL for fruits and seeds extracts against S. epidermidis. The fruits, seeds, and bark extracts of Z. armatum exhibited remarkable antibacterial properties against different pathogenic bacteria causing several diseases, which suggests the potential use of this plant for treating different bacterial diseases such as skin infection, urinary tract infection, dental problems, diarrhea, and dysentery.

Zanthoxylum armatum DC.: Current knowledge, gaps and opportunities in Nepal.

ETHNOPHARMACOLOGICAL RELEVANCE: Zanthoxylum armatum DC. possesses several medicinal properties and has been commonly used in different indigenous medicinal practices to cure several diseases because of its stomachic, carminative and anthelmintic properties. AIM: This review paper aims to provide an update on and analysis of information about the ecology, uses, phytochemistry, pharmacology, trade opportunities, policy gaps for the commercialization of this species forming a basis for further scientific innovations MATERIALS AND METHODS: Information was gathered through a search of different books, journals, articles, annual reports, proceedings and web-based materials. RESULT: Alkaloids, sterols, phenolics, lignins coumarins, terpenoids and flavonoids have been identified from leaves, fruits, stem, bark and seeds. Its trade value is also very high with its manifold applications in Ayurveda, allopathy, general pharmacy, and other industries. Antimicrobial, antiviral, antioxidant, anti-inflammatory, cytotoxic, hepato-protective, insecticidal/larvicidal effects are of particular relevance. CONCLUSION: It is one of the prioritized medicinal plants for economic development in Nepal. Owing to its diverse applications, the species can be developed as an important commodity for alleviation of poverty in rural areas. The various ethno-pharmacological applications of Zanthoxylum armatum have been verified by several related researches. More extensive study on the individual specific phyto-component can lead to novel innovations for the well-being of mankind.

New flavonoid glycosides from Aconitum naviculare (Brühl) Stapf, a medicinal herb from the trans-Himalayan region of Nepal.

Three new flavonoid glycosides, 3-O-[beta-D-glucopyranosyl-(1-->3)-(4-O-trans-p-coumaroyl)-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranosyl]-7-O-[beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl]kaempferol, 3-O-[beta-D-glucopyranosyl-(1-->3)-(4-O-trans-p-coumaroyl)-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranosyl]-7-O-[beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl]quercetin and 7-O-[beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl]quercetin were isolated from the aqueous extract of the aerial parts of Aconitum naviculare. Their structures were elucidated by spectral analysis (HRAPI-TOF MS, 1H, 13C NMR, HMQC, HMBC, DFQ-COSY, ROESY and TOCSY).

Triterpene derivatives from Abies spectabilis leaves of Nepalese origin.

Our ongoing studies of Nepalese medicinal plants has led to the isolation and characterization of five new triterpenes, two known triterpenes and two phenolic derivatives from Abies spectabilis (D.Don) Mirb leaves grown in the high mountain. The structures of the isolated compounds were characterized by means of 1D and 2D NMR spectroscopic and MS techniques.

Two phenolic glycosides from Curculigo orchioides Gaertn.

One new glycoside derivative from syringic acid and one new phenol glycoside, curculigoside E (1) and orchioside D (2), were isolated and characterized from the rootstock of Curculigo orchioides collected in the Nawalparasi District (Nepal). The structures of the new isolated compounds were elucidated by means of spectroscopic methods such as 1D, 2D NMR and MS.