Background: Herbal drug delivery is limited by poor solubility and bioavailability which can be overcome with suitable nanomaterials that will enhance their pharmacokinetics and performance. Objective: This study aimed to analyze the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from three spices. Materials and Methods: AgNPs were prepared using 0.1 M silver nitrate and aqueous extracts of Allium sativum L. (garlic), Zingiber officinale Rosc. (ginger), and Capsicum frutescens L. (cayenne pepper). The AgNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Results: The AgNPs were formed within an hour of the reaction and showed maximum UV-Vis absorption in the 375–480 nm range. SEM and TEM revealed well-dispersed spherical particles with little agglomeration, average sizes of 3–6 nm, 3–22 nm, and 3–18 nm for garlic, ginger, and cayenne pepper, respectively. FTIR showed that amine, protein, phenolic, aromatic, and alkynes groups contributed to AgNP synthesis and XRD confirmed their crystalline and face-centered cubic nature. Antibacterial action of the AgNPs was in the following order: ginger (minimum inhibitory concentration [MIC] garlic> cayenne pepper (MIC 125 μg/mL). Antioxidant action showed cayenne pepper > ginger > garlic (inhibitory concentration 50% [IC50]: 40, 240, and 250 μg/mL, respectively) against 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and garlic > cayenne pepper > ginger (IC50: <31.25, 40, and 120 μg/mL, respectively) against 1,1-diphenyl-2-picrylhydrazyl. Conclusion: Optimization of this green synthesis would support the production of AgNPs with great therapeutic potentials. Abbreviations used: AgNPs: Silver nanoparticles; UV-Vis: ultraviolet-visible; SEM: Scanning electron microscopy; TEM: Transmission electron microscopy; EDX: Energy dispersive X-ray; XRD: X-ray diffraction; FTIR: Fourier transform infrared; GaNPs: Garlic nanoparticles; GiNPs: Ginger nanoparticles; C.PeNPs: Cayenne pepper nanoparticles; FCC: Face centred cubic; SPR: Surface Plasmon resonance; ABTS-2: 2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid); DPPH-1: 1-diphenyl-2-picrylhydrazyl.

The use of medicinal plants for the management of diabetes mellitus is on the rise in the developing countries, including South Africa. There is increasing scientific evidence that supports the claims by the traditional healers. In this review, we compare the families of previously reported anti-diabetic plants in the Eastern Cape by rating the anti-diabetic activity, mode of action and also highlight their therapeutic potentials based on the available evidence on their pharmacology and toxicity. Forty-five plants mentioned in ethnobotanical surveys were subjected to a comprehensive literature search in the available electronic databases such as PubMed, ScienceDirect, Google Scholar and Elsevier, by using “plant name” and “family” as the keywords for the primary searches to determine the plants that have been scientifically investigated for anti-diabetic activity. The search returned 25 families with Asteraceae highly reported, followed by Asphodelaceae and Alliaceae. Most of the plants have been studied for their anti-diabetic potentials in vivo and/or in vitro, with most of the plants having a higher percentage of insulin release and inhibition against carbohydrate digesting enzymes as compared with insulin mimetic and peripheral glucose uptake. Almost all the investigated plants also inhibit oxidative stress as part of their hypoglycemic activity with less toxicity. However, the isolation of their bioactive molecules is still lacking. This review provides a resource to enable thorough assessments of the therapeutic profiles of available medicinal plants used for the management of diabetes in the Eastern Cape, South Africa. Further studies such as the identification of the active ingredients of potent plants still need to be carried out; this may lead to new molecules in drug discovery and development.

The incidence of diabetes is on the rise and one of the medically active plants used for the treatment of diabetes in South Africa is Lauridia tetragona. The aim of this study is to investigate the antidiabetic property of the polyphenolics (PP) compounds isolated from the methanolic extract of Lauridia tetragona. The α-amylase, α-glucosidase, dipeptidyl peptidase IV (DPPIV), lipase inhibitory activities, and glucose uptake in HepG2 were investigated. The methanolic extract fractions of L. tetragona yielded six fractions (PP1–PP6) all of which showed weak inhibition against DPPIV and lipase compared to the standards. However, PP4 and PP6 showed the best inhibition against α-amylase (IC₅₀ of 359.3 ± 2.11 and 416.82 ± 2.58 μg/mL, respectively) and α-glucosidase (IC₅₀ of 95.93 ± 2.34 and 104.49 ± 2.21 μg/mL, respectively) and only PP4 (173.6%) resulted in enhanced glucose uptake in HepG2 cells compared to berberine (129.89%) and metformin (187.16%) used as positive controls. The previous investigation on PP4 and PP6 showed the presence of polyphenolics such as ferulic acid, coumaric acid, and caffeic acid. The results of this study suggest that L. tetragona could be suitable as an antidiabetic agent and justifies the folkloric use of the plant to treat diabetes.

