This study aimed to assess the optimal conditions for the extraction of chlorophyll and the stability of chlorophyll with postharvest storage period in Moringa Oleifera leaves harvested in 3 different years for its preservation and lifespan. For this purpose, chlorophylls a (Chla) and b (Chlb) were extracted from the leaves using acetone, methanol, N, N-dimethylformamide (DMF), and the ‘green’ solvent (ethanol). In addition, the chlorophylls were extracted under various conditions, including temperatures (4, 25, and 45 °C), and times (10, 30, and 60 min) from dry leaves that were harvested in different years (2020, 2021, and 2022). The results showed that the Chla content extracted exceeded that of Chlb in the four solvents in all temperatures and extraction times, except for acetone and ethanol extracts under 45 °C at 30 and 60-min extraction times in samples harvested in 2022. An increase in extraction time and temperature resulted in higher chlorophyll content. Overall chlorophyll content decreased with the increasing postharvest storage period, particularly in methanol and ethanol extracts. The Chlorophyll Stability Index showed that chlorophyll is stable in moringa, such that the chlorophyll content obtained in a 2-year postharvest storage period samples was also found to be high. In general, the chlorophyll obtained from this study was found to be compatible with what is used in the industrial market. This suggests that the chlorophyll from moringa is stable and can be considered a major source of chlorophyll.

Portulacaria afra, is indigenous to South Africa and has been identified to have several medicinal properties according to traditional knowledge and few studies. The drive around this research is to evaluate the medicinal properties of the leaves, stems and for the first time the roots extracts of Portulacaria afra, using four solvents with different polarities. The aqueous (60°C), methanol, n-hexane and ethyl acetate whole plant extracts of P. afra were investigated for their phytochemical properties, antimicrobial and antioxidant activity. The phytochemical screening revealed that the methanolic and aqueous extracts of the leaves displayed high presence of secondary metabolites compared to n-hexane and ethyl acetate extracts. The methanolic leaves extracts showed strong presence of quinones, phenols, steroid and coumarins while the aqueous leaves extracts contained a moderate presence of saponins, terpenoids, quinones and coumarins. Ethyl acetate leaves extracts revealed a strong presence of tannins, moderate presence of phytosteroids and a low presence of volatile oil. Meanwhile, the leaves extracts with n-hexane showed a considerable amount of saponins with a moderate presence, and a low presence of tannins, volatile oils and terpenoids. The methanolic stems extracts displayed the most significant presence of secondary metabolites, showing a high presence of terpenoids, steroids, phenols and coumarins. The aqueous stems extracts showed a strong presence of glycosides with a moderate presence of saponins. However, ethyl acetate and n-hexane stems extracts displayed a few secondary metabolites with their concentration ranging from medium to low. The ethyl acetate roots extracts displayed a significant elevated amount of quinones with a strong presence. n-hexane roots extracts showed a moderate presence of volatile oil and a low presence of tannins and steroids. Methanolic roots extracts showed a moderate presence of coumarins and glycosides while aqueous roots extracts showed a low presence of glycosides. The overall highest total phenolics contents (TPCs) and total flavonoids contents (TFCs) in all the plant parts, were found to be in the methanol stems extracts and aqueous roots extracts respectively. Next to the methanol leaves and aqueous leaves extracts respectively. However, in the root’s extracts, the aqueous extracts showed the highest total phenolics content while the water extracts had the highest total flavonoids contents. The antimicrobial activities of P. afra whole plant extracts with the various four solvents were tested against three microorganisms Escherichia coli, Staphylococcus aureus and Streptomyces griseus using agar-well diffusion method. The Antimicrobial activity of the n-hexane extracts of the leaves, stems and roots of P. afra presented a wide range of inhibition against all the test microorganisms, ethyl acetate leaves extract showed a considerable effect against Staphylococcus aureus while the methanolic extracts were not active. Aqueous roots extracts demonstrated a strong antimicrobial activity against Staphylococcus aureus while the other extracts were not active. The zones of inhibition ranged from 13 to 24 mm for the plant extracts. The antioxidant activity potential of the aqueous, methanol, n-hexane and ethyl acetate extracts of P. afra leaves, stems and roots extracts were observed through a 2, 2 diphenylpicryhydrazyl (DPPH) free radical assay, hydrogen peroxide scavenging (H₂O₂) and metal chelating activity assay. Ethyl acetate roots extracts exhibited the strongest hydrogen peroxide scavenging activity compared to the other extracts. Meanwhile, aqueous stems extracts showed the highest antioxidant activity against DPPH radical. Aqueous and n-hexane roots extracts displayed the strongest metal chelating ability. These findings reveal the efficacy of the use of several solvents with different polarities for effective and more accurate extraction of various compounds and indicate that the antimicrobial and antioxidant activity of P. afra parts are dependent on the solvent extracts.

