Anthelmintic A-Type Procyanidins and Further Characterization of the Phenolic Composition of a Root Extract from Paullinia pinnata

Anthelmintic Agents from African Medicinal Plants: Review and Prospects

Soil-transmitted helminthiasis affects more than 1.5 billion people globally and largely remains a sanitary problem in Africa. These infections place a huge economic burden on poor countries and affect livestock production, causing substantial economic losses and poor animal health. The emergence of anthelmintic resistance, especially in livestock, and the potential for its widespread in humans create a need for the development of alternative therapies. Medicinal plants play a significant role in the management of parasitic diseases in humans and livestock, especially in Africa. This report reviews anthelmintic studies that have been conducted on medicinal plants growing in Africa and published within the past two decades. A search was made in various electronic databases, and only full articles in English were included in the review. Reports show that aqueous and hydroalcoholic extracts and polar fractions obtained from these crude extracts form the predominant (80%) form of the extracts studied. Medicinal plants, extracts, and compounds with different chemical groups have been studied for their anthelmintic potential. Polyphenols and terpenoids are the most reported groups. More than 64% of the studies employed in vitro assays against parasitic and nonparasitic nematode models. Egg hatch inhibition, larval migration inhibition, and paralysis are the common parameters assessed in vitro. About 72% of in vivo models involved small ruminants, 15% rodents, and 5% chicken. Egg and worm burden are the main factors assessed in vivo. There were no reports on interventions in humans cited within the period under consideration. Also, few reports have investigated the potential of combining plant extracts with common anthelmintic drugs. This review reveals the huge potential of African medicinal plants as sources of anthelmintic agents and the dire need for in-depth clinical studies of extracts, fractions, and compounds from African plants as anthelmintic agents in livestock, companion animals, and humans.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

Bioactive constituents from the leaves of Metapanax delavayi with anti-benign prostatic hyperplasia activities

In the course of our continuing search for biologically active compounds from medicinal sources, we further investigated the aqueous extract of Metapanax delavayi (Franch.) J. Wen & Frodin (Araliaceae) leaves. Five undescribed terpene glycosides, liangwanosides B-F referring to two megastigmane glycosides, one monoterpene glycoside, and two sesquiterpene glycosides, together with seven known compounds were isolated. Their chemical structures were elucidated by detailed spectroscopy (1D/2D NMR), HRESIMS data analysis, hydrolysis, and comparison of experimental and calculated electronic circular dichroism (ECD) data. The biological evaluation of benign prostate hyperplasia (BPH) inhibition revealed that some compounds, including liangwanosides B-D, benzyl-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranoside, methyl 2-O-β-D-glucopyranosylbenzoate, and 3,4-dihydroxybenzaldehyde, exhibited moderate inhibitory activity against BPH-1 cells with inhibition rates ranging from 13.8% to 23.8% at 100 μM. Among them, liangwanoside B showed the comparable effect to positive control (finasteride) at 100 μM, and its possible mechanism was then explored by molecular docking studies.

Triterpenoid saponins and others glycosides from the stem barks of Pancovia turbinata Radlk

In our continuing search of saponins from the plant of Sapindaceae family, phytochemical investigation of the stem barks of Pancovia turbinata Radlk., led to the isolation and structural characterization of two new triterpenoid saponins, named turbinatosides A-B (1-2), one new farnesyl glycoside, named turbinoside A (3), one new coumarin glucoside, named panturboside A (4), together with a known saponin (5). The structures of the new compounds were established, using extensive analysis of NMR techniques, mainly 1D NMR (¹H, ¹³C, and DEPT) and 2D NMR (COSY, NOESY, HSQC, HSQC-TOCSY and HMBC) experiments, HRESIMS and by comparison with the literature data, as 3-O-β-d-xylopyranosyl-(1 → 3)-α-l-arabinopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosylhederagenin 28-O-β-d-glucopyranosyl ester (1), 3-O-α-l-arabinopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosylhederagenin 28-O-β-d-xylopyranosyl-(1 → 4)-β-d-glucopyranosyl ester (2), 1-O-{β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranosyl}-(2E,6E)-farnes-1,12-diol (3), and 5-O-β-d-glucopyranosyl-5,6,7-trihydroxy-8-methoxycoumarin (4), respectively. Our findings highlight the presence of -³Rha-²Ara-³hederagenin oligosaccharidic sequence usually described in saponins from Sapindoideae subfamily of Sapindaceae family, as well as farnesol glycosides, and represent therefore a valuable contribution to the chemotaxonomy of the Sapindoideae subfamily.

Plant genomics in Africa: present and prospects

Plants are the world's most consumed goods. They are of high economic value and bring many health benefits. In most countries in Africa, the supply and quality of food will rise to meet the growing population's increasing demand. Genomics and other biotechnology tools offer the opportunity to improve subsistence crops and medicinal herbs in the continent. Significant advances have been made in plant genomics, which have enhanced our knowledge of the molecular processes underlying both plant quality and yield. The sequencing of complex genomes of African plant species, facilitated by the continuously evolving next-generation sequencing technologies and advanced bioinformatics approaches, has provided new opportunities for crop improvement. This review summarizes the achievements of genome sequencing projects of endemic African plants in the last two decades. We also present perspectives and challenges for future plant genomic studies that will accelerate important plant breeding programs for African communities. These challenges include a lack of basic facilities, a lack of sequencing and bioinformatics facilities, and a lack of skills to design genomics studies. However, it is imperative to state that African countries have become key players in the plant genome revolution and genome derived-biotechnology. Therefore, African governments should invest in public plant genomics research and applications, establish bioinformatics platforms and training programs, and stimulate university and industry partnerships to fully deploy plant genomics, particularly in the fields of agriculture and medicine.