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The global pandemic of COVID‐19 began in December 2019 and is still continuing. The past 2 years have seen the emergence of several variants that were more vicious than each other. The emergence of Omicron (B.1.1.529) proved to be a huge epidemiological concern as the rate of infection of this particular strain was enormous. The strain was identified in South Africa on November 24, 2021 and was classified as a "Variant of Concern" on November 26, 2021. The Omicron variant possessed mutations in the key RBD region, the S region, thereby increasing the affinity of ACE2 for better transmission of the virus. Antibody resistance was found in this variant and it was able to reduce vaccine efficiency of vaccines. The need for a booster vaccine was brought forth due to the prevalence of the Omicron variant and, subsequently, this led to targeted research and development of variant‐specific vaccines and booster dosage. This review discusses broadly the genomic characters and features of Omicron along with its specific mutations, evolution, antibody resistance, and evasion, utilization of CRISPR‐Cas12a assay for Omicron detection, T‐cell immunity elicited by vaccines against Omicron, and strategies to decrease Omicron infection along with COVID‐19 and it also discusses on XE recombinant variant and on infectivity of BA.2 subvariant of Omicron. [ABSTRACT FROM AUTHOR]

• Erigeron bonariensis (EB) or Conyza bonariensis is an endangered species of South Africa. • EB contains quercetin, naringenin, stigmasterol, apigenin, baicalein, rutin, luteolin and caffeic acid. • An RP- HPLC method was developed to identify and estimate quercetin in EB extract. • The method was validated as per ICHQ2 R1 guidelines. • Developed RP-HPLC method was found linear, accurate, precise and reproducible. Erigeron bonariensis Linn (EB) is a species of Erigeron , belonging to Asteraceae. It found throughout the tropics and subtropics as a pioneer plant ; its precise origin is unknown, but most likely it stems from Central America or South America. It has become naturalized in many other regions, including North America , Europe and Australia. In South Africa, this plant is well known as Conyza bonariensis and listed under "Red List of South African Plants". Its extract contains many bioactives such as quercetin, naringenin, stigmasterol, apigenin, baicalein, rutin, luteolin and caffeic acid. These have good therapeutic potential. Among them, quercetin (QUE) is widely found in EB's extract. In this current research, QUE was successfully detected in EB extract utilising a gradient reverse phase high performance liquid chromatography (RP- HPLC) method. The method was developed and validated using a C18 column (250 mm length x 4.5 mm internal diameter). The mobile phase used was methanol and water. A flow rate of 1 mL/min was used during the elution. Initially the water-to-methanol ratio at 75:25 v/v (water: methanol) for 3 min, then at 50:50 v/v (water: methanol) for 3–7 min, then at 50:50 v/v (water: methanol) for 10–15 min, and lastly at 10:90 v/v (water: methanol) for 20 min, to achieve the best elution. The developed analytical technique was validated in terms of linearity, LOD, LOQ, recovery, precision, and specificity using ICH Q2 R1 guidelines. The amount of QUE in EB was determined and reported by us for the first time. The extraction was carried out using 970 g of whole plant powder, was macerated in 4 L of hydroethanol (50: 50 v/v) and was concentrated under vacuum. The percentage yield was found to be 5.5% w/w (2.75 g/55 g of EB extract) and HPLC method was developed using sample concentration of 60 mg/100 mL (600 µg/mL) in methanol and retention time (RT) of the standard and QUE in extract was found to be 15.3 and 15.7 min, respectively. The linearity, correlation coefficient, limit of detection (LOD), limit of quantification (LOQ), and RSD were found to be 200–1000 µg/mL, 0.9991, 35.66 µg/mL, 108.18 µg/mL, and smaller than 1 % respectively indicating the developed method was precise. Hence the current research laid a platform to identify the important drug leads like QUE (1% w/w) and further research targeting the phytochemical and biological exploration is in progress. The current analytical investigation was successful in phytochemical fingerprint and quantification of QUE in EB. [ABSTRACT FROM AUTHOR]

• Erigeron bonariensis (EB) L. (Conyza bonariensis L.) is endangered plant of south africa. • Quercetin, stigmasterol and caffeic acid are the major secondary metabolites present in EB. • EB extract possesses antimicrobial, anti-aging, anti-oxidant and anti-cancer activities. Hairy Fleabane, or Erigeron bonariensis var. microcephala Cabrera (EB), is a fast-growing annual or biennial weed in the Asteraceae family that blooms in the summer. Although it is originated in the southern part of the continent, this weed can now be found all over Asia and Africa. There exists limited information on phytochemistry and biological potential of this weed. According to the few available ethnomedicinal reports, the tea made from EB's part have been used as diuretics, hemostatic agents, and anti-diarrheal agents. This weed is reported to possess antioxidant, antibacterial, and anti-inflammatory properties. As per the available literature, quercetin, naringenin, stigmasterol, apigenin, baicalein, rutin, luteolin and caffeic acid are the prime constituents present in various parts of EB. No comprehensive studies or systematic reviews have yet been conducted to highlight the traditional values, biological and phytochemical values of this weed. Hence, there is a need to conduct more study for better understanding of this medicinal weed, particularly with regards to its isolation and pharmacological screening of its isolates for various biological activities. This review has been aimed to compile up-to-date information regarding the presence of phytochemicals in relation to their ethno medicinal uses, extraction processes, pharmacological uses and future prospects of EB. [ABSTRACT FROM AUTHOR]