Bulbine abyssinica is a succulent medicinal plant indigenous to South Africa. The species has been commonly used traditionally by indigenous people for the treatment of various skin related ailments as well as the management of diabetes mellitus. To date, limited studies have been conducted on the underground stems and roots, as well as comparative analyses across the different plant parts of the species. Methanolic extracts of B. abyssinica leaves, underground stems and roots were used to perform phytochemical screening, quantitative phytochemical analyses, antioxidant and antibacterial assays. The leaves contained most of the phytochemical groups tested, as well as higher total phenolic (1841.7 ± 4.8 mg/100g GAE), total flavonoid (809.2 ± 75.6 mg/100g QE), total tannin (2850 ± 70.01 mg/100g GAE) and total proanthocyanidin (636.67 ± 1.67 mg/100g CE) contents compared to the underground stems and roots. The antioxidant activity results showed that the roots exhibited the strongest scavenging power against 2, 2 diphenylpicryhydrazyl (DPPH) (0.105 ± 0.01 mg/ml), whereas the leaves showed a higher antioxidant power against hydrogen peroxide (0.66 ± 0.07 mg/ml) and metal chelating radicals (2.68 ± 0.16 mg/ml). All three plant parts showed intermediate zones of inhibition (10 - 19 mm) against Staphylococcus aureus and Escherichia coli. The current study validates the use of different plant parts of B. abyssinica in the traditional medicine context, and suggests the plant’s potential application in the pharmaceutical and cosmetic industries.

Introduction: Bulbine natalensis is a succulent plant native to South Africa, used to treat various skin conditions. The purpose of this investigation was to analyse the phytochemical content, as well as antioxidant and antibacterial activities of various parts of B. natalensis. Methods: Phytochemical screening tests were performed to investigate the presence of ten compounds from B. natalensis methanol extract. Total phenolic, flavonoid, tannin, and proanthocyanidin content assays were followed to determine their concentrations in B. natalensis. The 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide (H2 O2 ), and iron chelating assays were used to assess the antioxidant activity. To determine the antibacterial properties of B. natalensis against Staphylococcus aureus and Escherichia coli, the agar-well diffusion method was adopted. Results: The phytochemical screening revealed more compounds present in the leaves. The underground stems yielded higher concentrations of total phenolics (1909.2 ± 4.8 mg gallic acid equivalent [GAE]/g), total flavonoids (259.7 ± 27.2 mg quercetin equivalent [QE]/g), and total proanthocyanidins (858.3 ± 1.7 mg catechin equivalent [CE]/g) in comparison to the leaves and roots. The roots showed stronger DPPH (0.36 ± 0.02 mg/mL) and H2 O2 (0.24 ± 0.04 mg/mL) scavenging activities. Only the underground stems and roots showed inhibition against S. aureus with the values of 15.33 ± 0.67 mm and 15.67 ± 0.33 mm, respectively, whereas the leaves displayed the highest inhibition against E. coli (18.33 ± 0.88 mm). Conclusion: The methanolic extracts of B. natalensis leaves, underground stems, and roots possess significant phytochemical content, in conjunction with antioxidant and antibacterial activities.

Extreme changes in climate, especially in temperature, could have implications for herbal plants in various world regions. Medicinal plants often produce a wide variety of natural phytochemicals to enhance their defence and survival mechanisms against harsh environmental conditions, and when these mechanisms fail, plants consequently die. We investigated the impact of high temperatures coupled with the specific duration of exposure on the yield and composition of essential oils and trichomes in leaves of Lippia javanica. Plants were exposed to increasing temperatures (25 °C to 47 °C) for different durations (48 h to 144 h). Response surface methodology was applied to assess the interaction between temperature and length of exposure on the essential oil yield, trichome length, and trichome diameter. Essential oils were recovered from the control and treated leaf samples using hydrodistillation and volatile compounds were identified through gas chromatography–mass spectrometry (GC-MS). Multivariate analysis modelling allowed different clustering patterns to be detected. That is, increasing temperatures raised the oil yield, trichome length, and diameter from 1.007 mg/100 g to 3.58 mg/100 g, 50 µm to 160 µm, and 25 µm to 60 µm, respectively. Significant chemical differences between the essential oils were confirmed by the principal component and orthogonal projections to latent structures, which identified separate clusters for the control and treated samples. The current findings indicate that L. javanica has coping mechanisms against high temperatures.Significance: High temperatures significantly alter the trichome morphology and secretion of essential oils in L. javanica, which adversely affects the shrub’s medicinal properties. Regardless of climate change, this finding could have major implications for indigenous people who continue to use the shrub for therapeutic purposes. L. javanica showed coping mechanisms against high temperatures for a maximum of six days; however, a prolonged exposure would be more detrimental. As a result, climate change will negatively influence the plant’s developmental and defence mechanisms.

There is a global concern that rising atmospheric CO2 concentrations may impact the medicinal or nutritional properties of medicinal plants. Portulacaria afra is a South African medicinal plant that is used by traditional healers to treat various skin conditions. The aim of this study was to determine whether elevated CO2 concentrations would affect the medicinal properties of the leaves of P. afra. This was achieved by comparing the phytochemical presence, antioxidant and antimicrobial activity of the leaves of P. afra which were exposed to ambient (420 ppm) and elevated (600 ppm) CO2 concentrations of plants grown in greenhouse conditions. The results revealed that leaf samples that were exposed to elevated CO2 concentrations exhibited a significant increase in flavonoid presence, compared to the control group. The antioxidant activity of the leaves of P. afra (DPPH activity) remained mostly unchanged in the samples that were exposed to elevated CO2 concentrations. The antimicrobial activity efficacy against Cutibacterium acnes increased with increasing global atmospheric CO2 concentration. These findings suggest that P. afra is a resilient medicinal plant and that its leaves may continue to provide relief against certain ailments, despite rising atmospheric CO2 concentrations. Significance: Portulacaria afra is a South African medicinally important species that shows great resilience against elevated CO2 concentrations. It is important to anticipate how changing environmental factors, such as rising CO2 concentrations, may affect natural resources. The phytochemical profile and antioxidant and antimicrobial activities of the various plant parts either remained the same or increased after exposure to an elevated CO2 concentration of 600 ppm.