Lippia alba, commonly known as Bushy Matgrassis a well-known traditional herb. Besides being used as a food supplement, for seasoning and as a drink, this plant species possess several pharmacological properties, allowing its use in folk medicines to treat various diseases, especially those related to digestive and respiratory conditions. These properties are mainly attributed to the presence of compounds such as myrcene, linalool, β-ocimene, α-guaiene, germacrene, carvone, limonene, eucalyptol, camphor, caryophyllene, neral, geranial and piperitone in the essential oils of L. alba. Variation in essential oil components and the high phenotypical plasticity of L. alba provide a strong evidence of an exciting high number of chemotypes in this aromatic herb. In the current review, we report the botanical, geographical and ecological features of L. alba. In addition, chemical composition of essential oil is addressed followed by in vitro and high efficiency micropropagation protocols. Finally, the therapeutic potential of L. alba against important non-communicable diseases is discussed.

Background: The cytotoxic properties of nanoparticles have attracted a great deal of attention in the field of nanoscience and nanotechnology due to their small size and ability to penetrate cellular membranes. Methods: The silver nanoparticles were synthesized using Elaeodendron croceum stem bark and characterized. The oral acute toxicity studies were carried out by administration of 500, 1000, 2000 mg/kg body weight to Wister rats in respective groups. An in vitro cytotoxicity assay was evaluated in MDA-MB-231 breast cancer cells using the WST-1 Cell Proliferation assay. The percentage of cell viability after treatment with aqueous extracts of Elaeodendron croceum (ECE) and Elaeodendron croceum silver nanoparticles (ECAgNPs) was compared with that of paclitaxel. Results: The in vivo studies revealed that the LD ₅₀ was higher than 2000 mg/kg and there was no significant difference (p>0.05) between the treatment groups compared with the control group for mean organ-to-body weight ratio except in the liver and in all hematological parameters except WBC and hematocrit. Similarly, there was no significant difference (p>0.05) for serum electrolytes (Na ⁺ , Mg ²⁺ K ⁺ , Cl ⁻ , and Ca ²⁺ ), total protein, urea, ɣ-glutamyl transferase (GGT), Aspartate aminotransferase (AST), Alkaline phosphatase (ALP), Alanine aminotransferase (ALT), albumin, total and conjugated bilirubin between the treatment and the control group. However, there were changes in creatinine, urea, and cholesterol. In the in vitro assays, ECE and ECAgNPs showed IC ₅₀ values of 70.87±2.99 and 138.8±3.98 µg/mL respectively against MDA-MB-231 cells compared to paclitaxel, which showed an IC ₅₀ value of 80 ng/mL. Conclusion: The results showed that the LD ₅₀ of the ECE and ECAgNPs in Wister rats was determined to be greater than 2000 mg/kg body weight. The aqueous extract also showed more cytotoxic than the ECAgNPs suggesting that the toxic compounds in aqueous extract were involved in the capping of the AgNPs.

Objective: The bulb of Albuca bracteata Jacq., and Albuca setosa commonly used in Eastern Cape Province of South Africa for the treatment of several types of disease conditions including diabetes, was investigated for their phytochemical contents and antioxidant activities. Methods: The antioxidant activity was determined by evaluating the effect of various solvent extracts (acetone, methanol, ethanol and water) on 2,2 – diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, 2,2′ – azino-bis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS), ferric reducing power, hydrogen peroxide and nitric oxide scavenging activity while the various extracts were also analysed for phytochemical their contents. Results: The results obtained indicate that polyphenols, proanthocyanidins, saponins and alkaloids are present in higher concentrations. The composition of phenols (117 mg/g), flavonols (26.28 mg/g), proanthocyanidins (84.85 mg/g) and flavonoids (5.36 mg/g) were significantly higher in the acetone extract while saponin and alkaloids contents were higher in the aqueous extract. Antioxidant studies of the extracts for nitric oxide, hydrogen peroxide, ABTS and DPPH showed high antioxidant potential in a concentration-dependent manner that was not significantly different from Vitamin C, BHT and Rutin used as standard references. The methanol extract showed higher ferric reducing potential compared to the aqueous extract but was significantly different from Vitamin C, BHT and Rutin. Conclusion: This implies that the bulb of Albuca bracteata may serve as a natural source of antioxidants, which together with the numerous phytochemicals present, could account for its folkloric use as a medicinal plant